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It's Official: For The First Time Neutrinos Have Been Detected in a Collider Experiment
(www.sciencealert.com)
this post was submitted on 28 Sep 2023
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Physics
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Light hits matter, causing it to get blocked. This is super convenient for seeing things, but super inconvenient for seeing through things.
The early universe was super dense and light couldn't escape it. However, at some point it got cool and sparse enough that nutrinos could. If we could detect those nutrinos from the early universe we could learn things about what the universe was like in the early part of the big bang.
The CNB (Cosmic Neutrino Background), not to be confused with the CMB (Cosmic Microwave Background), composed of photons and which you mention in another reply further down this thread.
As neutrinos were able to liberate themselves in a straight line from the post-Big Bang pinball soup earlier than photons, the CNB would let us peek further back in time.
The holy grail would be the Cosmic Gravitational Background, basically the fading "GONNNNNG...!" of spacetime ripples created at the Big Bang itself, as if it was a bell that was struck.
This summer the detection of low-frequency gravitational waves was announced, and while that's about "a" gravitational background, it's not "THE" Gravitational Background, by which I mean not the one from the Big Bang itself.
Could it also help us determine a more accurate age of the universe?
Probably but I'm not sure.
Right now we use stuff like the expansion rate of the universe and what we know about how stars develop and as far as I'm aware those are pretty roughly accurate already.
Like, we can see the haze of the CMBR, which was "only" thought to be about half a million years after the big bang, so that's pretty darn good when we're talking about a universe that is though to be 13 billion years old. (We already see back like 99.99 percent the age of the universe)
So I'm guessing this wouldn't be a big deal for how old the universe is unless there is a big new discovery about that early universe that contracts what we know (which to be fair will probably happen).