Duda Jarek

Extraordinary claims require extraordinary evidence - there is a lot of general talk here, but I am asking about some details: convincing experimental evidence and argumentation. Imagine civilization without Einstein: weak field effects can be introduced "the Standard Model way": as sequence of corrections - first terms of Taylor expansion of GR. What experimental evidence could be used to convince them that spacetime is not flat but needs intrinsic curvature: that only non-renormalizable GR can explain it? There are needed strong field effects e.g. using black holes - but how such argumentation could look like?

Indeed, hence it is extremely important to reflect what of it really comes from nature - is universal, should be also found by hypothetical other civilizations ... and what is just an artifact of physics being a social construct, for example evaluating concepts based on number of articles people can write about them - this way promoting exciting solutions and forgetting the simple ones.

While I agree that it might be practically impossible to verify it, I have asked if it might be already happening there - these are two separate questions, and I wouldn't be surprised if the answer to the latter was positive. But maybe it could be tested through some Monte-Carlo by adding hypothesized Feynman diagrams into considered ensemble? But if considered for BH, they are created by collapse of neutron stars, many of which have extreme rotation (with some fluxes, shockwaves etc.), with orders of magnitudes higher brightness than what we can explain ... but baryon decay possibility seems completely neglected for neutron stars - should we be so certain about it?

Having GEM in analogy to EM, which was known 20 years before GR, gravity in QFT can be made analogously to EM - through photon/graviton exchange, e.g. with additional summation over alpha=0,1,2,3 as you have written ... so after Higgs they might be confident of having (renormalizable) theory unifying all the forces. While I don't see how the above could lead to acceptance of non-renormalizable theory, the strong field regime might (?) Using GEM instead of GR, such hypothetical civilization wouldn't be aware of black holes, probably expecting heavy neutron stars instead ... what might convince them that it just wrong?

Marcus, the experiments in https://en.wikipedia.org/wiki/Tests_of_general_relativity use low order corrections if seeing GR as Taylor expansion - a civilization without Einstein could be just adding such succeeding terms. Extrapolating to GR from such corrections seems quite nontrivial and might be tough to accept due to non-renormalizability for a civilization which had developed QFT first. For really convincing arguments we should rather think of qualitative consequences for intrinsic curvature, like black hole horizon or wormholes ...

"Can baryon number be violated" is one of the most fundamental questions of physics, it seems we still don't really know answer to (?) Indeed it seems necessary for hypothesis that our Universe has started from a single point, but there is alternative of fixed baryon number of the Universe as kind of additional constant, in Big Crunch preceding our Big Bang. So do we have any chance to answer this question in some future? - what could be accessible convincing experiment? Could it already be happening in LHC? Be accessible in some future colliders? If so, could it be verified there? If not, what about astrophysical possibilities like neutron stars, GRBs with orders of magnitudes higher energies than what we could imagine? ... or Hawking radiation which finally turns baryonic matter into massless radiation ...

For a few decades they have unsuccessfully searched for proton decay in room temperature water, what seems interpreted as disproof of this possibility ... but is it really? The same way we could "disprove" nuclear fusion as it practically doesn't happen in room temperature water ... but happens in extreme conditions. So maybe it didn't disprove baryon number violation, only it needs extreme conditions e.g. to get into some higher energy state before decay? Baryon number violation is hypothesized in baryogenesis, Hawking radiation - which need quite extreme conditions. It is required in many models like supersymmetric, or now popular sphaleron. How can we verify this possibility? Talking with particle physicists, they say we just cannot know if it happens e.g. in LHC, checking baryon number is practically impossible there (?) So maybe astrophysical objects to understand orders of magnitude higher energies than we can explain in standard way? For example https://www.space.com/35846-brightest-farthest-neutron-star-discovered.html

General relativity has this huge problem of being non-renormalizable ... while it wasn't an issue when it was introduced, a few decades later it would make GR extremely difficult to accept - there would be needed very strong experimental evidence to give up renormalizability - which experiment could it be? GR can be seen as a sequence of corrections in Taylor expansion - without Einstein we might now slowly introduce such succeeding terms ...

But mathematically GEM is also Maxwell, can be analogously realized with Lorentz invariant F_munu F^munu in Lagrangian ... why do you think it cannot be Lorentz-invariant? Exactly! GR has renormalization problem as e.g. Feynman ensemble of all shapes of specetime leads to "larger infinities than usual" ... In contrast, flat spacetime GEM is just second F_munu F^munu in Lagrangian - is trivial to unify with the rest of physics, renormalize. Without Einstein, a few decades later a non-renormalizable concept would be nearly impossible to accept (needed extremely strong evidence), definitely more difficult than adding new terms/corrections to GEM to repair experimental disagreements, like in the "Standard Model way".

