Time from the origin of universe

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Discussion Overview

The discussion revolves around the nature of spacetime at the origin of the universe, particularly in relation to the Big Bang and inflation. Participants explore whether spacetime has been constant throughout the universe or if it breaks down at certain points, especially near the Big Bang. The conversation touches on concepts of time dilation, the conditions of the early universe, and the implications of black holes.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions if there are specific points in space today where inflation originated, suggesting a curiosity about the relationship between spacetime and dark energy.
  • Another participant asserts that the Big Bang is not a singular point but rather an event that occurred everywhere, proposing that the universe was infinite from the beginning.
  • Concerns are raised about time dilation, with a participant asking if it is only applicable under special relativity, while others clarify that general relativity also accounts for time dilation.
  • There is a discussion about the nature of spacetime consistency for objects at rest and moving, with some arguing that all observers agree on events but not on their timing or location.
  • One participant expresses confusion about the size of the universe shortly after the Big Bang, suggesting a misunderstanding of different models of the universe's expansion.
  • A later reply introduces the idea that the energy density of the early universe may have varied across different regions, leading to inflation in some areas but not others, emphasizing the chaotic initial conditions of the inflaton field.
  • Gravitational time dilation is mentioned as a significant factor in general relativity, affecting observers in different gravitational potentials.
  • Concerns about singularities are raised, with a participant noting that they are generally not considered physical by physicists, suggesting that quantum gravity may play a role before singularities form.

Areas of Agreement / Disagreement

Participants express various viewpoints on the nature of spacetime and the Big Bang, with no consensus reached on whether spacetime is consistent everywhere or if it breaks down at certain points. Multiple competing views remain regarding the implications of inflation and time dilation.

Contextual Notes

Participants highlight limitations in understanding the early universe, particularly regarding the definitions of time dilation in different contexts and the implications of singularities in black holes. There is also a noted confusion about the size of the universe shortly after the Big Bang, indicating a need for clarity on different models.

emc2cracker
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I have a question for the bright minds here. I have often wondered if spacetime has been constant thoughout the universe or if there are places where spacetime breaks down. One of these points I often imagine about is the very origin point of the Big Bang. Does anyone know of any papers addressing this question or have any input?

Basically I am wondering if the age of the universe would be the same at all points in space, in particular from the very origin of the inflation. In my imagination this point seems a likely spot for the source of dark energy, and I often wonder if I could build a spaceship and fly to one of these points of inflation or dark energy would time exist there as we know it?
 
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Big Bang is not a point, it is EVERYWHERE. If Universe is infinite now, then it was infinite from the very beginning, and Big Bang was also infinite.

The age of the Universe (13.7 b y) is maximum proper time - for all objects at rest to CMB - this is true for all objects we see. However, for, say, very high speed particle the proper time from the Big Bang can be much shorter.
 
Yes I know everything was in that little space and there was no outside... but wouldn't there be a point in space today where the inflation started from?

And as far as you know the only time dilation possible is under special relativity? Spacetime is consistent for all objects at rest no matter where they are? I would think if there are literally holes in spacetime inside of black holes then there time would not exist at all at least?

Maybe someone can dumb this down for me on the infinite from the beginning part its hard to imagine that even for me lol. I was under the impression that the universe 1 trillionth of a second after the big bang would have been the size of a softball? Are there two different models I am thinking of here?

Thank you very much dmitry and everyone, I don't know what I would do to satisfy my curiosity without this place!
 
emc2cracker said:
1 but wouldn't there be a point in space today where the inflation started from?

2 And as far as you know the only time dilation possible is under special relativity?

3 Spacetime is consistent for all objects at rest no matter where they are?

4 I would think if there are literally holes in spacetime inside of black holes then there time would not exist at all at least?

5 I was under the impression that the universe 1 trillionth of a second after the big bang would have been the size of a softball?

1 no, all points are equal.
2 'only'? what do you mean? SR is a particular case of GR, so there is time dilation in GR as well
3 Spacetime is consistent for all objects - at rest and not at rest. They all agree on if some event happened or not - they just don't agree on when and where.
4 No. Except for singularities (and future theory will definitely get rid of them) everyhting is smooth, even inside the black holes
5 This is about the radius of VISIBLE universe.
 
I agree, thanks that makes perfect sense. If anyone has anything to add I'm all ears and taking notes :)

So Gerald Schroeder is just a quack, I thought so I didn't find one published paper on that guy.
 
If I could add a little...

1. Perhaps. In the early universe just after the big bang, the energy density of the universe could have taken on different values at different points in space. The inflaton is typically believed to have had chaotic initial conditions, so that in many places in the universe the conditions weren't right for inflation. However, in some patch of spacetime, the conditions were just right (spacetime was sufficiently smooth and the inflaton field dominated the local energy density). This patch inflated and became our entire observable universe (and probably then some). So, in a sense, inflation did occur in perhaps a small region of spacetime (not a point, though).

2. Gravitational time dilation is unique to general relativity and is very important cosmologically. Time is dilated for observers in gravitational potential wells relative to those in free space.

4. There's little use in talking about singularities. No physicists believes them to be physical. It is instead believed that quantum gravity becomes relevant before such a singularity forms physically.
 

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