Sunday, October 28, 2018

Physics may be up against the wall, anno 1986

I thought you’d enjoy this gloriously prescient NYT article from 1986 which my husband has dug out. In it, Malcom Browne reports that Alan Chodos (then at Yale) worries about the future of particle physics:
“Unable to mount experiments that would require energies comparable to that of the Big Bang genesis event, Dr. Chodos believes, growing numbers of physicists will be tempted to embrace grandiose but untestable theories, a practice that has more than once led science into blind alleys, dogma and mysticism.

In particular, Dr. Chodos worries that “faddish” particle physicists have begun to flock all too uncritically to a notion called “superstring theory.” […] Deprived of the lifeblood of tangible experiment, physicists will wander off into uncharted regions of philosophy and pure mathematics,'' says Dr. Chodos, leaving true physics to wither.””
Chodos later became the Associate Excecutive Officer of the American Physical Society, a position from which he retired in 2014.

26 comments:

xxx said...

How could he see it? Amazing!

naivetheorist said...

bee:

WOW!. guess you didn't need to write your book after all!

Seriously, it's important to keep pointing to the Emperor's new clothes. and what we also need is a new positive research agenda.

and maybe dropping the idea of there being a 'fundamental' or 'foundational' physics subfield (i just read a pop science article that stated that the goal of physics is to determine the basic constituents of the universe) and placing the reductionist paradigm on the same level of basicness as the emergence paradigm in theoretical physics research.

naive theorist

naivetheorist said...

bee:

sorry, i forgot to correct the pop science article's claim. the correct aim of physics is to 'explain as much of the observed phenomena that occurs in the world as possible in terms of general and specific laws of behavior that are expressed mathematically. At least that's been my goal.

naive theorist

Koenraad Van Spaendonck said...

“wander off into uncharted regions of philosophy and pure mathematics,'' says Dr. Chodos, leaving true physics to wither "

..and leaving the wallets to wither of woeful tax payers while waiting for wonderful new physics.

stefan said...

The NYT article is based on a text by Chodos in the "American Scientist",

Marginalia: String fever
Alan Chodos
American Scientist
Vol. 74, No. 3, Special Book Issue (May-June 1986), pp. 253-254
https://www.jstor.org/stable/27854098

Actually, I was just trying the track the origin of the quote attributed to Max Born, that "physics, as we know it, will be over in six months."

Lawrence Crowell said...

I think the real problem is not just with theory, but with experimental and observational techniques as well. As I see it we should let nature do the heavy lifting. The recent result from ANITA https://arxiv.org/abs/1810.00439 indicates possible high energy/mass SUSY. I have been thinking about quantum hair on black holes and signatures in gravitational waves. Chodos is right that we will not build a collider or machine capable of probing the Planck scale in the lab. However, nature does this, and I think both theory and experiment need to be fashioned accordingly.

Lindsay Forbes said...

Amazingly perceptive. I also like the emperor's clothes' comment, a phrase I use often. Thanks for sharing this Sabine.

neo said...

@Mitchell

Mitchell, if experiments rule out both higher kaluza klein dimensions and SUSY, how would that change your views on string theory?

Could the claims you make about string theory be a mathematical artifact

Uncle Al said...

Let’s play with that! The Big Bang birthed only neutrons and photons. CKM matrix CP-violation during decay (re Sakharov criteria) obtains a net matter universe, leptogenesis, and electrical neutrality. Mixing angles reflect trace chiral anisotropic vacuum re Einstein–Cartan gravitation, achiral spacetime curvature doped with chiral spacetime torsion.

Rejection of beauty requires testable alternatives. One day in a microwave spectrometer repeating a published experiment with a molecule crafted to the task heals theory.

https://www.youtube.com/watch?v=3I_Ds2ytz4o
… To criticize is to volunteer.

jim_h said...

Amazing. Although, he didn't know what to do about it either.

Jeff said...

@Lawrence Crowell As I understand things, in string theory, "high energy" is near the Planck scale. By this standard, the ANITA results would be "low energy" supersymmetry (assuming the ANITA observations hold up over time). This is true even though the events appear to be higher energy than we can generate in particle accelerators. For those not familiar with the matter, this sub-discussion is about "The ANITA Anomalous Events as Signatures of a Beyond Standard Model Particle, and Supporting Observations from IceCube" (https://arxiv.org/abs/1809.09615).

