While I am willing to entertain arguments and evidence to the contrary, I very strongly doubt that any of the following (which are common components of beyond the Standard Model theories except the last which is part of "core theory") are true (some of which are redundant):
1. The PMNS matrix has more than four parameters or does not imply percentages that add to 100%.
2. Sterile neutrinos that oscillate with active neutrinos exist.
3. There are right handed neutrinos and left handed anti-neutrinos.*
4. Neutrinos have Majorana mass.*
5. A seesaw mechanism gives rise to neutrino mass.*
6. Neutrinoless double beta decay is possible in a manner that does not conserve lepton number.
7. Proton decay occurs.
8. There are tree level flavor changing neutral currents.
9. Lepton number is not conserved or baryon number is not conserved outside sphaleron interactions.
10. The baryon number of the universe at t=0 plus an infinitesimal amount was 0.
11. The lepton number of the universe at t=0 plus an infinitesimal amount was 0.
12. The baryon number of the universe minus the lepton number of the universe at t=0 plus an infinitesimal amount was 0.
13. Dark matter particles (other than gravitons) exist.
14. Axions exist.
15. Supersymmetric particles exist.
16. There is a fourth generation of Standard Model fermions.
17. There are pseudo-scalar, charged or different mass scalar Higgs bosons.**
18. There are fundamental fermions other than those identified in the Standard Model below the GUT scale.**
19. There are fundamental bosons not identified in the Standard Model below the GUT scale, other than gravitons and possibly one or two bosons related to neutrino mass and/or neutrino oscillation.**
20. CPT symmetry is violated under any circumstances.
21. There are any interactions involving massless carrier bosons that show CP violation.
22. There are any massless particles that interact via the weak force.
23. There are any massive particles that do not interact via the weak force.
24. There are any neutrinos with zero mass.
25. There are massless fundamental fermions.
26. Thera are leptoquarks.
27. There are tachyons.
28. Negative mass exists.
29. There are more than four dimensions of space-time, either large or tiny.***
30. Mass-energy conversation is violated locally at t=0 plus an infinitesimal amount.
31. The topology of space-time is sufficiently warped or non-local to give rise to traversable worm-holes.****
31. Fundamental physical constants vary in space-time for any reason other than energy-scale.
32. Gravitons that have non-zero rest mass exist.
33. The actual physical value of muon g-2 differs from the correctly calculated value under the Standard Model.
34. The neutron lifetime discrepancy is anything other than measurement error or a theoretical error.
35. The muonic hydrogen radius discrepancy is anything other than measurement error or a theoretical error.
37. The CKM matrix has more than four parameters or does not imply percentages that add to 100%.
38. It is possible for anything resembling life as we know it to enter a black hole without dying.
39. The observed Higgs boson has properties different from those that the Standard Model Higgs boson is predicted to have at its experimentally observed mass.**
40. Gravity behaves exactly as predicted in classical General Relativity (as applied today) in all circumstances without modification even in the extremely weak field limit.
I doubt that any of the following (which are common components of beyond the Standard Model theories) are true (some of which are redundant), but far less intensely:
1. It is impossible to derive any of the experimentally determined physical constants of the Standard Model from a deeper theory.
2. The sum of the square of the fundamental particle masses does not when evaluated at some proper energy scale such as pole masses or the Higgs vev, equal the square of the Higgs vev.
3. The probability of a transition from a first generation fermion to a third generation fermion in the CKM matrix is ever not equal to product of the probability of a transition from a first generation fermion to a possible second generation fermion and to the probability of a transition from that possible second generation fermion to a third generation fermion.
4. There are violations of lepton universality significantly greater than the square root of the ratio of the neutrino masses to the charged lepton masses.
5. Koide's rule for charged leptons is inaccurate by significantly greater than the square root of the ratio of the neutrino masses to the charged lepton masses.
6. The reason that Koide's rule works for charged leptons cannot be generalized in some manner to explain the quark and neutrino masses.
7. The differences in mass between the charged leptons and the neutrinos is unrelated to the relative strengths of the electromagnetic coupling constant and the weak force coupling constant.
8. The neutrinos have an inverse mass hierarchy.
9. The lightest neutrino mass is as large as the difference between the lightest and second lightest neutrino mass.
10. The net electric charge of the universe is non-zero.
11. Sphaleron interactions actually occur physically.
12. There is a multiverse other than an anti-universe at times before the Big Bang.
13. Cosmological inflation occurred.
14. The temperature of the Big Bang was not finite.
15. The temperature of the Big Bang can be exceeded in the universe at latter times.
16. There are (or were) primordial black holes for more than an instant.
17. There are substances in the universe with greater density than the most dense possible neutron star or the smallest possible stellar black hole.
18. Dark energy is a non-Standard Model substance of some kind (other than a gravity modification).
19. Massless gravitons do not exist.
20. Gravitational energy cannot be localized.
21. There are ever violations of mass-energy conservation involving gravity.
22. General relativity correctly models the self-interactions of gravitons.
23. The strong equivalence principle is not violated by an external field effect.
24. Lorenz violation is possible in detectable amounts for long distances (e.g. kilometers or more) in a time period comparable to the age of the universe.
