- NPR page of the program (35 minutes)
Click "Listen" - and I am sure you will be able to do the rest. Ira Flatow, a favorite host of mine, makes an entertaining and reasonable introduction. Lee, who is a bit nervous, is doing a fair job in spreading all of his strange misconceptions that science should work like a democratic society; string theory has been unsuccessful and all kinds of people always thought so; that he has even been working on string theory now and then; and all this spleen and material destined to be recycled.
Brian Greene, on the other hand, makes a great job in explaining how things actually are and why certain ideas make sense. Greene, who is on the phone, says that we always want the progress to be bigger than it is but the reality has actually exceeded his personal expectations from the mid 1980s. Brian offers an elementary introduction to string theory.
Smolin claims that string theory makes no predictions - this extraordinarily dumb wide-spread myth is even "not controversial", he says - and he disagrees with Brian about the expectations, and insists that experiments proving theories must always be found within 5 years because it's been always like that. This is such an incredibly silly comment that I won't honor it with detailed feedback except for saying that the theory of atoms has waited for a proof for about 2,000 years. The interference of light in double slit experiments was observed a few centuries after the light was described as a wave. The photons were waiting for the ultimate proof - the Compton scattering - for 25 years since Planck's calculation of the black body spectrum. The electroweak gauge bosons were discovered 20 years after the first reasonable theories that included them. There are dozens of other examples but even if there were no examples, it would be incredibly stupid to argue that there must exist such a deadline. Deadlines and ultimatums belong to politics but Nature does not care about this kind of nonsense.
Lee then promotes and praises loop quantum gravity advocates without any rational justification - except for the comment that they haven't learned string theory so they must be as good as Galileo and Einstein. Wow.
Brian is asked when we can expect an experimental confirmation. He describes the supersymmetric and extra-dimensional chances of the LHC and other experiments including those in string cosmology that he has been working on for a couple of years. He says that the precise timescale of the discoveries obviously can't be calculated. But most importantly, he insists that string theory doesn't change anything about the scientific method according to which the validity of theories is ultimately decided by experiments. You are not supposed to just believe a theory because not even we believe: we will see and we are doing the best to see.
He apparently doesn't realize that this opinion differs sharply from Lee's opinion who proposes that the scientific method as used in the last 50 years doesn't work anymore. His new book - which I have already digested - is full of this crazy postmodern crap. For example, when I read how physics has been controlled by the nasty American craftspeople in the last 50 years and how Coleman, Glashow, and Weinberg could not be compared to Smolin's heroes who preferred prophecies and philosophy, I learned how serious Smolin's attitude is.
To show that the string theorists unequivocably encourage diversity, Brian mentions his students who work on as unconventional theories as modified Newtonian dynamics - also my favorite long shot. ;-) Others work on bread and butter particle physics. Of course, we need to support people's creativity - who could have thought otherwise?
A listener named Jeffrey asks Lee what alternatives he proposes if he wants to kill string theory. Lee answers with an incredibly weird answer - that there are about six active competitors of string theory - six either marginal theories unrelated to quantum gravity or semi-crackpot theories that he apparently considers to be on equal footing with string theory. His book should have been called "Seven Roads to Quantum Gravity" instead of "Three...". ;-)
He only wants to enumerate them, hoping that Ira Flatow and others will just accept this complete bullshit about "many alternatives of string theory" without a glimpse of rational explanation: he is used to the intellectual standards of the "Not Even Wrong" community where such an empty comment is probably enough to convince everyone because everyone is an idiot, to put it very politely. However, Flatow asks him what the ideas mean and imply.
You can hear that this is what Lee Smolin would never expect. In fact, he was actively trying to force Flatow not to ask by saying that "the names [of the alternative theories] won't mean much". Analyzing any ideas more deeply is a kind of sin; the right approach of Lee is to enumerate 2, 6, or 2006 alternatives by five-word titles (that can even be omitted) and use the principles of democracy to reduce the role of string theory to 1/3, 1/7, or 1/2007 of physics at the fundamental scale even though string theory is clearly the only framework we have to say anything about the physics at this scale.
Flatow, however, has been interested in real science since his boyhood and prefers a test or a rational analysis so Smolin has to say one sentence about doubly special relativity - especially his favorite commercial for the extremely undemanding audience that DSR is great science because it will be tested soon. ;-) It is very clear that he couldn't say much more than this single cheap sentence because there is almost nothing else known about this "science" except for the bizarre ad hoc modifications of dispersion relations that can't be reconciled with any semi-realistic theory. Similar half-a-sentence explanations for dynamical triangulations and loop quantum gravity follow.
Flatow asks whether loop quantum gravity predicts a Universe before Big Bang; Lee's answer is very uncertain, stuck, and vague but I understand that he essentially answers Yes. It is not clear to me what papers support such a strange connection because two of my friends, the Bogdanoff brothers, have not yet proved that their bestseller "Before the Big Bang" is equivalent to loop quantum gravity. ;-) After my discussions with them about quantum groups etc. that were rather intimidating because they might indeed know more about them than I do, I am convinced that they are the only ones who are able to publish a paper on such an equivalence. :-)
Ira asks Brian whether it is frustrating not to decide about the validity of string theory for years. Brian says that of course, it is frustrating because string theorists are physicists and they want to know whether the world works according to a certain theory or not. However, Brian also explains the string revolutions and a huge number of successful consistency checks that have re-energized us many times and that lead us to think that we are on the right track. String theory is incredibly tight logically and embraces all the good ideas of the 20th century physics - which is what new theories should always do.
