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Maps of Time by David Christian - Samantha_Kathy tutoring sjmccreary

75 Books Challenge for 2012

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1sjmccreary
Edited: Mar 17, 2012, 9:40pm Top

I've been looking forward to this book for a long time. So excited, in fact, that I just couldn't wait until March to begin, as Samantha and I had originally agreed. The plan, such as it is, it to do about one chapter per week.

Books picked by Samantha from Christian's suggested reading lists:

3/12/12: Chapter one - The First 300,000 Years
Primal Myths by Barbara C Sproul
The Universe in a Nutshell by Stephen Hawking
Life of the Cosmos by Lee Smolin

2sjmccreary
Feb 20, 2012, 12:30am Top



Maps of Time: An Introduction to Big History
by David Christian
foreword by William H McNeill

Previewing the book: Table of Contents.. There are 15 chapters, divided into 6 parts. These are preceded by lists of illustrations and tables, the foreword by McNeill, and acknowledgments and an introduction by Christian. At the end of the book come 2 appendices, notes, a bibliography, and an index.

The list of illustrations runs 2-1/2 pages including timelines, maps (yay!), and figures. Another page and a half of tables is listed (which looks more like economics than either science or history – “long-term trends in urbanization”, “total industrial potential”, “gross national income per capita” – this is surprising).

Then comes the foreword. William H McNeill sounds vaguely familiar. Who is he, and why should I care what he thinks about this book? Normally, I skip these things, but this one is only 4 pages so I may go ahead and read it.

The author’s acknowledgments look like he is giving a shout out to everyone he’s ever met. I might skip this.

“Introduction: A modern creation myth?” I don’t normally read introductions that are written by someone else, but this is from the author, so I will read it. It runs 14 pages and looks like he is attempting to explain the “whys” and “hows” of the book. It concludes with a 3-page bibliography. Skimming this, I recognize a few authors - William H McNeill is here – and only a couple of titles. I’m pretty sure I’ve never read, or even attempted, anything on this list. Is there anything here that you would consider mandatory reading?

I’ll go and read these sections, then come back with comments and questions, if any, before moving on to chapter 1.

3Samantha_kathy
Edited: Feb 20, 2012, 6:53am Top

Found you!

I read the foreword and it explains how Big History came about, what it is and why the author is the man to write a book about it. It's not long and the information is - in my opinion - a helpful introduction to the way the book works. I'd recommend reading it.

Edited to add: I'll await your questions :D

4Samantha_kathy
Feb 20, 2012, 8:27am Top

One other suggestion before you really start to delve in the book. Many (if not all) of the ideas in this book build on the previous ideas mentioned. So if you get lost at one point in the book, you will continue to be lost or get even more lost.

It's therefore in my opinion a good idea that if you have a lot of questions in a chapter that you ask before you read on. Because even within a chapter you can get lost pretty fast. The chapters are often subdivided into smaller parts, so my suggestion would be to ask your questions in smaller parts as well. For instance, chapter 1 The First 300,000 years begins with The problem of beginnings (page 17-21). If you have any questions about that part, I would ask them before going on to read the next part of chapter 1 (Early scientific accounts of the universe)

Of course, this is only a suggestion - feel free to take it or leave it.

5sjmccreary
Feb 20, 2012, 10:18am Top

#4 I'd noticed the chapter divisions. I'd thought about asking questions as I read - one or two sections at a time. I thought it might be slow going in the beginning - more than a week per chapter perhaps - but maybe it will pick up later in the book. And if it doesn't, well, I guess I'm not in a rush to finish by a certain time as long as you're not either.

6sjmccreary
Feb 20, 2012, 11:52am Top

OK, I finished reading the foreword and introduction. Lots of enticing bits that I want to know more about, but I assume they will be explained in more detail in the main body of the book.

In the foreword, McNeill is giving a short biography of Christian's career. BA in modern history from Oxford, then an MA from University of Western Ontario. Back to Oxford for a PhD as a specialist in Russian history. Then on to Sydney, Australia to teach at Macquarie University - "... Russian history ... along with other courses in Russian Literature and European history." (pg xvii) Then McNeill tells us that, "Influenced by the Annales school in France, his interests shifted to everyday aspects of Russian lives." As a result, 2 new books were written, one about Russian food and the other about Russian vodka.

Q - what is the Annales school? Why would Christian have been influenced by it since he doesn't seem to have studied in France?

Christian's introduction was hard reading this morning. I hope this is not a bad omen. Hopefully, the main text will be better - when he is not merely telling us about the book, but is actually explaining his material in detail. Or, maybe it was just too early for me to be tackling anything with this much substance. I am not an early morning person and generally do not attempt any heavy-duty thinking before 10 am.

In any event, I did appreciate his explanation of the title of the book:
Trying to look at the whole of the past is, it seems to me, like using a map of the world. No geographer would try to teach exclusively from street maps. Yet most historians teach about the past of particular nations, or even of agrarian civilizations, without ever asking what the whole of the past looks like. So what is the temporal equivalent of the world map? Is there a map of time that embraces the past at all scales? (pg 3)

I bogged down in the creation myth section, but enjoyed the four arguments against big history and his rebuttals to each one.

I also looked more closely at the "further reading" bibliography. I'm sure I've never read any of these works, but I think I finally figured out why William H McNeill's name seemed familiar. I read a book of his many years ago. A World History was first published in 1967, and the fourth edition came out in 1999. I would have read the 3rd edition (1979) in the early 1990's. That was the book that sparked my interest in the history of civilization, which eventually led to our present book. Because of that book, read 20 years ago, I am having trouble understanding why the concept of "big history" is noteworthy. McNeill already did it, and it was an eye-opening experience. Granted, he did not go back to the big bang like Christian will be doing in chapter one. But, when combined with Shadows of Forgotten Ancestors by Carl Sagan, which I read shortly afterwards, it was possible to get the same scope of history 10 years before Maps of Time, without reading a dozen books. For whatever all that is worth.

On to chapter one!

7Samantha_kathy
Feb 20, 2012, 12:26pm Top

Q - what is the Annales school? Why would Christian have been influenced by it since he doesn't seem to have studied in France?

The Annales School is a group of French historians that developed a style of historiography in the earlier decades of the 20th century that focused more on social than political or diplomatic themes. Historiography is how historians look at history. This was a fairly radical change when it was first implemented by this group. So Christian being influenced by this school means that he started to look at social themes – everyday life of ordinary Russians in his case – instead of political or diplomatic themes, which mainly deals with the upper layers of society.

From 1929 on they had their own journal. During the 1960s the school had vast publishing network throughout Europe and the rest of the world, spreading their ideas. They systematically reached out to other countries but it wasn’t until the 60s that they actually had a large impact – although Christian, working as a historian, would certainly have heard of them. In the academic world, new ideas spread rapidly because contact between scientists is extensive, even if they do not work in the same country. The academic world in and of itself is small, specific disciplines are even smaller. It’s really an everybody knows everybody type of world.

********

I am having trouble understanding why the concept of "big history" is noteworthy.

I think one aspect of it you mentioned yourself, Christian takes all known time and compresses it into one big history. Another aspect is the fact that, 10 years after McNeill’s book, big history is still not a generally accepted way of looking at history. And 10 years in science is a lot. And although I do not know McNeill’s book, Christian finds integrating several (as many as possible) scientific fields to be important and I get the feeling that previous big history authors perhaps managed to take a larger view when it comes to time, but did not look at things multi-disciplinary. But that last bit is speculation, as I have not read any big history books other than this one.

I bogged down in the creation myth section

Was there anything you didn’t understand or did you just not like the metaphor? I haven’t seen the metaphor return yet, so I don’t think it’s a big problem. Personally I liked it, but it might be a bit too philosophical if you’re not that into it.

Christian's introduction was hard reading this morning. I hope this is not a bad omen.

I think his text is very readable and he does explain his science – he’s clearly writing for a general audience – but on the other hand my foreknowledge is rather extensive, so my point of view might be a little skewed. Which is why I recommended not letting too many questions stack up, because that’s guaranteed to make reading harder.

8sjmccreary
Feb 20, 2012, 3:57pm Top

Christian being influenced by this school means that he started to look at social themes – everyday life of ordinary Russians in his case – instead of political or diplomatic themes, which mainly deals with the upper layers of society.

On the surface, it seems like attention to the details of ordinary lives is going in the opposite direction from big history, where we take a step back and look at the whole in a single view. Maybe looking at mundane aspects of life and civilization make it easier to see the commonalities that exist among humans over time and distance? The Russians made vodka, but every culture has its alcoholic drinks. Why? Because it is a reliable way to preserve local produce? Because they are basically healthy beverages that do not spoil? Because we all have a need to escape the burdens of daily life occasionally through intoxication? Whatever - the reason will be a universal one, not unique to a particular time or place. Is that the connection?

previous big history authors perhaps managed to take a larger view when it comes to time, but did not look at things multi-disciplinary

That is certainly the case in the pair of books I read so long ago. Sagan was the scientist who explained the physics and chemistry and biology of the origin and development of our natural world. McNeill chronicled the migration and advancements of early humans and the development of technologies and increasingly complex societies through time. Neither of them, nor any other author I remember reading, attempted to cross disciplinary lines to provide a complete picture in a single volume.

I bogged down in the creation myth section

Taking a second look, I think I didn't like the metaphor, and the philosophy might have been too much for me. On a second reading, what I am seeing is that, in any story about "us", "we" loom large. A different group of "us" needs a different story. We are no longer primitive, superstitious people so we need a new story that doesn't rely on those elements. We need a scientific, fact-based story. I also think I gleaned that he isn't saying that those old stories are less accurate than this new one, just that they aren't our stories.

I think his text is very readable and he does explain his science

Going back this afternoon for a second look, the writing does seem easier. I think it might have been too early in the day for me to read profitably. I will make every effort in future to take this book on during my more productive hours later in the day.

-----------------------------------------

For my own reference, here is Christian's outline of the chapters in the book (pg 6-7):

Chapters 1-5: "topics that normally fall within the sciences of cosmology, geology, and biology", including "the origins and evolution of the universe, of galaxies and stars, of the solar system and the earth, and of life on earth"

Chapters 6-7: "Origins of human beings and the nature of the earliest human societies"

Chapter 8: "The earliest agrarian societies, which existed without cities or states"

Chapters 9-10: "the emergence and evolution of cities, of state, and of agrarian civilizations"

Chapters 11-14: "the modern world and its origins"

Chapter 15: "the future"

9sjmccreary
Feb 21, 2012, 11:19am Top

Part I – The Inanimate Universe

Chapter 1 – The First 300,000 Years: Origins of the Universe, Time, and Space

The Problem of Beginnings

“How can something come out of nothing?” (pg 17) “Was there a ‘time’ when there was no time? Is time a product of our imaginations?” (pg 19) I followed these discussions pretty easily, and especially liked that he combined Stephen Hawking and the Australian aborigines together in the same paragraph when suggesting that time has no beginning and no ending – we’re simply around a corner and can’t see far enough back, or ahead, to know that it loops around infinitely.

However, in the very next paragraph, he introduces another possibility: the universe is eternal, there is no beginning so there is no need for a creation story. “Religions on the Indian subcontinent, in particular, have tended to adopt this strategy. So has the steady state theory, the most serious modern alternative to big bang cosmology.” (pg 20)

Q – What is the “steady state theory”? Why haven’t I heard about it?

Continuing, he mentions other theories where there are “universes that breed other universes whenever they create black holes” and where “the universe we see may be merely one tiny atom in a much larger ‘multiverse’.”

Q – How many theories are there? Is there really so much disagreement in the scientific community about this?

-----------------------

I've also finished the next section, but that is where there is physics involved. You should see my book. There are notes and questions and marks filling up the margins and overlapping the text. Needless to say, I will have many questions, but I'll need more time than I have right now to construct them. Still, I'm pleased with myself for not skimming through it. I forced myself to read, and re-read, every word.

10sjmccreary
Feb 21, 2012, 11:59pm Top

Continuing chapter one:

Early Scientific Accounts of the Universe

“Though many pioneering scientists, like Newton, were Christians who believed deeply in the existence of a deity, they also felt the Deity was rational, so their task was to tease out the underlying laws by which the Deity had created the world.” (pg 21)

Personal anecdote: This reminded me of a time when my oldest son, Bill, was about 10 or 11 years old – 5th grade or so. He had a neighborhood friend over one day and was watching one of those Discovery Channel programs on TV about space and the cosmos. The friend wasn’t paying attention to the television and Bill, slightly exasperated, turned to him and said, “Michael, watch this. This is how the stars were born!” We are Christian, but Michael’s family was/is rather more fundamental than us. Michael glanced up for a moment, and then said, dismissively, “That’s a lie. God made the stars.” Not missing a beat, Bill replied, “Yes, but this is how He did it.”

I got through all the discussions until the point at which God was taken out of the equation. “But there were problems. One arose from the theory of thermodynamics.…” (pg 22). He doesn’t know the half of it! At this mention of thermodynamics, we are referred to Appendix 2.

Appendix 2: Chaos and Order

Skimming through the first page and a half until we get to the discussion beginning at the bottom of page 506, about the First Law of Thermodynamics. This seems to say that there is a fixed amount of energy in the world. It doesn’t disappear or get used up – it just changes form. “The second law of thermodynamics seems, at first sight, to contradict the first: it says that in a closed system (which the universe seems to be), the amount of free energy, or energy capable of doing work, tends to dissipate over time.” (pg 506)

Q – Are the first and second laws of thermodynamics actually contradictory? How can they not be? Which one is favored as true? Why does the free energy dissipate? Where does it go? Is there another kind of energy which is not capable of doing work? Does it dissipate as well, or does it increase?

The example he gives to illustrate this dissipation of energy: “A waterfall can drive a turbine because the water at its top has been lifted to higher levels, and the energy used to lift it (supplied by the Sun, which evaporated water vapor and lifted it into the clouds) is returned as water falls toward the sea. By the time the water has reached the sea, it can no longer do work, because all the water at sea level has about the same amount of available energy; it is in a state of thermodynamic equilibrium.” (pg 506-507)

Q – I’m not even sure what to ask. This really doesn’t make sense. The energy used to lift the water is returned – where? how? – as it falls towards the sea. At sea level, none of the water can do work, because it all has the same amount of energy. If it has energy, then why can’t it do work? What does “thermodynamic equilibrium” mean?

“The second law predicts that over colossal periods of time, and in a closed system, all differentials will diminish; as they do so, there will be ever-diminishing amounts of free energy available to do the hard work of creating and sustaining complex entities. This seems to mean that the whole universe will eventually become less and less ordered as it tends toward a state of thermodynamic equilibrium.” (pg 507)

Q – There’s that phrase again, “thermodynamic equilibrium”. It’s beginning to sound like this law says that eventually everything will stop moving and that nothing will happen after that. All the energy has dissipated and none is left? But what about that equalized level of energy in the sea water above?

“In the nineteenth century, this depressing idea was described as the ‘heat death’ of the universe.”

Q – Finally someone else thinks “thermodynamic” sounds like heat! Why does it heat up? Heat sounds like energy – is that where it has all gone to?

The “steadily increasing pile of unusable energy” is called entropy. “In the very long run, it seems, entropy must increase, and complexity must diminish. … The second law apparently implies that everything in the universe is riding down the same escalator toward chaos.”