... and approval for military use in China:

Also China and probably others ... and minimizing e.g. expected number of casualties, this might be a reasonable behavior. Personally, if having opportunity to participate in such test, if only not having some nasty side effects, I don't think if I would have any doubts.

https://www.bbc.com/news/world-europe-53735718 Coronavirus: Putin says vaccine has been approved for use Two more Stage III (8, +1 "approved") in https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html

I have just added: https://en.wikipedia.org/wiki/Frame-dragging starts with "More generally, the subject that deals with the effects caused by mass–energy currents is known as gravitomagnetism, which is analogous to the magnetism of classical electromagnetism. " https://en.wikipedia.org/wiki/Lense–Thirring_precession starts with "It is a gravitomagnetic frame-dragging effect." I still don't know where do you see a disagreement?

This article starts with below diagram with caption "Diagram regarding the confirmation of gravitomagnetism by Gravity Probe B" - which is this second set of Maxwell's equations. https://en.wikipedia.org/wiki/Frame-dragging starts with "More generally, the subject that deals with the effects caused by mass–energy currents is known as gravitomagnetism, which is analogous to the magnetism of classical electromagnetism. " https://en.wikipedia.org/wiki/Lense–Thirring_precession starts with "It is a gravitomagnetic frame-dragging effect." Where do you see a disagreement?

Most of them directly use GEM, like Gravity Probe B - please specify experiment and we can discuss it. This question is not only "alternative history", but also many e.g. in SETI hypothesize existence of other civilizations - it might be worth understanding if their physics would be based on GR, or maybe on adding corrections to GEM - which might asymptotically reach GR? Not having Einstein, which experiment could convince e.g. them that it is necessary to give up flat spacetime and introduce intrinsic curvature?

But which experiment would bring certainty that we need to give up flat spacetime? From https://en.wikipedia.org/wiki/Tests_of_general_relativity : - Perihelion precession of Mercury is GEM: "Gravitoelectric effects" + Lense–Thirring precession - Deflection of light by the Sun - would need some EM-GEM coupling: slowing down of EM propagation in presence of gravitational field, - gravitational time dilation - clocks are usually based on EM propagation e.g. in atoms, so slowing down of EM would slow down clocks ... the question is other interactions: what do we know about gravitational time dilation e.g. for muon decay? - Gravity Probe B tested GEM, - gravitational waves - also in GEM ... ... black holes - sure we have objects of extremely high density, but how to distinguish what is happening inside?

Indeed special relativity did not require Einstein, as it was already e.g. in EM/GEM Maxwell's equations. General relativity introduced intrinsic curvature of spacetime, while earlier it was thought to be flat. So which experiments bring certainty that spacetime is curved? Sure we need it e.g. to bend photon trajectories, but looking e.g. at glass of water reminds that there are also other ways to bend photon trajectories - like some slowing down of EM propagation in presence of strong gravitational field here (some EM-GEM coupling), what would also lead to some gravitational time dilation effects.

A valuable thought experiment from neighboring thread - how would physics develop if there would be no Einstein, especially regarding gravity? While modern physicists might say that without him there would be "weeping and the gnashing of teeth", his introduction of general relativity a century ago seems to be event of extremely low probability (?) - so what if it wouldn't happen? Or imagine some hypothetical other civilization e.g. SETI is looking for - would it automatically get to GR? If not, how their physics would develop? Beside Newton's gravity, there was also known GEM before ( https://en.wikipedia.org/wiki/Gravitoelectromagnetism ) - just take Maxwell's equations to gravity, making it Lorentz-invariant theory. "The best confirmation of GR": Gravity Probe B in fact has confirmed GEM as approximation of GR. Without Einstein we would probably develop further Heavisides' GEM - adding corrections to Lagrangian (like in "Standard Model approach"), starting with EM-GEM coupling to bend photon trajectories by Sun ... the big question is if gravitational time dilation could be explained by such slowing down? GEM has no renormalization problem, trivially unifies with the rest of physics as it is just another F_munu F^munu in Lagrangian - many approaches to solve this problem like string theory might never appear (?) Where the problems would start - which experiments leave no doubts that we have to use GR instead of GEM? Which cannot be repaired with added terms to GEM Lagrangian?

