If you want to get an understanding of the ideology that many string theorists subscribe to, you should check out Lubos Motl’s latest posting. Besides the usual dismissal of non-believers as idiots, incompetents and crackpots (an attitude that unfortunately seems to be all too common among string theorists), Lubos does actually address some scientific issues.
There’s nothing at all in what he has to say that actually makes any connection between string theory and the real world. The effort to find such a connection is completely ignored, including the work of the large part of the string theory community that continues to unsuccesfully work on this. No mention of “string phenomenology”, the landscape, or anything of this kind. He chooses instead to address scientific issues in a resolutely unscientific way, basing everything upon faith and ideology, beginning with the opening part of his argument:
I will treat the “whole Universe” and “all of string theory” as synonyma because I am not aware of any controllable framework that would allow me to separate them sharply.
Most of the rest of the posting is a series of criticisms of other ideas that people have advanced as alternatives to string theory. At one, point, after criticizing John Baez and Urs Schreiber for their interest in 2-groups and gerbes, he makes clear what he sees as the proper way to approach new ideas about fundamental physics that one is not familiar with:
The previous paragraph also clarifies my style of reading these papers. The abstract has so far been always enough to see that these fundamental gerbes papers make no quantitative comparison with the known physics – i.e. physics of string theory – and for me, it is enough to be 99.99% certain (I apologize for this Bayesian number whose precise value has no physical meaning) that the paper won’t contain new interesting physics insights.
This attitude makes life very simple. You don’t have to bother doing the hard work of trying to understand what non-string theorists are doing. All you need to do is to read the abstracts of their papers, note that they aren’t doing string theory, and then you can be sure you don’t need to read any farther, because if it isn’t string theory, it can’t provide any interesting new insights into physics.
Lubos dismisses various ideas about string theory one after the other. Much of this is devoted to dismissing the idea that has led particle physics to many of it’s biggest successes: that of looking for new symmetries or new ways of exploiting ones that are already known. He insists that:
we have learned that the gauge symmetries are not fundamental in physics.
with the idea being that because of dualities, the character of gauge symmetries is not fundamental but what he calls “social scientific”. This argument doesn’t make any sense to me. An equivalence of two different gauge theories is very interesting, but it in no way tells you that gauge symmetry is not fundamental. Making such an argument is like arguing that representations of Galois groups in number theory are not fundamentally important because of Langlands duality.
More seriously, Lubos does mention the philosophically trickiest aspect of gauge theories: the physical degrees of freedom are not parametrized explicitly, but as quotients by the gauge group action of a larger space of degrees of freedom. It’s certainly true that this is how gauge theory works, and one can try and argue that one should just ignore gauge symmetry and work directly with gauge invariant degrees of freedom. In terms of representation theory, physical states are gauge-invariant ones, so one could hope to just work with these physical states. The problem is that in most interesting cases this isn’t possible. The space of connections modulo gauge transformations is non-linear and in general can’t be parametrized in a useful way. Working with the linear space of connections, which can be easily parametrized and understood, and then taking into account the action of the gauge group, is the method that actually works and has been hugely successful. All experience shows that fundamental theories are best understood using an extended space of states, together with a method for picking out the physical subspace.
After dismissing alternatives to string theory, Lubos finally gets around to explaining what he sees as the fundamental principle of string theory. Amazingly, it’s the bootstrap philosophy, the failed idea that guided much of particle theory during the sixties and early seventies, before the advent of gauge theories and the standard model. The bootstrap philosophy is that symmetries are nothing fundamental, what is really fundamental are certain kinds of consistency conditions. All you need to do is impose these consistency conditions, and miraculously a unique solution will appear, one which describes the real world. In the sixties the hope was that the strong interactions could be understood simply by imposing things like unitarity and analyticity conditions, and that this would lead to a unique solution of the problem. It turned out that this can’t work. While unitarity and analyticity properties are very useful and tell you a lot about the implications of a theory, they in no way pick out any particular theory. There are lots and lots (a whole landscape of them, even) of QFTs that satisfy the consistency conditions. There never was evidence for uniqueness, and the bootstrap philosophy was from the beginning built on a pipe dream and large helpings of wishful thinking.