Q – the pile of unusable energy – is that what we have in the sea water which just sits there in deep holes and doesn’t do anything or go anywhere? As energy dissipates, the universe loses its complexity? Why, then, is that called “chaos”? The opposite of complexity is simplicity, which sounds completely different than chaos. Do these words have different connotations in this context?

Q - The next paragraph seems understandable to me – about why the present condition of the universe seems to be inconsistent with the second law. “As far as we know, the early universe was remarkably homogenous” – which is the opposite of high levels of energy, right? And at the beginning of the universe, there must have been the highest-ever energy levels because they’ve been decreasing ever since, if the 2nd law is true. Does that mean that the 2nd law isn’t true?

----------------------------------

I'm going to stop here until you have time to respond. I read another page and a half in the appendix before returning to chapter one. There are more questions, but maybe your explanations of these will help me figure them out on my own.

11Samantha_kathy
Feb 22, 2012, 5:58am Top

What is the “steady state theory”?

Steady State Theory is the next most likely theory after the Big Bang Theory. The Big Bang Theory states that there was one moment in time where matter was created (the big bang) and the universe began to expand afterwards. The Steady State Theory states that there is a continuous creation of matter (mostly in the form of hydrogen) even as the universe is expanding. This would mean that even though the universe is expanding it does not change its appearance over time – it’s in a steady state.

Why haven’t I heard about it?

Because the Big Bang Theory is so popular is the easy answer. In biology you have the same thing. Everybody knows the evolution theory, but there are alternatives. What the Steady State theory is to the Big Bang theory, the Intelligent Design theory is to the evolution theory. Both alternative theories are viable, but their counterparts are seen as the most likely theories – which in part comes from the evidence and in part simply due to popularity among scientists in that field.
And then what is most popular is also what is taught as the ‘truth’ as far as we know it. Alternate theories are mentioned in academics, but even then they do not get much attention. A theory has become a dogma – a ‘law’ that everybody takes to be true. For the evolution theory or the big bang theory to be rejected a scientist has to come up with some pretty convincing prove that the ruling theory is wrong.

How many theories are there? Is there really so much disagreement in the scientific community about this?

I’m not sure how many theories there are in total, as cosmology is not my field, but I can say: a lot. As long as the leading theory (the big bang theory) does not explain everything that is observed there will be other theories. But no, there’s not so much disagreement in the scientific community. Most scientists will agree with the leading theory, even though there are flaws in it. Most will try to explain the things that do not fit the leading theory by either showing that the observations do in fact fit within the theory in some way, or by slightly tweaking the leading theory so their observations fit while all previous observations also still fit. But there are always scientists that will develop a completely different theory – no matter if their theory fits the evidence there already is or not – to explain their own observations.

12Samantha_kathy
Feb 22, 2012, 5:59am Top

Thermodynamics

All right, you’ve got a lot of questions about thermodynamics, which is understandable. Thermodynamic laws seem like they are simple at first glance, but the fact that I had 6 hours of lectures about them just to understand them says enough about how complex they really are. I will try to explain some general concepts by using a biological example (because that’s what I’m most familiar with) and in the process I hope I can answer your questions. It’s long though! You’ve been warned :).

I’m going to take a cell in our body as an example of a closed system. I’ll leave out unimportant details of how some things work and in the beginning of my explanation I will also ignore the fact that a cell is not a truly closed system, but I will get back to that later on.

All right, a cell in our body. It does a lot of things, has a lot of machines inside it with their own tasks, and the cell itself as a whole also has a task in the body. For all of these tasks, energy is needed to perform them. Energy in a cell occurs in the form of ATP molecules. ATP molecules have a phosphate group attached to them and when the bond that holds this phosphate group to the rest of the ATP molecule is broken, energy comes free which can then be used by one of the machines in the cell to do something. This process is called splicing and you are then left with an ADP and a phosphate molecule.

Here you can see the first law of thermodynamics in action. Energy is never lost, merely transformed. In this case, the energy that comes free from the splicing of ATP is used (=transformed) to perform another task that costs energy. An example would be building an enzyme by binding together amino acids. Each binding costs energy, just like splicing gives energy. So the energy of splicing an ATP is used to bind two amino acids to each other. The energy is thereby transformed, but not lost.

Now, the second law of thermodynamics says that in a closed system the amount of free energy, or energy capable of doing work, tends to dissipate over time. Free energy in a cell is ATP, because only the energy gained from splicing ATP can be used for work – to do the tasks. But ATP in a cell is limited, so over time there is no more ATP in a cell. In fact, in a human body the ATP will run out within 24 hours. So that neatly demonstrates this law.

But wait! We know that we do not run out of ATP, or else we wouldn’t live longer than a day. Our cells continue to function, so there must be ATP! There are two ways for there to be ATP – free energy – in our cells. The first way would be a thermodynamic equilibrium. That means that things are in balance and for it to be in balance it would need to be homogenous. A cell is not a thermodynamic balance – it is not homogenous, as it is constantly doing work and therefore changing.

A good example of a thermodynamic equilibrium would be a drop of water looked at on the molecular level. Water is basically a hydrogen and two oxygen molecules bound together. If you added hydrogen molecules and oxygen molecules together in a tube, you would see these molecules would start to bond together forming water molecules. During this period of bonding, free energy is transformed into hydrogen bonds, resulting in hydrogen molecules – water in other words. This is the first law of thermodynamics in practice. But then there comes a time that all the hydrogen bonds that can be made, have been made. There is no more free energy in the tube This is the second law of thermodynamics in practice – through time, the amount of free energy has dissipated. We have now arrived at a thermodynamic equilibrium: a homogenous balance in the tube, which is now filled with water molecules. Without an outside force there will be no change anymore.

But that still does not explain what is happening in a cell. It’s certainly not a thermodynamic equilibrium. So what is happening? The answer is relatively simply. There is a constant production of ATP, where ADP and phosphate are bound together to form a new ATP molecule. But the forming of ATP would need energy, you might think – and you’d be right. At this point, our assumption that a cell is a closed system is proven false – it isn’t. We constantly provide our cell with new energy to make ATP molecules by eating food. This food is broken down in our body – basically the bonds between the food molecules are broken, which results in the same thing as an ATP molecule’s bond with its phosphate group being broken – free energy. This free energy is then put to work to make new ATP molecules.

Now, the waterfall example should be easier to understand. Let’s look at it in the way of ATP (even though a waterfall does not have ATP). Heat from the sun is applied to water at sea level. Heat is free energy, and in this case it charges the water with free energy causing it to evaporate. This charged water cools down – which means it loses some of its energy – and ends up raining down on earth in a river up on a mountain. That river flows downwards, ending in the waterfall where it comes crashing down. The charged water loses all of its ATP during this downward crash, so when it reaches the bottom of the waterfall which is at sea level, it is once again without ATP. It needs to wait for the sun to heat it again to get ATP.

Now, in the waterfall example we’ve seen that to lose heat is the same as losing energy. This is because heat is energy – free energy to be exact. So when a system cools down, it is actually losing free energy. This is called entropy. So when the universe started to cool down, it was actually slowly starting to lose it’s free energy. This free energy was not simply lost – the first law of thermodynamics tells us that – it was simply transformed. Into matter, for example, there at the very beginning. As it was said, where the free energy came from at the very beginning isn’t known, but from the very second the universe started to expand – and with it cool down – free energy was transformed into other things. First simple things, like matter, later into more complex things like stars.

Eventually, if the universe is truly a closed system, all free energy will have been transformed into complex things. But these complex things are very orderly, they follow patterns. Even the simple things, like single cell organisms or molecules, follow patterns. As we’ve seen, all things, like human cells, need an input of free energy to exist. So when there is no more free energy, these complex things cannot function any longer and they cannot maintain their pattern. They will fall into disorder – chaos in other words. Simplicity is therefore not synonymous with chaos – in fact, it’s quite the opposite.

Okay, so that was the general story. In think there are a few questions you asked that I haven’t answered above, so I did that below. Anymore questions are always welcome though – this is a though subject that some people spend their entire lives studying.

Are the first and second laws of thermodynamics actually contradictory?

I basically answered this above, but it’s easy to miss because I don’t explicitly state it. No, they are not contradictory. The second law only states that free energy in a closed system dissipates over time – the first law applies to all systems (closed or not) and tells us what happens to that free energy: it is transformed.

Why does the free energy dissipate? Where does it go?

Also kind of answered already. Free energy dissipates because it is transformed – this transformation can take many forms – or because it is lost in the form of heat. Ice melting is a good example of free energy dissipating into heat.

Is there another kind of energy which is not capable of doing work? Does it dissipate as well, or does it increase?

Yes, two actually. The useful kind – energy bound up in bonds like those between an ADP and a phosphate molecule, which can be freed and then put to work somewhere – and the non-useful kind, the energy that’s transformed into heat, which cannot be used for work anymore. This last is why in a closed system thermodynamics law #2 predicts that eventually all free energy will have dissipated. The heat is lost.

The next paragraph seems understandable to me – about why the present condition of the universe seems to be inconsistent with the second law. “As far as we know, the early universe was remarkably homogenous” – which is the opposite of high levels of energy, right? And at the beginning of the universe, there must have been the highest-ever energy levels because they’ve been decreasing ever since, if the 2nd law is true. Does that mean that the 2nd law isn’t true?

Well, this is a question that’s still not completely answered. For one, we don’t know where the free energy that was present at the beginning of the universe came from. For another, we don’t know why the universe that seems so homogenous – and thus in a thermodynamic equilibrium – was knocked out of its equilibrium. But this last is something that is possible. Forces that can disrupt a thermodynamic equilibrium are for instance gravity, electricity and magnetism. We know that in the very beginning, electricity and gravity also started to appear, so that may have something to do with why the universe did not become a thermodynamic equilibrium.
Taking that into account, the 2nd law is true – free energy has been dissipating in the universe. But as long as we don’t know where the starting budget of free energy came from, we cannot say for certain that the universe is a closed system (although that’s the working theory) and if the universe is not a closed system, the 2nd law wouldn’t be in effect.

13Samantha_kathy
Feb 22, 2012, 6:02am Top

And as a PS to your personal anecdote: I'm so totally agreeing with your son!

I believe in a higher power myself and many of my fellow scientists do not understand how I can have faith while still doing science. But every time we clarify how something works, it appears to be so much more complex than previously thought. And it still all works! It produces us humans! If you think about it, it really is a miracle. My question is how you can think that's just coincidence?

14sjmccreary
Feb 22, 2012, 10:20am Top

Let me summarize my initial understanding. Later today I'll read over the material again with your answers at hand.

Equilibrium = hot = stable = nothing changing = homogeneous. This was the state at the time of the big bang. Then, universe expanding = cooling off = unstable = lots of available energy to make things happen and change. As available energy gets used up, then it approaches equilibrium again & heats up. Chaos = systems broken down due to lack of energy to keep them going.

Since the universe is still expanding, does that mean more energy is still becoming available? (Like the food we eat each day to provide new energy to the cells?)

I left off just before the addition of gravity & electricity to the mix. I want to have a grasp on this first.

15Samantha_kathy
Feb 22, 2012, 1:43pm Top

Equilibrium = hot = stable = nothing changing = homogeneous

It's almost correct. Equilibrium does not necessarily mean hot - equilibrium at the beginning of time was hot, though, that part is correct.

universe expanding = cooling off = unstable = lots of available energy to make things happen and change.

Correct.

As available energy gets used up, then it approaches equilibrium again & heats up.

Not correct. As free energy is used up, we approach equilibrium, yes. But it does not heat up again. In fact, when the universe as a closed system approached equilibrium, we are approaching absolute zero - the lowest temperature you can imagine. If something heats up again, it means free energy is being added to the system somehow. For instance, gravity pulls molecules together to form a star, these molecules then collide which causes energy to come free, thus the center of a star is hot.

Chaos = systems broken down due to lack of energy to keep them going

Correct.

Since the universe is still expanding, does that mean more energy is still becoming available? (Like the food we eat each day to provide new energy to the cells?)

No, the universe is expanding, true. But the expansion is actually using energy. We know this because the universe is still cooling off --> losing energy. Considering the Big Bang theory as true, energy is lost and there is no replenishing it. The universe is a closed system that adheres to the 2nd law and is slowly going towards chaos.

16sjmccreary
Feb 23, 2012, 10:34am Top

What caused the heat from which the universe has been cooling down since the big bang?

17sjmccreary
Edited: Feb 23, 2012, 10:35am Top

#13 how you can think that's just coincidence? - My opinion, as well!

18Samantha_kathy
Feb 23, 2012, 1:55pm Top

What caused the heat from which the universe has been cooling down since the big bang?

We don't know, just as we don't know where the free energy came from that started it all. Not a very satisfactory answer, is it?

19sjmccreary
Feb 23, 2012, 7:17pm Top

#15 OK, let me try again.

equilibrium = before big bang was hot, but can also be cold (either/or - not in between?) = stable = no energy being expended (none available or no work to do?) = homogeneous. After big bang: universe expanding = cooling = lots of energy expended, lots of changes, work being done. As available energy gets used up = approach equilibrium again = cold.

So, for pre-big bang universe to be hot, then something/Someone had to "load" it with energy? Is that what caused big bang "explosion"? Expansion will stop when energy is used up. Then chaos, right? And very cold since all energy/heat has dissipated.

I want to skip the gravity and electricity discussion in Appendix 2 for now and get back to Chapter 1.

#12 this is a though subject that some people spend their entire lives studying - Oh, I won't be doing that! I've been thinking about this for only 2 days and I'm thinking that's enough! Assuming I'm getting closer to understanding this, I'd like to move on to see where he is going with with his mention of thermodynamics. (So, please stop me if I'm still not "getting it".)

20Samantha_kathy
Edited: Feb 24, 2012, 2:12pm Top

equilibrium = before big bang was hot, but can also be cold (either/or - not in between?) = stable = no energy being expended (none available or no work to do?) = homogeneous.

Correct. Equilibrium can indeed be found at any temperature.

Equilibrium will be cold relative to the systems former state, because to reach equilibrium things loose free energy and thus cool down. So the system will be colder, though not necessarily cold.

Equilibrium is reached when there is no work to do. If there was no free energy available, you would have chaos.

After big bang: universe expanding = cooling = lots of energy expended, lots of changes, work being done. As available energy gets used up = approach equilibrium again = cold.

Not entirely correct. Approach equilibrium again should be approach chaos, because when all free energy is used up you end with chaos, not equilibrium.

So, for pre-big bang universe to be hot, then something/Someone had to "load" it with energy? Is that what caused big bang "explosion"?

Yes, the free energy had to come from somewhere/Someone. That could have caused the "explosion" that fuels the expansion of the current universe, but that's pure speculation.

Expansion will stop when energy is used up. Then chaos, right? And very cold since all energy/heat has dissipated.

Yes, expansion will stop when all free energy is used up. Then the universe will slide down to chaos. Chaos is said to be at the temperature of absolute zero, which is a theoretical temperature. Scientists have come very close to absolute zero - when no more heat (= free energy) can leave the system - but it has never been reached. Absolute zero corresponds with 0 Kelvin, which is -273.15°Celsius, which is −459.67°Fahrenheit. So very cold indeed.

I want to skip the gravity and electricity discussion in Appendix 2 for now and get back to Chapter 1.

I think you can get back to Chapter 1 now. You've got a good enough graps on thermodynamics to understand the chapter.

21sjmccreary
Feb 24, 2012, 9:31pm Top

Equilibrium is reached when there is no work to do. If there was no free energy available, you would have chaos. - This is a distinction that I was missing before. Now it makes a little more sense.

