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The interesting thing about the universe is that it appears, as far as can be measured, to be flat. This implies that it’s either infinite or so large that if i

The interesting thing about the universe is that it appears, as far as can be measured, to be flat. This implies that it’s either infinite or so large that if it’s curved then we can’t detect the curve over 90 billion light years. Either way, the universe is unbelievably, vastly bigger even than the observable 90 billion light years we live in.

EMM_386 6y ago
What my mind fails to understand is, if the universe was infinite, how does that work with the "big bang" theory? Apparently the universe originally (somehow) began as a point of infinite density and expanded outward from this point. During this process, it would seem to need a defined size in order to be expanding at all. Even with the "blowing up a balloon" way of thinking of the universe, while the individual galaxies are growing further apart, the surface area is measurable (not infinite). I am likely thinking of this incorrectly but I can't fit "infinite size" in with "expanding universe" in my head. Unless these theories are incompatible, and to get infinite size you need the steady-state theory.
- yazantapuz 6y ago
  I think you should read this article "Misconceptions about the Big Bang": http://pages.erau.edu/~reynodb2/LineweaverDavis_BigBang_SciAm_March05p36.pdf http://pages.erau.edu/~reynodb2/LineweaverDavis_BigBang_SciA... The big bang was an "explosion" of space itself. There was not previously empty space.
  - EMM_386 6y ago
    > The big bang was an "explosion" of space itself. There was not previously empty space. I am very familiar with all of this. My question was merely around the opposing concepts of "expansion" and "infinite". Not infinite size AT the big bang. Infinite size of the current universe.
    - simonh 6y ago
      Technically I think yes, it may have a finite extent. If inflation theory is correct though, it will continue to inflate at extreme rates (if unevenly) for infinite time and so depending on how you think about infinity will have infinite extent in spacetime. On the other hand if Roger Penrose is correct about Conformal Cyclic Cosmology, and cosmic inflation is false, then ultimately the universe will reach a state where scale ceases to matter and it will become mathematically indistinguishable from a hot dense big bang again. https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology
- EA 6y ago
  Some shapes have finite volume and infinite surface area. https://en.m.wikipedia.org/wiki/Gabriel%27s_Horn https://en.m.wikipedia.org/wiki/Gabriel%27s_Horn
- thechao 6y ago
  The size of the universe is governed by an equation like this (this is pure analogy): D = d * (t - t0) Where “d” is space, “t” is “time” and “t0” is “the beginning”. Notice that when t=t0, we get a 0 term.
aortega 6y ago
But if we can only access, interact or see a bubble of 62 billion light years like the paper says, do the rest really exist for us?

EMM_386 6y ago

What my mind fails to understand is, if the universe was infinite, how does that work with the "big bang" theory? Apparently the universe originally (somehow) began as a point of infinite density and expanded outward from this point. During this process, it would seem to need a defined size in order to be expanding at all. Even with the "blowing up a balloon" way of thinking of the universe, while the individual galaxies are growing further apart, the surface area is measurable (not infinite). I am likely thinking of this incorrectly but I can't fit "infinite size" in with "expanding universe" in my head. Unless these theories are incompatible, and to get infinite size you need the steady-state theory.

yazantapuz 6y ago
I think you should read this article "Misconceptions about the Big Bang": http://pages.erau.edu/~reynodb2/LineweaverDavis_BigBang_SciAm_March05p36.pdf http://pages.erau.edu/~reynodb2/LineweaverDavis_BigBang_SciA... The big bang was an "explosion" of space itself. There was not previously empty space.
- EMM_386 6y ago
  > The big bang was an "explosion" of space itself. There was not previously empty space. I am very familiar with all of this. My question was merely around the opposing concepts of "expansion" and "infinite". Not infinite size AT the big bang. Infinite size of the current universe.
  - simonh 6y ago
    Technically I think yes, it may have a finite extent. If inflation theory is correct though, it will continue to inflate at extreme rates (if unevenly) for infinite time and so depending on how you think about infinity will have infinite extent in spacetime. On the other hand if Roger Penrose is correct about Conformal Cyclic Cosmology, and cosmic inflation is false, then ultimately the universe will reach a state where scale ceases to matter and it will become mathematically indistinguishable from a hot dense big bang again. https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology https://en.wikipedia.org/wiki/Conformal_cyclic_cosmology
EA 6y ago
Some shapes have finite volume and infinite surface area. https://en.m.wikipedia.org/wiki/Gabriel%27s_Horn https://en.m.wikipedia.org/wiki/Gabriel%27s_Horn
thechao 6y ago
The size of the universe is governed by an equation like this (this is pure analogy): D = d * (t - t0) Where “d” is space, “t” is “time” and “t0” is “the beginning”. Notice that when t=t0, we get a 0 term.

aortega 6y ago

But if we can only access, interact or see a bubble of 62 billion light years like the paper says, do the rest really exist for us?