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The Trouble with Physics
SpaceAdmiral writes "You've likely heard of Lee Smolin's book The Trouble with Physics. It has created a lot of controversy because it argues that string theory gets far too much attention and money, despite a complete lack of evidence. It accuses string theorists of groupthink. Smolin has dabbled in string theory from time to time but he's a proponent of the alternative loop quantum gravity. Although irrelevant to this book review, he has also suggested that it is possible that universes reproduce via black holes, making them prone to pressure similar to natural selection (universes that produce a lot of black holes are more successful spawners than those that don't). In The God Delusion, Richard Dawkins quotes Nobel-winner Murray Gell-Mann as once saying, "Smolin? Is he that young guy with those crazy ideas? He may not be wrong."" Read the rest of SpaceAdmiral's review.
The Trouble with Physics
author
Lee Smolin
pages
392pp
publisher
Houghton Mifflin Company
rating
9
reviewer
Fane Henderson
ISBN
0618551050
summary
The Rise of String Theory, the Fall of a Science, and What Comes Next
The Trouble with Physics is very unlike most pop-physics books not only in its criticism of string theory, but in its open adulation of Einstein and skepticism of the Copenhagen interpretation of quantum theory. Having said that, it does provide a very decent summary of 20th century physics (including string theory) for laypeople, not unlike more traditional pop-physics books (e.g. by Hawking and Greene).
The book's main criticisms of string theory are that it makes no testable predictions and that some things string theorists take for granted haven't been rigorously proven mathematically. Smolin is highly skeptical of many string theorists' reliance on the Anthropomorphic Principle.
The book becomes most interesting somewhere in the middle where he discuses truly controversial approaches to physics. This includes things like MOND, which, interestingly enough, Smolin is skeptical of.
In case you've forgotten your high-school physics, I'm going to use this paragraph to refresh your memory of special relativity to prepare you for the next couple paragraphs. The basic idea of special relativity is that the speed of light is constant. Pretend that I am shining a light at you while (A) standing still relative to you; (B) moving towards you at half the speed of light, and; (C) moving away from you at half the speed of light. In all three scenarios, I will accurately measure the light moving away from me at 3,000,000 km/s and you will accurately measure the light moving toward you at 3,000,000 km/s. To ensure this result, distances and times will have to be different for me than they are for you, except in case (A).
Now I'll quickly remind you of the Planck length: This is a theoretical limit on how small something can be. According to Smolin, all versions of quantum gravity seem to suggest the Planck length as a limit. But would observers moving relative to each other disagree about the Planck length?
I used to be a big fan of MOND (in a layperson sense) until Smolin introduced me to DSR (doubly special relativity) and DSR II. The basic idea is that it may be possible to modify the theories of relativity such that observers agree not only on a constant speed of light, but also on a constant Planck length. It's not unreasonable to guess that a modification of this sort could solve some of the same problems MOND does (e.g. explain astronomical observations without resorting to dark matter and dark energy). Furthermore, since DSR in its current incarnation predicts that more energetic photons are slightly faster than less energetic photons (only the speed of the least energetic photons is constant in DSR), it could also explain away, for example, inflation in the Big Bang model. (Immediately after the Big Bang, everything was hotter and more energetic, so the average speed of light would have been faster than it is now if DSR is correct.) Although I'm not qualified to judge the actual mathematics of such a theory, I find it very appealing for reasons of consilience.
I was slightly disappointed with the final chapters of Smolin's book since, despite an obvious effort to the contrary, it struck me as awfully bitter and reeked of sour grapes. Leaving physics in favor of sociology, he lambasted the current tenure and peer review systems (particularly in the United States) as favoring Master Craftspeople (like those scientists who developed the standard model of particle physics) over Seers (like Einstein, Bohr, and de Broglie) who look at the deep questions of physics that border on the philosophical rather than the latest technical problem. A few interesting things do emerge in these chapters. One such thing is that Smolin seems to have a soft spot for Paul Feyerabend as a philosopher of science (despite describing himself as a proud Popperazzo in an endnote). Another is that Smolin thinks a scientist who is hated by half his senior colleagues and loved by the other half is likely better than a scientist who is liked by all his senior colleagues. I strongly recommend this book.