It would be interesting to derive (and confirm) general relativity corrections to Jefimenko equations ... Many GR confirmations like Gravity Probe B are in fact of GEM - what confirmations of higher order terms are there? GEM was introduced by Oliver Heaviside in 1893 and is Lorentz invariant ... interesting thought experiment: how physics would look like without Einstein? I believe they would build on GEM - adding corrections to Lagrangian, starting with EM-GEM coupling to bend photon trajectories by Sun. GEM has no renormalization problem, trivially unifies with the rest of physics as it is just another F_munu F^munu in Lagrangian - many approaches to solve this problem like string theory might never appear (?) Where the problems would start?

Looks like GEM approximation of general relativity (confirmed e.g. by Gravity Probe B): https://en.wikipedia.org/wiki/Gravitoelectromagnetism You can use standard methodology/tools from electromagnetism for that, like avoiding PDEs with Green's function e.g. in static https://en.wikipedia.org/wiki/Biot–Savart_law or general https://en.wikipedia.org/wiki/Jefimenko's_equations ps. Kepler problem simulator using this approximation: https://demonstrations.wolfram.com/KeplerProblemWithClassicalSpinOrbitInteraction/

Sure, it is also possible that there are teapots flying throughout the Universe ( https://en.wikipedia.org/wiki/Russell's_teapot ). While we cannot exclude unimaginable amount of stuff, a practical rule to get anywhere is Ockham's razor ( https://en.wikipedia.org/wiki/Occam's_razor ) : "entities should not be multiplied without necessity" - before going to "exciting explanations" (loved by the bibliometric evaluation system), really explore the the nonmagical ones first.

So you agree or disagree? Such hypothetical "increased probability in presence" can be alternatively written e.g. as positron + gammas + proton-> 2 protons electron + gammas + antiproton -> 2 antiprotons with some exchange in Feynman diagrams with this additional particle (e.g. electron, proton, neutron). Our knowledge about violation of baryon number conservation is practically zero - couldn't observe any, which reason might be trying to get proton decay in room temperature, while it is hypothesized for muuuuuch more extreme conditions like baryongenesis or Hawking radiation (so maybe also center of neutron star?) My point is only that CPT violation is not necessary to explain domination of matter - other ways are e.g.: - fixed baryon number of the Universe - in Big Crunch preceding our Big Bang, - statistical symmetry breaking - some positive feedback mechanism like above, making "the more of one type, the easier to get even more" - finally leading to domination of one type, which initially could be chosen at random, analogously to chirality of life. ps. Regarding claim that proton decay is impossible because we couldn't observe it in room temperature water - we could disprove nuclear fusion in the same way ... some processes just need much more extreme conditions, much more for baryon number violation than for fusion.

So assume there is possible proton decay, for simplicity we can write: proton -> positron + gammas In hypothetical baryogenesis there would be needed some opposite process, e.g. with leptons from pair creation: gammas -> electron + position. If possible, it would be still extremely unlikely, its nearly negligible probability (cross section) could be affected by local situation, like "catalyzed by presence of slow positive charge" (e.g. flying nearby, with photon exchange in Feynman diagram) improving a bit this probability - what would be sufficient for statistical symmetry breaking by two CPT symmetric rules: positron + gammas -> proton (with increased probability in presence of proton) electron + gammas -> antiproton (with increased probability in presence of antiproton) This kind of catalyzing property: increased fitness of L-aminoacid based life in presence of L-aminoacid based life, or increased probability of creation of proton in presence of proton, allows for symmetric set of rules leading to statistical symmetry breaking - nearly complete domination of one of them, initially chosen at random.

Parallel universe explanation seems as coming from some Star Trek fans. Going back to earth, sounds a bit like CPT analogue of laser: with involved particles going in opposite direction, neutrinos here.

Baryogenesis hypothesis requires violation of baryon number conservation - like Hawking radiation or unobserved (at least in room temperature) https://en.wikipedia.org/wiki/Proton_decay : we can search for CPT symmetric rule which makes 1/2-1/2 ratio situation statistically repelling, like in presence of some matter (proton, electron) it is a bit more likely to create proton, and symmetrically in presence of antimatter it is a bit more likely to create antiproton. Otherwise: if baryon number is ultimately conserved, there remains e.g. Cyclic Universe hypothesis: that baryon number was the same in Big Crunch preceding our Big Bang - shifting this problem to minus infinity. Regarding biology, indeed alternative explanation is that creation of life is so improbable that it just happened only once around here - this way randomly choosing one of chiralities. Synthetic biology is currently running to synthesize mirror version of a cell, e.g. mirror polymerase was synthesized in 2016, but such mirror life might turn out extremely dangerous as not having natural enemies: https://en.wikipedia.org/wiki/Mirror_life