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Could someone explain to a layman what is our best theory as to the limits of the universe as it pertains to the start of the big bang? How do we know the big b

by sak5sk 7y ago

Could someone explain to a layman what is our best theory as to the limits of the universe as it pertains to the start of the big bang? How do we know the big bang is not just a tiny spec in the middle of a giant ocean (similar to a supernova, but on a larger scale) that's part of something much much bigger? I am guessing it's just beyond our knowledge to figure out what lies beyond the big bang, but if that were true, wouldn't dark matter truly exist way before any big bang(s) took place?

sidcool 7y ago
The answer is that we don't know if big bang is a tiny spec in the entire universe. What we do know is that big bang is a huge deal in observable universe.
- sjwright 7y ago
  Definitely. Before the advent of telescopes and modern astronomy, we naturally assumed that the sun revolved around us because that's as far as we could physically (and cognitively) see. We were being egotistical to assume that the universe was here just for us. In a contemporary context, it would be similarly egotistical to assume that the whole of the universe began with the furthest event we puny humans are able to infer from our vantage point on this little speck of a planet. Context should teach us that we have no reason to assume that our local "big bang" is special or unique in any way. Just because we can't see or infer any further out (and we might never be able to) gives us no right to declare the big bang to be any sort of beginning.
philipov 7y ago
> How do we know the big bang is not just a tiny spec in the middle of a giant ocean This is referred to as the Cosmic Landscape, or, Eternal Inflation. In eternal inflation, the cosmological constant becomes a field in its own right, the Inflaton field, and our universe is a pocket of spacetime where that field has randomly adopted a value allowing nontrivial structure to form. https://en.wikipedia.org/wiki/Eternal_inflation https://en.wikipedia.org/wiki/Eternal_inflation The big problem is that science is based on repeatable experiments, and it's very difficult to make a theory of what happens outside the observable universe that can be tested even in principle. If a theory doesn't make falsifiable predictions, then it isn't science. Until someone comes up with a prediction that can be tested, one might as well ask, "How do we know the world wasn't created by God?" There are infinitely many things we don't know, the challenge is coming up with something we can know.
- hprotagonist 7y ago
  no debates from me here. i will add though that from “it’s not science” it does not necessarily follow that “and therefore it’s not useful.” the obvious example is that the idea of falsifiability as a criterion for what is and is not science is itself unfalsifiable — but very useful!
- sak5sk 7y ago
  Thanks for the explanation and the link!

by sak5sk 7y ago

sidcool 7y ago

The answer is that we don't know if big bang is a tiny spec in the entire universe. What we do know is that big bang is a huge deal in observable universe.

sjwright 7y ago
Definitely. Before the advent of telescopes and modern astronomy, we naturally assumed that the sun revolved around us because that's as far as we could physically (and cognitively) see. We were being egotistical to assume that the universe was here just for us. In a contemporary context, it would be similarly egotistical to assume that the whole of the universe began with the furthest event we puny humans are able to infer from our vantage point on this little speck of a planet. Context should teach us that we have no reason to assume that our local "big bang" is special or unique in any way. Just because we can't see or infer any further out (and we might never be able to) gives us no right to declare the big bang to be any sort of beginning.

philipov 7y ago

> How do we know the big bang is not just a tiny spec in the middle of a giant ocean This is referred to as the Cosmic Landscape, or, Eternal Inflation. In eternal inflation, the cosmological constant becomes a field in its own right, the Inflaton field, and our universe is a pocket of spacetime where that field has randomly adopted a value allowing nontrivial structure to form. https://en.wikipedia.org/wiki/Eternal_inflation https://en.wikipedia.org/wiki/Eternal_inflation The big problem is that science is based on repeatable experiments, and it's very difficult to make a theory of what happens outside the observable universe that can be tested even in principle. If a theory doesn't make falsifiable predictions, then it isn't science. Until someone comes up with a prediction that can be tested, one might as well ask, "How do we know the world wasn't created by God?" There are infinitely many things we don't know, the challenge is coming up with something we can know.

hprotagonist 7y ago
no debates from me here. i will add though that from “it’s not science” it does not necessarily follow that “and therefore it’s not useful.” the obvious example is that the idea of falsifiability as a criterion for what is and is not science is itself unfalsifiable — but very useful!
sak5sk 7y ago
Thanks for the explanation and the link!