Does Godel's Rotating Universe Theory Suggest Time Repeats Itself?

[BadgerBadger92]

TL;DR

I have been reading about "Godel's Rotating Universe," and had a question, I don't think I fully get it.

Mainly, does this mean that time repeats itself?

Also, can someone put in simple terms what this theory is all about?

I have been reading about "Godel's Rotating Universe," and had a question, I don't think I fully get it.

Mainly, does this mean that time repeats itself?

Also, can someone put in simple terms what this theory is all about?

 

[PeterDonis]

Moderator's note: Thread level changed to "B".

 

[PeterDonis]

I have been reading about "Godel's Rotating Universe,"

Where? Please give a specific reference.

does this mean that time repeats itself?

I'm not sure what you mean by "time repeats itself", but the experience of an observer following one of the closed timelike curves in Godel's universe would be of a series of events of finite length in time by his clock, repeated endlessly.

can someone put in simple terms what this theory is all about?

The most important thing about Godel's universe is that it is not a model of our actual universe. It is a mathematical model which is a possible solution of the Einstein Field Equation, but that solution does not describe anything like our actual universe. Godel constructed the model in order to investigate what kinds of mathematical models were possible in General Relativity, and in particular whether models could be found that had closed timelike curves.

 

[BadgerBadger92]

Sorry for such a noob question, I am not educated in this field. I have been reading about it in numerous websites and am still confused.

Mainly what I am asking is does time repeat itself, in that all the same events happen over and over again?

Please reply, I am trying to learn more about Godel.

 

[PeterDonis]

I have been reading about it in numerous websites

As I said before, please give specific references. And be aware that "websites" are generally not good sources if you actually want to understand the physics. That is going to be particularly true for a case like the Godel universe, which has a number of highly counterintuitive properties.

does time repeat itself, in that all the same events happen over and over again?

Again, this question is too vague. I have described what happens along a single closed timelike curve in the Godel universe. But not all observers in that universe are limited to traveling on such closed timelike curves, and the set of events in the universe as a whole is still infinite; there is no finite set of events (more precisely, set of events occupying a finite time by any observer's clock) that all observers are limited to experiencing.

 

[BadgerBadger92]

What is a good book I can get on the rotating universe and timelike curves? Preferably one that is more accessible to someone like me. I would like a trustable source.

 

[PeterDonis]

What is a good book I can get on the rotating universe and timelike curves?

I don't know that there is one at the beginner level. The Godel universe is a rather advanced solution and the only treatments I know of in books are those in advanced textbooks.

It might help to know why you are interested. What is it that you want to learn about the Godel universe?

 

[BadgerBadger92]

I am autodidactic, and don't have much money for schooling.

So you are implying that Godel's universe is an prediction that is a possible solution to Einstein's gravitational field equations? If it were true, does this mean the universe, simply put, rotates? Is this built on the idea that many things in our universe rotate? (Planets, stars, galaxies, etc) And what is the connection between this rotating universe and closed time like curves? I just want a simple explanation, which may not be possible, but I am interested in this topic.

 

[PeterDonis]

So you are implying that Godel's universe is an prediction that is a possible solution to Einstein's gravitational field equations?

I'm not implying it, I'm stating it.

does this mean the universe, simply put, rotates?

With a suitable interpretation of "the universe rotates", yes.

Is this built on the idea that many things in our universe rotate?

No. As I said, the Godel universe does not describe anything like our actual universe. For one thing, the "rate of rotation" is the same everywhere in the Godel universe.

what is the connection between this rotating universe and closed time like curves? I just want a simple explanation, which may not be possible

Unfortunately I don't know of any simple explanation of the connection you are asking about, if indeed there is one.

 

[BadgerBadger92]

Thanks, this helps a lot. I guess my main question is Godel's prediction and it's connection to time. I guess I need to get started on math.

 

[PeterDonis]

I just want a simple explanation

One highly heuristic way of viewing the Godel universe is as a variation on the theme of the Einstein static universe. In the Einstein static universe, there is a positive density of matter and a positive cosmological constant, and the two are precisely matched so that the attractive gravity of the matter exactly cancels the repulsive gravity of the cosmological constant, so the universe remains static.

In the Godel universe, on the other hand, there is a positive density of matter and a negative cosmological constant. So there is attractive gravity from both the matter and the cosmological constant, which exactly balances the centrifugal effect of the rotation. Because rotation is present, the Godel universe is not static, but it is stationary (the rate of rotation is the same everywhere and at all times), and there is a family of observers who remain stationary at all times (but they rotate about each other--this is one of the ways of interpreting the statement that "the universe is rotating" in this solution).

 

[Herman Trivilino]

I am autodidactic, and don't have much money for schooling.

Start with the Wikipedia page on world line.