I Before the Big Bang

[Jaime Rudas]

TL;DR Summary

Did time and space exist before the Big Bang?

The article Where did the Big Bang happen? states:

According to standard cosmological models, which are based on general relativity and are found to agree well with observations, time and space did not exist before the Big Bang

Is this really the case?
Wouldn't it be more correct to say that the current consensus cosmological model is unable to describe anything that happened before, for example, the Planck time?

 

[DaveC426913]

TL;DR Summary: Did time and space exist before the Big Bang?

The article Where did the Big Bang happen? states:

Is this really the case?
Wouldn't it be more correct to say that the current consensus cosmological model is unable to describe anything that happened before, for example, the Planck time?

I believe the idea is that space-time was created by the Big Bang.

No BB = no space and no time.

 

[phyzguy]

One possibility, known as the Hartle-Hawking no boundary proposal, is that if you go backward in time towards the big bang, you reach a point where space and time cease to exist. In this proposal, asking, "What was there before the big bang?" is similar to asking "What is north of the north pole?"

Here's a Wikipedia link: https://en.wikipedia.org/wiki/Hartle–Hawking_state

 

[phinds]

TL;DR Summary: Did time and space exist before the Big Bang?

Wouldn't it be more correct to say that the current consensus cosmological model is unable to describe anything that happened before, for example, the Planck time?

I agree that that's the case but I'm not an expert.

 

[Jaime Rudas]

I believe the idea is that space-time was created by the Big Bang.

No BB = no space and no time.

One possibility, known as the Hartle-Hawking no boundary proposal, is that if you go backward in time towards the big bang, you reach a point where space and time cease to exist. In this proposal, asking, "What was there before the big bang?" is similar to asking "What is north of the north pole?"

Here's a Wikipedia link: https://en.wikipedia.org/wiki/Hartle–Hawking_state

It seems to me that, according to these two hypotheses, time was created in the Big Bang. Which makes me realize that saying that time did not exist before the Big Bang is, in fact, an oxymoron because if there was no time, there could not have been a before.

 

[Jaime Rudas]

"What is north of the north pole?"

Polaris?

 

[DaveC426913]

saying that time did not exist before the Big Bang is, in fact, an oxymoron because if there was no time, there could not have been a before.

I disagree. It certainly wouldn't have been anything like we understand it, but that doesn't mean it couldn't exist.

 

[PeterDonis]

if there was no time, there could not have been a before.

In Hawking's "no boundary" model, the portion of the model "before" the initial time (which is shaped, heuristically, like a hemisphere, so there's no singularity anywhere, and it joins to the initial time spacelike hypersurface smoothly) is purely spacelike; that's why there's no "time" there. But it is "before" the initial time in the sense that it's not at that time or any later time. "Before" might not be the best ordinary language word to capture the math, but the math itself is consistent, although counterintuitive.