I just finished reading Niels Bohr's times: In Physics, Philosophy and Polity by Abraham Pais. It is an amazing book on the life of an extraordinary genius. This book really got me thinking into the state of physics in the 21st century. The last great discovery, unless I am mistaken, was the Standard Model of particle physics way back in the 70s. Since then, physics has hardly progressed with more and more strange theories of extra dimensions, string particles etc. popping up. I have read a lot on the history of physics and this reminds me of the year 1895 when physicists thought that almost all of physics had been explained and only a few small things remained. It seems that the time is ripe for another Einstein or Bohr to revolutionise physics as we know it. String theory, even though I am still a second year college physics student, seems to me to not be 'revolutionary' enough. It builds on previous ideas which of course is important BUT maybe that is not the path. The time may be ripe to seriously question the basic ideas of quantum physics (interpretations since the mathematics and physics are sound and backed up by tonnes of evidence) and maybe modify existing theories. I keep wondering what would have happened if Einstein never thought of his 'crazy' ideas. The aether theory would have gone on and dominated science and we would have to make lots and lots of modifications to keep that theory alive. The same thing seems to be with string theory with the ideas of extra dimensions, branes and exotic particles. Anyways I would like to know what you all think about the state of physics right now and whether there has to be a radical change in ideas.
Well, I doubt that data from the LHC will provide conclusive proof that proves or disproves any current scientific theory regarding the unification of the four forces. As Lee Smolin mentioned in his book, The trouble with Physics, theories like string theory are extremely hard to falsify because apparently certain parameters can be set that would agree with the experimental evidence. To add on what I said above, Einstein and Bohr's ideas did not spring out of thin air, they came from already existing principles. In Einstein's case, the photoelectric effect came as a result of Planck's work and Bohr's ideas were a combination of Rutherford's scattering experiments and the failure of classical mechanics to explain things like electron orbitals. In both cases, existing theories were interpreted differently but were not thrown out of the window. The existing unification theories as far as I know do not aim to modify existing theories per se but attempt to get around it. Smolin summed it up best in his book when he said that radical theories were getting too marginalised. All I can say is that I await the next revolutionary physics thinker with open arms!
I agree with you. This is what I wrote in another topic: ---------------- When we approach the truth we make sacrifices on every step: we give up eucledian space, we give up flat spacetime, we give up realism in QM. On every step science gains a lot, but there is always high price to pay, and each time this price is higher and higher and more and more contre-intuitive. I doubt the superstring/TOE theory will be just new formulas in the 10,11 or 26 dimensional space. I think the reason why we still dont have a final theory is that all these M-theories do not suggest any sacrifices... Something which makes all people say "oh, no, this is really crazy, I can not believe, something is definitely wrong here... I can believe in non-realism or curved spaces, but not this!"
No one seems to be addressing the deeper issues of physics but instead, seem to be happy calculating equations and spending an awful lot of time on mathematics. What happened to the Physics community of 50 years back where debates about the interpretations of space,time and the nature of particles were argued? It seems like we have reverted to the 'Shut up and calculate' mode that does not seem to be getting us anywhere. Obviously, we should not base our radical ideas that vehemently do not agree with any known physics principle or we should not argue for the sake of arguing but we need to take a break from calculating and make sense of it all.
I think most people will agree a revolutionary new model of a fundamental nature is necessary to move physics in the direction of a greater understanding of nature. The revolution started by Einstein was two fold. It was Einstein that proposed quanta as well as the transformations of dimensions necessary to uphold the laws under the constancy of the speed of light. Einstein took a very pragmatic approach in developing SR. He accepted the empirical evidence of the constancy of the speed of light and the evidence that electromotive force contradicted the notion of absolute rest. He put these two ideas together and showed us what must be happening in our observations (dilation) if the laws are to be upheld. I think the next revolution will not begin until physics is willing to accept a fully relativistic theory of dimension. It will require the same kind of pragmatic approach Einstein adopted, extended to the most fundamental notions of physics - dimension. The problem of reconciling QM and GR is a problem of Time - time in QM is the clock on the laboratory wall, time in GR is the evolution of the metric, an evolution that occurs because time occurs. Neither of these notions of time will suffice to resolve the conflict between QM and GR. The problem stems from the notion of quantization first proposed by Einstein (from Planck's work). How does the universe present a continuous (and relative) nature of dimension on one scale and yet become finite and discrete dimension on another? Is this a question of spatial scale and/or temporal scale? Are space and time the same thing at each scale but greater and lessor at each? Or is the scale of dimension the determining factor in what dimension is in the first place? If space and time are a continuum and each is a relativistic measure of the other, at what point does space become finite and what happens to time at that point? At what point does time become finite and what happens to space at that point? I think the next revolution will begin when physics is prepared to consider space, time and mass are relative measures of each other, their continuous and discrete nature are simply a question of recognizing the quantities we measure are determined by what we measure and at definite and relative scales our measures of space and time are in fact a measure of mass. This is not very radical when you think about how we define mass.
