Posted: Jul 31, 2010 11:31 pm
by Calilasseia
Actually, parts of the relevant cosmology are testable now. Such as proton decay. Since the mechanism of proton decay postulated to arise from Grand Unified theories is well documented and understood, and the physical results of this mechanism are known, scientists can conduct experiments to determine [1] if proton decay is a physically real phenomenon, and [2] what the half life of this process is. Indeed, they have already conducted experiments in this vein, and on the basis of those experiments placed a lower limit for the half-life of proton decay at 1036 years, because if that half-life were lower, it would have been observed by now. This, incidentally, also falsifies those versions of Grand Unified physics that postulated a shorter half-life than 1036 years.

Now, if proton decay is finally announced in the scientific press, we shall have a handle on the likely half life. This in turn dictates the length of time that we have to wait in order for baryonic matter to cease existing (for a proton decay half-life of 1036 years, the time required is 1040 years), and then, it's a matter of waiting for all the black holes to evaporate. Since the Hawking mechanism was first published in 1974, scientists have developed more thorough analyses of the process, and determined what phenomena to search for in the universe that would signal black hole evaporation, and in 2008, NASA launched the Fermi Gamma-Ray Space Telescope, one of whose missions is to search for these events. I've yet to hear of any positive data being returned from the FGST, but since scientists know what to look for, they are now in a position to detect the relevant events if they have occurred.

Consequently, since we can place a lower limit of 1036 years on proton decay, and therefore a lower limit of 1040 years on baryonic matter disappearance, the remainder of the figures for the other events leading to the universe becoming a sea of photons fall into place in line with these. The only problem that will arise with respect to this cosmology is if proton decay is not observed within any of the periods that would support any of the extant Grand Unified theories, in which case, a rewrite of the Standard Model minus proton decay is needed, but this simply extends the time for heat death and the Photonic Era beyond 101000 years. If proton decay does not exist, and protons are indeed stable, then we have to wait a lot longer for all the baryonic matter to disappear, because it has to be swallowed up in black holes, which is going to take a lot longer than 1040 years. Indeed, if dark energy is verified, and results in accelerating expansion of space-time in the distant future, then baryonic matter may never disappear completely if protons are stable, and things start to get interesting in a heat-death universe in which baryonic matter still exists.