Originally Posted by
nykkyo
How do we know that the €œCMB€ we measure today is not from a large supernova in a pre-existing universe 14 billion years ago? The black-body radiation in the remnants would be the same.
Obviously a critical portion of your post did not come through - on this site you can't copy and paste from other applications. Please retype the question. But I suspect that you're asking how do we know that the
Big Bang was something other than a large super nova. There are a couple of ways that what we see in the universe today is not consistent with a supernova in place of the Big Bang:
1. The elements that make up the universe. Most of the original material from the Big Bang was hydrogen and a bit of helium, plus a trace of lithium. All other heavier elements - oxygen, nitrogen, iron, etc - were formulated through nuclear fusion reactions inside stars long after the Big Bang itself, and these elements were later expelled through novae, and made available for incorporation into later stars and planets. Prior to the formation of stars these elements did not exist. So if the Big Bang was some sort of super nova then we would expect that these heavier elements would have been in great abundance in the early universe, and astronomers would see evidence of them in the spectra of the oldest stars, but they don't.
2. Size. No nova, no matter how large, comes within many many orders of magnitude of the Big Bang. There is no known mechanism that would allow a single star to grow to the magnitude of the entire universe, and then nova.
