On Sunday, March 17, 2019 at 6:17:01 PM UTC-6, Lawrence Crowell wrote: > > On Sunday, March 17, 2019 at 1:36:22 PM UTC-6, agrays...@gmail.com wrote: >> >> >> >> On Sunday, March 17, 2019 at 12:12:58 PM UTC-6, Brent wrote: >>> >>> >>> >>> On 3/17/2019 4:50 AM, agrays...@gmail.com wrote: >>> >>> >>> >>> On Sunday, March 17, 2019 at 3:05:14 AM UTC-6, agrays...@gmail.com >>> wrote: >>>> >>>> >>>> >>>> On Sunday, March 17, 2019 at 2:49:43 AM UTC-6, Bruce wrote: >>>>> >>>>> On Sun, Mar 17, 2019 at 7:38 PM <agrays...@gmail.com> wrote: >>>>> >>>>>> >>>>>> >>>>>> On Thursday, March 14, 2019 at 8:27:58 PM UTC-6, agrays...@gmail.com >>>>>> wrote: >>>>>>> >>>>>>> IIUC, the combined mass of an electron and proton is larger than the >>>>>>> hydrogen atom they form at recombination time. Thus, I would expect a >>>>>>> very >>>>>>> narrow pulse of energy as a result when recombination occurs. This >>>>>>> apparently being the case, why does the CMBR have a black body >>>>>>> distribution >>>>>>> and not a pulse with a very narrow spread? TIA, AG >>>>>>> >>>>>> >>>>>> Is this a really dumb question and the reason for zero replies; or is >>>>>> it because no one here has the answer? Or maybe just no interest in >>>>>> another >>>>>> puzzle? AG >>>>>> >>>>> >>>>> Dumb question. CMB is thermal radiation, not the recombination energy. >>>>> It reflects the temperature at the time the universe became transparent >>>>> to >>>>> radiation of all wavelengths -- because the electron-proton plasma >>>>> recombined to form less reactive hydrogen. >>>>> >>>>> Bruce >>>>> >>>> >>>> But the recombination energy must be part of the mix at recombination >>>> time and this is never mentioned in the texts I have read. I suppose this >>>> is another dumb question. AG >>>> >>> >>> What this thread shows is that I don't understand the CMBR. Maybe no one >>> does. ISTM that the universe was cooling *prior* to recombination time >>> and therefore must have had a thermal spectrum *independent* of the >>> recombination. Yet the going assumption, AFAICT, is that the CMBR *comes >>> into existence* at recombination time, but is independent of the >>> physical recombination which is never included or mentioned as part of the >>> observed spectrum. Can anyone explain what is actually going on in this >>> model? TIA, AG >>> >>> >>> Your mistake is assuming that this recombination is one big jump from >>> complete dissociation to bound hydrogen atom. A hydrogen atom has lots of >>> energy states and, as the plasma cooled due to expansion, there would be a >>> continuous shift of energy from the proton/electron to the gamma rays. >>> >>> Brent >>> >> >> In fact, hydrogen has a countably infinite set of energy states, which I >> forgot. Is it correct to say that these recombination states form the >> thermal signature which is observed (in which case Bruce's explanation is >> misleading)? AG >> > > I am presuming you are raising the prospect of there being absorption > lines in the spectrum, just as we see the same with the sun. There were > such lines for the hydrogen atom after recombination that would have been > visible. However, with red shifting by z = 1100 and spectral broadening > they have been smeared out. > > LC >
If that's the case, then there's no visible remnant of the recombination in the observed CMBR, and what we observe is simply the cooled BB radiation of pre-combination times. So what does the CMBR tell us? AG > > [image: spectrum of the sun.jpg] > > -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
