Richard A. Muller (2) (1944–)

I enjoyed reading Muller’s book, maybe as much for its loose ends as its clear discussions along the way. He combines a reconstruction of some basics of relativity and quantum physics with an over-riding question — time’s arrow and our experience of a “now” in time — and a general, philosophical position on the limits of scientific knowledge. And, despite the subject matter, it’s written in an almost breezy manner, although you’ll certainly find yourself going back to read show more passages a second or third time to understand subtle points.

The bulk of the book really is Muller’s laying out of his own understanding of the current landscape of physics and cosmology.

It deserves being called a “reconstruction” because he seeks to overturn some popular scientific misconceptions along the way. The expansion of the universe, for example, does not mean that galaxies are moving away from one another, but that the space between them is expanding. That may seem like a difference between two ways of describing the same thing, but the difference will become important later when Muller addresses the question of time, “now”, and time’s arrow. Just as space is continually created by cosmological expansion, he will claim that time is also expanding.

He also corrects the popular construction of space-time as three axes of space and a fourth time axis, similar to the spatial axes. That popular picture gives us the impression of a linear expanse of time — past, present, and future — on which we just happen to sit at a point we call the present, as if future and past also existed as accessible points, at least in principle. Again, correcting this picture will play an important part in his own conception of time later in the book.

Muller devotes extensive discussions to indeterminacy and entropy. He recounts Einstein’s opposition to indeterminacy as an objective characteristic of reality. This is part of his general argument that physics is “incomplete”. Despite Einstein’s protests, indeterminacy actually does turn out to be a feature of objective reality. The common sense determinism of scientific thought, that the past determines the future, turns out to be false. Physics, in turn, is incomplete, in that it cannot compute the future even given complete knowledge of the past and present. The idealized “complete” knowledge of the past and present — the position and velocity of all particles — is unobtainable, because there simply are no such determinate, objective positions and velocities.

His discussion of entropy takes up the perhaps dominant explanation of time’s arrow, by Arthur Eddington — that the arrow of time is the arrow of increasing entropy. Muller considers Eddington’s account in some interesting discussions of the relation between local entropy and cosmological entropy. Certainly we, through intentional activity, can decrease local entropy. Our experience of time’s arrow is not one of ever-increasing entropy. Muller wants us to see that, in an important sense, the idea that time as entropy cannot go backwards is illusory — local entropy certainly does go backwards. The familiar illustration of entropy’s direction — reversing the film sequence of a cup breaking, now showing the pieces of the cup bizarrely flying together — is misleading. Cups do actually come together, reversing entropy, when we make them.

I’m unsure exactly how to understand the relation between the problem of time’s arrow in physics and the importance that Muller gives to the human experience of time (and local entropy). But he certainly does mean to claim that physics turns out to be incomplete in another sense beyond that implied by objective indeterminacy. That other sense of incompleteness has to do with conscious experience, such as our conscious experience of time.

Muller is a scientist who does not think the reach of scientific knowledge is complete — there are phenomena beyond the reach of scientific knowledge. In particular, science cannot grant us knowledge of conscious phenomena, e.g., what it is like to see blue. We can certainly have scientific accounts of what happens when we are conscious (e.g., that certain areas of the brain are active), but that is not a description of the conscious experience itself (see Thomas Nagel’s classic paper, “What Is It Like to be a Bat?” for a fuller treatment of the problem, although Muller doesn’t cite Nagel).

All of these themes come together toward the end of the book in Muller’s speculations about “now”. The direction of time, and our position at “now”, are not adequately explained by our current physics. Our experience of “now” is likewise unaccounted for in physics (actually our conscious experience of anything is unaccounted for by physics).

We do however, from quantum physics, have a way of distinguishing the past from the present and the future. What separates the past from “now” is the determination of the past — quantum uncertainty has been resolved in the past (through “measurement” — a still mysterious natural process that collapses the wave function of quantum physics). In the present, and in the future, no such determination has occurred. In fact, Muller thinks that time is continuously created, just as space is, in the cosmological expansion of the universe.