You can purchase The Trouble with Physics from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
The Trouble with Physics is very unlike most pop-physics books not only in its criticism of string theory, but in its open adulation of Einstein and skepticism of the Copenhagen interpretation of quantum theory. Having said that, it does provide a very decent summary of 20th century physics (including string theory) for laypeople, not unlike more traditional pop-physics books (e.g. by Hawking and Greene).
The book's main criticisms of string theory are that it makes no testable predictions and that some things string theorists take for granted haven't been rigorously proven mathematically. Smolin is highly skeptical of many string theorists' reliance on the Anthropomorphic Principle.
The book becomes most interesting somewhere in the middle where he discuses truly controversial approaches to physics. This includes things like MOND, which, interestingly enough, Smolin is skeptical of.
In case you've forgotten your high-school physics, I'm going to use this paragraph to refresh your memory of special relativity to prepare you for the next couple paragraphs. The basic idea of special relativity is that the speed of light is constant. Pretend that I am shining a light at you while (A) standing still relative to you; (B) moving towards you at half the speed of light, and; (C) moving away from you at half the speed of light. In all three scenarios, I will accurately measure the light moving away from me at 3,000,000 km/s and you will accurately measure the light moving toward you at 3,000,000 km/s. To ensure this result, distances and times will have to be different for me than they are for you, except in case (A).
Now I'll quickly remind you of the Planck length: This is a theoretical limit on how small something can be. According to Smolin, all versions of quantum gravity seem to suggest the Planck length as a limit. But would observers moving relative to each other disagree about the Planck length?
I used to be a big fan of MOND (in a layperson sense) until Smolin introduced me to DSR (doubly special relativity) and DSR II. The basic idea is that it may be possible to modify the theories of relativity such that observers agree not only on a constant speed of light, but also on a constant Planck length. It's not unreasonable to guess that a modification of this sort could solve some of the same problems MOND does (e.g. explain astronomical observations without resorting to dark matter and dark energy). Furthermore, since DSR in its current incarnation predicts that more energetic photons are slightly faster than less energetic photons (only the speed of the least energetic photons is constant in DSR), it could also explain away, for example, inflation in the Big Bang model. (Immediately after the Big Bang, everything was hotter and more energetic, so the average speed of light would have been faster than it is now if DSR is correct.) Although I'm not qualified to judge the actual mathematics of such a theory, I find it very appealing for reasons of consilience.
I was slightly disappointed with the final chapters of Smolin's book since, despite an obvious effort to the contrary, it struck me as awfully bitter and reeked of sour grapes. Leaving physics in favor of sociology, he lambasted the current tenure and peer review systems (particularly in the United States) as favoring Master Craftspeople (like those scientists who developed the standard model of particle physics) over Seers (like Einstein, Bohr, and de Broglie) who look at the deep questions of physics that border on the philosophical rather than the latest technical problem. A few interesting things do emerge in these chapters. One such thing is that Smolin seems to have a soft spot for Paul Feyerabend as a philosopher of science (despite describing himself as a proud Popperazzo in an endnote). Another is that Smolin thinks a scientist who is hated by half his senior colleagues and loved by the other half is likely better than a scientist who is liked by all his senior colleagues. I strongly recommend this book.
You can purchase The Trouble with Physics from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.
I see two sides to this. Smolin has a point. Most string theory papers are garbage. (True of many fields). But Smolin himself has not been research active in a long time. And it is unlikely that he understands enough mathematics to judge string theory - like most people.
Nothing for you to see here. Please move along.
Although irrelevant to this book review, he has also suggested that it is possible that universes reproduce via black holes, making them prone to pressure similar to natural selection (universes that produce a lot of black holes are more successful spawners than those that don't). doesn't the same despite a complete lack of evidence quote apply to this just as well?
You can't handle the truth.
Really? I didn't realize giving human characteristics to subatomic particles was a part of any current mainstream physics theory. :)
I'm assume you mean the *anthropic* principle.
Not very accurate. It should be 300,000 km/s. Or 299,792.458 km/s to be precise.