22Samantha_kathy
Feb 25, 2012, 3:05am Top

Glad to have it cleared up :D.

23sjmccreary
Mar 5, 2012, 10:08pm Top

Sorry to have been neglecting this so long - between home improvement projects and out of town travel, there hasn't been much time for concentrated reading. However, this week I am out of town alone, and there is nothing but peace and quiet in my hotel room. Yay!

OK. I left off after the detour to the appendix for a discussion about the first and second laws of thermodynamics. I don't claim to have a good understanding of the details of them, but at least I feel like I understand what they are about. Thermodynamics was identified as one of the problems with the early scientific theories of an infinitely old, infinitely large universe. Olber's paradox is another - if the universe contains an infinite number of stars, then shouldn't it be infinitely bright? The section ends with this comment: "Of course, all scientific theories contain problems. But as long as the theories can answer most of the questions put to them, such difficulties can be ignored. And the problems faced by the Newtonian theory were largely ignored in the nineteenth century." (pg 22)

Q - In light of that last statement, is science certain - absolutely certain - about anything? At what point does a theory become a law? (Is that the correct term?)

24sjmccreary
Mar 5, 2012, 11:26pm Top

Next section:

The Big Bang: From Primordial Chaos to the First Signs of Order

In the first half of the 20th century, a new theory began to develop which solved many of the problems of the older theories. According to big bang cosmology, the universe is not infinitely old, it is not infinitely large, and it is expanding too fast for gravity to cause it to collapse in on itself. This theory is similar to the traditional emergence creation myths in that the universe begins as one thing and evolves into something different over time. Since there is a specific beginning, and a sequential life of its own, then there is the implication that it may die at some point in the future. This theory addressed many of the problems with the earlier theories, and was also consistent with new information that was being gathered "about stars, matter, and energy" (pg 23).

Then the explanation goes into the timeline of the universe under the big bang scenario: Beginning as an incredibly dense and very tiny speck of matter, the universe suddenly began to expand very quickly. And has continued to do so ever since.

----------------------------

About the beginning, we can say nothing with any certainty except that something appeared. We do not know why or how it appeared. We cannot say whether anything existed before. We cannot even say that there was a "before" or a "space" for anything to exist in, for (in an argument anticipated by St. Augustine in the fifth century CE) time and space may have been created at the same time as matter and energy. So, we can say nothing definite about the moment of the big bang, or about any earlier period.

However, beginning a tiny fraction of a second after the big bang, modern science can offer a rigorous and coherent story, based on abundant evidence. Many of the most interesting "events" occurred within a fraction of a second. Indeed, it may be helpful to think of time itself as stretched out during these early moments, so that a billionth of a billionth of a second then was a significant, in its way, as many billions of years in the later history of the universe. (pg 23)


Q - How did anyone think this up? What "evidence" is there? (rhetorical question, as the next section is about the specific evidence for the big bang) But, how did it come about - this "rigorous and coherent story"? And how in the world can anyone claim such enormously large and small intervals of time and space with any certainty? It all seems like hyperbole.

----------------------------

As the universe expanded, it became less homogeneous. Its original symmetry was broken, distinct patterns appeared, and matter and energy began to assume forms that we can recognize today. Modern nuclear physics can tell at what temperatures particular types of energy or matter appear.... So, if we can estimate how fast the universe cooled, then we can estimate when different forces and particles emerged from the flux of the early universe. Within the first second, quarks appeared, and from these were constructed protons and neutrons the main constituents of atomic nuclei. Quarks and atomic nuclei are held together by the strong nuclear force, one the four fundamental forces that rule our universe. (pg 24)


Q - Can we estimate how fast the universe cooled? How does physics know the temperatures associated with the appearance of different energies and matter? Can any of this be replicated in a modern laboratory? Protons and neutrons remind me of how confusing I found chemistry to be! Electrons are missing from this paragraph, but that is explained a little later, and I think I followed that discussion pretty well. I just continue to be amazed/impressed/skeptical of the authority and confidence with which all these claims are made. The time line in this section has only 7 entries covering the first 300,000 years. The first 4 events occur within the first 1 second. The 5th event is at 1-10 seconds. The 6th is 3 minutes. The 7th is 300,000 years. How can anyone state these as certain facts? I am beginning to understand why Christian referred to this as a modern creation myth in the introduction - it is no less unbelievable than some of the early human stories. The four fundamental forces which rule the universe: the first one, mentioned here, is nuclear. Mentioned in a later paragraph is electromagnetic. What are the other two?

The rest of this section was fairly easy to follow, I think. He hasn't proven anything to me yet, but I was able to follow his arguments.

25Samantha_kathy
Mar 6, 2012, 4:00pm Top

No problem! You should take a look at the pace of my tutored read for North and South – glacial doesn’t even begin to describe it! Take all the time you need.

In light of that last statement, is science certain - absolutely certain - about anything?

Short answer – no, not really. Slightly more nuanced answer – mechanisms are pretty much known at this point in time, because we can observe them. However, sometimes we do not have the complete picture. And that causes us to draw the wrong conclusion. Or only a partly correct one.

Genetics is a field where I can easily explain what I mean. First we knew nothing of genetics – if your parents had brown eyes and you had them, you looked like your parents. How or why you got brown eyes was unknown – although there were theories, many of them wrong but plausible with the information they had at the time (no matter how ridiculous some of them now sound – hindsight really is 20/20). Then it was discovered that traits – like flower color eyes – were passed down from parents to children in a particular ratio (1/4 – ½ - ¼) with a famous experiment. That experiment is still the basis for all we know about genes today. However, the ratio proved to be too simplistic, but for a long time we couldn’t find out more. Then techniques and technology were developed and all of a sudden we can sequence genes, see the order of the base pairs, and discover differences between individuals! We can now also look at mechanisms that turn genes on or off.

There’s still a lot we don’t know, but what we have observed is true. But sometimes when we discover another piece of the puzzle, the sky we thought we were puzzling together turns out to be an ocean.

At what point does a theory become a law? (Is that the correct term?)

It has much to do with the field you’re in. Mathematicians and physicists often call theories that can be distilled into neat little equations laws. If you can prove it – or sometimes more accurately, of others can’t disprove it – and it gets used a lot, then the term becomes popular and all of a sudden the laws of thermodynamic are thought to students, instead of the theories of thermodynamics.

But, how did it come about - this "rigorous and coherent story"? And how in the world can anyone claim such enormously large and small intervals of time and space with any certainty? It all seems like hyperbole.

Lots of different tests and observations, which provided lots of puzzle pieces. Then people starting putting those pieces together to come up with a coherent theory. Like Charles Darwin (and others in his time, by the way) started putting their observations together to put forth the evolution theory – and others had collated observations and put forth other theories – so did astronomers/physicists about the beginning of our universe. Then when there’s a theory, you can test it – or parts of it. CERN, a very famous research institute, played a big part in testing several assumptions of this theory and proving them right, I belief.

Can we estimate how fast the universe cooled? How does physics know the temperatures associated with the appearance of different energies and matter? Can any of this be replicated in a modern laboratory?

I think we can indeed estimate the speed of cooling. It’s all a matter of tests, and yes they can (and are) being done in modern laboratories. I know small parts can be replicated, although the entire sequence can’t. It’s a bit like the first life on earth. We can replicate specific steps that need to have happened separate, but we can’t replicate that 1 in however many billions chance that produced the very first life form, so the entire sequence has not been repeated.

How can anyone state these as certain facts?

Part tests and observations, part mathematical models. Absolutely certain it is not, of course, but they’re probably pretty close. New data is generated every day about this, and so far none of it has proved the timeline false.

What are the other two?

The four fundamental forces are: gravity, the electromagnetic force and then two that act in and around the atomic nucleus, known as strong and weak. If you want to know more, here’s a link to a lecture about this (it’s either video, just audio, or a bit in text form) that’s easy to follow and really interesting. Not necessary, but in case you want to know. http://www.gresham.ac.uk/lectures-and-events/the-forces-of-nature

26sjmccreary
Edited: Mar 17, 2012, 12:41pm Top

Determined to finish chapter one and get on with the rest of this book!

Evidence for Big Bang Cosmology

Hubble and the Redshift

Essentially, there is evidence which proves that distant stars are moving away from us in all directions indicating that the universe is expanding. Since it is expanding at a measurable rate, then it should be possible to calculate the length of time the expansion has been taking place if we know the current distance between objects. Putting the expansion into reverse takes us back to a time when all the mass of the universe was contained in a single location.

I think I followed all these arguments and examples, although I would have liked more detailed explanations of some of the building blocks used in making his case. For example, Cepheid variable stars regularly expand and contract, becoming brighter and darker. By comparing the length of the expansion cycle (an indication of size) to the apparent brightness, it is possible to calculate its distance from earth. Fine, I get all that. But how did anyone figure out that the length of the cycle was based on its size? If a star appears less bright, how did astronomers know that it wasn't just smaller than a brighter star rather than farther away?

Also, the part about looking at a star's light spectrum to learn whether it is moving towards us or away from us is easier to accept than the claim that it can also indicate the elements which are present in the star. I've seen photos of these spectra, but I think I would like to watch an actual demonstration of this sometime. What corroborating evidence is there?

Relativity and Nuclear Physics

Einstein's theory of relativity implies that the universe is not stable - it must either be expanding or contracting. Einstein himself rejected this possibility. If he didn't believe the outcome, then why did he promote the theory? Then Friedmann "showed that the universe really might be either expanding or contracting". (pg 32) How did he do that? What finally convinced Einstein? That was in 1922. "In the 1940s, the idea of an expanding universe still seemed odd to most astronomers." Really? Twenty years later? Why? "Then, between the 1940s and the 1960s, new evidence accumulated in support of the idea until, by the late 1960s, the big bang theory had become the standard account of the origins of the universe." What new evidence? Hubble's discoveries from the last section? It took nearly 50 years from the time Friedmann and Einstein agreed on an expanding universe before the big bang theory was widely accepted? And it was explained here in just a couple of dozen pages? Why was science so slow to embrace this theory?

Ok, so after the big bang was accepted, physicists "began to work their way through the implications of this new view of the universe. What would a tiny universe look like?" They're talking about just prior to the big bang? Because the last reference to size was just one paragraph ago when "most astronomers still assumed that the universe was infinite, humogenous, and stable" (in the early 20th century). So they think it must have been hot, like a bicycle tire over-inflated (although the example that occurred to me was a pressure cooker - same principle?) That was when they realized they already knew how to work with energy and matter at different temperatures and could use that knowledge to predict behavior in the early universe. One of the people named as working on this was Fred Hoyle - "who was to become a fierce critic of big bang cosmology". What happened? Why did he decide to change sides on the question? Especially since "it soon became apparent that the idea of an early, dense, and hot universe was perfectly consistent with all that was known in the emerging field of particle physics." (pg 33)

Cosmic Background Radiation

I've heard of this before and have a lot of trouble with it - the big bang theory predicts that there should have been a huge pulse of energy, the remnants of which should still be detectable today. Why must this early energy be specially detectable? The static noise picked up by radio antennae - how can anyone say it is anything at all, much less leftover big bang energy? Another thing here that I don't understand: PJE Peebles predicted "the existence of remnant radiation at an energy level equivalent to a temperature of ca. 3 degrees C above absolute zero. This was remarkably close to the temperature of the radiation found by Penzias and Wilson." (pg 33-34) So, how can energy, especially energy that registers as a sound, have a temperature? And how can that temperature be measured? It isn't a physical thing, after all - is it? So, this is the decisive bit of evidence for the Big Bang. Heh. Static.

Other Forms of Evidence

Hydrogen and Helium are present in precisely the amounts which are predicted by the big bang theory. 76% and 24% respectively. That accounts for 100% of the universe. Everything else gets rounded out. But this doesn't make sense: "the amount of hydrogen has fallen to ca. 71 percent as reactions within stars have converted hydrogen into helium, which now accounts for ca. 28 percent of all matter." (pg 34) If the actual levels are 71% and 28% now, how do they know what the original levels were? And another thing that doesn't make sense: "we live in a corner of the universe that happens to have high concentrations of other elements", so the dominance of hydrogen and helium are not as obvious to us. Why would one part of the universe have a concentration of other elements? I won't ask whether this concentration is related the fact that we live here, since he already indicates that this will be discussed more in chapters 2 and 3. But wouldn't the big bang have dispersed matter evenly throughout the universe?

Another piece of evidence - no dating method has ever identified anything as being older than about 12 billion years. He says it would be surprising for there to be anything older than that since we haven't detected it. I think that is inconclusive. And slightly arrogant.

And, since the big bang theory says that the universe has been in a constant state of change, we ought to be able to see evidence of that. By looking at distant objects in the universe, we are actually looking at something that occurred long ago when the light we're seeing now first left the far-away object. Nearer objects are seen more quickly. And it is true that older light shows a different scene than more recent light. I think this point is very cool.

How Trustworthy is Big Bang Cosmology?

The universe is flying apart faster and faster? That isn't consistent with Big Bang which would have the rate of expansion slowing down before the universe eventually collapses. (Did I get that right?) This sounds interesting and I'll be anxious to read more about it in coming years. But until then, it seems Big Bang theory is the best fit for the evidence at hand.

Wrap up chapter one: The notes about exponential notation were helpful. This is probably the first time I've thought about that since high school. The summary of information in chapter one only took 90 seconds to read. I just spent nearly 3 weeks trying to absorb the same information! And about the list of further reading - is there anything here you would recommend? I thought I already had A Brief History of Time on my wishlist, but I see that it's not. Would it be worthwhile reading?

ETA - it was way past midnight last night when I posted these comments. This morning I found that they were hard to decipher, so I bolded my questions, since they were embedded in the summary instead neatly set apart. Hopefully, they will be easier to see. I also tried to fix most of the sentence fragments and run-ons. I'm happy to have chapter one finished. I hope chapter two will be quicker and easier for me.

27Samantha_kathy
Mar 17, 2012, 1:37pm Top

Determined to finish chapter one and get on with the rest of this book!

From what I’ve read so far, the first three chapters are the most science dense, with lots of theoretical physics and astronomy. I got the feeling that each chapter had less difficult details, perhaps because those details become more and more about things we can wrap our heads around easier. It’s simply easier to envision how a star is born than how a whole universe is born.

But how did anyone figure out that the length of the cycle was based on its size? If a star appears less bright, how did astronomers know that it wasn't just smaller than a brighter star rather than farther away?

How does anyone ever come up with a theory? I’m sure someone suggested size instead of distance as a reason for the difference in brightness. It could be that someone else suggested distance as the deciding factor in brightness, and the two theories co-existed until one was proven, or it could be that an existing theory was disproved which caused scientists to have to search for another explanation. The last is how most theories are developed – there’s no (good) explanation, so someone tries to think of one, and then goes in search of evidence. (Actually, to be a proper scientist, you have a theory and constantly try to disprove it – as long as you can’t, you assume your theory is the correct one.)

Also, the part about looking at a star's light spectrum to learn whether it is moving towards us or away from us is easier to accept than the claim that it can also indicate the elements which are present in the star. I've seen photos of these spectra, but I think I would like to watch an actual demonstration of this sometime. What corroborating evidence is there?

When you’re talking about light spectrums and elements, you are talking about emission spectrum. It’s a method that has been around since the 1850s. Each element has a unique emission spectrum and that’s something that we can test right here on earth. With emission spectrum you’re actually measuring the decay of elements – the loss of photons by an element. Some of this decay results in visible light, but radioactive decay is also part of this science.

