(posted on my blog: davenichols.net)

Lee Smolin is a well-respected physicist who isn't currently working on string theory (yes, there is such a person). The Trouble with Physics represents Smolin's well-developed and highly-engaging view of the current landscape of physics, the problems presented by string theory's dominance, alternative research underway in the field, and a call to academia to reform for the sake of science.

The first part of the book is largely an extension of the first half of his earlier book, Three Roads to Quantum Gravity. Here, Smolin expands the story and gives a more robust picture of some of the key players and key parts of various theories, beginning by defining five main problems which physics must attack directly.

In the second section, Smolin gives a broad and balanced view of string theory's history, successes, and failures. He does this in a very humane and reasonable way (unlike the bitter negative view in Peter Woit's book Not Even Wrong). Smolin himself worked on string theory for several years before coming to his senses and looking for new ways to attack the five problems of physics.

For me, the third section was the best in the book. Smolin gives us an overview of the world of physics after string theory, introducing unexplainable phenomenons and exploring several alternative areas of research currently underway, including cutting edge thoughts like double special relativity, the 'axis of evil', and twistor theory. Smolin advises us not to lose heart even if string theory is ultimately discredited (he argues politely but firmly that it already is so as the ultimate unification theory while conceding that it has opened up other areas of insight and advancement).

Finally, Smolin's last section is aimed primarily at his peers and those in positions of power in the academic world, though the non-academic reader should really take in his points here as they apply to our understanding of the academic world and the politics that often hinder the advancement of science. He challenges traditional notions of scientific method, peer review, and tenure, while arguing for more opportunities for alternative thinkers and researchers. His chief argument is that the Einsteins of the current physics world are unable to get jobs unless they give in to academic pressure to work on a very narrow range of accepted theories (most especially string theory), often leading them to abandon the independent thinking which may have lead to breakthroughs in the field. This, Smolin states, is a primary problem for physics to overcome in order to complete the revolution Einstein and other started decades ago.

I had just finished up Smolin's Three Roads prior to this one, so let me offer just a few thoughts. In Three Roads, Smolin was much more diplomatic about string theory's place in physics. While Trouble offers many reasons why string theory deserves attention, it also shows Smolin's hardened stance that alternative theories must be given much greater attention than they currently receive. Smolin also offered predictions in Three Roads which he has clearly backed away from, namely string theory's ultimate role in the unification of forces (he now shows considerable doubt that such a theory may even exist). To be fair, in Trouble, he also admits his disappointment of his own loop quantum gravity theory to provide results he thought showed great promise in Three Roads.

This is the book that needed to be written about Physics. It is well balanced, with loads of cutting edge science and personalities, but it is broader than most, less stary-eyed, more sober. It challenges traditionally held beliefs in how the physics world moves forward, and advocates strongly for a revolution in academia to preserve the vital nature of science itself.

What more can I say? Smolin is level-headed, presents an engaging and insightful book, and develops his thoughts with a hopeful but measured eye toward the future. Trouble with Physics is the book you should read if you like Brian Greene or Michio Kaku's books, but need to understand a more balanced, reality-based view of the world as physics really understands it (which is to say, not nearly as well as Greene, Kaku, and other string theorists would have us believe). Five stars, one of the best popular science books I have read in a long time. ( )

If only more scientists wrote for popular audiences with the humility Lee Smolin does. Whilst it occasionally gets bogged down in the detail of its own material - there are more minutiae on particle physics here than most people will care for in a bedtime read - Lee Smolin's major points are clearly made and they ring like a bell.

In some ways this is a work of popular philosophy of science, not popular science itself: Smolin approaches his subject through the prism of the failings of string theory to coagulate over the last thirty years, but only in the loosest sense is this an attempt to prove string theory wrong and his own favoured research programme, quantum loop gravity, right. For one thing, he accepts from the outset that there are significant issues with his own programme.

Smolin's concern is more around the practice of modern physics; how the gradual disappearance of anything resembling testable empirical evidence has given way to ever more theoretical modelling which in turn has led to hypotheses of increasingly incredible (literally, that is) implications. For any variety of string theory to work (it is more of a cluster of similar possible theories, rather than a discrete theory as such) the mathematics require something like *eleven* spatial dimensions, some of which, it is variously hypothesised, must be so small as to be conceptually unobservable (the image we are invited to consider is dimensions which curl up into little donuts smaller than an atomic particle across), or which appear to require an infinity of alternative universes - a "multiverse" if you will - into which these dimensions can be projected. (I may well have not understood or expressed this perfectly: the important point is that the theory must account for the absence of any physical evidence for the extra dimensions: solution - they're invisible, of course!)