Lawrence Crowell said...

@Jeff, The ANITA results are at around 10^9 GeV energy, which is 10^{-10} the Planck or quantum gravity energy. The term high energy is somewhat relative, where LHC physics is usually call high energy physics. TeV physics compared to Planck energy is downright low energy. The term is somewhat ambiguous.

The de Sitter vacuum during inflation would have had a Ricci curvature RIC ~ 10^{-10}/ℓ_p^2 or larger. Supersymmetry would have been not just a broken symmetry, but to use or abuse language SUSY was violently broken. With reheating the high energy/curvature vacuum collapsed to a small value with the cosmological constant we observe today of Λ ~ 10^{-52}cm^{-2}. As with some phase transitions sudden changes in variables can leave a system in a phase not standard for those conditions. An example would be liquid water of a great purity at subfreezing temperatures. So SUSY might then be strongly broken.

Liralen said...

Yes, the concerns about physics have existed for some time, even referenced in my favorite video game (https://en.wikipedia.org/wiki/Sid_Meier%27s_Alpha_Centauri), released in 1999, such as the science faction leader stating:

“A brave little theory, and actually quite coherent for a system of five or seven dimensions -- if only we lived in one.”

The fact that video games are considered frivolous, yet the developers recognized the problem, is my point.

sean s. said...

I guess I take hope from Dr. Chodos's comment that "Physicists have been incredibly successful in solving or side-stepping seemingly insoluble experimental problems".

Maybe we're just approaching a point where someone needs to come up with a new way to side-step a seemingly insoluble problem.

sean s.

bud rap said...

The central problem of modern physics: mathematical models have supplanted empiricism at the core of the scientific endeavor. The model centric paradigm has decimated science at the theoretical level.

It is simply unscientific to claim that 95% of the matter-energy content of the 'universe' is comprised of some undetectable stuff, the only salient characteristics of which is that it reconciles the standard model with empirical observation. The model determines the nature of physical reality? That approach turns the scientific method on its head.

Both standard models are defined by entities and events that have no presence in empirically observed reality. That this is considered a reality problem, not a model problem, by the scientific community - that is the problem.

Uncle Al said...

@bud rap "events that have no presence in empirically observed reality"

Perform matter diffraction, a molecular beam through a multi-slitted barrier, obtaining a non-classical throughput pattern. The molecules' wave function traverses the dissipationless near-field grating, Schrödinger's cat, to accomplish it. Attempts to localize trajectories collapse the wave function, obtaining classical throughput. QM validates to 15+ decimal places. Ding it 50%.

Use a resolved chiral (i.e., all left shoes) molecular beam. The wave function is [|Lefthanded> + |Righthanded>]/√2 (should be two kets). Lefthanded versus righthanded are parity inversions (all three coordinate axes reverse signs). They sum to zero, no wave function, Hund's paradox. Chirality exists because the chiral object is incessantly bombarded, continuously collapsing its wave function, disallowing Schrödinger's cat. Diffraction has no dissipation.

If the pattern obtains, the throughput is racemic. A supersonic vacuum expansion is ~2 kelvin rotational temperature and ~200 m/s. If the grating near-field spans 1 mm length, then ~350 kcal/mole inversion energy is cheated within 5 microseconds at 2 kelvin. Really?

I defy you to describe an observed result that does not falsify a vast fraction of science. Markus Arndt (matter gratings); Anton Zeilinger (photon gratings), and

http://brightspec.com/wp-content/uploads/2015/06/ProductFlier-Chirality-Nov2014-Press.pdf
… sub-nanogram analyte enantiomeric excess quantitation.

Look.

Lockley said...

It seems that Relativity and Quantum Theory both have workable descriptions which are mathematically, and for the cognoscenti some consciously, understandable. Progress is being made in solid-state physics and other areas once viewed as too exotic for serious study. There remains the problems highlighted in "Lost in Math" and "Through Two Doors at Once"
So the problem remaining is the insight necessary to drill down to the fundamental nature of what we call Reality. Language chopping in philosophy or mathematical gaming in computer labs is unlikely to bring resolution. We are left with the hope that continued observation in higher energy labs and investigation into fundamental particles coupled with astronomical observation will direct someone's attention toward a glimpse of a more fundamental description.