The new version of the bootstrap that Lubos wants to promote goes as follows:
In the context of quantum gravity, many of us more or less secretly believe another version of the bootstrap. I think that most of the real big shots in string theory are convinced that all of string theory is exactly the same thing as all consistent backgrounds of quantum gravity. By a consistent quantum theory of gravity, we mean e.g. a unitary S-matrix with some analytical conditions implied by locality or approximate locality, with gravitons in the spectrum that reproduce low-energy semiclassical general relativity, and with black hole microstates that protect the correct high-energy behavior of the scattering that can also be derived from a semi-classical description of general relativity, especially from the black hole physics.
So, the idea is that, at its most fundamental level, physics does not involve simple laws or symmetry principles, just some consistency conditions (of a much more obscure kind than the analyticity ones of the original bootstrap). Lubos avoids the crucial question of how big the space of solutions to these consistency conditions is. All the evidence so far is that it is so large that one can’t hope to ever get any predictions about physics out of it, and the string theory community is now divided between those who hope this problem will magically go away, and those who want to give up and stop doing science as it has traditionally been understood.
In 1973 the theory of strong interactions was heavily dominated by string theory and the bootstrap philosophy. The willingness of Veltman and ‘t Hooft to do the hard work of understanding how to properly quantize and renormalize non-abelian gauge theories ultimately led to asymptotic freedom and QCD. This pulled the plug conclusively on that era’s version of the bootstrap. Perhaps sometime in the future, new hard work on gauge theories will lead to insights that will pull the plug on this latest version, which thrives despite conclusive failure due to the kind of unscientific ideological fervor that Lubos so perfectly embodies.
I read LM’s blog maybe twice, decided it was rubbish and have not gone back. But now I’m reading (bits and pieces) of it over here. There is no escape. I am doomed.
I think I’ll commit ritual suicide. It won’t solve anything, but at least I’ll feel better.
Peter,
What year did many people abandon the bootstrap stuff in favor of QCD? Was it gradual, or was it very sudden and quick?
I wasn’t there, but I believe there were some “dead enders” who continued publishing bootstrap stuff well into the 80’s.
Many years ago, a friend recommended that I read the Urantia Book. I put it down after I read this nonsense about electrons:
•
• ” Mutual attraction holds one hundred ultimatons together in the constitution of the electron; and there are never more nor less than one hundred ultimatons in a typical electron. The loss of one or more ultimatons destroys typical electronic identity, thus bringing into existence one of the ten modified forms of the electron. ”
I recalled that when I read about string theory. Urantia’s ultimatons sound a lot like strings. So, was the string revolution inspired by the Urantia book? A lot of L.M. ‘s ranting sound like religious fundamentalism. Fundamenatlists don’t read anything which challenges their beliefs, just like L.M.
Actually if you look at the latest edition of “The Tao of Physics” it will tell you that QCD doesn’t work, and the bootstrap was a big success, so there are probably still some really dead-enders out there.
By 1975 when I started at Harvard, gauge theory was what everyone there was doing, but Harvard had never really been a place where the bootstrap was very popular. You’d have to ask someone who was at Berkeley during those years how long it took them to come around to gauge theory.
To some extent, lots of people who had worked on the bootstrap and early versions of string theory just picked up where they had left off when string theory came back into fashion in 1984. There really only was a period of about 10 years (1974-1984) when QFT was completely dominant.
What year did many people abandon the bootstrap stuff in favor of QCD? Was it gradual, or was it very sudden and quick?
I’m not PW, but anyway, it was quick. BUT ….
The bootstrap stuff was not abandoned “in favor of QCD”. The nuclear democracy idea was abandoned in favor of the quark model (with concomitant electroweak + QCD). This happened shortly after the J/psi November Revolution, after the discovery of additional resonances and D-mesons (charmed mesons), indicating a spectroscopy of bound-states.
The quark model could readily explain this. The acceptance of the Standard Model was rapid. It is true that bootstrap holdouts persisited into the 1980’s but nobody paid attention.
