The Curvature of Space-Time and the Big Bang Theory

[exponent137]

Hi
We know that our universe is closed and that outside of our universeis no space, neither empty space. So, space is only where matter is. There are also other arguments that space is always connected with matter.
What are the main arguments that space does not exist outside our universe as connected with bing-bang and general relativity?

 

[ZikZak]

We don't know that the universe is closed at all. The data ar consistent with the universe being either open, flat, or closed.

The universe is all of spacetime. The phrase "outside of the universe" does not refer to any place or event in spacetime, and so your question is a nonsense question. I could ask you to tell me what color the grass is north of the north pole, and it would make just as much sense.

 

[exponent137]

Let us assume that space is closed.
I believe you about grass on north poll. I believe in this theory.
But I think that these theories have some deeper arguments than this one. So I ask for these arguments?

Additional conclusion is also, where is no matter is no space. So this is an interesting question for me.

 

[Nabeshin]

So, space is only where matter is.

Have you ever heard of a vacuum? I understand what you're trying to characterize with a statement like this, but it's simply not true. ZikZak's statement that "The universe is all of spacetime" is much better, and you should think of the universe as being defined to be all that is. Of course, this precludes multiverse theories, but it's certainly a good enough starting point for a discussion.

In this framework, the main argument for no spacetime outside our universe were if there existed such spacetime, it would [by definition] be in our universe. That's not very satisfying but if you think about it for a while it might start to make a little bit more sense to you. Another argument which applies much more generally is that we have no evidence to support the fact that there is anything else [other than the space we know]. Why assume the existence of something when we don't have to? Here's an interesting quote which is somewhat related but jumps into my head, from Hawking's book "A Brief History of Time":

A well-known scientist (some say it was Bertrand Russell) once gave a public lecture on astronomy. He described how the Earth orbits around the sun and how the sun, in turn, orbits around the center of a vast collection of stars called our galaxy. At the end of the lecture, a little old lady at the back of the room got up and said: "What you have told us is rubbish. The world is really a flat plate supported on the back of a giant tortoise." The scientist gave a superior smile before replying, "What is the tortoise standing on?" "You're very clever, young man, very clever", said the old lady. "But it's turtles all the way down!"

 

[exponent137]

I will ask a little differently. Is it possible to put curved 4D space-time in 4D flat space -time?

For instance, let us assume that light travel at infinite speed (or much larger speed). This means that its path is not curved, when it travels close to the sun. Of course, so the definition of time becomes elusive (but let us ignore this). So, is it possible in this case to prolong space out of our universe?

Is it possible to put a black hole in a flat space time, but to say that observer inside or close to the black hole feel different times dilatations and different distances than before, and those are connected with labels in space time before black hole originated in this space-time.

Othewise, this question about general relativity is unclear to me. This is only a question for imagination of general relativity, not for changing it.

 

[Laidback]

I will ask a little differently. Is it possible to put curved 4D space-time in 4D flat space -time?

For instance, let us assume that light travel at infinite speed (or much larger speed). This means that its path is not curved, when it travels close to the sun. Of course, so the definition of time becomes elusive (but let us ignore this). So, is it possible in this case to prolong space out of our universe?

Is it possible to put a black hole in a flat space time, but to say that observer inside or close to the black hole feel different times dilatation's and different distances than before, and those are connected with labels in space time before black hole originated in this space-time.

Otherwise, this question about general relativity is unclear to me. This is only a question for imagination of general relativity, not for changing it.

If you are after facts, this thread won't get you anywhere...

If you don't have access to a subscribed encyclopedia try wikipedia, as its almost as good..

Cheers,

Pete..

 

[DaveC426913]

I will ask a little differently. Is it possible to put curved 4D space-time in 4D flat space -time?

This makes no sense.

For instance, let us assume that light travel at infinite speed (or much larger speed). This means that its path is not curved, when it travels close to the sun.

Infinite is silly. Even if much larger, the fact that it curves verfy little doesn't mean space-time is less curved.