Message from @Alphonsus
Discord ID: 444890578518278164
So is this infinity in concern to the passing of time or is it everything?
Infinity, being never ending, not expanding either. So this particular infinity deals with all of creation which is guided and defined by time.
No infinity has not at all been discredited by physicists
I never said all of them.
I simply gave examples where it has been.
Where?
George Lemaitre, one of the theorists behind the theory of the big bang, seen here.
You realize even the most basic calculus relies on infinities
Almost every branch of physics that we even study in undergrad has infinities within the theory
Infinity in theory or infinity in practice? That is, infinity for hypothesis, or infinity with regards to metaphysics?
That question doesn’t really make sense
And I'm not colluding the two, I'm simply saying is infinity being used for theoretical purposes or for actual explanations of the natural world?
Help me understand as you do.
Actual explanations
GR is the best example
It requires no discrete lengths in space or time basically so that you can for any given curvature in space create a locally “flat” thing called a spacetime metric
To do that the world has to be continuous in time and space, so infinitely divisible
It’s really analogous with epsilon delta I think it’s callled from calculus one. Which is why infinities are also required there
I understand the necessity of it, but I fail to see how this correlates with infinity with regards to creation? While I certainly hold no credentials, and that should be apparent, how does this figure into the Lemaitre-Tolman-Bondi model?
I mean how can accelerated expansion be believed in an infinite understanding?
Let me look that up tbh I haven’t heard of it. Are you saying howncould they theorize that the universe expansion is accelerating indefinitely?
The expansion of the universe, and the theory of it, seem to contradict the idea of an infinite universe. I mean, how could infinity expand infinitely? That makes no sense.
Oh the ltb metric is inhomogenous which our universe isn’t
Again that's why I brought up Lemaitre and Edwin Hubble, that was their bread and butter
Yeah they are describing an inhomogenous universe which ours isn’t. But as for how infinity can expland that depends on a few things. We can pm about it if you want because my background is actually in GR and I feel like people here won’t really care
So the idea is that the universe is expanding at an accelerated rate flies in the face of the theory that the big bang is just an infinitely recurring event in the history of the universe, right?
Yes it does
An infinite universe can expand though
So is in inhomogeneous and also not isotropic?
Expansion means that the space between the points has become greater. Not that more “points” have been created. That’s one of the big confusing points in GR
Our universe is homogenous and isotropic
Oh I misread what you said my bad.
Meaning the average energy density is the same roughly everywhere, and the universe looks the same from wherever you are in it
So it would just keep expanding and never retract to the point where there is another big bang
I mean, I was taught, albeit in high school, that galaxies could be moving away from the Earth.
And that would just kind of never end?
Yes but it’s worth noting that most people don’t believe in the cyclical universe. And yes there are galaxies that move away from us due to expansion, and then there are some closer ones that move towards us regardless of expansion
The further away something is, the more the expansion has an effect. That’s why we have an “observable universe”. Beyond that point the space between us and objects there expands faster than light so we could never interact
I'm still not understanding how expansion of the universe can be at all possible when its infinite.
So what does that say about the state of the universe before the big bang?