25. Free glueballs (i.e confined composite structures made purely of gluons) exist.
At some point, I may want to make an additional list of the beyond the Standard Model physics theories which I do believe are possible given these constraints. But, not today.
I believe that these principles would be a better and more fruitful guiding force for hypothesis generation in theoretical physics than many of those those commonly in use today such as (1) "naturalness", (2) the "hierarchy problem", (3) the "strong CP problem", (4) the hypothesis that at at t=0 plus an infinitesimal amount the aggregate baryon number of the universe was zero and the aggregate lepton number of the universe was zero, (5) the anthropic principle, and (6) multiverse reasoning.
Footnotes and Clarifications
* To be clear, I don't claim to have the answer to the source of neutrino mass, I simply think that all of the above statements are not true and that some other mechanism than those set forth is the actual source of neutrino mass.
** This is subject to the caveat that there could be more fundamental fermions or bosons that can only combined to, or interact to give rise to dynamically, the Standard Model particles. For example, I do not rule out the possibility that the Higgs boson is a composite particle made up of a W+ boson, a W- boson, a Z boson and a photon, or that all Standard Model fundamental particles are vibration modes of a fundamental string.
*** Dimensionality might, however, be an emergent property of space-time and not fundamental.
**** I do not rule out the possibility that there are microscopic non-local connections at approximately the Planck length scale that could connection to profoundly distant points in space-time that are not traversable.
Why do you think geniuses like Ed Witten believe in many of these statements?
ReplyDeletehttps://www.youtube.com/watch?v=9O-5ujTgZiQ
1. A lot of these statements were much more plausible until fairly recently as new data has come in (e.g. the case for gravity modification v. dark matter particles has only really tipped the balance in the last half dozen years or so). An experienced famous physicists rarely revisit the basics that they think that they already known.
ReplyDeleteWe've come to know that a simple GeV supersymmetric WIMP is inconsistent with the data, and that modified gravity theories can explain a lot of hard cases. Widespread acceptance of modified gravity probably won't come until someone can show that it produced the same third peak in the cosmic background radiation that CDM does, but I am confident that that day will come. The 21cm data and impossible early galaxy problems are already starting to undermine the infallibility of CDM at the cosmological scale.
2. Cognitive biases related to spent costs. A lot of physicists have put a lot of blood, sweat and tears and built their careers upon explanations of some of the BSM approaches that now seem far less likely.
3. Beauty is seductive . . . until you seize up a different way to evaluate it in a paradigm shift. For example, the pure energy Big Bang is so fabulously pretty that it has gone largely unquestioned even though we have known for a couple of decades at least that you can't get from the Standard Model to the observed baryon asymmetry with the SM. Indeed, part of the reason that I'm comfortable with it, is that I have a narrative in which the macro-universe does have B=0 and L=0, but half of that is in a mirror universe.
Once you are committed to new physics that will get you from B=0 and L=0 to the existing values of B and L in the post-Big Bang time period, you have a very strong desire to come up with BSM processes that don't conserve B and L like Majorana mass neutrinos, proton decay, neutrinoless double beta decay and flavor changing neutral currents at the tree level. This leads you down the wrong path.
Similarly, one of the reasons that the hierarchy problem doesn't bug me is because I have a narrative in which the Higgs boson mass flows naturally from the masses of the other fundamental particles and the Higgs vev. From that direction, the Higgs boson mass looks perfectly natural. Another narrative is to start at the boundary between stable and metastable and to reverse engineer the beta function of the Higgs boson which also makes its mass look perfectly normal. In only looks crazy when you are conceptualizing it has the sum of a whole lot of huge positive and negative numbers which isn't a very helpful perspective as it turns out.
Similarly, if you look at a naive generic Lagrangian for QCD, the strong CP problem looks like a problem since there is a potential moving part that isn't used. But, if you look at CP violation from the perspective that only something that experiences time (unlike massless gluons, photons and gravitons) can violate CP, then it makes perfect sense that QCD doesn't have a CP violating parameter.
My narratives may not be right. But, having them makes it psychologically much easier to consider the evidence in a new light.
4. I may not have a deeper understanding than the geniuses in their specific areas, but I have a much wider base to draw from. I've skimmed almost every new pre-print in astrophysics, HEP-experiment, and HEP-phenomenology, and almost every article notable enough to be reported in the popular press for at least eight years, in addition to some HEP-Lattice, HEP-Theory, and GR. I've actively researched new concepts I haven't seen before. I have a much greater familiarity, as a result, with all of the possibilities that are currently being actively investigated and can expect recent data across disciplines and subdisciplines. For example, there are heaps of new CDM papers churned out every data that ignore constraints from other subfields of astrophysics and particle physics and hence propose new models that are really dead on arrival. Any CDM theory that produces an unmodified NFW halo, for example, is contrary to the observational evidence. But, if you only read papers in your own sub-field you are oblivious to that fact. Imposing cross-disciplinary consistency checks is the biggest factor I have going for me that other geniuses in the field don't. They have to spend their time working on their field, not spending hours a day looking at what everyone else has come up with comprehensively.