The claim is speculative, and probably requires a lot more physics (especially concerning measurement). But Muller offers some thoughts on experiments we might make to go forward.

Muller’s claims on indeterminacy, local entropy, and the unattainability of scientific accounts of conscious experience also lead him to some conclusions about free will. Certainly indeterminacy is not the same thing as free will — indeterminacy has nothing to do with intentional behavior. But indeterminacy at least may remove one obstacle to accepting free will, that our future actions are not strictly determined by the past or present. His account of free will is, like his account of the continuous creation of “now”, speculative, but interesting. He would like to say that, since “now” and the future are undetermined, in the physical sense, they are open to willful determination — explained by him as generation of local decreases in entropy. Those local decreases are the province of life and its productions (order, structure, intentional action . . . civilization).

In my own understanding, from reading Muller, the marriage of all of these themes isn’t really consummated. The flow of time, free will, and what blue looks like are all phenomena that appear not to be well understood, certainly by science, and possibly will never be understood by scientists. I’m just not sure how all are related to one another, or if “now” does not turn out to be inextricable from the conscious experience that Muller thinks cannot be adequately described in scientific terms.

But Muller is refreshingly provocative. And I think it is especially refreshing, in not only a scientific but a scientistic age, to find a physicist who does not think that physics can encompass everything.

One minor quibble. Well maybe not minor. Muller delves deeply into some important philosophical problems — the status of conscious experience, free will, the limits of objective knowledge. And he does discuss some philosophical treatments of those issues. But, given that he teaches at a university with one of the world’s leading philosophy departments, there’s no evidence (that I could find in the book) that he’d actually walked over to the philosophy department to find out what they thought. Doing so may have substantially enriched and applied additional rigor to his treatments of those issues. show less

Richard A. Muller is a professor of physics at the University of California, Berkeley. For years, he taught a course entitled “Physics for Future Presidents” to undergraduates. Much of that course was condensed into a highly regarded and favorably reviewed book of the same name.

Muller has employed his formidable explication skills in a new book, Now, subtitled, The Physics of Time. In it, he sets forth his theory of why time - the fourth dimension - flows, proceeds, or progresses show more inexorably into the future. The extremely elusive concept of NOW is how we perceive time. Early on, Muller refers to the concept of now as “indescribable.” He even reprises Supreme Court Justice Potter Stewart’s famous [to lawyers] bon mot: “I can’t define [it]…but I know it when I see it.” Stewart was trying to define “obscenity,” but his sentiment aptly characterizes most efforts to define time.

Muller, on the other hand, has a definite concept of time that he wants to impart; but before he does so, he wants to bring the reader “up to speed” with a crash course in modern physics. He then segues into his personal musings on the concept of free will, intertwined with the laws of physics.

The first 250 pages of the book might serve as a pretty decent undergraduate Physics 101 course for liberal arts majors who aren’t afraid of a little algebra. Most of it is very comprehensible, even to those with no affinity for math. However, he occasionally inserts sentences like:

"Energy is the canonically conserved quantity corresponding to the absence of explicit time dependence in the Lagrangian."

and

"Entropy is the logarithm of the number of quantum states accessible to a system."

Well, if you already knew that, you can probably skip much of the first two thirds of the book.

Muller begins by summarizing what physicists know about time before he speculates about the definition of and nature of now and why time seems to flow. Spoiler Alert! Muller argues that the cause of the flow of time lies “not in the concept of entropy, but in the physics of cosmology.” [Entropy is a property of physical systems. It is often calibrated in joules per Kelvin, that is, energy divided by temperature. It is a measure of the extent of disorder of the system.]

The concept of time permeates classical physics in subtle ways. For example, Emmy Noether proved that the law of the conservation of energy could be derived from the principle of time invariance. Emmy Noether was a German female mathematician known for her landmark contributions to abstract algebra and theoretical physics. Time invariance means the laws of physics don’t change with time. But then Einstein (who referred to Noether as one of the most significant and creative mathematicians of all time) showed that time itself varies with relative velocity.