In biology (and archeology, and other sciences) things can be dated by a method called carbon dating – the decay of the naturally occurring radioisotope carbon-14 is measured here, and it can date carbon-carrying material (like all (previously) living things) up to about 58,000 to 62,000 years ago.

In astronomy, where they look at stars and the like, the most often used method is to look at absorption spectra of light. Its basic method is that light gets absorbed my molecules and re-emit it at certain frequencies. This re-emitting is unique for each element (see emission spectrometry above). When talking about gasses (here on Earth) or nebulae, we’re looking at light that passes through them. When we’re talking about stars, we’re talking about light that is emitted by the stars themselves.

Einstein's theory of relativity implies that the universe is not stable - it must either be expanding or contracting. Einstein himself rejected this possibility. If he didn't believe the outcome, then why did he promote the theory?

I’m not entirely sure why he himself rejected the possibility, but I think it had something to do with the fact that Einstein was a religious man. Perhaps the possibility of an expanding or contracting universe was not compatible with his worldview? But that doesn’t make the theory go away.
In fact, you could say that Einstein believed his theory was correct, but that there was something he didn’t know yet that would make the universe stable within the bounds of his theory.
But truthfully, I’m just guessing here. While familiar with Einstein’s theories, I’m not very familiar with the man himself, let alone his views on things.

Then Friedmann "showed that the universe really might be either expanding or contracting". (pg 32) How did he do that? Then Friedmann "showed that the universe really might be either expanding or contracting". (pg 32) How did he do that? What finally convinced Einstein? That was in 1922. "In the 1940s, the idea of an expanding universe still seemed odd to most astronomers." Really? Twenty years later? Why? "Then, between the 1940s and the 1960s, new evidence accumulated in support of the idea until, by the late 1960s, the big bang theory had become the standard account of the origins of the universe." What new evidence? Hubble's discoveries from the last section? It took nearly 50 years from the time Friedmann and Einstein agreed on an expanding universe before the big bang theory was widely accepted? And it was explained here in just a couple of dozen pages? Why was science so slow to embrace this theory?

I had to wikipedia this, since it’s more about the history of a theory than actual science, but here’s what wikipedia had to say:

The first general relativistic models predicted that a universe which was dynamical and contained ordinary gravitational matter would contract rather than expand. Einstein's first proposal for a solution to this problem involved adding a cosmological constant into his theories to balance out the contraction, in order to obtain a static universe solution. But in 1922 Alexander Friedman derived a set of equations known as the Friedmann equations, showing that the universe might expand and presenting the expansion speed in this case. The observations of Edwin Hubble in 1929 suggested that distant galaxies were all apparently moving away from us, so that many scientists came to accept that the universe was expanding.

As to why it took so long for this theory to take hold, I think religion might be an important factor here – until well in the 1970s, many people were still pretty religious and while a lot of science can be easily explained within a worldview that includes God, an expanding universe instead of a static one certainly is not one of the easier explained ones.

Ok, so after the big bang was accepted, physicists "began to work their way through the implications of this new view of the universe. What would a tiny universe look like?" They're talking about just prior to the big bang?

Actually, they’re talking about just after the big bang. Expansion made the universe the size it is now, but it had to be smaller – too small a long time ago to hold planets and galaxies, which is where the tiny universe in the sentence comes into play.

although the example that occurred to me was a pressure cooker - same principle?

Yup, same basic principle – too much energy in a small space heats up.

One of the people named as working on this was Fred Hoyle - "who was to become a fierce critic of big bang cosmology". What happened? Why did he decide to change sides on the question?

Ah, another question for which I had to call in some Wikipedia reinforcement. Here’s what it had to say:

While having no argument with the Lemaître theory (later confirmed by Edwin Hubble's observations) that the universe was expanding, Hoyle disagreed on its interpretation. He found the idea that the universe had a beginning to be pseudoscience, resembling arguments for a creator, "for it's an irrational process, and can't be described in scientific terms". Instead, Hoyle, along with Thomas Gold and Hermann Bondi (with whom he had worked on radar in World War II), argued for the universe as being in a "steady state". The theory tried to explain how the universe could be eternal and essentially unchanging while still having the galaxies we observe moving away from each other. The theory hinged on the creation of matter between galaxies over time, so that even though galaxies get further apart, new ones that develop between them fill the space they leave. The resulting universe is in a "steady state" in the same manner that a flowing river is - the individual water molecules are moving away but the overall river remains the same.

Remember, we talked about steady states and alternative theories a few posts ago? Well, here’s the origin of the most important alternative theory to the Big Bang. Another nice fact, the Big Bang theory actually got its name from Hoyle:

He is responsible for coining the term "Big Bang" on BBC radio's Third Programme broadcast at 1830 GMT on 28 March 1949. It is popularly reported that Hoyle intended this to be pejorative, but the script from which he read aloud shows that he intended the expression to help his listeners. Hoyle explicitly denied that he was being insulting and said it was just a striking image meant to emphasize the difference between the two theories for radio listeners.

I've heard of this before and have a lot of trouble with it - the big bang theory predicts that there should have been a huge pulse of energy, the remnants of which should still be detectable today. Why must this early energy be specially detectable? The static noise picked up by radio antennae - how can anyone say it is anything at all, much less leftover big bang energy?

According to the models the scientists have made, the huge pulse of energy was necessary for the expansion rate of the universe we see today. I’m not telling you that this is true – even the scientists have no undisputed evidence for this. But in the leading theory of today (the Big Bang theory), this pulse of energy was emitted at the beginning of our universe. If this is true, then this energy (because it was so huge) should have left a trace. Scientists believe that the static noise – background energy – is that leftover trace because it’s so uniform all over the galaxy. It could of course be that they are wrong – we won’t know until evidence against this assumption turns up, but that’s the same as a lot of things in science. Assumptions like this stand until someone can disprove it.

So, how can energy, especially energy that registers as a sound, have a temperature? And how can that temperature be measured? It isn't a physical thing, after all - is it?

This stems back to what temperature actually is. The definition of temperature is: the derivative of the internal energy with respect to the entropy. Now, in the definition of temperature you can see that temperature is actually a measurement of energy. When you’re measuring temperature, you’re actually measuring the speed of particles of an object – and speed of particles is correlated with the energy that object has. Remember, add energy to an object and the molecules of that object speed up, causing collisions, causing it to heat up. It comes back to thermodynamics again (in fact, thermodynamics kind of says it already – thermo for temperature, while the whole subject deals with temperature).

So energy can be measured in temperature. Now, you have to understand that sound is its own form of energy. Energy moves in waves, sound does as well. We can’t hear energy move normally – the human ear isn’t equipped to pick up those waves. But a radio can – so we can hear background energy. So we hear background energy as static sound and we can measure the amount of energy in temperature. And from our thermodynamic discussion, you know that less energy means a colder temperature. The pulse from the Big Bang has lost lots of energy since the Big Bang, therefore it’s very, very cold when you measure the temperature – close to absolute zero, which is when there’s no energy in a system at all anymore. This is also a reason scientists believe that the static noise on radios is the pulse of energy emitted at the beginning of the Big Bang.

If the actual levels are 71% and 28% now, what do the original 76% and 24% amounts represent?

The original amounts represent the state before stars started their reactions – this is explained more in chapter 2. Basically, without gravity and stars, the amounts would still be 76% and 24%.

Why in the world would one part of the universe have a concentration of other elements?

Gravity is the answer here – more details in chapter 2.

I won't ask whether this concentration is related the fact that we live here, since he already indicates that this will be discussed more in chapters 2 and 3.

You didn’t ask, but I’ll answer anyway. Yes, this concentration is related to the fact that we live here, but probably not in the way you think. The concentration is not different because we live here, but the other way around. We live here, because the concentration is different here – without such a high concentration, we would not even have a planet to live on, let alone exist ourselves.

But wouldn't the big bang have dispersed matter evenly throughout the universe?

More details about this in chapter 2, but the short answer is no.

Another piece of evidence - which I think is weak - no dating method has ever identified anything as being older than about 12 billion years. He says it would be surprising for there to be anything older than that since we haven't detected it, but I think that is inconclusive.

Inconclusive – perhaps. Truly, this goes back to how science works and has worked for hundreds of years. A theory (which is an explanation that fits with all the known facts) is true until it is proved false. When doing research, you’re always pose a hypothesis (your theory) and then try to find evidence against it. With experiments you can either a) find more facts that fit your theory (making it likely true – but you can never be sure) or b) prove you theory was not correct by finding evidence against it. So in science, we can only ever say with 100% certainty that something is not true, but never with 100% certainty that it is. However, the more evidence we have for a certain theory (the more facts that fit without facts that don’t), the likelier the chance is that we are correct.

By looking at distant objects in the universe, we are actually looking at something that occurred long ago when the light we're seeing now first left the far-away object. Nearer objects are seen more quickly. And it is true that older light shows a different scene than more recent light. I think this point is very cool.

I think this is very cool as well – seeing a star being born in the night’s sky (or die) and realizing it happened thousands of years ago? That’s indescribable.

The universe is flying apart faster and faster? That isn't consistent with Big Bang which would have the rate of expansion slowing down before eventually collapsing. (Did I get that right?)

Yes, you got that right. Measurements have the universe expanding faster, while the Big Bang theory predicts the expansion rare should slow down due to less energy available for expansion.

Summary of information in chapter one only took 90 seconds to read. I just spent nearly 3 weeks trying to absorb the same information!

Ah, but you only understand the summary because you understand the material in the chapter – otherwise it would just be a pretty, but meaningless, story.

This list of further reading - is there anything here you would recommend?

I have not read any of these books, but Primal Myths by Barbara Sproul sounds really interesting – although that’s more mythology/creational myths than this kind of science. I’ve heard good things about Stephen Hawking, knowledgeable and readable are often words connected to him. If you decide to read him, I’d go for his latest book, because that should have the most up to date information – lots of new things have been discovered in the last few years. Life of the Cosmos by Lee Smolin sounds like it’s looking at the universe with the view of a biologist.
Just a side note though, I would wait to read any of the suggested books until you’ve finished this one – all books he mentions (except perhaps Primal Myths) will go much more in depth on topics than this one. So this book is a good primer for them.

Well, it looks like you’re ready to tackle chapter 2! I found it to be an easier read than chapter 1, because it deals with stars and galaxies, which are more logical and the human mind is much more able to grasp their concepts. Also, because they are there (as opposed to the Big Bang, an event that happened billions of years ago) scientists can do more measurements and the theorizing is based on better (more) experimental evidence and observations.

28Samantha_kathy
Mar 17, 2012, 1:39pm Top

RE: your ETA. I'd already finished my response to your questions, but bolding them does make them easier to see. And like I said, I think chapter 2 will be easier for you.

29sjmccreary
Mar 17, 2012, 9:29pm Top

I haven't looked ahead yet to later chapters, but I've been hoping they would get easier as we go. I'm glad to hear that you think that it will work out that way.

I'd still like to watch a demonstration of emission spectrum. I wonder if I could find one on YouTube?

Tiny universe - where do we hide the planets? It makes more sense the way you explain it than the assumption that they were talking about pre-Big Bang.

I think it's interesting that Hoyle dismissed the big bang because it resembled creationism, but the scientific community as a whole was slow to accept the same theory because it was hard to fit into an explanation that included God.

Thermodynamics again. Great. So, as the pulse of energy continues to dissipate, its temperature will approach absolute zero? And then the static goes away? Unless the static is not energy from big bang, in which case it will remain unchanged.

I figured that the concentration of other elements here might be the reason we are also here. Does that imply that the chances of intelligent life elsewhere is nonexistent?

I'll just make a note about which books you've suggested and then decide which, if any, I'm interested in reading after finishing this one.

30Samantha_kathy
Mar 18, 2012, 9:04am Top

So, as the pulse of energy continues to dissipate, its temperature will approach absolute zero? And then the static goes away? Unless the static is not energy from big bang, in which case it will remain unchanged.

Correct. Unfortunately, the dissipation of this energy is so slow, it will take many human lifetimes to measure if it is truly dissipating - no definitive answer for a while yet!

I figured that the concentration of other elements here might be the reason we are also here. Does that imply that the chances of intelligent life elsewhere is nonexistent?

No, it implies that intelligent life is only possible in 'pockets' of high concentrations of elements - something that is talked about in more detail in the next chapters.

I'll just make a note about which books you've suggested and then decide which, if any, I'm interested in reading after finishing this one.

When we're done with this book and you decide to read another one, I'd be happy to tutor you should you want it.

31sjmccreary
Mar 18, 2012, 12:48pm Top

When we're done with this book and you decide to read another one, I'd be happy to tutor you should you want it.

Thanks! :-)

32sjmccreary
Mar 18, 2012, 2:29pm Top

I've reading back over the posts covering chapter one - what really stands out is my reluctance in accepting as true scientific theories that can't be proven. You've explained over and over - very patiently - how in science an explanation which seems to address all the known facts is put forth and then everyone tries to prove or disprove it. You said that the only thing which can be know for certain is when something is wrong. I'm an accountant, and that is simply not the way things are done in my world! I don't know whether it is the years of training/indoctrination in the world of business, or whether it is an innate predisposition towards one way of thinking, but I see that I will need to make an additional effort not to get hung up on the way scientists work and think, and concentrate more on what they are learning instead.

33Samantha_kathy
Mar 18, 2012, 3:09pm Top

It's a pretty backwards way of working, and one which mathematicians and statisticians (who I as a biologists sometimes work with when (trying to) interpret results and generalize trends by building models) have a real problem with as well, despite the fact that . Their world is one in which 1 + 1 is always 2. And you can prove that's true.

Even so, it's hard for a lot of people to understand that you can prove something wrong, but not truly prove something right in science. It's often explained to biology students by the following example:

Take the statement "all swans are white". You can never prove this is true, because you can never see and check each and every swan in the world. So while every swan you see is white - it could be that there's a swan of another color. Yet people will believe you if you say "all swans are white" because they have no prove otherwise. (Incidentally, we know know this statement is false, because there are black swans - it just took us a while to find them).

The same can be said of the statement "the sun rises each morning". So far it has, yes. But we can never say this statement is 100% true, because we cannot look into the future and see that the sun will rise each and every morning. Yet everybody will accept "the sun rises each and every morning" as true, until the day it doesn't happen. That's the way (almost) all science works.

Perhaps these examples will help you understand and accept the concept.

34sjmccreary
Mar 21, 2012, 9:42am Top

I won't say it's a backwards way of working - it's just a different kind of job that's being done from what I do and the mathematicians and statisticians do. For us, 1 + 1 always equals 2. For you - eh, maybe not. And that is how you make the amazing discoveries that you do. There aren't so many amazing discoveries going on in accounting these days!

35sjmccreary
Mar 21, 2012, 10:37am Top

Moving on to chapter two.