ReplyDelete5. Lots of geniuses are unwilling to consider that nobody has yet come up with the right answer to a problem and immediately jump to multiple choice. For example, nobody has done the work to show a modified gravity theory that reproduces the CMB peaks, but nobody has established that you can't do that either, and the prediction of the CMB peaks are less impressive once you know how they were "predicted."
The easiest solution to cosmic inflation, for example, is to simply start with initial conditions a dozen Plank time units later than the conventional Big Bang. Not emotionally satisfying but it gets the job done without new physics and recognizes that beyond that point we may not have the means to know the truth.
Likewise, the popularity of the neutrino mass seesaw solution comes from the inapplicability of the Higgs mechanism as conventionally formulated to fermions that don't have both L and R parity possibilities, and the existing of a Majorana mass possibility. There is probably a variation on the Higgs mechanism that can explain neutrino mass (and after all, we just answer the question of fundamental particle masses with a new almost identical question about Yukawa constant determination). But, nobody will devote effort to coming up with one and get a warm reception in the physics community unless you reject the other two options. My best guess is that the W boson has more to do with mass generation than we give it credit for, even though I can't prove that.
But, since a lot of people won't jump away from what they have without a fully worked out solution, they cling to ideas that have lots of other problems and aren't favored by experiment and observation.
Here are my 40 serious doubts stripped of redundancy, leaving only 10, at least a couple of which are almost redundant.
ReplyDelete9. Lepton number is not conserved or baryon number is not conserved outside sphaleron interactions.
18. There are fundamental fermions other than those identified in the Standard Model below the GUT scale.**
19. There are fundamental bosons not identified in the Standard Model below the GUT scale, other than gravitons and possibly one or two bosons related to neutrino mass and/or neutrino oscillation.**
20. CPT symmetry is violated under any circumstances.
29. There are more than four dimensions of space-time, either large or tiny.***
30. Mass-energy conversation is violated locally at t=0 plus an infinitesimal amount.
31. The topology of space-time is sufficiently warped or non-local to give rise to traversable worm-holes.****
31. Fundamental physical constants vary in space-time for any reason other than energy-scale.
38. It is possible for anything resembling life as we know it to enter a black hole without dying.
40. Gravity behaves exactly as predicted in classical General Relativity (as applied today) in all circumstances without modification even in the extremely weak field limit.
I can break it down even further to four points:
ReplyDelete1. The Standard Model is not an accurate description of reality up to the GUT scale in every area where it has an explanation.
31. The topology of space-time is sufficiently warped or non-local to give rise to traversable worm-holes.****
38. It is possible for anything resembling life as we know it to enter a black hole without dying.
40. Gravity behaves exactly as predicted in classical General Relativity (as applied today) in all circumstances without modification even in the extremely weak field limit.
Basically, for the entire 65 point list, I am very conservative in terms of deviations from the SM.
ReplyDeleteI am limiting my concerns to "within the Standard Model" explanations for why it is the way that it is and guesses about unmeasured parameters (1-3 and 5-9), and suggesting that a couple of things that the SM permits but that have never been observed don't actually happen (i.e. sphalerons and free glueballs) which are 11 and 25 in the second list.
Meanwhile, I am fairly aggressive about the subtle ways that I think that conventional GR and cosmology is likely to be wrong.
Even then 31 and 38 in the first list are both conventional wisdom already as are 4, 10, 14, 15, 19 and 24 in the second list. 17 is widely believed but rarely identified as something approaching a rule. These points are tamping down ideas that already don't have much support. Similarly, 19-21 are generic to pretty much every graviton based quantum gravity theory.
On the second list 12 (multiverse), 13 (inflation), 16 (primordial black holes) and 18 (dark energy substance as opposed to cosmological constant or something else) are already controversial.
I am going out on a limb on 40 in the first list, and 22 and 23 which spell out ways in which I think that 40 is the case. All of these, however, have a strong observational basis from modified gravity interpretation of astronomy observations that work well.
You could sum up the approach as don't try to fix what isn't broken (the SM), even though you want to understand the SM more deeply. And, do fix what is broken (gravity) in ways well supported by observation. And, don't make shit up that is basically unprovable and doesn't have a compelling reason to exist (12, 13 and 16 in the second list for example).
ReplyDeleteI focus on 14, 15, 16 and 17 because they provide ways to put UV and IR completion points into quantum gravity theories like asymptotic safety, while being certain that we aren't contrary to anything that is observed or that can be physical. It is taking what are usually view as accidental bounds on what is possible and treating them like physical rule bounds instead.
this is a lot.
ReplyDeletei favor starting with what is supported by evidence, the SM + gravity, and wonder what is the most minimal extension that explains the remaining unsolved problems as vetted by Sabine Hossfeld good problems and nonproblems. modifying gravity to accommodate MOND seems simpler than adding new particles to the SM.
LQG is more minimal than strings.