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I have a simple question which I think about often but have no answer.

If The Big Bang is true, than if the whole space was just a point 14 billion years ago, then what was around that point, some other kind of "space" or nothing? In latter case how do we define nothing.

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This is a common question that comes up - one I've (at least tried to) answer a few times.

Let's try to understand what the Big Bang is. The Big Bang Theory is a model, and scientists came up with it when they observed the universe expanding - and thought that since the universe is now expanding it must have been smaller in the past. Running the clock backwards eventually means all of the universe was squeezed into a "singularity". Our physical models of the universe break down at this point - so we are not too sure of what the universe was like at the Big Bang.

Notice that I said the universe was squeezed into a singularity - not the stuff inside the universe. This means space-time was also compressed into a single point. The universe is not expanding out into empty space - it is space-time itself that is expanding. Hence, there was no "before" the Big Bang - time (as well as space) was created when the Big Bang happened. There is no outside the universe! This means there is no outside the Big Bang!

You can't go back in time and watch the Big Bang - since there is no universe or space (or time) outside the singularity. This can be very confusing, but I hope this helps!

For a few places to look for more info:

https://en.wikipedia.org/wiki/Planck_epoch

https://en.wikipedia.org/wiki/Big_Bang#Singularity

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  • $\begingroup$ Base on what you are saying, space and time are limited. What will happen if I travel to the edge of the universe and shoot a laser beam from there? Will, it hit a wall? Will it increase the universe's space/time? Is your answer to this question remains the same in all times? $\endgroup$ Nov 30 '20 at 18:29
  • $\begingroup$ @IlyaGazman Space and time are to be considered the same thing, your hypothetical assumes they are not, basically, space expands with time (at the speed of light) so you would never be able to reach the "edge" of the universe with anything in this context since the edge of the universe is defined by itself, so hypothetically if you were at the edge and shot a laser, your laser would just be like a surfer riding a wave, as it is going at the same speed as the edge $\endgroup$
    – Tofandel
    Apr 15 at 12:17

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