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"Since we know that infinite densities cannot actually happen in the universe" How do we "know" that?
by davidgrenier 3y ago
"Since we know that infinite densities cannot actually happen in the universe"
How do we "know" that?
- vitehozonage 3y agoYeah, I stopped reading when i got to that sentence
- echelon 3y agoInfinity and singularity are mathematical constructs. They look great on paper, but we don't know if they have actual physical analogs. It could be that relativity and the physics around black holes, the big bang, etc. are wrong.
- vitehozonage 3y agoCould be true that there is nothing with infinite density. But it is certainly not known with certainty, so the statement is horribly wrong. >It could be that relativity and the physics around black holes, the big bang, etc. are wrong. Of course, that's almost certain
- bell-cot 3y ago> Infinity and singularity are mathematical... THIS. That I've seen, the [astro]physicists are confident that there are no actual physical infinities nor singularities. With the public, they'll use those terms for situations "approaching" infinities and singularities. But in private, they're busy using all sorts of clever mathematics and calculations and arguments to avoid having any infinity or singularity occur, even on paper. A very basic example: https://en.wikipedia.org/wiki/Dirac_delta_function#Motivation_and_overview https://en.wikipedia.org/wiki/Dirac_delta_function#Motivatio...
- dandare 3y agoAre you saying that we have evidence that universe is not infinite?
- swamp40 3y agoBecause we exist. If infinite density existed, our atoms would be in there.
- tomcatfish 3y ago(This is not sarcastic) How do we know we aren't?
- senttoschool 3y agoWell, there have been thoughts that we are living in a blackhole from another universe. So there's that. These questions aren't answerable at the moment. It's all just speculation.
- danra 3y agoNot true. For example we could be surrounded by a sphere of uniform infinite density, in which case our atoms wouldn't be pulled in either direction.
- zdragnar 3y agoFor those of us like myself who are terribly naive, why wouldn't that just cause all of the atoms to be torn apart? Unless the sphere were infinitely far away, only the center point would be in balance, and everything else would be immediately sucked to the edge of the sphere. If the sphere's radius was infinite, that might explain the expansion of the universe itself, but not the presence of infinite density within the universe itself.
- consilient 3y ago> Unless the sphere were infinitely far away, only the center point would be in balance This is false. https://en.wikipedia.org/wiki/Divergence_theorem https://en.wikipedia.org/wiki/Divergence_theorem
- Dylan16807 3y agoWhen you do the math for gravity inside a shell of material, the quadratic falloff exactly counteracts the distances and the total pull is exactly zero. https://en.wikipedia.org/wiki/Shell_theorem https://en.wikipedia.org/wiki/Shell_theorem