Einstein’s special and general theories of relativity imply many counterintuitive aspects of time without explicitly defining it. The first startling idea from the special theory of relativity is that not just velocity, but time itself, depends on the reference frame. Observers in relative motion perceive time differently, but they agree on how it would be perceived in the other’s reference frame.

Muller provides the most lucid explanation of the famous Twin Paradox that I have ever seen. Why does Twin #1, Mary, who takes off in rocket and travels at very high speed, age more slowly and return to earth at a younger age than Twin #2, John, who remains on earth? After all, both were moving at high speed relative to one another? The flippant answer often given is that Mary had to accelerate (change speed) to return to earth. I never understood why that mattered until I saw Muller’s answer (provided in the Appendix) that actually does the math and provides an insightful graph showing how the two actually age at different rates.

A key transition takes place when Mary must stop and turn around to return to earth. While she has stopped (even if only instantaneously), her reference frame makes a discrete jump and becomes the same reference frame as that of John because the two of them are no longer in relative motion. So, if one has been traveling at great speed and suddenly stops, her proper time frame jumps to a different reference frame and so does the time of a distant event, namely what is happening back on earth!

Unfortunately, Einstein failed to account for the fact that time moves. Arthur Eddington observed that the second law of thermodynamics was the only principle of physics that operates in only one direction of time. Under the second law, in the absences of outside forces, physical systems unavoidably evolve from less probable (more ordered) states to more probable (less ordered) states, not the other way around. Think of getting older (alas) or the shattering of a tea cup dropped on the floor. We do not get younger and broken tea cups do not reassemble themselves. Physicists characterize these phenomena as increases in entropy. From those facts, Eddington concluded that the second law caused the motion of time in the direction of what is called “time’s arrow.”

But Muller thinks Eddington got things backward — Muller argues that time’s ineluctable forward movement is the cause of the Second Law, not vice versa. He points out that Eddington’s “theory” makes no predictions that would make it falsifiable. It merely explains. Moreover, Muller contends that if increasing entropy caused the direction of time, shouldn’t the rate of time passage change locally when there is a local decrease in entropy, as when the entropy of the Earth’s surface decreases at night?

Muller’s concept of time fits in nicely with modern cosmology and the Big Bang theory. Astronomers infer from the red shift in starlight that galaxies are all moving rapidly apart, the greater the distance, the more rapid the velocity difference. The observable universe is expanding. In the standard formulation of Einstein’s general relativity and the Big Bang theory, the galaxies are not so much moving through pre-existing space as the three dimensions of space itself are expanding. In Muller’s view, time is a fourth dimension, expanding right along with the other three. Now is the leading edge of that expansion—the furthest extent of the dimension of time.

Muller also discusses some of the counterintuitive aspects of quantum physics, not so much because of their relevance to the physics of time but because they affect other issues he raises later in the book. He describes the wave function that characterizes atomic particles as “ghostlike.” He says the wave function of an electron:

"…isn’t really the electron. It is the amplitude, the spirit of the electron, its apparition, its soul."

[Muller likes the concept of souls. He employs it later in his discussion of free will.]

In what was a revelation to me, he also shows that Heisenberg’s uncertainty principle follows from the fact that particles display wave-like properties:

"Virtually all waves will have some uncertainty in both their velocity and their position….The math of the Heisenberg uncertainty principle follows exactly the math of classical waves….The mathematical statement of Heisenberg’s principle…is identical (except for the multiplication by Planck’s constant h) to the equation that describes classical waves, including water waves, sound waves, and radio waves."

Despite its title (and subtitle), Now isn’t only about the physics of time. I’m guessing that in Muller’s mind, his most important points are his thoughts about free will and the incompleteness of physics. He agrees with Immanuel Kant, of whom he says:

"[Kant] felt that he had nonphysics knowledge, true knowledge, of ethics and morality and virtue. Given his certainty of this knowledge, free will must indeed exist….But it would take advances in physics, particularly in understanding its quantum aspects, to see the true compatibility between physics and Kant’s thoughts on free will."

