How could an infinite universe be possible?

Question

if the universe where infinite, wouldnt it mean that it is constantly outgrowing its boundaries? how can anithing physical not have an end?

Answer 1

the universe is finite, not infinite, yet it has not edge (boundary) and no center. it seems to be something like the two-dimensional surface of a sphere. there is, therefore, nothing "outside" the universe. spacetime itself seems to have originated in the "big bang". to quote a dead writer (1874-1946) "there's no there, there".

read these:
http://universeadventure.org/
http://map.gsfc.nasa.gov/m_uni.html
http://www.astro.ucla.edu/~wright/cosmo_01.htm
http://www.sciam.com/print_version.cfm?articleID=0009F0CA-C523-1213-852383414B7F0147

Answer 2

Well, if it's infinite, it doesn't HAVE boundaries to outgrow. It just keeps going... and going... and going....

The problem with inifinity is that you can never know that it's inifinte, so you have to develop theories that either say it is or it isn't, and go from there. Some current theories say that the universe is finite but expanding -- sort of -- but there isn't anything beyond it (because you'd be outside the universe, right?), since space is only defined by the matter and energy within it. So if you had three atoms and sent them off in separate directions, they would describe a plane. If these three atoms were all the matter in the universe, then the universe would be a triangular, two-dimensional region of space bounded by these three specks of matter. The same goes for us, only with much larger scales and in three dimensions.

For those theories that say the universe is infinite, well why not? Worlds without end... just because our minds aren't capable of fathoming infinity, does that mean it isn't so? I was never able to wrap my mind around higher level calculus and vector multiplication, but that doesn't mean that it ceases to be a valid system.

Answer 3

If it isn't infinite, then it must have a specific size. Then the question is what is be boundary? A brick wall? Glass? Then once you ask that question, you then must ask what lies beyond this boundary. This could mean other dimensions, or...God.
1000 years ago everybody on the face of the earth used God or some super-being to explain the origin of the Earth and the universe. 500 years ago everybody used God to explain the origins of Mankind.
What will we know in the future?
Either humans are not able to comprehend this or we will find out in a few hundred years.

Answer 4

I think to fathom the concept of an infinite universe, it may be important to consider it from Einstein's space-time point of view. That is, in addition to having a dimension of space, the universe also has a dimension of time. Both dimensions are interwoven. As such, there can be no space (i.e., matter) without time, and there can be no time without space.

Since it is probably easier to fathom infinite time rather than infinite (physical) space, it may be easier to understand an infinite universe from its time perspective. To do so, just imagine that each day of your life is similar to moving through the space-time continuum. As each day passes,space-time grows larger without their seeming to be an end. Likewise, the universe can be thought of as expanding (much like filling a ballon with air) in the same way. Except unlike our life (which supposedly has a finite point that we associate with death--although, much speculation exists as to what happens after death), the universe presumably has an infinite time line.

I am sure that everything stated above sounds like a fancy way of saying the universe is expanding. However, the big difference here concerns the ability of the space-time conceptualizion to explain what the universe is expanding into. This question would be analogous to asking yourself what will happen to you one second, one hour, one day, one year, etc. from now. We don't know, because when we think about the future, at this point we transition from a space-time continuum to an imagination-time continuum.

So basically, the universe is as infinite (and expands into) one's imagination.

Answer 5

Asking what the universe is expanding into is the root of the problem for the question. According to the Big Bang Theory, not just space, but time itself, came into existence about 14.5 billion years ago. It's not expanding "into" anything. All that is contained inside that expanding space is called our universe. There is no "outside" - no time, no space. It's like asking "what am I NOT thinking of?" You can't identify something if it doesn't exist. Even the vaccuum of empty space is "something" -- there is quantum potential even in a vaccuum, energy potential field lines, virtual particles winking into and out of existence for less than a nanosecond. But all that exists within our universe. Here's another way to look at it: If you're standing at the North Pole and somebody asks you which way is north, you'd tell them the question makes no sense. You can't go north from the North Pole. The only direction you can go is south. Hope that helps.

Answer 6

Trying to understand the expansion of the universe is a headache (for me atleast) because really understanding it involves giving up on ever comprehending it in the same way that you comprehend your everyday physical world. An infinite yet expanding universe goes against our understanding of common knowledge, which is why it is so difficult to comprehend. It may even be that we simply don't have a good enough understanding of our universe. There are many facts, like the Doppler effect, that support an expanding universe, but it is still difficult for many of us to comprehend.

Answer 7

Looking as far away (and as far back) as we can observe - approx. 12billion light years - we see that the distribution of galaxies doesn't vary much from one line of sight to another.

Furthermore, the galaxies get more and more youthful the farther out we look. Even farther back we observe a very uniform background radiation that was emitted before any galaxies even formed.

I would suggest that we are not in any special spot in the universe. That, coupled with the facts above implies that an alien astronomer a billion light years away would basically see the same things we do - only his 12billion light-year 'horizon' would contain some galaxies that we cannot see, while ours would contain some he cannot see.

In effect he observes a 'different universe', but one that overlaps with our own. You can extend this line of reasoning indefinitely.

Answer 8

The Universe is infinite because beyond the things contained within the vicinity of where all things like atoms, stars, galaxies, pulsars, etc., exist, there is continued space minus the existence of those things previously mentioned. This is the area with which the Universe itself proceeds to expand into........infinity.

Answer 9

Based on our best information right now, cosmologists don't think the universe is infinite. Depending on various calculations that have been made based on astronomical observations, it may be around 46-78 billion light years in radius.

See below for a couple of articles on this subject that may provide further illumination.

Answer 10

Well it could for example be infinite in 4 dimensions (space time) but have limits in 5th or 6th.

It depends on how you look at it I suppose, and in 3 dimensions it at least looks infinite, but that's not really a fact as far as I see it. :)