I don’t think the bootstrap was such a bad idea in the 1960s. If the only nice quantum field theory you’ve got to look at is QED, you could easily get the impression that that’s all there is to gauge theory. QED is the only Abelian gauge theory; if you try to generalize QED by changing things around, you tend to either get nonsense or QED with a different set of parameters (possibly including a photon mass). So it was not unreasonable to think that maybe there just were not very many quantum field theories.
Also, before the discovery of asymptotic freedom in non-Abelian gauge theories and the development of lattice gauge theory, it wasn’t obvious that quantum field theory was even something meaningful to discuss in the strong coupling regime. I’ve met people who say they worked on the bootstrap stuff not because they believed quantum field theory was really wrong, but because they didn’t have the faintest idea how to apply it when the coupling constant was large. The discovery of asymptotic freedom, which opened up high-energy strong phenomena to perturbative treatments, was really unexpected. Antishielding is extremely counterintuitive, in large part because it seems to violate the idea of Le Chatelier’s principle, that the dynamics of a system should work against disruptions. That principle holds (at least in spirit) not just for chemical equilibria, but also in classical E&M (in Lenz’ Law) and in the screeing responsible for charge renormalization in QED. Perhaps people could have taken the hint from lower-dimensional models that antishielding was possible; however, the assumptions of the bootstrap model, while optimistic, were not so foolish, given what was known at the time they were formulated.
Hee, hee. It just gets funnier and funnier. Many of the talks here at the String theory Maths conference bear some relation to gerbes or tensor categories. I would love to see Lubos call these people crackpots!
‘t Hooft may have pulled the plug on the bootstrap, but he also introduced 1/N expansions which link gauge theories to strings, and lie at the heart of gauge/string duality, AdS/CFT duality, matrix models, and more beautiful ideas floating around nowadays.
I think we need to keep an open mind about these things.
Brett,
It’s not that I think the bootstrap program was so unreasonable, it’s just that it was wrong, and wrong in very much the same way that string theory is (and also perhaps right in the way that string theory is, as a way of understanding strongly coupled gauge theory). If you look at Chew’s writings from that era, there’s a lot of the same kind of wishful thinking you see in string theory. Not knowing about asymptotic freedom of gauge theory, you could argue that the bootstrap was “the only game in town”, but we’re very lucky that Veltman didn’t think this way, and worked on something else (despite lots of people telling him he was wasting his time). If the bootstrap had been even more dominant than it was, and Veltman and a few others had decided to work on it, we might still be doing bootstrap theory today.
Peter, have you seen any report or blog about
THooft fest ?
If so , maybe you could pointa link. the program is a mixture of interesting
talks in string theory, LQG, CDT, QCD, technicolor, grand unification.
would be interested in a hearing a report
Shantanu,
I’ve heard a bit about the ‘t Hooft fest, was planning on writing about it soon, but hoping the organizers would put up slides for the talks.
Didn’t someone [significant] say or write that the more different ways there are to express the same thing in physics, the more fundamental it seems to be?
Didn’t someone [significant] say or write that the more different ways there are to express the same thing in physics, the more fundamental it seems to be?
Something doesnt become more fundamental via transformation to something else unless in doing this transformation a new phenomena is explained.
I was a grad student in a Regge Pole department when ‘t Hooft pulled the plug on the bootstrap, but the bootstrap was motivated by intriguing ideas plus the desperation born from 25 years of QFT failure in the strong interactions. I think a suitable mileage marker for the end of the bootstrap might be when Gell-Mann went to Berkley, and noticing Chew in the audience, said some nice things about it.
Chew, GM said, replied with “Thank you, but I’m working on field theory now.”
Peter didn’t mention it, but LM saved a lot of his wrath for those who believe in a discretium. This is a much older war in physics, dating back to perhaps the seventeenth century. Boltzmann was, some say, persecuted to the pont of suicide by the anti-atomists. Ironically enough it was Einstein who drove the stake through the heart of continuous physics, both for matter and energy. Lubos is still fighting that battle, albeit on another front.