Perry E. Metzger said...

Just read the original essay from American Scientist by Alan Chodos. It really is prophetic, and it's pretty short. It's absolutely worth someone reprinting the original.

Plasmoid Anomalies Study Group said...

Exactly! Nothing can replace the constant observation and testing of Reality and empirical evidence has precedence over ANY preexisting ideas/theories of Reality.
But theoreticians had identified their models of Reality with Reality itsel giving precedence to theories over empirical evidence and that is a departure from objectivity, not surprising then to have a failed String Theory for more than 40 years as a very active mainstream scientific concern, or "serious" talks about post-empirical Science, etc.

This is a very serious systemic problem, but theoreticians are too biased/compromised to free themselves from it.

Mitchell said...

@neo

"if experiments rule out both higher kaluza klein dimensions and SUSY, how would that change your views on string theory?"

The obvious step (obvious to me) would be to look at non-geometric, non-supersymmetric "string theory".

These already exist separately. Non-geometric string theory is like the noncommutative standard model of Connes et al, there are extra "dimensions" that aren't spatial at all, and which are expressed in the 4d gauge group and fermions. As for non-supersymmetric string theory, see Keith Dienes et al.

It is unclear to me how such an approach would relate to Susskind's inflating anthropic landscape (now mildly challenged at the mathematical level by Vafa's conjectures). The "non-geometric vacua" may be "theory islands" with a common framework but not physically connected, the way that AdS/CFT pairs are all string theory but describe separate possible worlds.

It would be curious if string theory, mathematically, includes a "mainland" of "10^500" metastable vacua which all show up together in eternal inflation, and an "offshore archipelago" of theory islands (similar to Tom Banks's approach to quantum gravity in dS space) - and we were to find that we live on one of the theory islands, rather than on the big connected mainland.

Ambi Valent said...

Dr Hossenfelder,

I've listened to the audio of the radio talk you gave. And while I agree with you on your skpticism towards string theory, I'm not so sure that you're aware the root cause is an all-too-human phenomenon that you're not immune to. At first it's just confirmation bias supported by hope that the new theory can solve the problems, but when already enough people believe in it, things can escalate, and simple confirmation bias can become full Cognitive Dissonance Avoidance, where disagreeing results are thought of as coming from people who don't have a clue and stubbornly hold on to their more primitive ideas, and that their concerns don't have to be taken seriously.

I think it's laudable and even impressive that you don't just use your scientific skepticism with double- and triple-checking the math and observations on fields like string theory but also the new work that you develop yourself. This skepticism probably stopped several works early, but the surviving ones have become stronger and more reliable because of it.

There appears to be a field of ideas where you (like many people) do NOT use this healthy skepticism, and that's with the ideas that you first were sure you intuitively understood when you were a young student or even before. Of course, you only readily accepted those ideas because they were accompanied by a mathematical tool derived from a theory that was constantly supported by observation. But you didn't check what your reasoning did with it.

While the theory is indeed correct, and the tool returned (within its range of applicability) results for the elements it could physically test that faithfully mirrored aspects of the physical universe, your mind added more. Because it looked so similar to what you knew from other context, you thought you could also autmatically draw the same "natural" "beautiful" conclusions.

While you yourself remarked that those "beautiful" conclusions can be right on occasion, you should be aware that those are indirect conclusions. The trouble comes in if you accept them as "reality", and when you're later faced with other derivations from the same theory, but this time with directly PHYSICALLY TESTABLE conclusions, that you treat these new informations as inferior because they disagree with what you've accepted as reality.

And even if you've learned it from your teachers - well, would you accept a string theorist's results as truth because he learned his beliefs from his teachers and role models?

I know that you're smarter than me, and I've only come to a better understanding of physics because you had shattered my previous certainties in the past. I think you still could get a lot farther than now if the cautious scientist you are now would have a long talk with the remnants of the teenage subconcious beliefs that survived inside you.

WRL said...

...there are similar prophesies in the Bible, but not so specific to physics and its drive toward cost-impractical experiments.