ORIGINS OF THE GALAXIES AND STARS
The Beginnings of Complexity

This was an interesting and informative section. Stars "are the most important inhabitants of our universe." (pg 39) They "gather into the huge cosmic societies we call galaxies each of which may contain 100 billion stars." (The rest of this was new to me.) There are "communities" of galaxies called groups (20 or so galaxies, and millions of light-years in diameter) and clusters (hundreds or thousands of galaxies, and up to 20 million light-years across). These groups are, of course, held together by gravity. (I knew that.) "But there are even larger structures, structures so large that they are stretched out by the expansion of the universe." Super-clusters contain 10,000 galaxies and are up to 100 million light-years wide. At this large scale, the universe "appears to be remarkably homogeneous" - the "complex patterns" that we are interested in are apparent only at scales smaller than the super-clusters. Despite the existence of these enormous structures, "most of the mass of the universe (90 percent or more) is not visible, and the exact nature of this mass (known appropriately as dark matter) remains a mystery." (pg 41)

Q - I enjoyed the way he wrote this in an active voice - the stars are out there doing things, coming together in communities, not just floating around in the night sky. Is this anything more than a literary device? Is the fact that stars have wound up in these groupings of various sizes, and groups within groups, due to anything other than randomness? Is it any different than the way twigs and foam collect in certain places along the banks of a stream, and not in others?
- The very large structures he mentions "include super-clusters". What other kinds of large structures are there?
- The "fact" that patterns are not visible at the largest scales of the universe - is that a case of us not being able to see enough on a larger scale to be able to discern patterns? Or can we see clearly enough to be confident that there are no patterns to be seen? I find it hard to believe that, with as many patterns as there are at every other scale of creation, there wouldn't also be universal patterns.
- I think I've heard of dark matter before. Why isn't it visible? Is this the same as the black holes? 90% of the mass of the universe is a lot. Considering all that we can see, why do they think there is so much more that is hidden?

36Samantha_kathy
Mar 21, 2012, 2:45pm Top

So, do you think this chapter is easier reading than the first one?

I enjoyed the way he wrote this in an active voice - the stars are out there doing things, coming together in communities, not just floating around in the night sky. Is this anything more than a literary device?

It’s both a literary device and there’s more to it. There’s no conscious decision from stars to cluster together – not like with us humans. But the analogy of calling the clusters communities was not just used by the author because it sounds nice (which is what a literary device usually is about). He uses these terms to show the reader the patterns that occur at every level of existence – from the stars in our galaxies, to humans and animals, to our genes. There are ‘communities’ of stars – called galaxies, there are communities of humans – called cities, there are ‘communities’ of genes – called gene clusters. When you refer to them all as communities, you start to see the general pattern of life, which is what Big History is all about.

Is the fact that stars have wound up in these groupings of various sizes, and groups within groups, due to anything other than randomness? Is it any different than the way twigs and foam collect in certain places along the banks of a stream, and not in others?

The fact that stars have wound up in these groups is not randomness, it’s due to gravity. Gravity pulls planets in orbit around stars, but it also puts stars in ‘orbit’ around the center of galaxies (black holes), and so on. All these groupings are formed due to gravity.

This is quite different from the way twigs and foam collect in certain places along the banks of a stream. Here, the places where they collect are low-flow parts of a stream – the water flow slows down (usually because of certain landscape elements) and then the water loses its grip on the twigs.

When looking at orbits of for instance planets, there’s no slowing down of ‘water’, instead gravity pulls a moving object in a steady orbit. Basically, instead of racing along on a straight highway (kind of like comets, who have no gravity pulling them into orbit as they hurtle through space), the planets are bound to ride circuits on a racetrack.

I hope that made it clearer as to the difference between the two situations, and not worse :D.

The very large structures he mentions "include super-clusters". What other kinds of large structures are there?

Well, you’ve got the “Great Wall”, which is a ‘wall’ of galaxies more than 500 million light years long and 200 million light years wide, but only 15 million light years thick. Recently they discovered another one of those great walls, called the “Sloan Great Wall”.

Voids – the space between galaxies – also count as large structures. In August 2007, a possible supervoid was detected in the constellation Eridanus. And the “Newfound Blob”, a collection of galaxies and enormous gas bubbles which measures about 200 million light years across, also counts as a large structure but is not a true super-cluster.

The "fact" that patterns are not visible at the largest scales of the universe - is that a case of us not being able to see enough on a larger scale to be able to discern patterns? Or can we see clearly enough to be confident that there are no patterns to be seen? I find it hard to believe that, with as many patterns as there are at every other scale of creation, there wouldn't also be universal patterns.

Hmm, compare the universe with looking at the Atlantic Ocean from space. All you see is a large, blue mass that looks perfectly homogenous – all the same. It is only when you zoom in, say, look at it from an airplane, that you begin to see lighter and darker blue – shallower and deeper water. If you zoom in more, say, looking at the Atlantic ocean from a boat, you can see calm water and waves, and larger animals. If you zoom in even more, say, pull up a bucket of water and look at it with a magnifying glass, you can see tiny animals within it and no bucket you pull out will be the same. Zoom in even more – a drop of water under a microscope – and you will see tiny microscopic animals – a huge diversity in every drop.

That drop would be like looking at a solar system. Looking at a bucket would be comparable with looking at a galaxies, looking from a boat would be the level of galaxies, and the airplane would be looking at clusters of galaxies. Looking from space is like looking at the entire universe – you see one homogenous mass. The patterns that are there get lost – to see them you need to zoom in, but by zooming in you can no longer look at everything. Even from an airplane you cannot see the entire Atlantic ocean.

I think I've heard of dark matter before. Why isn't it visible? Is this the same as the black holes? 90% of the mass of the universe is a lot. Considering all that we can see, why do they think there is so much more that is hidden?

Dark matter is kind of well known (but don’t confuse it with anti-matter, made (in)famous in science fiction, both in books and on tv and in movies), so it’s not surprising you’ve heard of it.

Dark matter is not the same as a black hole at all. A black hole is a space where gravity has such a large pull on matter that it is scrunching up the matter in such a small space that even light photons get squashed – that’s why the dark hole is dark, even light cannot escape gravity’s pull to be seen by us.

Dark matter neither emits light (thus it cannot be seen directly, like say the sun) nor absorbs light (like a black hole, so we can see it because the light is absent where it should be), or other electromagnetic radiation. So we can’t see dark matter. We know there is dark matter, because there are discrepancies between the mass of large astronomical objects determined from their gravitational effects, and mass calculated from the "luminous matter" they contain – in other words, to behave as they do within the confines of gravity, the need to consist of more mass than we can see. Therefore, there has to be mass we can’t see – dark matter. If we calculate how much matter we can’t see that should be there, we get that 90% figure.

A little extra for this chapter - probably best viewed when you've read the next part of this chapter "The early universe and the first galaxies"



The galaxy NGC 4414, about 60 million light-years from our own Milky Way galaxy. The picture was taken with the Hubble telescope. It shows that the central regions of this galaxy, as is typical of most spirals, contain primarily older, yellow and red stars. The outer spiral arms are considerably bluer due to ongoing formation of young, blue stars, the brightest of which can be seen individually at the high resolution provided by the Hubble camera. The arms are also very rich in clouds of interstellar dust, seen as dark patches and streaks silhouetted against the starlight.

37sjmccreary
Mar 22, 2012, 11:05am Top

Yes, so far the reading has been easier in chapter 2. I'm gaining back some of the confidence I lost in chapter 1. I was very aware, as I began chapter 2, just how helpful it has been having you here to answer questions. I don't know how far I would have gotten if I were totally on my own with this material. Thanks for taking the time to answer my questions and explain things to me. Sometimes more than once (*cough* thermodynamics).

The patterns - I understand now what he is doing. I remember seeing someplace in regards to this book that it is all about the patterns of life and creation. Tangent: A few years ago, my two oldest sons moved away to go to school. I wanted to get them each a book that they could read and enjoy and remember. There was a thread here on LT somewhere about the books people read as young adults that had the biggest impact on them. It was a great starting resource. For my second son, Mark, I chose Catch-22 - he is very concerned with the way people deal with one another and behave in groups. But for Bill (the same kid who was watching the TV show about the birth of stars I told you about before) I chose Godel, Escher, Bach by Douglas Hofstadter. One of the comments on that LT thread was that that book taught the reader how to see patterns in life - the ways that everything is connected or related. I thought he would enjoy that. He had just decided to change his major to biology. It was slow going for him, on top of reading for school, but I think he did enjoy it. It has ended up back in my house for now and I thought about reading it for myself. Are you familiar with it?

Pressing on. Stars are pulled into groups by gravity, twigs are snatched out of the stream by rocks or deadfall. Not the same thing.

I've never heard of any of these large structures - are they mentioned again in this book? Are they recent discoveries? "Newfound Blob" - I thought the people who discovered new things got to name them (after themselves, usually, right?), what happened in this case? More seriously, though, is the discovery of these structures going to have any implications on science's understanding of the origin of the universe?

Dark matter is still confusing, but I think it is discussed a little more later on in the chapter, isn't it?

That is a beautiful photo - and since I had already finished reading the next section (just not my comments and questions), I didn't hesitate to thoroughly enjoy it right away!

38Samantha_kathy
Mar 22, 2012, 11:24am Top

No, I'm not familiar with either of the books you mention, although the title Catch-22 does seem familiar, I am sure I've never read it before.

Stars are pulled into groups by gravity, twigs are snatched out of the stream by rocks or deadfall. Not the same thing.

Absolutely correct!

I've never heard of any of these large structures - are they mentioned again in this book?

No, at least, not in the second or third chapter, and after that we zoom in to life on Earth, so I highly doubt there is any mention of that in the rest of the book.

Are they recent discoveries?

Yes, most of them are pretty recent - in the last decade - although some are known a little longer. The Hubble telescope's pictures that started pouring in in the 90s really were a big jump forward in discovery of space.

"Newfound Blob" - I thought the people who discovered new things got to name them (after themselves, usually, right?), what happened in this case?

Ah, if I look at the names astronomers have given gorgeous things like some of the nebula's, I'm not really surprised by "Newfound Blob". Other than that, I've got no clue what happened there.

One common misunderstanding I want to clear up though is the fact that naming things after yourself is not done. In biology (and I assume in other disciplines) it's actually forbidden to name things after yourself - this to prevent people from discovering "new things" (which turn out to be not-so-new things, but just something a tiny bit different than the norm) in order to have something named after themselves. Mostly, the things that are named after someone were named after that person in honor of that person, but not by that person himself/herself.

More seriously, though, is the discovery of these structures going to have any implications on science's understanding of the origin of the universe?

On the origin not so much, but it does have implications on things like dark matter and how things work exactly. It's a bit like trying to understand a car engine. Before these recent developments we only had a car engine from a car that's about 50 years old, not we have a car engine from the most recent model. Both still work on the same principle, but we can understand the recent model much better because there's more detail. (Okay, that analogy is a bit wonky, but you get the picture, I hope).

Dark matter is still confusing, but I think it is discussed a little more later on in the chapter, isn't it?

If I remember correctly, it is. If you still have the questions at the end of chapter 2, go ahead and ask them. Or just ask them now, doesn't matter to me either way.

39sjmccreary
Mar 22, 2012, 12:14pm Top

Catch-22 is a novel set in WWII and is a hilarious look at the bureaucratic mess that can be cause by something like an army. There was a movie based on the novel. I'm not doing it justice, but I liked it very much. (I already took Mark's book and read it - Bill's I'm not so sure about.)

Thanks for the clarification on the naming of newly discovered objects. Who decides the name, if not the discoverer?

I'll wait until I've read the section that talks about dark matter before I think about what questions I have. I'm still working on my comments/questions for the early universe/first galaxies section.

40Samantha_kathy
Edited: Mar 22, 2012, 12:22pm Top

Well, the discoverer does decide the name, and then it is approved by a commitee (which one depends on what the discovery is), but the discover just can't name it after himself/herself.

Edited to remove a spelling error.

41sjmccreary
Mar 23, 2012, 2:08am Top

Next section - this is a long one.

The Early Universe and the First Galaxies

In the first minutes, the universe cooled so rapidly that only the simplest elements were formed: hydrogen, helium, and small amounts of lithium. (Numbers 1, 2, and 3 on the periodic table, appropriately.) "From a chemical point of view, the early universe was very simple." (pg 41) But the first simple stars that were formed "turned hydrogen and helium into all the other elements of the periodic table" in their super-hot cores.

Here is where gravity is introduced. As explained by both Newton and Einstein, gravity is the force that pulls things together, counteracting the big bang energy that is driving things apart. Gravity affects energy as well as matter. Not surprising, since Einstein showed that "matter is really a sort of congealed energy". This constant "pulling on both matter and energy" (pg 42) is what caused the universe to develop a shape and structure. According to Newton, gravity has a greater effect on items closer together, and on items that have greater mass, but "less impact on light, fast-moving objects that carry energy, and thus it shapes matter more effectively than energy". As a result, gravity has created a number of different structures at different scales. This can seem to run counter to the 2nd law of thermodynamics ("the universe will become less ordered and less complex"). The pushing and pulling between the opposing forces of the big bang and gravity has resulted in large scale expansion and smaller scale clustering. But gravity only works if there are differences in the environment - if the big bang had distributed the hydrogen and helium of the early universe absolutely uniformly, then gravity could not have been able to pull together the lumps needed to form stars and other complex objects. (And thus answering the question I asked back in chapter one.)

And speaking of Bill just above, here is how stars are born: clouds of hydrogen and helium collapse in on themselves (gravity) and are packed tighter and tighter, increasing the pressure at the center of the mass thereby raising the temperature. Inside these clumps, there were smaller areas of higher density and more extreme heat. These hot pockets were the "nurseries" that gave birth to the first stars.

This is the point in the section where I began to have questions, although some of the first questions I noted were answered in later paragraphs, so I won't ask them again here. First came the explanation of nuclear fusion - the clearest explanation I think I've ever read. As the temperature rises, the atoms move faster and faster until they are finally able to overcome the natural repulsion between the positively charged nuclei and join together, becoming something else. The more positively charged protons, the higher the temperature needed to accomplish this fusion. Hydrogen atoms, the smallest and simplest of all the elements with only 1 proton each, require a temperature of 10 million degrees C to become helium, with 2 protons per atom. More complex elements require even higher temperatures. (That is mind-boggling.) When this fusion occurs, a tiny amount of mass is lost and converted into an enormous amount of energy - the basis of the hydrogen bomb. This was explained with Einstein's famous formula, E=mc2, in which E = the amount of energy that is generated from the lost mass = m. The heat and energy generated in this fusion reaction resists gravity (is that the same thing Newton was saying above? That gravity has "less impact on light, fast-moving objects that carry energy, and thus it shapes matter more effectively than energy"?) So, the force of the nuclear explosions counteracts the force of gravity and stars become stable, durable structures.

“The lighting up of the first stars was a momentous turning point in the history of the universe, for it marked the appearance of a new level of complexity, of new entities operating according to new rules.” (pg 44). And it seems that the change happened in a moment – the exact moment when “a slight increase in temperature ignited fusion reactions through-out the core of the proto-star, thereby transforming gravitational energy into heat energy and creating a new and more stable system of energy flows.”

Q - Pause here for a moment – what does that last phrase mean, exactly? Beginning with “transforming gravitational energy into heat…” It was the excessive heat that cause the fusion in the first place – does even greater heat result? And what is the new system of energy flows?

Continuing in the same paragraph, “This, we will see, is the characteristic pattern of all such thresholds. New configurations emerge quite suddenly as once independent entities ar drawn into new and more ordered patterns, held together by an increasing throughput of free energy.” (pg 45) Followed by another mention of the 2nd law of thermodynamics – complexities eventually break down and die, but simpler structures live longer. Stars live longer than humans.

Q – I get the point he made in the quoted sentences – I’ll expect to see a pattern of thresholds throughout history when a leap forward occurs suddenly. But I don’t understand that last bit – “held together by an increasing throughput of free energy” – what is he saying here?