Also, the 1970’s boostrap was hardly barren. It gave birth to duality and string theory.
Brett writes:
That’s a good point! Were there actually people around who were clever enough to object to asymptotic freedom because it violated Le Chatelier’s principle? I can imagine Feynman doing it, just to get people thinking.
In week94 I summarized Wilczek’s intuitive description of asymptotic freedom as analogous to paramagnetism, where one atom with spin makes its neighbors want to line up with their spins pointing the same way. This may seem reasonable (since we’re all familiar with a more drastic phenomenon along the same lines: ferromagnetism), but in fact it does seem to violate Le Chatelier’s principle. What would seem more “reasonable” from the viewpoint of Le Chatelier’s principle is diamagnetism, where a spinning atom makes its neighbors want to spin the other way, counteracting the influence of any magnetic field. Diamagnets screen magnetic fields; paramagnets antiscreen them.
But in fact, in volume II of his Lectures on Physics, Feynman argues that in classical physics, both diamagnetism and paramagnetism are impossible in thermal equilibrium:
So, both paramagnetism and diamagnetism can only be understood using quantum mechanics! For more on how quantum mechanics gets around the above argument, and how paramagnetism is related to asymptotic freedom, see week94.
Peter’s post said “… Lubos … sees as the fundamental principle of string theory.
Amazingly, it’s the bootstrap philosophy …”.
Maybe it is not so “Amazing” when you consider the PhD lineage:
Chew (founder of bootstrap) – Gross – Witten
and
the fact that Lubos is a devoted follower of Witten.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Then again, maybe this is just a milestone in LM’s own evolution into a right-wing, rude version of Fritjof Capra—someone who ceased to be a serious researcher decades ago, and whose outlook on particle physics (and physics generally) seems to be thoroughly ossified.
I believe at one point, Newton proved that a “simple harmonic” gravitational force, proportional to 1/r, would lead to elliptical orbits. He wasn’t satisfied, and went on to prove the case for 1/r^2 laws. A lot of the time in science, you’ve just got to keep on going the way you feel is the right one. A little ideology sort of drives you. Of course, it’s important not to let it control you.
Obsessive MF,
The key difference between stringers and Newton iscorrect predictions. He knew the distance of the moon and its orbital period, so using his equation a=(v^2)/r, he knew the strength of centripetal acceleration (gravity) at the Moon’s distance. This was smaller than the measured gravity at earth’s surface by the square of the number of earth radii that the Moon is away. Hence Newton empirically validated the inverse-square law theory.
People lament that Newton kept quiet and took 22 years to publish (1665-87), checking and improving his theories. Darwin took a similar period before publishing, under pressure. Why can’t string theorists take the hint from these giants?
Dear mr Woit,
I must ask, why do you spend so much time on the outbursts from this man? Even for me, who only is a graduate student in string theory, it is quite obvious that he can not represent the string theory community as a whole. I think that for most people it should be quite obvious that his level of emotional identification, with the debate over string theory, has passed the acceptable limit. Thus, would it not be better to focus on more ‘scientific’ related stuff concering the progress (or non progress) of string theory? Atleast I, who enjoy many of your posts, would find that more educational.
Happy weekend!
P
John Baez highlights the impossibility of dia- or any other sort of magnetism in classical statistical physics, so deftly explained by Feynman. This seemingly counter-intuitive result was first proved by Bohr in his Copenhagen thesis in 1911, and given a thorough going over in the guise of what van Vleck called, in a more gentlmanly time, Miss van Leeuwen’s theorem. It’s tempting to suppose that it was this finding that first set Bohr off on the road to quantum mechanics.
People lament that Newton kept quiet and took 22 years to publish (1665-87), checking and improving his theories. Darwin took a similar period before publishing, under pressure. Why can’t string theorists take the hint from these giants?
They are. The only thing is that String theorists are publishing their results 22 years before they have anything of value to say. This is the same as Newton and Darwin, apart from the application of the Time Reversal operator.