English is not this
Smolin is research active, but I seriously doubt he understands what Ed Witten did in the 1990's, for example.
did he write this book using 12 sided dice and a lot of caffeine?
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Seastead this.
A quick search on arxiv.org will show you that he is indeed very active, since he is still publishing very technical papers.
...
Not only that, Lee Smolin seems one of the very very few physicists who understands BOTH string theory AND other approaches (that is _the_ other approach, loop quantum gravity).
In any case, it seems that many predictions of loop quantum gravity will be actually tested within the next couple of years trough the GLAST satellite, so, we will get news relatively soon
We learn from history that we learn nothing from history - Tom Veneziano
Why is it that suddenly people are working out ways to mention Dawkins in as many articles as they can that have little if nothing to do with him? Are we playing a six-degrees-to-Richard-Dawkins game here?
"Do not be swept up in the momentum of mediocrity." - anon
I used to be a big fan of MOND (in a layperson sense) until Smolin introduced me to DSR (doubly special relativity) and DSR II.
Personally, I've been a fan of Heim theory, not necessarily because I think it's definitely true even though it makes nice predictions about particle mass, but because I just really want a space drive to be possible.
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
There's an interesting article in the last issue of New Scientist, discussing work by physicist Gerard 't Hooft in refining his theory of a determanistic level of reality below quantum physiscs, from which the apparent randomness and Copenhagen state collape of quantum physics appears.
m g19025504.000
http://www.newscientist.com/channel/fundamentals/
Maybe Einstein was right that "God doesn't play dice" (a rather misunderstood statement given that Einstein was an ardent aetheist).
Presumably efforts such as string theory to unite general relativity & quantum mechanics may be quite shaken up if this new theory is correct.
A big problem amongst educated people is to think that scientists are not prone to the same illogical behavior as average people. We think that they are immune to "following the flock" or otherwise being influenced by their peers.
While scientists are in general better than average people at being objective, they still tend to have their own biases. Spending you life working on a particular theory makes it hard to give it up even when the evidence disproves it. Even an objective scientist is going to have problems throwing away their life's work.
--
-- All that is necessary for the triumph of evil is that good men do nothing. -- Edmund Burke
Vilenkin has published an interesting paper which suggests a problem with Smolin's "natural selection of life-friendly universes via black holes" theory; OTOH Smolin strikes back! Ahhh, I love it when cosmologists attack ;)
"None are more hopelessly enslaved than those who falsely believe they are free." -- Goethe
OK, so he has a paper on M-Theory, so he probably does understand the latest stuff. But my main point still stands. This is just a thing about who gets to build the bigger empire and get more publicity, power and money. Just like the entertainment industry!
Because theres not a lot else in fundamental theoretical particle physics to spend it on. Basically we've reached the point where everything we can test right now is tested and understood and there hasnt been any significant surprises in the last 30 years. Basically the cludge that is the Standard Model works far too well and its completely theoretically worked out. And the theorists are just screwing around with silly things now because they are waiting for experiment to catch up with theory. We hope that this will happen when the Large Hadron Collider (LHC) turns on and that we will find something unexpected. This will give us the clue what to try next theoretically. And as soon as that happens, the theorists interest in string theory will disappear as they will (hopefully) have something new to work on to explain (hopefully) very strange experimental results. Particle physics is either about to go through a golden age in two years time or its going to wither and die.
On the contrary, string theory is very interesting, and has a great deal of interesting things to say. The issue is more that it is mathematics not physics. There is, of course, nothing wrong with mathematics for its own sake. Indeed, many physics theories were preceeded by the development of purely mathematical work - where would general relativity be without Riemann's work on manifolds for instance? In many ways string theory could be classified in a similar sort of category - it is a lot of very interesting mathematics that could, one day, be applied to the development of a physical theory. The dilemma comes when people act as if it is physics instead of mathematics.
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Look how much money the pr0n industry makes.
...wait a minute! THAT string theory ... oops!
Help a man when he is in trouble and he will remember you when he is in trouble again.
