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The data we've received so far from satellites such as WMAP paints a near uniform distribution in intensity of the background radiation that we take as evidence that our universe had an origin, and that it went through (and continues to go through) a massive expansion - that which we call the Big Bang.

Hypothetically speaking, and assuming we arrived at this point in time without a Big Bang event - then what would we expect to observe as background on the sky?

Would we expect to see an even more uniform temperature at absolute zero?

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  • $\begingroup$ Such hypotheticals belong into world building or creative science fiction writing, but not into physics. Science can't tell you anything about alternative universes. I am curious that you should even ask, though. One could reformulate the question in a scientific way. Assuming that the universe will continue for some time, what will future scientists make of the origins without having access to the CMB? To them the sky may appear perfectly cold with no sign of structure. How can they get some of the information that we still have access to? $\endgroup$ – CuriousOne Jan 5 '16 at 18:46
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    $\begingroup$ At least some of the alternative theories were suggestive of less uniformity. See, e.g. en.wikipedia.org/wiki/… and maybe en.wikipedia.org/wiki/Non-standard_cosmology or en.wikipedia.org/wiki/… $\endgroup$ – Keep these mind Jan 5 '16 at 19:03
  • $\begingroup$ @CuriousOne What brought me to this question really had to do with the question: are there other sources of radiation (perhaps pair annihilation-production?) that are observed as part of the CMB. I don't know allot about it but I assume we use star maps to subtract out the 'foreground' radiation sources - but are there other sources? Can dark matter be contributing anything? So that's what led me. If you remove the big bang - what could we expect to still observe. Not trying to build an alternate universe; just trying to visualize the structure of this one. Thanks $\endgroup$ – docscience Jan 5 '16 at 19:45
  • $\begingroup$ @CuriousOne ... more of a thought experiment $\endgroup$ – docscience Jan 5 '16 at 19:46
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    $\begingroup$ There are certainly plenty of radiation sources that are impacting the CMB measurement. I have met an astronomer who was participating in cataloguing galactic gas and dust clouds that had to be cleaned from the raw CMB data set. I know next to nothing about the issue, but my best guess is that the CMB is essentially a black body spectrum, while other radiating objects usually have signatures in other wavelength ranges (optical, IR), so they are giving themselves away. I don't know if lensing makes a difference or not... maybe a CMB expert can answer that. Honestly, this is a better question. $\endgroup$ – CuriousOne Jan 6 '16 at 1:42

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