Moving on. Some of the oldest stars are still in existence – most inhabiting the centers of galaxies, as in the photo you posted, or in the globular clusters which orbit the galaxies. These early stars can be detected “by their erratic orbits”. The erratic orbits may be caused in part by the merging of early galaxies together. (Resulting in unpredictable centers of gravity?) They are also lacking any elements heavier than hydrogen or helium, since those were the only elements available at the time the first stars were formed.

Q – So the very oldest stars will generally be found in the very centers of galaxies, or far outside of them, in the globular clusters – right? If the old stars are mostly hydrogen and helium, the lightest elements, and gravity exerts greater force on objects with greater mass, then why will those old (lighter) stars be found at the center of the galaxies where the gravitational force is greater? And why would the other significant concentration of old stars be at the outermost reaches of a galaxy? Why not in-between? If not all in one relative location, then why aren’t they scattered evenly throughout the galaxies?

The text then goes on to explain how gravity has sculpted the galaxies into remarkably similar shapes – mostly variations of a spinning disk. Solar systems within galaxies are also disk-shaped. These regularly shaped galaxies were already in place by the time the 2nd generation stars were born. New stars are continually being formed – about 10 per year in the Milky Way.

Q – These flat, disk-shaped galaxies – are they all on the same plane, or on parallel planes? Or are they on randomly situated planes, pointing every which way? What about the solar systems within a single galaxy? How many generations of stars, roughly, have there been? Are there distinguishing features between them, too? Or is the 1st generation the only one which is easily identifiable?

The rest of the chapter consists of 4 more comparatively short sections. I'll work on them this weekend while I'm out of town and away from the internet. Hopefully I'll be able to post comments & questions about at least a couple of them by Monday.

My daughter (age 21, a painter and majoring in art & psychology) has been asking for regular updates on my progress (or lack thereof) in this book. We have a TV show in the US that is very popular called "The Big Bang Theory" about a group of geeky physicists who live together. (Do you get it there?) It's very funny. I told her that the theme song was what my book is about. (http://www.youtube.com/watch?v=lhTSfOZUNLo) So then she asked when I would be reading about the alien life forms. *sigh*

Have a great weekend.

42Samantha_kathy
Mar 23, 2012, 3:32pm Top

The heat and energy generated in this fusion reaction resists gravity (is that the same thing Newton was saying above? That gravity has "less impact on light, fast-moving objects that carry energy, and thus it shapes matter more effectively than energy"?)

Yes, it’s what Newton is saying in practice – although this is one example and Newton was speaking in general terms.

Pause here for a moment – what does that last phrase mean, exactly? Beginning with “transforming gravitational energy into heat…” It was the excessive heat that cause the fusion in the first place – does even greater heat result? And what is the new system of energy flows?

Okay, you know that the extreme heat – created by packing matter tighter and tighter together, which was caused by gravity – caused the fusion. The fusion itself is what is called an exothermal reaction – a chemical reaction that releases energy in the form of heat or light. Fusion releases energy in the form of heat, and it does so because the new molecule needs less energy to stick together than the two old ones did, so when they fuse there is excess energy – released as heat here. So gravitational energy is transformed into heat energy. As you’ve seen in chapter 1 (or at least, our discussions about thermodynamics) heat is a form of free energy.

Because fusion itself creates heat, and gravity is still working on the star, the core temperature of a star remains at the needed temperature to keep further fusion going, creating heat again, etc. This system – stable fusion, something we still have not really realized here on Earth – is a stable system (as long as there is fuel, as you’ve probably already read), and the energy flows within and through this system are more stable. Input and output of energy remain the same over a very, very long time. The input is the heat needed for the fusion, the output is the heat created by it.

I get the point he made in the quoted sentences – I’ll expect to see a pattern of thresholds throughout history when a leap forward occurs suddenly. But I don’t understand that last bit – “held together by an increasing throughput of free energy” – what is he saying here?

Well, a star needs a lot of free energy to be able to ‘function’ (i.e. perform fusion reactions in its core), but the same reaction also releases a great deal of free energy. In almost everything ordered there’s such a balance of input and output of free energy – the throughput he’s talking about. But (and here I go with biological examples again) a single-cell organism needs little free energy to function and also has a low output of free energy when it’s digested, a cow needs more free energy to function, as it’s more complex, but when we humans digest a cow we get far more free energy from it (that we need to function as well – and a lot of it!) than if we were to digest a single-cell organism. That’s what he means with the fact that more ordered patterns are held together by an increasing throughput of free energy. (If it’s still not clear, let me know, and I’ll try to explain in another way)

The erratic orbits may be caused in part by the merging of early galaxies together. (Resulting in unpredictable centers of gravity?)

No, there are no unpredictable centers of gravities. But mergers are very violent. Imagine you’re a star, circling your center of gravity in a nice elliptical orbit. And then “crash-boom” your whole world shifts, because another galaxy has crashed into yours. There’s a new center of gravity for you to circle around, but you legs are a little wobbly, so instead of the nice, elliptical orbit you had before, your orbit is now a bit erratic.



Above: picture of a computer simulation of the merging of two galaxies.

So the very oldest stars will generally be found in the very centers of galaxies, or far outside of them, in the globular clusters – right? If the old stars are mostly hydrogen and helium, the lightest elements, and gravity exerts greater force on objects with greater mass, then why will those old (lighter) stars be found at the center of the galaxies where the gravitational force is greater?

Yes, the oldest stars are near the centers of the galaxies, where the center of the gravitational force is now. Don’t forget – the centers of gravities are black holes, they pull everything towards them. Back when there were only old stars – in the old star’s ‘youth’ when the new kind of star wasn’t possible yet – they got pulled towards the center of the galaxy. Then, when other elements had appeared, a new kind of stars began to emerge. The old kind is not made any longer, so by the time we’re looking at the galaxy, all the old stars that are left have already moved toward the black hole, while at the edge new stars appear of the new kind. So even though they have more mass, the old stars had a head start to the center of the galaxy, so to speak.

And why would the other significant concentration of old stars be at the outermost reaches of a galaxy? Why not in-between? If not all in one relative location, then why aren’t they scattered evenly throughout the galaxies?

The other significant concentration of old stars is at the outermost reaches of the galaxy because they escaped the clutches of the black holes that are now the centers of our galaxies. So basically, gravity or the lack thereof contributed to their distribution. In-between isn’t really an option with gravity – either you are in reach or you are not.

These flat, disk-shaped galaxies – are they all on the same plane, or on parallel planes? Or are they on randomly situated planes, pointing every which way?

They are pointing every which way, basically. In fact, the Milky Way has another galaxy called the Sagittarius Dwarf Elliptical Galaxy (SagDEG) that is orbiting it almost at right angles – and in the next 100 million years it will collide with the Milky Way galaxy for what is probably the 11th time.



Above, picture of the orientation of the Milky Way (the horizontal disk, position of our sun is indicated) and the SagDEG (the vertical disk).

What about the solar systems within a single galaxy?

Same thing – any which way. Orientation of the discs are dependent on the direction of the angular momentum the system (whether galaxy or solar system) had when it formed, and that’s pretty much random. Our own solar system is tipped by about 63 degrees with respect to the plane of the galaxy.

How many generations of stars, roughly, have there been? Are there distinguishing features between them, too? Or is the 1st generation the only one which is easily identifiable?

There are three generations of stars that we can identify, mainly by their metal content compared to their hydrogen and helium content (their metallicity). The older stars have less metal in them than the younger groups – because in the beginning there were almost no other elements except hydrogen and helium.

To make things a bit confusing, the star generations were named in the order they were discovered, which is the opposite from how old they are. The youngest stars are therefore called Population I, then we have Population II, and Population III are the oldest. There’s never been a Population III star observed – all of them have (most probably) already burned out or gone supernova because they burned through their full so fast.

Extra for this chapter – The Periodic Table

I have no idea how much you know about it, so a quick rundown, as I’ve got the feeling this might be valuable knowledge later on – and even if it isn’t, it’s not bad to know it anyway. Below is a picture of the periodic table as it is known now.



The elements are left to right in sequence of their atomic number, with a new row started after a noble gas. The first element in the next row is always an alkali metal with an atomic number one greater than that of the noble gas. All elements from atomic numbers 1 (hydrogen) to 118 (ununoctium) have been isolated. Of these, all up to californium exist naturally; the rest have only been artificially synthesized in laboratories

The weight or mass of atoms of an element (their atomic weights or atomic masses) do not always increase monotonically with their atomic numbers. For instance tellurium, element 52, is on average heavier than iodine, element 53.

********

So, that’s it for the answers. During the next few weeks I’ll be pretty busy, so answers might not be as fast – although I’ll try to do it as fast as I can.

We receive “The Big Bang Theory” here, although I don’t really watch it. I’ve seen bits of it though. It’s appropriate for the first few chapters of the book though :D.

Have a great weekend as well!

43sjmccreary
Mar 27, 2012, 5:33pm Top

Take your time answering my questions - it's not like I've been burning things up with this book. Although I HAVE finished chapter 2!

Input and output of energy remain the same over a very, very long time. The input is the heat needed for the fusion, the output is the heat created by it. -- is this an illustration of the first law of thermodynamics? And here, too? In almost everything ordered there’s such a balance of input and output of free energy

Erratic orbits of stars in merging galaxies - comes from change in center of gravity to a new fixed point?

The weight or mass of atoms of an element (their atomic weights or atomic masses) do not always increase monotonically with their atomic numbers. For instance tellurium, element 52, is on average heavier than iodine, element 53. Do I really need to understand this? I was just beginning to think I was getting the hang of this chemistry, understanding how hydrogen atoms turned into helium and so on. So, why don't the mass of the atoms increase according to their atomic numbers? Why isn't that number an indication of mass, since it is an indication of the size of the nucleus? (isn't it?)

The rest of chapter 2 went pretty well, although I will have several questions on the section containing quasars and dark matter. But not right now.

44Samantha_kathy
Mar 28, 2012, 4:04am Top

Input and output of energy remain the same over a very, very long time. The input is the heat needed for the fusion, the output is the heat created by it. -- is this an illustration of the first law of thermodynamics? And here, too? In almost everything ordered there’s such a balance of input and output of free energy.

Yes and no. Yes, because no energy is lost in these examples, but also no, because the output of free energy is not necessarily the same amount as the input. So it can be in balance and remain the same over a long period of time, but that does not mean it is equal.

Erratic orbits of stars in merging galaxies - comes from change in center of gravity to a new fixed point?

As far as I have always understood, yes. Might be a bit more complicated than that when you start looking at the details, but I think this is the basic idea.

Do I really need to understand this? I was just beginning to think I was getting the hang of this chemistry, understanding how hydrogen atoms turned into helium and so on. So, why don't the mass of the atoms increase according to their atomic numbers? Why isn't that number an indication of mass, since it is an indication of the size of the nucleus? (isn't it?)

Needing to understand it - no, probably not. But it's not so difficult. The atomic number indicates the amount of protons in the nucleus, but an atom consists of protons, neutrons and electrons (protons and neutrons in the nucleus, electrons orbiting the nucleus). So the mass of an atom is the sum of the mass of the protons, neutrons and electrons. Therefore the atom number is not the same as the mass.

45sjmccreary
Mar 29, 2012, 7:07pm Top

The atomic number indicates the amount of protons in the nucleus -- Ok, and there are the same number of electrons as protons, right? So the reason why mass would not directly correspond with atomic number would be because of a variation in the number of neutrons. If that is the case, then what determines how many neutrons are in each atom on an element? Is it possible for two different atoms to have the same number of protons but different numbers of neutrons? In any event, thanks for the reassurance that I don't need to have a commanding understanding of this concept. The Periodic Table is so appealing - so neat and orderly - just like an accounting spreadsheet! I just never know what to do with it.

I'm going to post my last few comments/questions about chapter 2 and then move on to chapter 3. I'm looking forward to picking up the pace as we go farther into this book. Eventually, we will have to come across something that I already know, don't we?

BTW - thanks for the new vocabulary word: monotonically. I grasped its meaning from the context, but went back and looked it up for a better understanding. I don't think I've ever heard it before and I hope I can remember it if I ever get the chance to use it in an actual sentence!

46drneutron
Mar 29, 2012, 7:28pm Top

Pardon my jumping in...

Actually you can have atoms with the same atomic number and different numbers of neutrons. They're called isotopes. For instance, the most common form of carbon is carbon-12, 6 protons and six neutrons. Another isotope is carbon-14, six protons and eight neutrons. Both are carbon, but have different mass. Another example is hydrogen, deuterium and tritium, which have zero, one and two neutrons respectively, along with one proton.

47sjmccreary
Mar 29, 2012, 8:52pm Top

A Cosmological Menagerie: Black Holes, Quasars, and Dark Matter

The centers of most galaxies have a greater density, and greater gravitational force. These densities can become so great that the clouds of gas and matter collapse, despite temperatures high enough for fusion. This collapse can crush "matter and energy out of existence" (pg 46). This is how black holes are formed - regions so dense that nothing can escape them, not even light. This is all very familiar. But the next part...

There is speculation that a black hole is what a new universe looks like from the outside. The incredible density and heat might ignite another big bang inside the black hole which would form a whole other universe. The fact that everything in our universe is precisely arranged to create stars and other complex structures may be because it is descended from a parent which passed along these traits. Just like Darwinian evolution, those universes successful in producing black holes lead to more universes also like themselves. However unlikely the development of a black hole might be, it will become a dominant trait among universes because it is the only way for universes to multiply. If this is true, a "hyper-universe" could exist which is far older than the 13 billion years of our universe.

Q - This sounds more like science fiction than real science! Is this really a viable theory?

-------------------------------------------------​

The presence of black holes at the center of most galaxies helps to explain the presence of quasars. Quasars are the brightest objects in the universe - "they shine more brightly than even the largest galaxies, though they are no larger than our solar system." (pg 47) They are also very far away (2-10 billion light years), so what we can see is from the early days of the universe. But here is the part I don't understand:
Currently, it seems likely that their energy comes from huge black holes that suck in large amounts of matter from the galactic material surrounding them. Quasars thus consist of black holes plus star food. Quasars were particularly numerous early in the life of the universe, because at that time galaxies were crowded more closely together, and black holes were better fed. Since then, the universe has expanded, galaxy clusters have moved farther apart, and the pickings have become leaner for galactic black holes. So, though most galaxies may still have black holes at their centers, few of these beasts now consume enough to create quasars.

Q - It sounds like a quasar is so big that it actually contains a black hole - but what is the additional "star food"? ("Big" doesn't sound like the right word to use to describe a quasar - "dense"?) It has so much fuel that it burns very quickly and is rare in the current universe - because modern black holes don't capture enough matter/energy to sustain a quasar. I thought black holes were so dense that even light cannot escape. How is it, then, that a quasar, which contains a black hole, is one of the brightest objects of all?

-------------------------------------------------​

Scientists have concluded that only 10% of the matter in the universe may be visible, and that total may even be as small as 1%. The explanation of this "dark matter" is exactly as you gave it back in #36. The gravitational force emitted by some objects is too much to be accounted for by its visible matter. There must be more. Two theories are presented here. "First, it may consist of tiny particles, each smaller than electrons but collectively more massive than all other forms of matter." Such a particle might be the "neutrino" - which might be so small as to have no mass at all, but it is certainly no bigger than 1/500,000th the mass of an electron. But there are so many of them that, if they were visible, "the universe would seem like a huge neutrino fog, contaminated by tiny specks of matter." (I love that image.) The other possibility is that might be many large but invisible objects. Something that does not emit light or other radiation - like corpses of stars. A third suggestion has recently been made - the dark matter might really be dark energy. The "vacuum energy" which is causing the expansion of the universe to accelerate might also account for the additional gravitational pull on visible objects.

