Ask Ethan #75: How can we still see the Big Bang? (Synopsis)

“We like to admit to only that which already glows, although it is nobler to support brightness before it glows, not afterwards.” -Dejan Stojanovic

When we look back to greater and greater distances in the Universe, we're looking back to earlier and earlier times as well. At some point, we can see far enough back that we reach the location at which the Universe cooled enough to first form stable, neutral atoms.

Image credit: NASA / CXC / M.Weiss. Image credit: NASA / CXC / M.Weiss.

But this is no nearby location: it's presently located some 45.3 billion light-years away! All the stars, galaxies, clusters and gas clouds that we see that are closer than that had the leftover light that was released as the cosmic microwave background pass us by ages and ages ago.

Image credit: Wikimedia Commons user Unmismoobjetivo; of a logarithmic view of the Universe as centered on the Earth. Image credit: Wikimedia Commons user Unmismoobjetivo; of a logarithmic view of the Universe as centered on the Earth.

So what does it mean that the cosmic microwave background -- the leftover glow from the Big Bang -- is still visible to us today? Find out on this week's Ask Ethan!

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Thanks for a great article answering my question. I'd been pondering the issue for a while, but keep hitting a logical inconsistency on it after researching multiple sources implying a universe inflated to the size of a grapefruit at the time of the CMB radiation release. (Probably a misinterpretation on my part, or perhaps they were implying that the area of space we now see as our current "visible" universe was potentially that size at the time of the release?)

By Joseph McFarland (not verified) on 18 Feb 2015 #permalink

New data Planck: the stars and galaxies were formed almost at the same time ~ 13.2 billions years ago!!!
, something is wrong with the current BB model...

Really? Do you have any research results, or are we to take your word for it, and that it consisted solely of that claim?

I don't assume this will get responded to since this is a two month old post, but I was wondering: What would it mean if we stopped seeing the CMB, either in a particular region of space or in all directions?