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1

Actually there is a geometry that describes something like the naive idea of the Big Bang. But it's a bit of a cheat because it's really just a piece of the usual expanding universe metric. The first metric suggested to describe a collapsing star was the Oppenheimer-Snyder metric, which describes a spherical ball of dust collapsing under its own gravity. ...


1

What would happen if you were to release the energies of the big bang in our universe a second time? Have a look at this standard history of the universe, History of the Universe - gravitational waves are hypothesized to arise from cosmic inflation, an expansion just after the Big Bang Our universe is now at the far right. Note the beginning ...


-1

The answer to your first question can be answered regardless of your misunderstanding of Big Bang. The time passing before atoms begin to form is 379,000 years, which is the time it took for the temperature to drop sufficiently for atoms not to be constantly ionized. – pela, in a comment.


1

Pulling together what's been said in various comments: 1) General relativity admits models where spacetime is foliated by spacelike leaves, all of which are indexed by a global time coordinate. The simplest of these models is Minkowski space. All of your observations about models with comoving observers apply equally well to Minkowski space, so if you ...


2

Suppose two observers, Alice and Bob, are moving relative to each other since the beginning of the universe. While they do it, they construct the chronologies of all the events of the universe, as they record them in their frame of reference. They will construct different chronologies. However, and this is key, each can reconstruct the other's chronology. ...


2

A comoving observer and an observer that has been moving at $0.866c$ since Big Bang will disagree on their measured age of the Universe by a factor of 2. While both measurements are correct, we can say that the comoving observer measures a more "natural" age of the Universe. For instance, the comoving observer is the only observer who will measure the ...


1

Philo's answer is spot on, and I'll basically be rephrasing it here into a form that makes more sense to me. Hopefully it will help some others as well. Rather than only dialing back the clock 1B years, let's go waaaay back and see what things look like: we go back 13.82B years and look out into space... And there's no space! The universe is very ...


2

We cannot see anything closer than 380,000 years after the big bang because that is when radiation and matter decoupled. The CMB is a picture of what the universe looked like at that point. All clumping of matter into stars, galaxies, etc has occurred since then. If we had looked 1 billion years ago, we would see the same except that the CMB temperature ...


3

In a static universe it would indeed be true that if you looked at an object, say, 10 billion light years away you would be looking at it as it had been 10 billion years ago. This isn't really an application of special relativity and is merely a consequence of a finite speed of light. Our universe, however, is expanding and so you can actually see across ...


4

Why is the gravitational constant.. constant? We don't actually know that it is. Check out the Dirac Large Numbers hypothesis: "According to Dirac's hypothesis, the apparent equivalence of these ratios might not be a mere coincidence but instead could imply a cosmology with these unusual features: The strength of gravity, as represented by the ...


0

It's hard to see how gravitational repulsion between matter and antimatter would do any of those things, (1) because gravity is weak, and (2) because matter and antimatter are intermixed in the early universe, so the matter-antimatter repulsion would be competing with matter-matter attraction and antimatter-antimatter attraction.


14

Free neutrons can be generated by spallation reactions between cosmic rays and heavy metal targets. Such processes do occur in the cosmos. The free neutrons will then beta decay to yield protons (hydrogen nuclei) and electrons. This is a weak reaction, so the protons produced here were not present shortly after the big bang. So not all hydrogen atoms ...


1

Semantics is wrong in more than one way. First of all, there is no "first" without time, and time only exists in the universe, so the question is not well posed. If there was something before the big bang, then both are a part of the same "universe/multiverse" for which common laws must hold (you can't just discretely switch laws all of the sudden - and if ...


0

The "laws" we have found allow to predict how the "universe" manifests itself (including a concrete concept of universe) are nowhere to be found other than our social interactions as agents. They are in no way in the same phenomenological level than, well, actual observable phenomena (what you call the universe). You can see this hierarchy in the fact that ...


6

This is a metaphysical/philosophical question, imo. There is the platonic ideals school, in this case read for ideals=mathematics, which postulated that ideals existed and nature fell into their form. I have seen a number of theoretically inclined people who are really of that school. One does not have to think of the beginning of the universe to start ...


0

Closely related to your question is that of whether mathematics is discovered or invented. If it is discovered, where does it "live"? Also relevant might be the view of Tegmark on the Mathematical Universe Hypothesis Where he posits that everything is "made of mathematics" and that the physical world is just one such instantiation out of a possible ...


8

I believe a great answer to your question is: We don't know We still can't resolve the time before electroweak interactions, so how can we even come close to answering this question? You might get answers from some theories (or I prefer to call them theorems because they're only math until today) like string theory or loop quantum gravity or M-theory or ...


3

As far as I understand, Physics is not able to awnser this question, because the physical laws we use to describe the Universe are not valid up to the exact event of the Big Bang (the Big Bang is said to be a singularity of spacetime). Physics attempts to describe the Universe at a moment when it already existed, but does not states causes for its existence ...



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