Q - I find myself liking the neutrino idea best. I've heard that most of the area of an atom is empty space, that is hard to understand, since objects appear so solid. All that empty space is a perfect place to hide clouds of neutrinos. Which of these ideas is the most widely accepted by real scientists?

48Samantha_kathy
Mar 30, 2012, 1:07pm Top

46> Oh, drneutron, don’t confuse the poor dear ;). I wasn’t going to mention isotopes yet. Ah well, if sjmccreary runs screaming now, I’ll blame you :D.

45> The atomic number indicates the amount of protons in the nucleus -- Ok, and there are the same number of electrons as protons, right? So the reason why mass would not directly correspond with atomic number would be because of a variation in the number of neutrons.

Yes, an element in its basic form is without electrical charge and the number of protons and electrons are then the same. If an atom has an electrical charge it is called an ion and then the number of protons and electrons is no longer the same. Both forms – atoms and ions – occur in nature. The how and why of that is not important right now. And yes, mass does not directly correspond with the atomic number due to the neutrons.

If that is the case, then what determines how many neutrons are in each atom on an element? Is it possible for two different atoms to have the same number of protons but different numbers of neutrons?

drneutron already explained isotopes to you in 46. I hadn’t wanted to mention it yet, but this is important. I’m very happy that the example given was carbon, because it is the natural occurring carbon-14 that is used to date archaeological, biological, geological, and hydrogeological samples. So you’d have come into contact with isotopes somewhere in this book anyway.

Eventually, we will have to come across something that I already know, don't we?

Most probably :D. I think things will start to become more familiar to you once we get to human history.

49Samantha_kathy
Mar 30, 2012, 1:47pm Top

47>

This sounds more like science fiction than real science! Is this really a viable theory?

Yes, it is. But it has it’s problem areas, far more than the Big Bang theory does right now, and therefore it’s not widely accepted as true. But it certainly is a viable theory.

The theory of natural selection at the level of universes, including the black holes as parents for new universes, was proposed by Lee Smolin in 1992. Officially called the fecund universes hypothesis, it’s more widely known as the cosmological natural selection theory. Smolin basically theorized that when a black hole collapses, it creates a big bang event and thus a new universe on “the other side” of the black hole. Each universe therefore gives rise to as many new universes as it has black holes and fundamental constant parameters (speed of light, for instance) may differ slightly from those of the universe where the black hole collapsed. These two things are comparable to reproduction and mutation – two fundamental demands of natural selection as it is known in biology. The ‘natural selection’ comes from the fact that it is possible that some of the new universes will reach heat death with unsuccessful parameters before they have their own black holes that collapse. So, it’s kind of like a biological organism that can die without having offspring. Successful lines survive – such as universes with our own universe’s parameters.

However, there are critical sounds about this theory that point out some big problems. Astrophysicist Joe Silk suggested that our universe falls short by about four orders of magnitude of being maximal for the production of black holes. Another problem comes from Smolin himself. When he proposed his theory in 1992, he predicted that no neutron star should exist with a mass of more than 1.6 times the mass of the sun. If a more massive neutron star was ever observed, it would show that our universe's natural laws were not tuned for maximum black hole production. I’ll spare you the why of this prediction, as it’s a rather complicated story. Anyway, a 2-solar-mass pulsar was discovered in 2010, so that cosmological natural selection has been falsified according to Smolin's own criteria.

Nevertheless, others have observed that in biological natural selection, organisms are never tuned for maximum reproduction, only for fecundity. Fecundity (reproductive and germline processes) is always regulated by somatic (other body functions) and environmental (resource, population density) processes, and complex tradeoffs exist – in other words, organisms never reproduce to their maximum capacity, but to the maximum capacity within certain parameters that allow them to exist themselves for as long as they can (because that also means more time to reproduce, which eventually leads to a higher overall offspring count). As a biologist I have to concur with them – there’s never maximum anything in nature, because everything is a trade-off. So why should there have to be maximum reproduction on a universe scale?

(And that turned into a much longer answer than I anticipated when I started answering your question. Sorry!)

It sounds like a quasar is so big that it actually contains a black hole - but what is the additional "star food"? ("Big" doesn't sound like the right word to use to describe a quasar - "dense"?) It has so much fuel that it burns very quickly and is rare in the current universe - because modern black holes don't capture enough matter/energy to sustain a quasar.

Well, first of all, you could call a quasar big. “It’s no bigger than our solar system” means it’s still pretty big. The “star food” means galaxies – we’re talking about black holes that “eat” whole galaxies full of stars, hence star food. Your statement is correct.

I thought black holes were so dense that even light cannot escape. How is it, then, that a quasar, which contains a black hole, is one of the brightest objects of all?

Well, first of all, you must know that scientists are still not sure what a quasar is exactly. What they think it most probably is, is a super massive black hole. This black hole pulls in matter to “eat”, and does it with such a speed that the matter actually spins in an acceleration disk (the yellow/red zone in the picture below) towards it – kind of like water spinning into a drain. The matter spins faster and faster, causing it to heat up. The friction between all of the particles would give off enormous amounts of light and other forms of radiation such as x-rays. As this matter is crushed out of existence by the black hole, enormous amounts of energy would be ejected along the black hole's north and south pole (the white beams in the picture). So that’s why they are so bright even though they are black holes.



There are other theories of what quasars are, but this is the most popular one at the moment.

find myself liking the neutrino idea best. I've heard that most of the area of an atom is empty space, that is hard to understand, since objects appear so solid. All that empty space is a perfect place to hide clouds of neutrinos. Which of these ideas is the most widely accepted by real scientists?

I like the neutrino idea best as well, and as far as I know this is the idea that’s most widely accepted at the moment. Doesn’t necessarily mean it’s the right one though :D.

50sjmccreary
Apr 9, 2012, 11:24am Top

I was so anxious to move on that I decided to start chapter 3 without having finished reviewing chapter 2. That may have been a small mistake as almost immediately I found myself running into terms and concepts that I remember reading at the end of chapter 2 but not fully grasping. *sigh* (I know, you warned me about that before we even started.)

#46 Please feel free to jump in anytime. I see that you're going to tutor a reading of The Elegant Universe, which I attempted a couple of years ago and gave up somewhere near the middle - hopelessly confused. I'll definitely be lurking on that thread. I understood your comments about isotopes, but was totally unable to formulate a response because I just didn't know what to do with that information. (Does that make sense?)

#48 The how and why of that is not important right now. OK - I'll trust you on that. But I can't help wondering, if ions and isotopes both occur naturally, then what stops them from being different elements? I thought the structure of an element was basic and the building blocks of everything else. You know - elemental. Is it similar to the differences between a black cat and a grey one? Or more like the difference between a lion and a tiger? Cats and dogs are definitely different elements, right? (Pardon the metaphors.)

#49 Thanks for the explanation of fecundity in nature, and as it might apply to the universe. Made perfect sense.

Likewise, the explanation of quasars. So the extremely bright light is the concentration of matter as it compacts and swirls into the black hole drain?

Moving on, the section at the end of chapter two that I hung up on was the birth and death of stars. I thought I understood it as I was reading, but was unable to easily summarize it. Which is why I decided to skip that step. And even now, I don't want to attempt it again because it requires so much time. However, now I know that I really need to do that. I have some things that I must get done today, but will make this a priority later, after my work is done.

51Samantha_kathy
Edited: Apr 10, 2012, 2:38pm Top

Is it similar to the differences between a black cat and a grey one? Or more like the difference between a lion and a tiger? Cats and dogs are definitely different elements, right?

It's like the difference between a black cat and a grey one - still definitely the same, but with slight differences. Also, they can have different characters - or better said, characteristics, like stability. (And I don't mind metaphors, especially biological ones :D)

So the extremely bright light is the concentration of matter as it compacts and swirls into the black hole drain?

Yes, basically.

Moving on, the section at the end of chapter two that I hung up on was the birth and death of stars. I thought I understood it as I was reading, but was unable to easily summarize it.

Perhaps an easy way to summarize is this:

Stars are born when gravity pulls enough matter together that it reaches a high enough temperature that fusion happens. Fusion takes the existing elements and transforms them into another element. Stars die when fusion can no longer take place. When this is - and thus which kinds of elements the star can make during its lifetime - depend on the size of the star.

Edited to add:

Sorry for the drive-by answers, but I'm incredibly busy this week. I won't be able to answer your questions until the weekend, I'm afraid.

52sjmccreary
Apr 10, 2012, 6:36pm Top

I'm incredibly busy this week. I won't be able to answer your questions until the weekend, I'm afraid. -- No worries - I'm busy myself. I hope you're being more productive at it than I am, however. I'll leave my questions and comments and you take your time responding.

53sjmccreary
Jun 7, 2012, 11:12am Top

Well, my life has finally slowed down a little, and I hope yours has, too. I'm very excited about getting back to the book - especially since I'm getting to the part where I already have some knowledge of the subject.

I don't remember exactly where I left off, but it was at the end of chapter 2. I know I was struggling a little with the last section of that chapter, but don't recall whether that was all cleared up. In any event, I've managed just fine the past 2 months without a clearer understanding of the life cycle of stars, so I've just gone on to chapter 3.

54sjmccreary
Jun 7, 2012, 3:04pm Top

Chapter 3: Origins and History of the Earth

The Solar System

The sun and solar system were all created out of the residue of a nearby supernova about 4.5 billion years ago. The sun contains 99.9% of all the matter in the solar system and the remaining 0.1% represents all the planets (mind boggling). A very clear explanation is given of the forces which caused that small amount of matter to form into the various planets in different orbits on the same plane. Also, an explanation as to why the inner planets are rocky and the outer planets are gaseous, which I never knew before. Jupiter is so large that it is nearly capable of sustaining nuclear reactions in its core, which would have turned it into a small star. Had that happened, the solar system would have had two suns and life probably would not have developed on earth. In fact, all the large planets formed with their own nebulae, just like embryonic stars, as evidenced by the rings around them. Astronomers are now able to see planets around other stars, and believe that they may be fairly common. At least in this neighborhood of the universe.

Q - How much larger would Jupiter have had to be in order to develop into a star? How common are binary stars? (Is that what a solar system with 2 suns is called?) There was a comment about an enormous planet being discovered - much larger than Jupiter - that appeared to have been ejected from a binary system. How would that happen? If Jupiter is almost large enough to be a star, then how could that other planet have been so much larger without becoming a star?

The Early Earth: Meltdown and Cooling

Accretion (the action of planet-building) is a violent process, as evidenced by the "odd tilt and spin of many of the planets". As all the small chunks became stuck together into bigger and bigger bodies, eventually becoming planets, these violent collisions became rarer. Before it grew to full size, the earth didn't have enough gravitational pull to retain an atmosphere. As it became larger, it heated up due to increasing pressure of its size. Plus, much radioactive material was generated in the supernova that formed the sun releasing heat which is still present and stored in the insulated core of the earth. The built-up heat at the core caused the material to melt allowing elements to sort themselves out by density (differentiation). Eventually, the heavy metallic elements - mostly iron - sank to the core which gives the earth its magnetic field. That magnetic field has played a large role in protecting the chemical processes that led to life. With the heavy elements settling in the center, the lighter materials - such as granite - formed the outer layer of crust covering the planet like an eggshell. The gasses bubbled to the surface and escaped, but the increasing gravitational pull began to hold them close enough to form a stable atmosphere. As the earth cooled, water vapor in the atmosphere condensed and fell as rain, forming the oceans. The fact that earth has liquid water makes it uniquely capable of sustaining life - something that might be rare in the universe. The organic chemicals needed to form life might have been delivered to earth by comets hitting the planet. Likewise, the moon may have been formed when a glancing blow by a large proto-planet gouged material out of the outer layers of the earth which orbited the planet until gathered together into a single body.

Q - There are a couple of references to the earth reaching full size - is there a critical size that must be gained before a planet can be viable? Or is it more a matter of time to develop and the full size referred to is just the eventual size that earth became? Is the magnetic field caused by the earth's iron core an unusual thing? The combination of a molten core and magnetic field seems to be critical in the development of life here. Earlier you and I talked about the role of God in science. The author makes this statement, "Perhaps Earth proved suitable for life because of a rare combination of circumstances, suggesting that even if the universe contains billions of planets, few may be hospitable to life." To me, this implies Divine intervention. What do you think? How possible is it that different forms of life might develop on other planets in conditions that earth-life could not tolerate? (Extremes in temperature, for example, or a toxic atmosphere.) Why would comets have been needed to introduce water and chemicals into the earth's environment? Weren't they formed in the same supernova that formed the rest of the solar system? Wouldn't they consist of the same elements as everything else in the solar system? One last question - if the moon was formed by the accretion of material orbiting the earth dislodged as a result of a collision, then why hasn't the material in the rings of Saturn done likewise?

55Samantha_kathy
Jun 7, 2012, 4:07pm Top

Alright, here are the answer to the first part - The Solar System. Will answer the second part tomorrow.

How much larger would Jupiter have had to be in order to develop into a star?

There’s a bit of a debate about that. Some physicists say that you’d need at least 75-85 Jupiter masses to get fusion started. So, quite a bit bigger. Other estimates say between fifty and a hundred times more massive than it is now. All in all, though, Jupiter is quite far removed from being a star.

How common are binary stars? (Is that what a solar system with 2 suns is called?)

A solar system with 2 stars is called a binary star system, yes. It’s a bit difficult to say how common they are, because not all binary star systems have visible (for us, anyway) stars. Five to ten percent of the stars visible to us are visual binary stars. Then you have those binary stars that are so close together they appear to be one, even through a telescope. There are ways around this, though, called spectroscopic study – which deals with Doppler shifts of the wavelengths of lines seen in the spectrum, as the stars move through their orbits around the center of mass. It’s quite complicated and I won’t even try to explain it – I’ll probably only confuse you. Back on topic, careful spectroscopic studies of nearby solar-type stars show that about two thirds of them have stellar companions. Current-day scientists estimate that roughly half of all stars in the sky are members of binaries.


There was a comment about an enormous planet being discovered - much larger than Jupiter - that appeared to have been ejected from a binary system. How would that happen? If Jupiter is almost large enough to be a star, then how could that other planet have been so much larger without becoming a star?

Okay, I’ll answer these questions backwards. First, why a different planet that’s so large is not a star. First, there are three types of celestial objects that can reach a large mass: planets, brown dwarfs and stars. The difference between a planet and a star is that Planets shine by reflected light and stars shine by producing their own light. A planet doesn’t get hot or heavy enough to start fusion in its core like a star, because while a star is produced from gasses (enabling a very large mass to amass before it’s ‘stuck’ in its form), a planet is formed from dust particles left over from the formation of a star.

Brown dwarfs are objects which have a size between that of a giant planet like Jupiter and that of a small star. In fact, most astronomers would classify any object with between 15 times the mass of Jupiter and 75 times the mass of Jupiter to be a brown dwarf. Given that range of masses, the object would not have been able to sustain the fusion of hydrogen like a regular star; thus, many scientists have dubbed brown dwarfs as "failed stars". As an aside, all brown stars that have been identified up to this date have been part of a binary system. As another aside, the presence of brown dwarfs – which do not give off light and are therefore likely not to be discovered by us – might account for some of the ‘missing mass’ in the universe that was discussed in previous chapters.