It would seem that its worthwhile to seek a well-founded basis for Std model QFT quanta. This approach would add only qualitative confidence, unless it can also predict new phenomenology (but _not_ necessarily a new fundamental particle, which is hard not to rule out).
Well, it seems that fundamentally predicting neutrino oscillations would be a good empirical test. I'm doubting that the std-model extension approach to neutrino theory will model oscillations well... any takers?

Sabine Hossenfelder said...

Ambi,

I have biases like every one else has, which is why I don't like it at all if people ask me what to do. They shouldn't, and it's against my own advice to ask for my advice.

I am not a realist and don't understand your going on about accepting reality.

Having said this, your issue seems to be the use of mathematics per se. While I am willing to ponder the question that there may be better ways to do physics than that, no one has come up with one. I would recommend you read my book because I explain there that in science in general, and in physics in particular, new theories must tie to the older ones. You can't just yell "everything is wrong" and insist we should do something else. Not only is this not going to happen, it also doesn't make any sense. Best,

B.

Betzalel said...

It seems to me that fundamental physics is dead. If I were a young scientist today interested in fundamental theory, I would work on linguistics, how do human brains process language. There seems to be lots of unanswered questions in this field.

Ambi Valent said...

Dr Hossenfelder,

I think you've misunderstood me. I was not speaking out against the theories. The theories are well-supported by observation, and I want to support and protect them. The "certainties" that I think should be fought are the intuitive certainties in the cases where intuitive bias essentially whacked in the head of the correct scientific procedure and usurped its place in the Sun.

General Relativity is not the same as Newtonian Physics. It was much harder to formulate, and even after physicists like Einstein and Hilbert teamed up, who both had accomplishments before, they still needed more years until General Relativity was completed. But from this complicated theory scientists, starting with Einstein and Hilbert, started deriving instruments to make predictions which then could be compared with experiments and observations. And those predictions were then indeed supported by observation.

As time went on, scientists developed more instruments to derive predictions of many aspects of the physical universe from General Relativity, and observations have supported them. These instruments have a successful track records for decades of predictions being supported by observations. However, to predict a wide field of aspects one needs to consult General Relativity in different ways, which in effect means using several different instrument to get a full picture, while using just one instrument will give you only a limited part, and you won't really know what's beyond this part.

A loose analogy would be the many different types of world maps which differ in which aspects of the globe they faithfully represent. And while you could get from one map to another, you'd have to reconstruct the globe in between from the data, and then go to create the map you wanted from that globe.

But this process of getting successful predictions from General Relativity, as successful as it is, is not what intuition desires - it wants something "better", by which it means simpler and easy to understand. So if intuitive bias is allowed to kidnap the process, it will use force to create this simplicity.

Instead of consulting the different instruments for the information that could be received from them, intuition will look for an instrument it likes, searching for "beauty" and "naturalness". When it has found that instrument, it will exclaim: "Stop! I only need this!" It will then take the information from the aspect that instrument delivers and then use the "beautiful" form it found to directly conclude the remaining information it wants. It's not like intuition really likes the math, it just uses it: "I have proof for using this, and you're not allowed to complain, because General Relativity has been proven!"

Except of course that this extra step the intuitive bias forced in was not from General Relativity. The error was not done consciously, but one could consciously act to check it, by using the instruments that have been derived to get the information about the aspects involved, and compare them with the results.

It's at this point intuitive bias shows its darkest side, moving to prevent this checking by any means necessary. It will overload the reasoning with negative emotion (from the fear of losing the solution). It will put together statements intended to convince everyone that the alternate method would be inferior or even idiotic, but what intuition claims to be "logic" consists at best out of syllogisms created from soundbites with at best incomplete information, if not worse.

Nobody is supposed to even look at the alternate method, as it could destroy the beautiful solution. Even if the alternate method has been especially derived from General Relativity to get this information. Even if it has a track record of decades of predictions being supported by observation.

One should not be convinced by these emotionalised appeals, and instead make the test and then judge the solution by its result.

WRL said...

Ambi, One thing which can be done to improve intuition in GR is to treat the temporal curvature properly as an imaginary quantity. This puts GR (w/CC) in the form of e^(i-theta).