Did the Big Bang create space and time?

[Lunct]

As I understand it Georges Lemaître, upon learning about Hubble's discovery that space is expanding, came up with the big bang theory. He thought that if space is getting bigger, then it must have been smaller at one point, and if you go back far enough you get an extremely dense singularity. From this, all we would know is that the universe was once in a singularity, then expanded into the universe as we know it. So then why do people say that the big bang created space and time? How would we know this? And wouldn't this also imply that it created all matter and energy, because how could they exist with no space and time, unless they are in some other dimension separate from space and time? So did the Big Bang create energy and matter?

I understand that this question is probably breaking the bounds of physics, and entering into the territory of broader philosophy.

 

[phinds]

The "Big Bang Theory" is silent on what happened at the point you get to if you extrapolate time backwards, and only starts after the Inflation Era.

 

[Lunct]

The "Big Bang Theory" is silent on what happened at the point you get to if you extrapolate time backwards, and only starts after the Inflation Era.

So it would not assert that space and time were created?

 

[phinds]

So it would not assert that space and time were created?

The formal BB Theory does not, no, but there is great speculation as to just what was going on, just no evidence to support any theory.

 

[Lunct]

The formal BB Theory does not, no, but there is great speculation as to just what was going on, just no evidence to support any theory.

okay thanks that makes sense

 

[alantheastronomer]

The expansion of the universe implies that there was a point at which space began, as you point out. Since space and time are connected, as relativity shows, into spacetime, it's inferred that time also begins at the moment of the big bang.

 

[phinds]

The expansion of the universe implies that there was a point at which space began, as you point out. Since space and time are connected, as relativity shows, into spacetime, it's inferred that time also begins at the moment of the big bang.

That's just speculation and is not part of the Big Bang Theory.

 

[Dr. Courtney]

Do interpretations that space and time were created at the instant of the Big Bang make testable predictions that are different from interpretations that they were not created?

If not, these interpretations are not really science - just speculation. Real science assertions need to make testable predictions that are different from competing or opposing assertions.

 

[PeterDonis]

if you go back far enough you get an extremely dense singularity. From this, all we would know is that the universe was once in a singularity

It's important to realize that Lemaitre's original model, which had an "initial singularity" in it, is not the current model that cosmologists actually use. It's not just that refinements have been added as to the detailed expansion history of the universe; it's that the presence of the initial singularity is now viewed as an indication that the model is just an idealization, and stops being valid at some point as you go back in time. Our best current model uses the term "Big Bang" to denote, not the idealized "initial singularity", but the hot, dense, rapidly expanding state that is th earliest state of the universe for which we have good evidence. In models that include an inflation phase, the "Big Bang" state is the state at the end of inflation.

why do people say that the big bang created space and time?

In the idealized model in which there is an initial singularity, there is no space or time before that; so in that sense, in the idealized model, space and time are "created" at the initial singularity. But people who refer to this probably don't realize that that idealized model is not the one that cosmologists actually use.

 

[Lunct]

Thank you for all the replies, you have cleared things up.