On Sunday, December 31, 2017 at 8:10:39 PM UTC-6, [email protected] wrote: > > > > On Sunday, December 31, 2017 at 7:25:53 AM UTC-7, Lawrence Crowell wrote: >> >> On Saturday, December 30, 2017 at 8:33:17 PM UTC-6, [email protected] >> wrote: >>> >>> >>> >>> On Saturday, December 30, 2017 at 2:40:22 PM UTC-7, Lawrence Crowell >>> wrote: >>>> >>>> On Saturday, December 30, 2017 at 2:28:52 PM UTC-6, [email protected] >>>> wrote: >>>>> >>>>> >>>>> >>>>> On Saturday, December 30, 2017 at 1:03:58 PM UTC-7, Lawrence Crowell >>>>> wrote: >>>>>> >>>>>> On Friday, December 29, 2017 at 8:45:41 PM UTC-6, [email protected] >>>>>> wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On Friday, December 29, 2017 at 6:59:22 AM UTC-7, Lawrence Crowell >>>>>>> wrote: >>>>>>>> >>>>>>>> The cosmological constant is Λ ~ 10^{-52}cm^{-2} and the scale >>>>>>>> factor evolves as >>>>>>>> >>>>>>>> a(t) = a_0 exp(t sqrt{Λc^2/3}). >>>>>>>> >>>>>>>> The factor sqrt{Λc^2/3} ~ 10^{-18}sec^{-1}. For a billion years >>>>>>>> this is t ~ 3x10^{16} sec and so sqrt{Λc^2/3}t ~ .03 and the scale >>>>>>>> factor >>>>>>>> increases by 1.03. The CMB microwave background will be expanded by a >>>>>>>> small >>>>>>>> change. In 10 billion years this is t ~ 3x10^{17}sec and so >>>>>>>> sqrt{Λc^2/3}t ~ >>>>>>>> .3 and the scale factor expands by 1.4. At 100 billion and a trillion >>>>>>>> the >>>>>>>> scale factor expands by 20 and in a trillion years by 10^{13}. This >>>>>>>> means >>>>>>>> the CMB peak wavelength will be about 10^{10}m. That is not quite the >>>>>>>> length of the cosmos, but in 10 trillion years the expansion factor is >>>>>>>> close to ~ 10^{800} which means the wavelength at this point is larger >>>>>>>> than >>>>>>>> the cosmological horizon scale. At that point the CMB will be removed >>>>>>>> from >>>>>>>> the view of any observer. The time where wavelength becomes longer >>>>>>>> than the >>>>>>>> cosmological horizon occurs in about 2 trillion years. >>>>>>>> >>>>>>>> LC >>>>>>>> >>>>>>> >>>>>>> *Does the CMB just keep getting progressively redder as the cosmos >>>>>>> expands, or does it actually "wink out", meaning CMB photons which we >>>>>>> might >>>>>>> eventually observe, begin their journey beyond our horizon? Since no >>>>>>> new >>>>>>> ones are being created, and the original ones are within our immediate >>>>>>> neighborhood, like Andromeda, I don't see how they can wink out. AG * >>>>>>> >>>>>> >>>>>> Think of a cube with sides length L. This is a region that permits >>>>>> wavelengths of λ = L/2, L, 3L/2, ...as standing waves. By this as one >>>>>> photon of those wavelength leaves another enters. So we can think of >>>>>> space >>>>>> as having properties similar to a resonance cavity. As space expands >>>>>> this >>>>>> box expands, which means the permitted standing waves have longer >>>>>> wavelength. So as space expands electromagnetic waves within it also >>>>>> becomes stretched. This is the red shifting of light. >>>>>> >>>>>> Local clusters of galaxies that are gravitationally bound will not >>>>>> have this issue. These galaxies will remain in relative close proximity. >>>>>> If >>>>>> it were not for the fact Andromeda and the Milky Way are going to >>>>>> coalesce >>>>>> in about 4 billion years Andromeda would be observable from this galaxy >>>>>> far >>>>>> into the future in wavelengths of light emitted by stars. The other >>>>>> galaxy, >>>>>> M33 or Triangulum, the smaller of the three large galaxies in the local >>>>>> group, may orbit around this newly formed Androway or Milkomeda galaxy >>>>>> for >>>>>> a nearly indefinite time into the future. >>>>>> >>>>>> LC >>>>>> >>>>> >>>>> *So you agree with Brent that the CMB will grow redder as the universe >>>>> expands, but will never "wink out" as will be the case for galaxies not >>>>> gravitationally bound to the MW? The key difference is contained in the >>>>> concept of photons entering the box as others leave, and I suppose this >>>>> follows from the omnidirectional nature of the CMB. Correct? AG* >>>>> >>>> >>>> Once the wavelength of CMB radiation has expanded beyond any possible >>>> quarter wave stack size it it no longer detectable. Once it has expanded >>>> to >>>> a scale larger than the cosmological horizon it is absolutely impossible >>>> to >>>> detect. In that case we can say the CMB has winked out. This will happen >>>> in >>>> a finite time in the future, though two trillion years is 144 times the >>>> age >>>> of the universe now and almost eternity compared to our lifetimes. In the >>>> extreme time frame beyond from 10^{30} to 10^{110} years there will only >>>> be >>>> supermassive black holes. The cosmological horizon does emit >>>> Hawking-Gibbon >>>> radiation that is analogous to Hawking radiation. This radiation will >>>> perturb black holes, and potentially a civilization or collective of >>>> intelligent life that lives around such a SMBH using its angular momentum >>>> as energy might be able to detect this perturbation. The SMBH might not >>>> decay quite as it would in a pure vacuum. This might be the detection of >>>> the cosmological horizon. I will refrain from much comment on the >>>> plausibility of such civilizations. >>>> >>>> The box argument in part works because of the isotropy of the CMB >>>> radiation. >>>> >>>> LC >>>> >>> >>> *What is a quarter wave stack? I get the key point. TY. Since the CMB is >>> ubiquitous and isotropic, it can't be treated like a source which becomes >>> located beyond the cosmic horizon. AG * >>> >> >> An organ pipe is a quarter wave stack. It has open and closed, or Newman >> and Dirichlet, boundary conditions on either end. That way it is resonant >> with a wavelength by being a quarter of a wavelength in dimension. >> >> LC >> > > *Standing waves in an expanding box is a plausible model for analyzing the > evolution of the CMB, but in reality the photons comprising the CMB don't > bounce off a barrier, but keep moving away from the source event, some > 380,000 years after the BB. How would you overcome this deficiency in your > model? TIA, AG* >
>From an operational perspective they are equivalent. In any case the expansion of space expands waves in it. LC -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