Will someone please tell me where Lee Smolin got the number 10^500 string theories? I read his book "The Trouble With Physics" but, unless I missed it, the source of this number was never identified. I think Leonard Susskind used it in terms of the number of possible universes (each with their own distinct physics) that would be consistent with current versions of string theory. It's an unimaginably huge number. I was thinking, a number like this would actually be a sensible estimate of the number parallel universes in Hugh Everett's "Many Worlds" interpretation of QM. But, these parallel universes would need to have the same physics, so that can't work. Clearly, this number has to be pared down if string theory is to have any future...like say 10^50???
VandeCarr, I am not sure where Smolin got that number from, but I am guessing that it is accurate since he himself has done extensive research in the field of string theory. The fatal flaw with theories like Hugh Everetts many world interpretations and indeed string theory is that it seems an 'easy way out' of describing nature. The problem is it seems likely that string theory is going to have a possible future since many physicists, while brilliant in their own right, have trouble understanding the concept of scientific principles. It is unfortunate to hear many leading physicists like Michio Kaku or Edward Witten stating that string theory is our best chance to a quantum gravity theory. If it really was our best chance, you would think after 20 years working on it, there would be some progress. Instead, the theory has become more confusing with no underlying principle to connect it with quantum gravity as far as I know. And yes Chrisc, someone out there has to stop his calculations and think, just think about the meaning of space,time, the quantum nature of particles and keep asking why. In my first quantum physics course last year, in the syllabus, it stated that the important thing to note is that interpretations and thinking about the nature of quantum physics is not important but rather, its the calculations that sit in the front row. That to me stinked of conservativeness. You may say to me, hey why dont you do something important and then talk! All I am saying is read about the philosophy and history of physics because that is an important aspect of study as well. Discoveries in physics were not made purely by calculations, they were made by first thinking about what the problem is with existing principles, making new and brave insights based on the shortcomings of those principles and then the calculations and proofs began. Theories like string theory may have started out that way but unfortunately, somewhere down the line, something went wrong.
Math 04: If string theory is the 'easy way out', I shudder to contemplate the hard way. Can you imagine rotating the highly complex topology of the Calabi-Yau shape in six dimensions (or 7 depending on which string theorist you talk to)? Compare the math of string theory to the (relatively)simple beauty of Einstein's tensors. It's inadequate to say the math of string theory is to Einstein's tensors as Einstein's tensors are to simple arithmetic. The gap is wider than that. This is no complement to string theory. Just the opposite. All this hyper-math and ultra-computation is beyond any testable hypothesis. Yes, complex models can perhaps explain the world we observe, such as Ptolemy of Alexandria's (200 CE) complex system of cycles and epicycles which correctly predicted the motions of the planets. But is was wrong. Putting the sun at the center of the solar system was far simpler and actually correct.
Exactly, the laws of nature have always had a simple, underlying principle which holds for any branch of science. Darwinian evolution had natural selection, chemicals were organised according to the Periodic Table and physics has classical mechanics, electromagnetism and modern physics. Some of the quantum gravity theories out today seem to lack a fundamental principle that governs the theory. The mathematics may be beautiful but does the physics add up?
Theoretical physicists are looking for a way to put the Sun at the center of their solar system (the Standard Model). Until a successful model is found, there will be many ugly and overly complex attempts. I think you will find few (even string theorists) disagree with the tone of your objections. The complex maths of ST are not necessarily the final construct of the model. It is often the case that an overly complex mathematical modeling is developed on the road to what will eventually be a much simpler, more elegant model. We used to build airplane wings from hundreds of sticks of wood, cloth, glue, nails and twine. It was only after proving the sound principles of flight with these complex constructs that we could then replace all of these materials with a single sheet of metal.
What you bring up is intriguing, sort of the brute force tactics that shaped the physics scene from the early 50s. That was the transition from the classical way of thinking into the more modern method of research in physics. Reading into what the great physicists thought processes, every great discovery was made was shaped by simple thought experiments and phenomena that could not be explained. Actually fluid mechanics was well known in the early 20th century thanks mainly to the work of Bernoulli and company. Undoubtedly, very little was known about wings BUT the underlying principles were known way before the Wright brothers and Kitty Hawk. I am not saying that all quantum gravity theories are false and should be abandoned but what should be understood is that they are unproven and till then, should not be taken at face value. Many of my fellow students think that string theory is true and even some of its distinguished proponents believe that it is the BEST solution. For me, that just undermines others who work on different theories.