Feynman’s argument is specious, because the change in free energy is not
dG = -S dT + V dp
rather
dG = -S dT + V dp – M dH
in a magnetic field H. Thus it is entirely possible to discuss the equilibrium, in an applied magnetic field, of monatomic and diatomic iodine (one paramagnetic, the other diamagnetic) in the reaction
I I2
See Pauli, “Thermodynamics and Kinetic Theory of Gases”, Ch. 3.
These arguments that “X requires quantum mechanics!” are always wrong.
-drl
I wondering the same thing about the quoted Feynman derivation. What about the magnetization contribution to the (Gibbs) free energy? DRL sums it up nicely.
P,
Actually I’m trying to ignore Lubos as much as possible, but I do think this posting of his reflects the views of not all, but of a sizable proportion of the string theory community. Some string theorists (including one well-known one writing here on this blog) take the attitude that the only problem with Lubos is that he is “undiplomatic”, and it is extremely rare for them to publicly criticize him. From what I hear, many of his colleagues in Cambridge are quite supportive of him, some seem quite happy to have their views put out on his blog. He works regularly with, as he calls them, the “big shots” of this field, and claims in his postings to be reflecting their views, with no complaint from anyone on his blog that this is not true. His behavior is a huge embarassment to the string theory community, but this doesn’t seem to me to be a reason I should ignore it.
As far as I can tell, many of his attitudes are widely shared by other string theorists: the idea that string theorists are smarter than other physicists, that their critics don’t know what they are talking about, that there’s no point to reading non-string theory papers, that the possibility that string theory is wrong is so unlikely that it’s not worth thinking about, etc… There’s plenty of evidence that he’s far from the only one who thinks this way, and is just more up-front about it than others.
Drl said:
huh? You just made Feynman’s point. M is the quantum mechanical variable.
And just for your own general knowledge. Calculating M for an ensemble of refrigerator magnets and calculating M for an ensemble of atoms or particles are two complety different calculations.
drl, ksh95,
This is way, way off topic, enough.
John:
“In week94 I summarized Wilczek’s intuitive description of asymptotic freedom as analogous to paramagnetism,…”
–
Anti-shielding like effects do also occur with dielectric layers. Very actual are the new high k (high dielectric value) gates in CMOS transistors.
The coupling INCREASES if the very thin isolation layer (~1.2 nm) between the gate and the channel is replaced with a material with a HIGHER dielectric value. The same voltage on the gate will attract more charge-carriers in the channel instead of less.
This is exactly the opposite of what one would expect knowing the usual arguments about vacuum polarization and running coupling constants.
The higher polarized dielectric layer will have more charge carriers close to the channel pulling in more charge-carriers (of the opposite kind) into the channel. (Google for: high-k gates)
–
Regards, Hans.
Hmmm… isn’t this exaclty the “swampland” program? Examining additional constraints on effective field theories that don’t necessarily describe ST but enable cuts in the landscape as well?
I have achieved a new first at least for me. I was banned by Lubos before I made any comment. I guess I’m beginning to understand the string ideology. If it’s possible that you might question or disagree don’t allow you to speak at all. This is not how I understand science. If this is off topic please delete it.
**I have achieved a new first at least for me. I was banned by Lubos before I made any comment.**
that’s impressive but I don’t understand. did you not submit at least one comment?
Peter, off topic? We were talking ideology. I was talking physics, the kind I learned from Pauli, as opposed to hero worship, which is synonymous with ideology, in my book (cults of personality).
-drl
Danny Lunsford writes:
Feynman’s derivation shows that for a system of classical point charges in equilibrium, the magnetization M is zero.
This derivation breaks down when one allows current loops as primitive elements, as I point out in the addendum to week94.
Since John started this, I’d encourage people to discuss this with him at his blog. Except, wait a minute, he doesn’t allow comments there since moderating them is too much trouble….
Hmmm? Maybe I should start a thread on my blog for discussions too off topic for Peter’s blog?
I appreciated John Baez’s explanation and clarification.
CIP,
Anyone who wants to host discussions I don’t want to moderate here has my strong encouragement. But actually a better idea, if John sticks to his sensible decision not to host a place to discuss what he writes, would be for someone else to set up and moderate a forum for that purpose.
