Is the universe finite or infinite?

Is the universe finite or infinite?

  • I believe the universe encompasses a finite amount of space.

    Votes: 20 37.7%
  • I believe the universe has no end and it is infinite.

    Votes: 33 62.3%

  • Total voters
    53
Well, Newton's laws don't exactly govern everything. That's why we have quantum mechanics, which is basically a system of guessing, with the basis placed on Heisenberg's Uncertainty Principle. To put it simply, if we were to try to tell an electron to go somewhere using the laws of motion, it wouldn't go that way. So if Newton's laws are very difficult to apply to small things, I will return by saying it could be very difficult to apply to big things, like the universe. To me, the question is then harder to answer than that.
 
The theory of relativity and quantum physics breakdown at the point of a singularity. If the universe did start out as a singularity (which is where all the evidence points) then we have no idea how it would react. There are about 5 or 6 widely acknowledged theories, of what happened in the firts few fractions of a second after the universe started expanding. These theories concern the smoothness and the pressure in the early universe. They believe that right after it started expanding it couldn't have been perfectly smooth, yet when scientists have tested the x rays that come from all around us, they are perfectly equal in ALL directions. THIS IS WHY I THINK THE UNIVERSE IS NOT FLAT, BUT WHAT DO I KNOW.


Would time end after the universe starts to contract and eventually crunchs into what scientists call, the big crunch?

I mean, how could it? Atleast our definition of time doesn't allow for time to really end or begin. Because the definition of a beginning or and end of anything, is the end or the beginning for something else.

The concept of other universes doesn't seem very clear either. I mean, I think of EVERYTHING as being part of the universe. Including these "baby universes". Now Hawkings suggests that these "baby universes" (which are collapsed into singularity's right now) would/could have a completely different set of rules than our own universe. If they did have a completely different set of "laws" and also completely other dimensions (excluding or including space and time) then it would be impossible for both "universes" to exist, because then you'd theoretically be able to go into another universe that had completely different rules, and that just doesnt work. Hawkings, thinks that all of these universes operate according to their own individual set of laws. I am a bit unclear, on how he came to this conclusion.


I realize that steamy debates are for the REAL scientists on the verge of a breakthrough. We are all here to learn as much as possible. However, that might not be enough incentive for some people to join the topic, without anything to debate...oh, well.
 
Originally posted by 12sec. Civic
The theory of relativity and quantum physics breakdown at the point of a singularity. If the universe did start out as a singularity (which is where all the evidence points) then we have no idea how it would react. There are about 5 or 6 widely acknowledged theories, of what happened in the firts few fractions of a second after the universe started expanding. These theories concern the smoothness and the pressure in the early universe. They believe that right after it started expanding it couldn't have been perfectly smooth, yet when scientists have tested the x rays that come from all around us, they are perfectly equal in ALL directions. THIS IS WHY I THINK THE UNIVERSE IS NOT FLAT, BUT WHAT DO I KNOW.


Would time end after the universe starts to contract and eventually crunchs into what scientists call, the big crunch?

I mean, how could it? Atleast our definition of time doesn't allow for time to really end or begin. Because the definition of a beginning or and end of anything, is the end or the beginning for something else.

The concept of other universes doesn't seem very clear either. I mean, I think of EVERYTHING as being part of the universe. Including these "baby universes". Now Hawkings suggests that these "baby universes" (which are collapsed into singularity's right now) would/could have a completely different set of rules than our own universe. If they did have a completely different set of "laws" and also completely other dimensions (excluding or including space and time) then it would be impossible for both "universes" to exist, because then you'd theoretically be able to go into another universe that had completely different rules, and that just doesnt work. Hawkings, thinks that all of these universes operate according to their own individual set of laws. I am a bit unclear, on how he came to this conclusion.


I realize that steamy debates are for the REAL scientists on the verge of a breakthrough. We are all here to learn as much as possible. However, that might not be enough incentive for some people to join the topic, without anything to debate...oh, well.


im learning and i can join the topic, but i simply cant post so much at a time.......plus..........im already convinced the universe is fininte

Originally posted by Shadow
the universe is finite because i said so!!!:P

see?
 
I mean, how could it? Atleast our definition of time doesn't allow for time to really end or begin. Because the definition of a beginning or and end of anything, is the end or the beginning for something else.

How things change over a decade!

Here is Lawrence Krauss discussing (among other things), how time may not have existed before the Big Bang.

Makes sense to me that since physical dimension (which we use to describe space) had a beginning at the instant of the Bang, then Time, which is inextricably linked to Space, probably did too.

 
I can't fathom either without my brain hurting. I'd like to think infinite because I can't imagine anything outside of the universe. But who knows.
 
I really don't see how it's possible to have an infinite amount of space. Perhaps it's so big that it only seems infinite.
 
I don't know and I have no rush to know it.


