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ohwilleke
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The minimum mean lifetime of a proton is 1023 times the 13.8 billion year age of the universe (and this is as low as it is simply due to the limited of precision measurement by scientists).Suekdccia said:But as the universe aproaches heat death wouldn't there be less and less protons created as time passes if proton decay were true? I mean, less and less "useful" energy could be used to make new protons...
This is 100,000,000,000,000,000,000,000 x 13.8 billion years!
This is actually a conservative estimate that is a bit out of date itself:
[M]inimum proton lifetimes from research (at or exceeding the 1034~1035 year range) have ruled out simpler GUTs and most non-SUSY models. The maximum upper limit on proton lifetime (if unstable), is calculated at 6×1039 years for SUSY models and 1.4×1036 years for minimal non-SUSY GUTs.
(Source citing this peer reviewed journal article from 2023 about minimum proton mean lifetimes, and this 2007 article about maximum proton lifetimes in GUT theories.). There is also no observational evidence supporting the existence of any form of supersymmetry (SUSY) so far.
In contrast, every radioactive isotope that experiences beta decay creates new protons "gillions" of times a year, and natural nuclear fusion in stars creates new radioactive isotopes that will beta decay in the future on a regular basis.
These is not a single example of baryon number non-conservation in the entire history of science.
In the Standard Model, baryon number non-conservation can only happen at extremely high sphaleron energies, which by assumption isn't possible during a "heat death of the universe" scenario.
There are no outstanding experimental anomalies meaningfully suggesting that discovery any beyond the Standard Model physics that would give rise to baryon number non-conservation is "around the corner".
This is the wrong picture.Suekdccia said:Okay. I was pretty sure that massive particles travelling at some velocity were "redshifted" by the expansion of spacetime in a similar way to how photons have their frequency redshifted, so in the future we would have very low energetic photons and particles that would tend to be at rest. If this is the wrong picture then everything changes of course.
What is the right picture is that the density of neutrinos per cubic light-year in the universe is falling in proportion to the expansion of the universe, which makes it harder for neutrinos to clump in the future than it is today.
This is wrong so there will be no compact neutrino structures.Suekdccia said:It's not that I'm not willing to listen. The thing is that you were saying that since neutrinos do not interact with each other through any forces and they travel so fast that they could not be gravitationally attracted then they will never clump. But I though that you were referring only to the present universe where neutrinos have relativistic velocities, so I was asking what would happen if they lose enough velocity in the future due to the "redshift" that I though they suffered as spacetime expands. I though this would slow them down so in the future they could be gravitationally attracted. But if this is wrong then of course there will be no compact neutrino structures.
Yes.Suekdccia said:So then, will neutrinos always have high velocities even in far future timescales (so that they will never really be slow enough to be gravitationally attracted and clumped into structures)?
The density of neutrinos in the vicinity of galaxies (and galaxy clusters and closer to the "cosmic web") is somewhat higher than it is in the middle of cosmic voids.Suekdccia said:So, at most, neutrinos would aggregate or cluster into diffuse halos around galaxies instead of compact solid structures? Or this would also be impossible?
Neutrinos will never form compact solid structures.
Neutrinos will not even segregate from ordinary matter to form a halo distinct from stars, interstellar gas, dust, and (if it exists) dark matter particles. Streams of high energy neutrinos in all directions are generated in supernova events that the ICE neutrino detector in Antarctica detects now and then.
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