Not such a bad idea…
Perhaps I should set something like this up.
If anyone is interested in the details of asymptotic freedom and paramagnetism…
A number of people derived asymptotic freedom by showing that the vacuum is a color-paramagnet back in the late 70’s/early 80’s. There is a nice review article about this by N.K. Nielsen in the American Journal of Physics, vol 49, page 1171. Nielsen uses heuristic arguments, but the same mathematics follows from the use of the background-field method.
If you turn on a color-magnetic field, gluons (actually fluctations around said background field) will make Landau orbits. The gluons have some (Landau) diamagnetism, as do any particles making such orbits. Since they have spin and a color-magnetic moment, there is also (Pauli) paramagnetism). This more than makes up for the diamagnetism. So the overall effect is that the vacuum is paramagnetic.
Spin-1/2 particles don’t produce this effect, because with Fermi statistics, diagmagnetism wins out.
Paramagnetism means that the permeability of the vacuum at short distances is greater than one, for a strong field. In other words,
color-magnetic fields are screened at short distances. By constancy of the speed of light, the dielectric constant of the vacuum is less than one. This means that color-electric fields are anti-screened at short
distances.
OK, I give up, there seems to be an irresistible movement to discuss paramagnetism here.
I have a comment on the old boostrap idea. The original idea was to
study model-independent on-shell properties of field theory. Then
it somehow transmuted into an entirely different animal. If one views it as a tool for doing field theory, it has some successes. The problem
was that it then became the Booststrap Hypothesis, which said you
could find the S-matrix from a few simple assumptions crossing, symmeties and maximal analyticity – this is what turned out to be wrong.
Maybe the same is true of string theory – use it as a framework for the
True System of the World, but don’t take it seriously beyond that. I think this is the working philosophy of many people in the field, as it happens.
By the way, the Bootstrap works wonderfully for integrable quantum
field theories in 1+1 dimensions. You can even study off-shell properties, through form factors.
To Peter Orland,
Yes, but in 1 + 1 a lot of things happen automatically because of dimensionality. For example 1 + 1 QED confines because in one spatial dimension the Coulomb potential is linear in the distance. The dynamics play no role in this confinement. On the other, hand 2+1 QED confines because notrivial tunneling instanton effects provide an effective photon photon interaction that changes the effective interaction into one that is linear with the distance. This was shown by Polyakov in 1977.
So, while it is interesting that the bootstrap isquite succesful in 1 + 1 D, one should not read too much into it. If it was useful in a higher dimensional theory where the dynamics were not so much restricted by dimensionality than when one has a single spatial dimension.
David,
I am not sure how I should interpret your comments about confinement in this context, but you are absolutely right that
the success of the boostrap in 1+1 dimensions is very special
to that dimensionality.
I was only trying to point out that something useful arose from the bootstrap program – and it IS useful, since these 1+1-dimensional models are being applied to condensed-matter problems. There
are some good articles on this by Bhaseen and Tsvelik and by Essler and Konik in the Ian Kogan memorial volume (all of which
can be found on the web).
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It seems that no one is finding natural that after bootstrap we are using strings to pull up us…
As is well known, Pauli was the original author of the phrase, “not even wrong.”
Hitherto little-known is a recently translated correspondence between Pauli and Carl Jung, where the former argues for a unitary description of mind and matter, informed by quantum mechanics.
http://www.igpp.de/english/tda/pdf/paulijcs.pdf
The article begins with a fine discussion of symmetry.
This is all music to my ears, as I have long argued for this kind of thing, pointing to the symmetries and phase relations of such traditionally “mental” objects as colors and sounds.
I have also pointed to the fact, readily available to inspection, that colors define a projective vector manifold (Riemann, Weyl) which fibers over visual space — notions dismissed as “not even wrong” by certain persons, but which ought to be of interest to string theorists.
Dear Peter,
Thank you for writing Not Even Wrong. Well said!