As physics progresses we seek for something that was hidden from the previous generation of physics. For example we start with observing gravity happen. 100k years ago (or 6k years ago - depending on your worldview) Ogg drops rock, ogg gets sore toe. Then more recently someone figured out it is because of mass/proximity of objects. Then someone figures out a characterising equation. Then someone else figures it is because space is bent. Then strings. No longer are we improving our observations. Now we're coming out with mathematical models of things that don't really exist.
Engineering is the art of compromise.
As a layman, I'll wait until the mod points are assigned on this article's comments. Then I'll have a reliable introduction to theoretical physics.
"Science is prediction, not explanation" - Fred Hoyle
The serious problem with string theory is that it doesn't yield falsifiable predictions. Theories which don't yield falsifiable predictions are not useful - you can't check them by experiment, you can't effectively choose between them, and you can't develop engineering based on them.
This matters. From subatomic physics we got nuclear power. From quantum electrodynamics we got semiconductors and lasers. From string theory we got nothing. If you can't make predictions, you can't do engineering design.
With string theory, you can create pretty mathematical objects, but it's not clear that there's any connection to the real world. Smolin says that's bad physics, and he's probably right.
There's real progress in physics, but it's mostly at the low-energy, low temperature end. Seemingly impossible objects like Bose-Einstein condensates and materials with negative indices of refraction have both been demonstrated. Quantum computing is hard to do, but real. That's progress. But the high energy physicists and the cosmologists have been stuck for a while.
It's possible for an entire field to take a wrong turn like this. Artificial intelligence did, back in the 1980s, when the expert systems people were claiming that strong AI was just around the corner. Then came the "AI winter". Twenty years later, AI is moving again, but with new approaches (more statistics, less formal logic) and new people.
The real stuff is the equations, which all the interpretations agree on. And all the predictions spring from the equations.
The interpretations aren't right or wrong, they are just how we translate the math into our daily language. If the Copenhagen Interpretation works for you, use it, otherwise choose one of the others. It does not matter.
Below I'd like to repost something I once wrote trying to explain why string theorists think string theory is an important approach, to counter the inevitable "it's not science" claims I see on string-related threads.
(I would like to note first that Smolin himself has written string theory papers, and historically has advocated combining string theory with loop quantum gravity, so even he doesn't think string theory is nonsense — he just would like to see it mesh with his own theories and doesn't like the attention it gets relative to them.)
Anyway, my two cents on string theory and its justification and testability:
First, string theory could certainly be tested if we could probe the Planck scale. We will never be able to build an accelerator to do
that directly. There is some chance we might eventually do it indirectly by measuring fluctuations in the cosmic gravitational wave
background. In addition, string theory encompasses many scenarios in which the string scale could be probed at much lower energies, but nobody is very confident that those scenarios are likely to be correct.
That being said, there is a serious possibility that string theory might not be testable in practice, at least in the foreseeable future. I don't believe that puts string theory totally outside the realm of science altogether. String theory does at least make predictions, even if we can't test them. But that is a weak argument. More strongly, string theory is motivated by reason of consistency with known physics. Gravity has to be reconciled with quantum theory somehow. There are strong reasons to believe that string theory overcomes obstacles to quantizing gravity in a unique way that all other approaches can't duplicate, although this can't be proven. That is one of the main reasons why string theory is taken so seriously despite its experimental shortcomings (which are not surpassed by its alternatives, either).
Here are a couple of arguments in favor of string theory put forth by string theorists which I have begun to agree with:
In particle physics, it has been possible to write down theories of the non-gravitational forces while being ignorant of high energy
Planck scale physics. This is essentially due to the Applequist-Carrazone "decoupling" theorem, which uses renormalization
group arguments to show that low-energy physics can be made independent of high energy physics, because at sufficiently low
energies you can't excite the higher-energy modes; therefore, their contribution is irrelevant.
This decoupling breaks down for gravity. Because gravity is a universal interaction, it couples to everything (because everything
has mass-energy); the low energy effects of quantum gravity are never independent of high-energy physics. So you can't write down a theory of quantum gravity unless you purport to know everything about particle physics up to arbitrarily high energies — which of course you can't possibly say, unless you can do experiments at the Planck scale.