What's wrong about that?, Lee is asked by Flatow. Smolin says that it is a delightful situation because everything that Brian says is true. He tries to say something negative but what he eventually says makes no sense: he refers to the experiments that "we thankfully agreed about" - although no verb or other detailed information is connected with the word "experiments". He probably meant some simpletonic Woit-like comments about an inpenetrable gap between experiments and string theory that Brian Greene has falsified at the beginning by a stream of counterexamples. Then he says a couple of absurd sentences that string theory doesn't show how/that spacetime becomes quantum, if you allow me to translate Lee's incoherent confusion into a sharp but deeply flawed sentence. Lee also adds some insane comments that the other approaches are better conceptually and in their comparison with the experiments.
In a mountain-climbing analogy that seems to have nothing to do with the topics under considerations, Smolin proposes that the theories that have worked but have not yet given us the final answers should be abandoned - or thrown behind us. I listened to this incredible comment three times and I can assure you that it was not my misunderstanding.
In other words, everything goes (except for the things that work; those must be abandoned): the postmodern philosophers must be happy about this "understanding" of science.
Brenda advises the physicists to get a bigger box and Flatow rightfully laughs - and suggests a sand box - because it sounded a bit like one of the blonde jokes. She thinks that we don't need a supercollider because there is just a systematic distortion of the way how physics is done. Lee who understands that this woman tried to help him but a help from such a fan may look a bit embarrassing tries to save some of his scientific credentials and tells her that one must be not only a rebel but also a conservative. The lady proposes that the trees we see are just branches and we must return further which would be a great idea, especially if she could add some equations to it that would specify where we shall return and where we would continue from such a point. ;-)
Lee agrees with the woman except that her branches are his hills, and he says that he supports the people who believe various things like the "theory" that quantum mechanics is wrong - much like Lee the rebel himself, after all. ;-) Instead of a rational justification, he also mentions two authorities to support his weird attitude to quantum mechanics. They talk about the revolutions we need.
Brian Greene says that after the revolution, our perception of space and time will be changed dramatically. Brian's popular books are full of rather detailed considerations of these ideas that seem to be implied by string theory, and it thus looks a bit unnatural if Lee Smolin not only "borrows" them but he even tries to deny that Brian believes, together with many other string theorists, that the fundamental space and time are doomed.
Greene uses the statistical description of temperature as an analogy for the situation in which fundamental objects become emergent and morph to something completely unfamiliar. The main difference of Lee's opinion is that what space and time will morph into won't be unfamiliar but it will be nothing else than the standard and easy-to-imagine classical atoms of space that crackpots have loved for centuries and that can be drawn on a sheet of paper. But he fortunately doesn't get the space to say these things, at least not at this point.
I am always amazed how incredibly poor imagination most of the "alternative" physicists have. I would say that the models of reality they propose don't need any imagination whatsoever because they can easily be drawn and understood by kids from most kindergardens. It might be that many of the string theorists also have weak innate imagination skills but the equations of string theory simply force them (and force us) to learn new fascinating mechanisms how reality does work or can work and fit together even though the picture might look impossible at the beginning. Charges and momenta may become winding numbers of branes of various dimensions in a completely different spacetime whose physics is still equivalent; branes, strings, and particles can continuously morph into black holes; new dimensions can appear holographically and simple local field theories may be equivalent to vacua of string theory with infinitely many kinds of new objects. Realistic processes reflect mathematics at the cutting edge and they solve problems that mathematicians could not solve themselves. Completely unfamiliar but consistent ways to obtain microscopic descriptions of known processes and entirely new but rigorous mechanisms to cancel anomalies that no one would suspect are told us about directly by string theory herself.
However, the proponents of "alternatives" don't have any equations of string theory - or any other equations that would make sense - so they have to live with conceptions that everyone could invent and many crackpots indeed invent them on a daily basis. Conceptions whose basic intellectual evolution has stopped many decades or centuries ago - and the goal has been to convince everyone else about these shallow ideas without a glimpse of evidence. We are talking about ideas that have nothing to do with the abstract mathematical reasoning whose importance for theoretical physics has been clearly increasing throughout the last 100 years, to say the least. A goal of the alternative scholars is to remove abstract mathematical structures from physics and make physics simple-minded again.
At this point, Brian Greene gets the opportunity to say that our understanding of reality will be shattered because most of us think about all events as appearing at moments of time and places of space. Well, Lee finally has the opportunity to offer his most naive idea of "atoms of space". He is clearly completely uncapable to imagine that space doesn't have to be made of atoms even if it is not fundamental. The measure of "discrete" theories among all theories we can imagine is comparable to the measure of the integers among the real numbers - namely zero. In fact, this zero should be exponentiated to an infinite power because there are many assumptions in which the discrete physicists require physics to be discrete and special. And this measure whose value is zero is a good observable that quantifies the narrow-mindedness and the lack of imagination of the proponents of the discrete "alternatives".
Ira asks how does Brian feel if things go slowly. Brian says that they don't go that slowly if you are an insider, especially in the conceptual progress - something that is apparent in 50 great talks at every annual string conference. Theory might be moving slowly towards the experiments but the theory itself is being developed rapidly. In fact, it is hard to keep up.
I have always been afraid that Lee would "defeat" other debaters in similar discussions, slowly converting the public interested in physics to not-even-wrong-like debaters who are more opinionated than educated (and intelligent) - and the duel Smolin:Greene was certainly the main hypothetical example that we have always considered. Happily, such a thing certainly did not happen today. It's because of Brian Greene's virtues, based not only on his superior communication skills and psychological balance but also on his active knowledge of the topics and clean conscience of a real contributor to science.