As an example of an issue beyond physics, he asks, “What does blue look like?”

Muller attacks what he calls “physicalism,” a belief that science says all that can be said. Physicalism reaches its extreme when it asserts that all nonquantifiable assertions are illusions. He takes on deterministic philosophers and atheists like Richard Dawkins:

"Dawkins makes a fundamental error in his unstated but implicit postulate that logic requires us to ignore nonphysics reality."

After discussing the uncertainty principle in quantum physics, Mueller says:

"The philosophers’ key assumption that the past completely determines the future is not supported in modern physics. Their arguments that free will does not exist were based on a false premise. We can’t conclude that free will exists, but we can conclude that nothing in science rules it out."

Muller proposes his own test to determine whether free will exists:

"If humans always follow the laws of probability, then free will does not exist. If humans regularly do highly improbably things, things that are not predictable based on external influences, then such behavior constitutes free will."

As a physicist, Muller perceives improbable acts as decreasing entropy, at least locally. As you can imagine, he argues forcefully in favor of free will. You may ask, “What does all this have to do with the physics of time?” My guess is that Muller might answer that the importance of now is that it:

"…is the only moment when we can exercise influence, the only moment when we can direct the increase the increase in entropy away from ourselves so that we can orchestrate local entropy to decrease."

Muller concludes with some musings about the human soul, free will, and personal responsibility. As he says, “Free will can be use to break a teacup or to make a new one. It can be used to start a war, or to seek peace.” In his sixth, and final, appendix, he cites several quotations from leading physicists expressing their personal beliefs in God.

Evaluation: Now can be viewed as two books in one. The first is a lucid presentation of issues in modern physics dealing with the notion of time. Muller’s writing is comprehensible for the nonphysicist-lay-mathphobe, and in the Appendix he includes real equations (quite a lot of them) for the adventurous who seek a deeper understanding. This first book is exceptionally well done and pretty much incontrovertible.

The second is more controversial. Muller is highly critical of physicalism, and he argues that physics is incomplete in the way Gödel showed us all logical systems were incomplete. Although he is careful not to espouse any religious beliefs in the main body of the book, he sets forth his own semi-religious beliefs, a mild sort of deism, in the final Appendix. I wasn’t offended by his statement of belief, but I wonder what it has to do with the physics of time, besides perhaps motivating an interest in answering the big questions about existence. Nonetheless, this book was good enough to pique my interest in reading Muller’s Physics for Future Presidents.

(JAB) show less

The conceit of this book is, obviously, that it's addressed to whoever would win the Obama-McCain race: here are the bits of physics you need to understand if you're going to make the right decisions on terrorism, energy, nukes (both weapons and reactors), space and global warming. There's plenty of good stuff here as well as lots of fascinating facts that I'm sure I'll find myself tossing oh-so-casually into dinner-party conversations. The text is extremely readable, bouncing along at an show more exhilarating pace. But there are also some silly mistakes:

In the Manhattan Project, the scientists initially estimated that the amount needed for a critical mass was about 440 pounds. [. . .:] With a tamper, instead of leaking out, the neutrons are reflected back in, so the critical mass needed for an explosion dropped by about a factor four, down to only 33 pounds. (p129)

I've tried and I've tried and I've tried to make sense of that "factor of four" calculation, but I still can't get no satisfaction. The "440 pounds" is clearly a euphemism for 200kg, and I assume "33 pounds" is, in plain English, 15kg . . . but even looking at these somewhat easier-to-work-with numbers, hoping for some sort of four-related relationship between them, I can't imagine what he was talking about. Similarly here:

In 1974, the average refrigerator size in the United States had a volume of 18 cubic feet, and the energy it used was 1800 kilowatt-hours per year. That's 130 kilowatt-hours for each cubic foot. (p315)

If I divide 1800 by 18, I get 100, not 130. I've checked my calculation every which way, and I still think I'm right on this.