String theory does seem capable of reconciling general relativity and quantum theory and cannot therefore be consigned to la-la land. But its advocates overstate its promise to the point of irresponsibility. The typical first reaction of physicists to string theory, that it is ugly, seems to me to be healthy. String theorists remind me of drug addicts – once they are into it they see as wonderful something that others recognise as ugly and unhealthy. Perhaps they should be called “string addicts”. Theory has outrun experiment and moved toward the realms of science fiction.
Is string theory really “the only [unification] game in town,” as many claim? If general relativity and quantum theory do not want to go together then we should consider whether they have defects, before trying to enforce a shotgun wedding that carries those defects over into the marriage and its offspring.
Quantum theory has a basic flaw. Put a large number of electrons through a z-Stern-Gerlach apparatus and take those that emerge spin up. Now put these electrons through an x-Stern-Gerlach apparatus. Some will be spin up, some spin down and nobody in the world can say which. That’s OK – the job of theoretical physics is to improve prediction. I have the highest respect for those who predicted and measured (g-2) to such accuracy. But the job is not ended, and it is not OK is to say that you may not ask what the next electron will do, and that henceforth you are allowed to predict only probabilistically. Unhappily that is the Copenhagen view, and it stands against the very meaning of what it is to be a theoretical physicist.
From the start of quantum mechanics it has been recognised that any underlying deeper theory must have strange qualities – so strange that many physicists deny they exist. Since Bell we can be more specific: any underlying theory must be nonlocal and acausal. (The order of measurement on two correlated electrons in a Bell setup is not Lorentz invariant; consider also Wheeler’s ‘delayed-choice’ experiment.) Nonlocality is no big deal in physics – we have had 300 years to get used to it under the name “action at a distance” since Newton’s theory of gravity (although subquantum nonlocality does not fall off with distance). Acausality is more alarming, but should it be so alarming as to make us give up and not even think about it? Logically, it is impossible to rule out a hidden variables theory – all that can be done is to rule out categories of hidden variable theories, such as local ones. Even the name ‘hidden variables’ is loaded since we can see their effect – what we can’t do today is control them.
The challenge is to find a deeper theory that, with its extra variables suitably averaged (marginalised) over, reproduces the probabilistic predictions of quantum mechanics. We know that such a theory must be nonlocal and partly acausal. That is a tough assignment, but if you want easy problems you should stick to trainspotting. My worry is that nobody is trying.
How did the Copenhagen mind-clamp get into place? More than a century ago a similar debate took place between the atomists, and others who claimed that the jiggling Brownian motion of small particles seen under a microscope could not be predicted. The atomists won and physical prediction improved tremendously as atomic theory developed. To see why the debate went the other way at the next level down, a generation later, you must look beyond science at the culture it is embedded in. The findings of science are independent of culture but the doing of science is not, as Not Even Wrong recognises. I suggest that, at the time of the debate over atoms, there was sufficent belief that the universe was comprehensible for the scientific community to persist in looking for an explanation, but that by the time of the Copenhagen interpretation there was not. This belief stems from the Judaeo-Christian view, interwoven into Western civilisation, that the universe is comprehensible because it was created that way. (That is why science arose in the West rather than in another culture.) Similarly, the ancient Greeks had a prior faith that the skies were perfect but that terrestrial order was not – and the astronomy they developed was brilliant whereas their terrestrial physics was embarrassing. By the time of Copenhagen, the West had been under the influence of the secular Enlightenment for longer and was turning against the Judaeo-Christian worldview (church attendance was certainly falling); Eastern mystical ideas were received with interest, notably by several of the quantum pioneers.
So, rather than play with universes as string theorists do, I prefer to seek a theory that addresses a more humble question: where will the next electron go in my x-Stern-Gerlach apparatus?
Finally, the anthropic principle is not tautological and is clearly helpful when used correctly. In the 1950s Hoyle used the observed abundance of carbon, which is the basic element of life and is formed in stars, to predict a transition in its atomic spectrum (without which its abundance would be very different). He was later found to be right, and today we would call that anthropic reasoning. There are complementary categories in which we can consider why a theory has a particular feature, so that anthropic reasoning is not a threat to bottom-up research in cosmology or even string theory – all we need to do is get the reasoning right.