You're right, it was a poor analogy. I should have stuck to the principles of engineering the wing. It can be frustrating, but give them credit for having a passion for their work and providing a lot of new insight. Only time will tell.
The problem is there is no such thing as "string theory". Lee Smolin claims there are 10^500 string THEORIES! Real theories come in the singular, although there might be minor variations. String theorists cannot agree on the topological genus of the Calabi-Yau shape, which is basic to any string theory. Since topological transformations are the most general of all geometric transformations, there is no more general a frame for differing topological genae to inhabit. String theories can model many aspects of the Standard Model, but, as far as I know,there is no fleshed-out string theory that can offer a simplification of the Standard Model or a new testable hypothesis. Moreover, with so many to choose from, I don't see how progress can be made. A collider the size of the Galaxy wouldn't be sufficient to test any given string theory.
yes, hopefully there are buddying scientists like us out there who would think of alternative theories to what is currently being pursued.
I am only a grad student in Physics, but what I observe is a general unwillingness to entertain fundamental questions, among established researchers in the field. Let me qualify that ... as long as fundamental questions are discussed in a "pedagogical" setting, they may be very superficially discussed and then sort of brushed off as just a curiosity. However, if one raises fundamental issues in the context of a serious, ongoing research topic, it is met with great hostility. A past advisor put it very honestly. "Only the most famous researchers are allowed to think about big ideas". If anyone lower on the totem pole tries to explore fundamental questions as a serious research topic, they can expect to be dismissed as a crackpot.
You must not have searched very hard, because sources are quite easy to find. Even here : String theory landscape you will find "The statistics of string / M theory vacua", JHEP 0305, 46 (2003) "Counting flux vacua", JHEP 0401, 060 (2004) from which you will find plenty. Reviews : "Flux Compactification", Rev.Mod.Phys.79:733-796,2007 "Basic results in Vacuum Statistics", Comptes Rendus Physique 5 (2004) 965-977 Lectures : "Status of Superstring and M-Theory", @ Erice 2008 CALT-68-2714 "Les Houches Lectures on Constructing String Vacua" "Lectures on Nongeometric Flux Compactifications", Class.Quant.Grav.24:S773-S794,2007 up to recent PhD thesis (for instance), where you probably can find even more that you want to know Phenomenology from the Landscape of String Vacua
I recognize this too, but my experience is that some researchers lack the confidence necessary to have faith in their own questions, not matter how formally well educated, which is somewhat weird. My experience is that most people do acknowledge the deep questions, but they seem to somehow lack faith in their own ability to tackle them. They seems to somehow have "surrendered to reality" thinking that these questions are simply too difficult. But then why not step aside and let someone with some guts try, or at minimum encourage young students to go for it with all they've got instead of telling them they are fools to think they can solve the big issues :) I think most people with sanity realize that many people are likely to fail before one succeds, but without courage noone will even try hard enough to ever succeed. So I think encouragement is more in place than is leader trying to prevent the individuals with som guts to make mistakes. /Fredrik
My opinion is that we have a 'problem' with QM, because we can't think in quantum terms, we are constrained to a classical frame. Which is why we can have a general kind, or a specific kind, of understanding, but we can't have a 'global' one. We can only ever understand it 'momentarily', as soon as we think "I understand QM", we don't any more. We have to develop a group 'infomation velocity'; the individual contributions to it can only be a small interval. I've noticed that thinking about quantum processes, when you try to look "beyond the math" and grasp it ontologically, it vanishes immediately; understanding is like a wave that you see the top of now and then, and then it moves away. It's like you have to forget any preconceptions, based on 'what you know', every time you do encounter a QM phenomenon up close.
I used to have issues with quantum weirdness, but don't anymore. The old realism ideals are dead to me since many years. However if we just talk about quantum mechanics as in the formalism currently formulated, it's IMO not yet finished. Quantum mechanics is still a semiclassical construct. It still contains old style thinking in many ways. At the birth of the theory, the step from determinism to probabilistic thinking was probably a large step, but when you analyse the physical basis of probability, it is still very clear that there are still strong elements of old logic in there, that I think is very malplaced. Most people, with some exceptions that know QM, get uncertain when you probe these questions. Some acknowledge the problem but don't see how to resolve it, some educated people mysteriously manage to convince them selves that these questions are philosophical pottery that have no bearing to the future of physics. Given such attitude I think what we need to make progress is a solid fool. /Fredirk