Smolin's concern is not just that these are outlandish and faintly ridiculous consequences - though they surely seem to be - but precisely that they are systematically untestable. *By definition* there is no means to measure spatial dimensions smaller than the smallest subatomic particles. *by definition* we cannot see or measure physical effects occurring outside our own universe. These are not just difficult to say with a straight face, Smolin argues, but by any commonly understood sense of the term they're altogether unscientific: logically closed, untestable, unfalsifiable, unreliant on any kind of inductively gathered argument.

Precisely the sort of arguments, in other words, that give religious cosmologies a bad name: utterly verboten, you would think in the enlightened mead-hall of the physical sciences. (Yet, and without apparent irony, biologist Richard Dawkins makes favourable reference to the "multiverse" theory in his recent book The God Delusion!)

Smolin argues that this uneasy development collides head-on with some uncomfortable realities about the sociological aspects of the practice of science. Again, Smolin is persuasive here (though in my case preaching to the choir) in citing favourably the late, anarchic, philosopher of science Paul Feyerabend, whose general message is that for scientific methodology anything goes, and all theories have a role to play for the good of the "development of knowledge", and that determined insistence on an existing accepted theory for framing ongoing research hardens quickly and dangerously into dogma: you need the vistas that different theories offer, says Feyerabend, or they are "as useless as a medicine that heals a patient only if he is bacteria-free".

For his trouble, Smolin is duly criticised for exhibiting "postmodernist" or "relativist" tendencies, and while I don't think this *is* a criticism myself, it is in any case unfairly awarded, since Smolin avowedly retains a belief in the possibility of objective truth, and promises to (but in the end doesn't really) take issue with the work of the most celebrated "postmodernist" philosopher of science, Thomas Kuhn. (I'm a fan of Kuhn's so I was looking forward to the challenge, and was a bit disappointed to find it didn't materialise).

Practically, Smolin feels that String Theory is now a "paradigm in crisis". Certainly, the theoretical tail seems to be wagging the practical dog. It is difficult to see what practical utility a theory has which postulates invisible dimensions and which doesn't seem to point with any clarity to a possible solution at all, let alone one with the elegance of a f = ma or e = mc2.

I suspect this book will annoy the hard-core science-is-truth crowd, but anyone with a more open mind will find a valuable perspective here. ( )

First of all, this book neither touches upon the falsifiability debate with regard to the Anthropic Principle in string theorists’ and especially Susskind’s “Cosmic Landscape” theory, nor Smolin’s alternative CNS/black holes theory of “Cosmological Natural Selection.” Its concern is today’s state of physics as a science, and according to Smolin, it’s in a sorry state indeed.

I admit I was shocked at his critical assessment of what has effectively been achieved during thirty years of string theory. While its findings have been, time and again, exceptionally promising on the one hand, they have actually delivered very little—far less than I somehow thought it had. The strange feeling that string theory had lost its bearings or even its grounding in reality in its attempt to cope with the cosmological constant and other recent findings, a feeling that had slowly gripped me while reading Susskind’s The Cosmic Landscape, seems to bear out: there is no ground to stand on, and the promising advances of string theory seem to have led to a perpetuated self-delusion of the “it’s so good it just has to be true!” variety. Which makes me rather sad—I’ve been fond of string theory and of certain brands of string theory-dependent developments like brane theory, especially the Randall-Sundrum Model by Lisa Randall and Raman Sundrum ... all of which now seem to warrant a sober reassessment.

This should not be misconstrued. Smolin is not attacking String Theory as a theory, nor is he promoting (Loop) Quantum Gravity as his own, competing field of research: none of these and other theories have, according to Smolin, borne out so far. His criticism against String Theory is more pronounced only because it has been the predominant academic paradigm for so long, and this is where Smolin’s criticism is aimed at: the way we did research since the relativity/quantum revolution. The fourth and last part of The Trouble With Physics, consequently, is about the philosophy of science, and Feyerabend, Kuhn, and Lakatos figure large. What Smolin proposes, in a nutshell, is that we need less peer review and more risk taking (courtesy of Feyerabend); less “normal” science and more “revolutionary” science (courtesy of Kuhn); and a return to the drawing board and the foundational problems of quantum physics. The latter not only in order to “reconcile” quantum physics with relativity, but to develop a deeper understanding and with it a possibly underlying “deeper” theory that is background-independent, that makes sense of quantum physics beyond the Copenhagen interpretation, and that unifies gravity with everything else.

This is the most sobering, most convincing, and most self-critical account from and about theoretical physics I’ve read in a long time. And, concerning the history of string theory and today’s five fundamental problems of physics, one of the most readable and accessible texts to boot.

This book is smarter than me. ( )