This is a criticism that string theorists level against loop quantum gravity. LQG is usually attempted ignoring all realistic particle
physics, and even if that approach succeeded, you'd have to write down a different LQG theory to take into account real particles, which might work completely differently than a vacuum LQG theory. LQGers respond by saying that they want to start by just proving it's possible to quantize *any* kind of gravity using this approach, and then worry about "realistic gravity".
String theory, on the other hand, evades the whole problem. It has a very unique mathematical structure which provides "mysterious" exact cancellations at all orders, rendering low energy physics decoupled from high energy physics despite the universal coupling of gravity.
Thus, it can make predictions about high energy physics even without our being able to make measurements at that scale. No other approach to quantum gravity has shown any signs of being abl
One thing I like about this debate is the cool quotes :):
/ 03/14/MNGRMBOURE1.DTL
... Our sciences are becoming increasingly infected with quasi-theology, a tendency which needs to be openly debated."
http://en.wikipedia.org/wiki/Feynman
Feynman, "I don't like that they're not calculating anything. I don't like that they don't check their ideas. I don't like that for anything that disagrees with an experiment, they cook up an explanation - a fix-up to say, 'Well, it still might be true.'"
http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2005
Another Nobel Prize winner, Robert Laughlin considers string theory to be physic's version of postmodernism:
"I think string theory is textbook 'post-modernism' (and) fueled by irresponsible expenditures of money."
"People have been changing string theory in wild ways because it has never worked."
And don't ever mention string theory to Nobel Prize winner Phil Anderson,
"we from outside the (string) field are disturbed by our colleagues' insistence that every new semi-adolescent who has done something in string theory is the greatest genius since Einstein and therefore must occupy yet another tenure track.
The article has some quotes in defence of string theory too but they're not as interesting. The usual blah, blah, blah, give us more time and eventually you'll see that we're right thing.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
Your idea of "real object" is very very strange. Mass?? It's just a characteristic of matter.
Agreed. We cannot tell the difference betwen a "model" and something "real" other than our model of it fitting observations. But fitting observations only tells us how accurate our model is. It says nothing directly about wether something is "real" or not. Wrong models can still fit reality. But perhaps it does not matter. Ideally we would like to have the "correct" model, but a wrong model that produces all the answers the right one does could be equally useful from a technology standpoint (assuming it is not more complicated).
Table-ized A.I.
The review of the final chapter seems to me to downplay a pretty valid point:
If you have ever refereed a paper, you know that you can't much help approching it like a term paper. You look for places to take points off. Visionary papers are almost always unfinished and so get poor reviews. Perfectionist papers that confirm what everyone thinks any way are harder to ding for points. (And are more likely to be fraudulant.)
Smolin has urged at least one frind of mine to just publish a visionary work to the archives rather than deal with a referee. This does not help with publication metrics that people need to keep their jobs, but it does leave an open channel for stuff that might not be wrong.
Rather than sour grapes, I'd call it honesty.
The 90s called, they want their theory back.
If someone is passing you on the right, you are an asshole for driving in the wrong lane.
The point is that Gell-Mann hasn't written off Smolin, which may lend some degree of credence to him. The only reason Dawkins is mentioned is to properly attribute the quote. I understand your confusion though; proper attribution is so rare on the InterWebs these days.
Build a man a fire, he's warm for one night. Set him on fire, and he's warm for the rest of his life.
Before you say, "Well, anyone who knows ANYTHING about physics knows that, you retard, this book is not for you..." - well, I did think this was supposed to be a layperson's book. So, I clicked to read this review despite having an effectively non-existent knowledge of physics.
Well, anyway, here's your answer, at least according to Wikipedia (obviously, not being my field, I can't vouch for its accuracy):
Source: http://en.wikipedia.org/wiki/MOND
If I explained to every person mouthing off on Slashdot why they are wrong, I'd never have time to leave the house. Sometimes, you have to keep it short.
a t
In short: He's confusing string theory and old-fashioned quantum mechanics, while understanding neither. Schrödinger's cat predates string theory several decades, and it is actually meant as a criticism of early quantum theories.
http://en.wikipedia.org/wiki/Schr%C3%B6dinger's_c
http://en.wikipedia.org/wiki/Quantum_mechanics
http://en.wikipedia.org/wiki/String_theory
May the Maths Be with you!