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by dotnet00 773 days ago
The observable universe has a size, the cosmic microwave background is what we 'see' at the 'edge' in terms of photons (~400k years after the big bang). We could see further if we could map out the gravitational wave or neutrino backgrounds (1 sec after the big bang).

But for now we can't really say if the universe in its entirety has a finite size.
1 comments
mvkel 773 days ago
Fascinating. Do you think it's possible that we can map these out in the next 50 years?
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dotnet00 773 days ago
For the gravitational wave background, maybe with LISA we might be able to get a glimpse, but the neutrino background seems like it'd take some truly unprecedented breakthroughs in our ability to detect neutrinos to have any chance of mapping it out.
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mvkel 773 days ago
Funny, in reading up on both, I had higher hopes for the gravitational waves.

It seems like GWB is a superposition of infinite overlapping waves that would be impossible to single out and "unwind" in order to form a map.

And big bang neutrinos are very weak, which makes them undetectable. My assumption was we'd need a breakthrough in measurement sensitivity but is there more to it?

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datameta 773 days ago
Naive thought - can a subsurface detector on the moon serve as an ultracold shielded scenario?
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