I tend to believe that the universe had a begining of some sort. I'd like to read Krauss's book for instance (it looks to me a beautiful and intriguing idea). The idea of a infinite universe raises a lot of problems.
But I would be happy with any of the two possibilities.

Both would be marvellous.


ps: On a more personal perspective, it's finite. I'll be death in a few decades so... ^^
 
Two very good reads are

Krauss - A Universe From Nothing, and
Guth - The Inflationary Universe.

From the research behind these, the universe is bounded, and expanding. Way back, a zillionth of a second after the Big Bang, the universe was the size of a grain of sand, a pea, a coconut - choose your own spherical analogy, and was bounded in that volume.

The question "but what is outside that volume" has no meaning, since it doesn't exist. Takes a while to get your head around that concept!
 
Technically isn't the universe finite in that it does have a boundary, but it's also infinite in that boundary is also expanding?
 
Technically isn't the universe finite in that it does have a boundary, but it's also infinite in that boundary is also expanding?

Just because the boundary is changing size doesn't make it infinite. Think of a balloon which is being inflated.
 
If one defines "the universe" as the observable universe, then we have a boundary at the edge of the "Hubble Volume".

Beyond that boundary, nothing is observable, and, due to inflation, never will be. It therefore might as well not exist.

I throw this in not to disagree with anyone, but just to mess your minds up as much as mine is.
 
If one defines "the universe" as the observable universe, then we have a boundary at the edge of the "Hubble Volume".

Beyond that boundary, nothing is observable, and, due to inflation, never will be. It therefore might as well not exist.

I throw this in not to disagree with anyone, but just to mess your minds up as much as mine is.

Unless we invent warp drive and can travel faster than light :P
 
I always thought of it as not that the Universe has a 'boundary' that is expanding, but rather just everything in the Universe is getting further away from each other.
 
IIRC warp drives that I've seen speculated about in articles wouldn't cause something to go faster than light, instead they destroy space in front of them to get closer to their destination.
 
The grocery store is open 24/7, the universe is obviously infinite or else they wouldn't be able to say that.
 
I was going to say that if we cannot put a boundary on it, can it be finite? If we cannot circumnavigate it (as of now) then how can we pass judgement if it is finite or infinite?
 
IIRC warp drives that I've seen speculated about in articles wouldn't cause something to go faster than light, instead they destroy space in front of them to get closer to their destination.

From what I've seen it had something to do with negative energy, and bending space, but I'm far from an expert :P Either way, as far as I understand it, you could still end up travelling faster than the speed of light, you just wouldn't be going through space, so doesn't break any laws of physics. :)
 
Really helps to understand that time and space are the same thing. Not related, interchangeable.

The question of "Well then, Mister Scientist Smarty-pants, what was before the Big Bang?" that many believers in divine creation like to ask demonstrates a fundamental misunderstanding of space and time (aka space-time).

In order for there to be a before, time must exist. This relies on the existence of space-time. The Big Bang created space-time. There is no before. The Big Bang was the beginning

When we talk about finite versus infinite, we run into the issue of entropy the heat death of our universe, which is the other end of the book.

From a practical standpoint, space-time is even more finite for humans because it is physically impossible for us to travel fast enough to get past a finite area in the universe, even given an eternity. "Warp drives" are a cute way of sidestepping the law of the speed of light, unfortunately they do this at the expense of breaking several other universal rules.

At least this is the abridged version of my understanding. With topics like this everything in a theory can seem so perfect only to find out that it's entirely wrong or you understood it incorrectly. I sure would like somebody to come in and set me straight if I'm wrong.
 
I'm sure the universe is finite and they are infinite numbers of other universes, so how many other universes do you think they are?
 
The universe is finite of course, something of infinite size cannot expand like our universe does.
The space in which the universe expands may be infinite. Our expanding universe will always have a specific size.
 
The universe is finite of course, something of infinite size cannot expand like our universe does.
The space in which the universe expands may be infinite. Our expanding universe will always have a specific size.

As I understand it, the space in which the universe expands does not exist. At least not in the sense that "space" exists within our universe.
 
As I understand it, the space in which the universe expands does not exist. At least not in the sense that "space" exists within our universe.

Because space is time, the "space which the universe is in goes both ways", depending on which "direction" you look it does or doesn't exist.


I'm sure the universe is finite and they are infinite numbers of other universes, so how many other universes do you think they are?

Infinite universe, as you say (there is no plurality there, you can't have an infinite number of temporally-sizable universes, you can only have none, a very large none).
 
The universe is finite of course, something of infinite size cannot expand like our universe does.

There are orders of infinities. For example, the set of all integers is infinite, but smaller than the set of all real numbers.

I see no reason why an infinite space could not behave in a similar way, tending towards a higher order of infinity. It's a bit mind-bending if you try to think about it, but treated purely mathematically there's not real reason that I can see why an infinite space couldn't also be expanding.
 


In this talk there's a part where Jim Holt talks about a fininte universe vs an infinite universe (or universes).

It's a cool talk :)
 
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