# What was the Singularity point before the Big Bang?

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I know that it was a very very very small and dense point... but what it contained? Where there any kind of a very small particles moving inside? Or was it all "frozen"?

If there where moving particles (of any kind) inside the singularity point, then it means that there was also time inside, no?

Just trying to understand.

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A singularity is mathematical term; it means that the theory produces infinities at that point. So by naively extrapolating backwards using GR you get to a zero sized point containing all the mass and energy of the universe. As it would be zero size there could be no movement.

It does not represent physical reality. Our current physics can only take us back to a fraction of a second after the big bang. A future theory that includes quantum theory might tell us more (some attempts at this suggest that the universe may be infinitely old, for example).

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1 hour ago, Blind Watchmaker said:

I know that it was a very, very, very, small and dense point... but what it contained?

I don't believe we know it was a "point."  It could have started from any shape or size.  A universe of infinite size also started out as infinite in size.

Edited by Airbrush

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29 minutes ago, Airbrush said:

I don't believe we know it was a "point."  It could have started from any shape or size.  A universe of infinite size also started out as infinite in size.

It is true that singularities do not have to be a point. But I think in the case of the universe it does. (As always, I may be wrong!)

An infinite universe would still have started out as a (zero-size) singularity.

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The point is the observable universe portion as you extrapolate expansion backwards. It is the region of shared causality with our current observable universe.

In the case of an infinite universe each region of shared causality would extrapolate to different points.

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3 hours ago, Strange said:

An infinite universe would still have started out as a (zero-size) singularity.

My question is how does a zero-sized singularity grow to an infinite size?

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Quote

before the Big Bang

The above is a meaningless concept.
As an analogy (and analogy only), imagine you start from wherever you live and begin walking north. You walk and walk, and your map/GPS will continue to guide you north. Eventually though you reach the North Pole - and what happens then? No matter which direction you turn to, you will always face south. The concept of “north” has lost its meaning. There is no north of the North Pole.

The Big Bang is somewhat similar, you can think of it as a “pole in time” - if you somehow magically had a time machine, you could travel further and further back in time, until eventually you reach the BB. At that instant though, no matter how you configured your time machine, you would find that the only direction you can travel into is the future. At the Big Bang, the concept of “past” is meaningless.

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12 hours ago, Airbrush said:

My question is how does a zero-sized singularity grow to an infinite size?

I don’t see going from zero to some finite size any more or less implausible than infinite size. Mathematically it is the same thing. (And physically it is pretty meaningless.)

Although, given Mordred’s comment above, it may not be relevant.

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