As for why some large planets are called planet and other large objects that are not stars are called brown dwarfs? I’m not sure – the ones doing the classifying don’t seem to be very consistent in when it’s a planet and when it’s a brown dwarf.

The ejection of a large planet that seems to have been ejected from a solar system might actually be more common than thought. In fact, here’s a link to an article which talks about the likely possibility of our solar system having ejected a large planet early on: http://www.sciencedaily.com/releases/2011/11/111110142102.htm I imagine that the (re-)arranging of orbits in the specific binary system probably caused a planet to be ‘bumped out’ of the system in the same way.

56Samantha_kathy
Jun 8, 2012, 3:50pm Top

Okay, I’ve got some more time now to answer your questions. I’m pretty excited about getting back to this as well – this tutoring thing is fun! We’re getting closer to my area of expertise – chapter 4 and 5 especially draw on my formal education. But first, your questions I didn’t get to answer yesterday.

(This was getting a bit long, so I’ve divided it with easy-to-see headers and into two posts. Sorry for the lengthy answers, but none of the questions could be answered with a short answer. Well, they could, but then you’d probably have ten more questions :D).

Planet formation and size

There are a couple of references to the earth reaching full size - is there a critical size that must be gained before a planet can be viable? Or is it more a matter of time to develop and the full size referred to is just the eventual size that earth became?

Okay, so after re-reading the chapter, I am still not entirely sure if the author meant ‘full size’ as the final size Earth eventually reached or if he referred to the end of the final stage of planet forming. Since they’re the same point in time, I think it’s a bit of both actually. There’s not so much a critical size to be gained for a planet as most planets have to have a minimum size before they can fulfill all the requirements of being a planet that the scientists have thought up.

So there are several stages to forming a planet and those stages differ a bit between rocky planets (like Earth) and gas planets (like Saturn). I’ll focus on rocky planets like Earth for now. According to the nebular hypothesis of planet forming (as shown in the book and seen as the most probably explanation), coagulation of rocky grains form rocky planetesimals. These planetismals then form bigger and bigger ‘rocks’ – the bigger the ‘rock’ the faster it grows, until eventually there is a dominance of several hundred of the largest bodies called oligarchs. They continue to pull in planetesimals, until there are no more planetesimals that can merge with the oligarchs. The next phase is that planetary embryo’s form – about 100 Moon- to Mars-sized ‘rocks’ spaced fairly evenly apart. Then the last stage of rocky planet formation is the merger stage, where the embryo’s become large enough to get in the way of each other – pulling on each other with their own gravity and thus upsetting their orbits. They start to collide with each other until at the end a limited number of Earth-sized bodies remain. In our solar system, Mars and Mercury are probably planet embryo’s who managed to ‘stay out of the fight’ and remain as embryo’s, while Venus and Earth are rocky planets that required the merging of about 10-20 embryo’s to form.

Now, that’s how planets are formed, and from that you can see that you can definitely predict how large a planet is going to be. But there’s more to being a planet than just being a certain size. In 2006 there were three criteria formed by the International Astronomical Union (IAU) – the same criteria that took away Pluto’s planet status. Criteria 1: A planet is a celestial body in orbit around the Sun. Criteria 2: Has sufficient mass to assume hydrostatic equilibrium (a nearly round shape). Criteria 3: Has ‘cleared the neighborhood’ around its orbit. This last criteria means that the planet has become gravitationally dominant, and there are no other bodies of comparable size other than its own satellites (like the Moon for Earth) or those otherwise under its gravitational influence.

A celestial body that only fulfills the first criteria is called a small Solar System body (SSS). A celestial body that only fulfills the first two criteria is classified as a ‘dwarf planet’. Pluto is a dwarf planet since the 2006 criteria came into use, because it has not cleared the neighborhood – it’s only one of several large bodies within the Kuiper belt. As an aside, can I just say that it’s very cool that this belt is named after a Dutch astronomer, while right now in the International Space Station there is a Dutch astronaut in orbit around the Earth called André Kuipers (no relation as far as I can see).

Under these criteria there are currently eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) and five dwarf planets (Ceres, Pluto, Haumea, Makemake, and Eris) in the Solar System. Extrasolar planets – planets not in a solar system – are separately defined under a complementary guideline. Due to the fact that these criteria distinguishes planets from smaller bodies, it’s not useful outside the solar system, as we cannot find smaller bodies outside the solar system yet.

A nice, short, visual of this process is the first half of this youtube video: http://www.youtube.com/watch?v=-x8-KMR0nx8 while the second half (each half about 1 min long) is a very nice intro to the rest of chapter 3.

Magnetic planetary fields

Is the magnetic field caused by the earth's iron core an unusual thing? The combination of a molten core and magnetic field seems to be critical in the development of life here.

Actually, planets with a magnetic field are not as rare as you would think. To create a magnetic field there are only 2 requirements: magnetic material (like the iron in Earth’s core) and currents (which has to do with movement of the planet). Mars, for instance, does not have a magnetic field because the iron on that planet is on the surface and not molten. Likewise, Venus does not have a magnetic field, because it moves too slow to get a current. Planets that do have a magnetic field are Mercury, Jupiter, Saturn, Uranus and Neptune.

While Earth is a dipole - where the lines of force point in a direction out of the South (magnetic) Pole and into the North (magnetic) Pole – there are also planets known that are quadrupoles (4 poles) and octupoles (8 poles).

57Samantha_kathy
Jun 8, 2012, 3:51pm Top

God, Science, and extraterrestrial life (How’s that for a title *wink*)

Earlier you and I talked about the role of God in science. The author makes this statement, "Perhaps Earth proved suitable for life because of a rare combination of circumstances, suggesting that even if the universe contains billions of planets, few may be hospitable to life." To me, this implies Divine intervention. What do you think? How possible is it that different forms of life might develop on other planets in conditions that earth-life could not tolerate? (Extremes in temperature, for example, or a toxic atmosphere.)

Divine intervention – to even think it is cause for immediately being discredited in the scientific community as a scientist. So there’s probably not a single scientist in the world that you can entice to answer ‘yes’ to that question – not without them being already outside of the scientific community that their peers form. It’s something we’ll probably be discussing a bit more when we get to the evolution theory – and the Intelligent Design theory, which raises some good points about evolution theory but is shoved aside as a creationist theory that cannot by definition be based on good science.

From a purely scientific point of view, it’s very possible that there is (of was, if you look at Mars where the water has frozen but was liquid in the past) life outside of Earth. There have been a lot of discoveries in the area of biology in the last 5 to 10 years that have opened up a lot of doors for us to find extraterrestrial life.

First, there have been bacteria found near underwater volcanoes at temperatures biologist thought no life (even bacterial life) would be possible. Bacteria have also shown themselves to be able to survive in the most hostile of environments – even benefit from it. There are bacteria that live in anaerobic conditions (they’ve been known for a long time now), and bacteria that live in high-acid environments, to name a few. A year (or 2?) ago, during the big oil disaster near the US coast, a new bacteria was found that was actually ‘eating’ the oil – a compound nobody thought could be degraded by anything! So, hostile environment – no problem whatsoever when we’re talking about life. (As an aside, when scientists talk about finding extraterrestrial life, they’re almost always talking about finding micro-organisms, and mostly about bacteria/archeo-bacteria).

So, we’ve been looking for extraterrestrial life for a while now – mostly by taking samples from other planets (mainly Mars, as the most likely candidate due to the presence of water there, frozen though it might now be) and then using certain techniques (developed in the past decade) to amplify any possible DNA present in the sample and detect it. We’ve focused on DNA because it is ‘the corner stone of life’ and no living organism has ever been found without DNA (excepting those that consider a virus a life-form, most don’t). But, a few years back (maybe 2 or 3 years ago), a startling discovery was made (or rather, proven in an experiment): evidence that RNA could replicate itself was found. And not only that, experiments in the last 2 years have shown what theory already predicted: (certain) RNA molecules can do everything they need to survive on their own – without a cell, and without DNA. No longer was it necessary that a life-form had to have DNA – it could exist with just RNA! So while we’ve been looking for DNA ‘out there’, we should also have been looking for RNA! And to take it one step further, this article (April 28 of this year) shows that extraterrestrial life might not have to adhere to ‘Earth standard’ for life forms at all; they could very well do without DNA and RNA: http://www.dailygalaxy.com/my_weblog/2012/04/extraterrestrial-life-may-not-be-ba...

So, all in all, what we’ve proven in the last decade is that extraterrestrial (bacterial) life is very, very possible – we just don’t have the tools yet to effectively search for any life-form that’s not DNA or RNA based. But, it’s hard to look for something if you’ve got no idea what it ‘looks’ like or how it works.

To come back to the Divine intervention or not dilemma, from a purely scientific point of view life on Earth as well as life ‘out there’ is possible. With every decade we get more and more pieces of the puzzle and prove more and more of our theories in actual experiments. Will there come a day when we can create actual (simple) life in a laboratory? Maybe. For now, we can show steps that were necessary experimentally, but always separate, never in the exact sequence it needs to go from ‘nothing’ to ‘life’. How much coincidence and exactly right conditions were needed to get the sequence right? A lot, I’d say. Perhaps that’s where the Divine intervention comes in. Perhaps that is the deciding factor in whether we’re alone in this universe or not. On the other hand, if there is a Divine power out there, isn’t it a bit arrogant of us humans to think that it’s only on our planet that life was started?

Difficult questions, and to be truthful I don’t think it’s a bad idea to keep the science (mechanics) and the faith (reasons why something happens) separate. At work I’m a scientist and I focus on the how – leaving any thoughts of the Divine and the ‘why’ out of the equation (and thus my work). When I’m not at work, I have faith that there’s a reason behind the things I see at work, a reason why the world around me is as it is, a power that drives all those mechanisms I have devoted my life to discovering. But those are my thoughts and that’s my faith, and I keep it far, far away from the harsh, cruel world of science. Let the scientists prod and poke everything to figure out how it works, while I nurture my faith deep within my heart. I don’t need to shout it out from the rooftops, if I’m right I am right and if I am wrong I am wrong, I won’t know in my lifetime either way. Best not to ask the question at all then.

Comets, Meteors, and Asteroids.

Why would comets have been needed to introduce water and chemicals into the earth's environment? Weren't they formed in the same supernova that formed the rest of the solar system? Wouldn't they consist of the same elements as everything else in the solar system?

Okay, back to business and pure science. All kinds of chemicals, including water vapor, are floating around at the time the Earth is formed. But, as you’ve been able to read above, the Earth is a rocky planet. Rocky planets are formed from – you guessed it – rocky materials. As can be read in the chapter, several chemicals were present on the early Earth, spewed out by the volcanoes that littered the Earth’s surface. oxygen (almost 50 percent) and smaller amounts of iron (19 percent), silicon (14 percent), magnesium (12.5 percent), and many other elements of the periodic table (in small quantities) are within the Earth’s surface. But they are mostly inert - ‘stuck’ in their place and not useable to form or sustain life. Hydrogen (H), helium (He), methane (CH4), water vapor (H20), nitrogen (N), ammonia (NH3), and hydrogen sulfide (H2S), however, were spewed out by volcanoes in their gas-forms. However, it has to be said here that the amount of water vapor is nothing in comparison to the amount of water we have now – and water is very important to sustain life and probably was instrumental to creating it.

Now, while the early Earth had quite a vast amount of ‘building blocks’ to work with, we know from studying the world around us today that it was also missing quite some ‘building blocks’. Comets are the missing puzzle piece as to how those elements came to Earth. In order to understand that, it’s important to understand the difference between asteroids, meteors, and comets.

Meteors (typically known as shooting stars) come in several types: irons, stones, and stony-irons. These types are derived from their make-up, and as you can see from the names, meteors are rocky – like our planet – and don’t bring anything new to Earth. Most of them come from the Asteroid Belt between Jupiter and Mars – which is also were most asteroids are. Asteroids are remnants of planetoids. Asteroids in the outer part of the Asteroid Belt tend to be rich in carbon, while the “younger” asteroids in the inner part of the Belt are rich in metals and were made from melted materials. While the rare event of an asteroid hitting Earth can (and probably has) caused major changes on the Earth’s surface, neither carbon nor metals are the right elements that were lacking on early Earth.

And then we have comets. Comets are composed of water, frozen gasses and dust not incorporated into larger heavenly bodies at the dawn of the universe. And research backed with experiments have shown that this comet-ice has just the right ingredients that were missing from the early Earth – hence why comets were needed to introduce those elements. And, ice is water, as you now, so they also brought in more water – another essential step in the creation of life.

So while all elements are present in the universe, not all ‘bodies’ in the universe have all the elements in them, nor are they equal in elemental make-up. So what the early Earth was missing in terms of ‘building blocks’ needed for life, comets provided. If you’re interested in reading more, here’s an article from 2009 that talks a bit about this: http://www.sciencedaily.com/releases/2009/04/090428144126.htm

Moon Formation and the Rings of Saturn

One last question - if the moon was formed by the accretion of material orbiting the earth dislodged as a result of a collision, then why hasn't the material in the rings of Saturn done likewise?

I could give you the answer, but someone who studies this has actually answered this question in fairly down-to-earth language, so instead of butchering it, I’ll just give you Stuart Robbins’ answer:

“There are a few things that keep Saturn's rings roughly the way they are.

First, Saturn's D ring actually is "raining" down on Saturn currently. But, the phenomenon of shepherd moons prevents the vast majority of material from leaving the other rings: "The gravity of shepherd moons serves to maintain a sharply defined edge to the ring; material that drifts closer to the shepherd moon's orbit is either deflected back into the body of the ring, ejected from the system, or accreted onto the moon itself." (quote from Wikipedia)
Besides this, the majority of the particles within the ring system have almost no motion toward away from Saturn; no motion towards the planet prevents them from being lost.

Second, Saturn's rings cannot clump into "full-fledged" moons, but they can clump into moonlets up to several hundred meters to a few kilometers across. At last count, I think there were over 200 that had been found, and they also come out of numerical simulations.

Beyond these larger moonlets, quasi-stable clumps and clusters of ring particles form with great frequency the farther you get from Saturn. These clusters of particles are constantly changing size, trading material, etc., and so there's no time for them to become solid and cohesive.

This gets into the idea of the Roche Limit and Hill Spheres. The basic idea of the Roche Limit is that the closer you are to a massive object, the more tidal forces are going to tear you apart (or prevent you from forming to begin with). Hill spheres are related, where the idea is at what point you're gravitationally bound to one object or another. If you're within Saturn's Hill sphere versus a moon's Hill sphere, you're going to be pulled to Saturn. With both concepts, you'll need to have a moon forming farther away from Saturn than its rings are now to actually be stable.”

Now you know why we have a moon and Saturn has rings (and moons!).

As a closer, I’d like to point you to this youtube movie. It’s the birth of the moon as a ‘dramatized’ story – approximately 3 ½ minutes long – that gives you a great visual of Earth in its ‘cooling off’ period as well as shows you how the moon came into existence. It’s here: http://www.youtube.com/watch?v=IO45ZiGql8E&feature=related

Okay, I think that were all the questions. If I’ve raised any new ones with what I’ve written here, please let me know. Otherwise, see you for the next part!

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