The CMB is composed of radiation with a black body distribution peaked at around 1000nm. The radiation is now in the microwave band at about 1 mm wavelength. The IR photons were spread by the expansion of spacetime by a factor of 1000, and the actual z factor for the CMB is z = 1100. With the exponential expansion of the universe this z will increase until the CMB is in the radio wave band > 1m wavelength, and then eventually expanded beyond the dimensions of any practical antenna. It will take about 10 billion years for that to happan.
LC On Wednesday, December 27, 2017 at 2:17:49 PM UTC-6, agrays...@gmail.com wrote: > > Since galaxies were formed after the CMB came into existence about 380,000 > years after the BB, and those far away will wink out as they cross the > cosmic horizon, why doesn't the CMB also wink out? I know the latter is > reddening as the cosmos expands, and is ubiquitous, but when the question > was posed to me last night at a meeting in Pasadena with former JPL > colleagues, I didn't have a good answer. TIA, AG > -- 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.