Anthony Garrett
(PhD in theoretical physics, University of Cambridge, UK, 1984, then three university postdoctoral contracts. Not publishing currently but writing a monograph on probability in physics.)
Anthony Garrett said “… the Copenhagen view … stands against the very meaning of what it is to be a theoretical physicist …
Logically, it is impossible to rule out a hidden variables theory – all that can be done is to rule out categories of hidden variable theories, such as local ones. …
We know that …[a successful hidden variable]… theory must be nonlocal and partly acausal. That is a tough assignment … My worry is that nobody is trying. …”.
Actually Bohm did try (and substantially succeed) in formulating such a theory, but the reaction of the physics establishment (in the 1950s) to Bohm is similar to the reaction today of String Ideology proponents, such as Harvard Professor Motl, to any competing theories/models.
According to The Bohm biography Infinite Potential, by F. David Peat (Addison-Wesley 1997):
“… Max Dresden … read Bohm’s papers … errors were difficult to detect … von Neumann’s “proof” … did not rule out the sort of theory that Bohm had proposed. … Oppenheimer [said]…
“We consider it juvenile deviationism … we don’t waste our time …” [by] actually read[ing] the paper …
Dresden … present[ed] Bohm’s work in a seminar to the Princeton Institute …
The reception he received came as considerable shock to Dresden. Reactions to the theory were based less on scientific grounds than on accusations that Bohm was a fellow traveler, a Trotskyite, and a traitor. It was suggested that Dresden himself was stupid to take Bohm’s ideas seriously. … all in all the overall reaction was that the scientific community should “pay no attention to Bohm’s work” … Abraham Pais also used the term “juvenile deviationism”. Another physicist said that Bohm was “a public nuisance” …”.
The tactics of Bohr himself in support of the Copenhagen ideology have been described by Carver Mead in his book Collective Electrodynamics (MIT 2000), as follows:
“… Bohr gathered the early contributors [to]… Quantum Mechanics … into a clan in Copenhagen, encouraged everyone in the belief that they wre developing the ultimate theory of nature, and argued vigorously against any opposing views. … Bohr insisted that the laws of physics … are statistical in nature …[even though]… Statistical quantum mechanics … actively impedes our understanding by hiding the coherent wave aspects of physical processes. …
Einstein … believed … that the statistical nature of experimental results was a result of our lack of knowledge of the state of the system, and that the underlying physical laws can be formulated in a continuous manner. …
The disagreement culminated in a 1927 debate between Bohr and Einstein, refereed by Ehrenfest. Bohr was a great debater, and won the contest hands down.
A rematch was staged in 1930, and Bohr won again. …
At the time, there were no compelling experiments where the wave nature of matter was manifest in a non-statistical manner. …
Starting in the 1960s, … experimental demonstrations of numerous coherent, collective systems have … put us in a position to finally settle the Einstein-Bohr debate – with a resounding victory for Einstein. …
Bohr had won his debate with Einstein …[not by being correct but by]… an openly combative [technique]… the one who blinked first lost the argument … and the entire field adopted the style. … “.
Bohr’s unreasonable, unblinking, combative style in attacking better models than Copenhagen survives today in the String Ideology style of Harvard Professor Motl and his ilk.
For some reasonable alternatives to Bohr/Copenhagen, see the works of Bohm and his followers, and the book by Carver Mead.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Anthony Garrett:
Quantum theory has a basic flaw. Put a large number of electrons through a z-Stern-Gerlach apparatus and take those that emerge spin up. Now put these electrons through an x-Stern-Gerlach apparatus. Some will be spin up, some spin down and nobody in the world can say which.
In 80 years of quantum theory, we don’t have even approximate prediction of which electron will be spin up and which will be spin down. This is just a random effect. That’s what quantum mechanics tells us, and I believe there is no any deeper theory behind quantum mechanics.
If you are worried (as I do) about the inconsistencies between QM and SR, I would suggest you to pay more attention to the other part, i.e., special relativity. The problem is that Lorentz transformations were derived for events associated with light pulses and non-interacting particles. We extend these transformations to all events in systems with arbitrary interactions. Is it logical?