I have other concerns. In the long chapter on global warming, Muller adopts the position of being, not a climate change denier, but a denier of the need for draconian action . . . and he claims to produce the physics to support this. He obviously has a beef about Al Gore and the movie An Inconvenient Truth, because he loses no opportunity to carp at them, even in instances where quite clearly Gore's "error" was that the science he presented, while perfectly correct as of 2004, has since been amended. Perhaps Gore once farted in front of Muller's wife, or something. Even so, I was prepared to be educated on the subject, but then . . . well, what's this?

On page 283 we have a couple of diagrams credited to "Pielke & Landsea"? On p294 there's an approving mention of a correction to the climatologists' physics from Steve McIntyre and Ross McKitrick? The diagrams seem plausible and the correction to the physics may be fine for all I know, but nowhere is there a mention of the fact that Pielke, McIntyre and McKitrick are extremely controversial figures in the climate debate, being champions of the AGW-denialist movement. I for one would trust nothing emanating from any of these three until I had it confirmed in triplicate by independent authorities, and even then I'd be dubious. Yet Muller, who must have known that to much of his audience the names will mean nothing, fails to alert his readers to the fact that the arguments being produced in general on AGW by Pielke, McIntyre and McKitrick (and, again for all I know, Landsea) are, to euphemize, not universally accepted.

Similarly, on pp104-105 Muller discusses the estimated death toll from long-term cancers in the wake of the 1986 Chernobyl disaster, and tells us that the IAEA/UN best estimate for this number is 4000. I was surprised the figure was so low, since I was sure I'd heard of higher ones, but who was I to argue with the IAEA/UN? It was only by chance, in casual e-conversation with a friend a couple of days later, that I discovered there have been several estimates of this death toll, and the IAEA/UN one is controversial. Many of the other estimates, quick research revealed, have reliability problems of their own -- I mean, I love Greenpeace and have given them money, but they're an advocacy group and everyone knows you take with a pinch of salt the statistics produced by advocacy groups -- and it's quite possible the IAEA/UN estimate may be the best; but, for the sake of honesty, Muller should have indicated the existence of these other, far more pessimistic estimates.

The laffaloud irony is that, elsewhere, he's really quite strong about people who cherry-pick their information . . .

All in all, then, having found a few instances where I did not feel Muller was dealing fairly with his readers, I became uncertain as to how much of the rest of his text I could trust. And that's a pity, because I very much enjoyed the actual process of reading the book. show less

What information does a president of the United States really need to know to make informed decisions about some of the most important issues we are facing as a nation and as a global community? Richard Muller believes that some of this knowledge should be an understanding of the basic principles of physics.

I loved the format of this book. Muller writes this book as though the reader was the next president of the United States. The book applies basic physics to a better understanding of show more five key areas: terrorism, energy, nukes, space, and global warming. I found this book to be truly enlightening. Almost daily I am bombarded by news stories featuring the challenges we are facing in at least one of these areas. Muller presents the facts, in a fair and balanced manner (honestly, I really can't tell which political party he favors) , allowing the reader to draw their own conclusions.

For example, Muller explores why the greatest threats we face from terrorists are not "dirty bombs" or stolen nuclear weapons, and why solar powered cars are not really feasible, at least with our current technology. Personally, I was especially intrigued by the section on global warming, and I felt that this section alone would have justified the purchase price of the book. In each section he also presents a brief historical perspective with an emphasis on the physics involved in each situation. I was totally fascinated by his exploration of the facts surrounding the anthrax attacks which followed the 911 attacks.

Muller's writing style is pleasantly conversational, almost as though you were having a discussion with your own personal science advisor. He also strikes the right balance between simplifying the physics to the level of easy understanding without insulting the intelligence of the reader. I enjoyed this book so much that I lent the copy I borrowed from our local library to my husband, who promptly purchased a copy midway through reading the book. This was a great read, and one that I wouldn't hesitate to recommend, even to our current president. show less