# Is space infinite.

1. Mar 12, 2009

### cragar

I am just wondering if matter cannot be created or destroyed that would mean that
were are not making new energy we are just transforming it so then all the matter
in the universe is a fixed number at least the total between mass and energy is so space
would be finite, what do u guys think.

Last edited: Mar 13, 2009
2. Mar 13, 2009

### jmatejka

I think it I would run out of space in this text box to answer your question. I think the answer would be very deep,complicated and theoretical. Let me throw one thing out there, maybe some others will enlighten you more.

"matter cannot be created or destroyed", this is what they tell undergraduate Physic Students. There are "apparent"exceptions, at least on a quantum level.

I like to think of infinity as a useful math concept, but maybe not such much in reality, at least my own reality.

Last edited: Mar 13, 2009
3. Mar 13, 2009

### DyslexicHobo

I'm no physicist, but I have done some reading in that area. It's pretty interesting.

I read the book a long time ago, and don't even remember what it was titled, sorry. :( But from what I remember, your statement is correct. There is a fixed amount of mass/energy in our universe. Physicists are actually trying to determine exactly how much mass there is. If we can figure that out, we can find out if the universe will ever stop expanding.

4. Mar 13, 2009

### Bob S

It doesn't matter, because in the end we will all end up being sucked into the largest and final sources of potential energy, a black hole.

5. Mar 13, 2009

### DaveC426913

As generally understood, the amount of matter and energy are fixed and the size of the universe is finite.

6. Mar 13, 2009

### cragar

ya i remember reading a book by the physicist George Gamow and he said that space was finite , but if its finite whats on the other side.

7. Mar 13, 2009

### alxm

What 'other side'? Do you think there's a fence?
It can be finite and unbounded. The typical analogy here is to the surface of a sphere. Only in one more dimension.

On the other hand, it could be turtles all the way down.

8. Mar 13, 2009

### cragar

no i dont think there a god damn fence

9. Mar 13, 2009

### pallidin

I've also often wondered if space is infinite in all directions.

Indeed, if it were not, what type of "barrier" would there be? Well, the best I've heard, in short, is that a straight-line actaully slowly curves, and so at the "edge" of the spacial universe you curve back, even though you think you are traveling straight.

Of course, there is no way to prove this, and it still begs the question: what's beyond that?

Well, all I can offer is that thinking on that subject must include a universe "bubble" or dimensional considerations(above the 3 or 4 we now accept)
Other than that, I would be just as confused as anyone else.

Last edited: Mar 13, 2009
10. Mar 13, 2009

### DaveC426913

There is, in principle. Looking far enough into the universe, if we see spectra from distant obejcts that match spectra of nearby objects, we could determine that our observations are "wrapping around".

11. Mar 13, 2009

### DaveC426913

No need to swear. This is a family-friendly forum.

12. Mar 15, 2009

### Nanyang

I was thinking that if the universe was finite, then 'something' can be larger than the universe, which would mean that the finite space we call 'universe' is not really the universe. Hence the universe cannot be finite.

But the space we live around is finite, since energy is conserved. So it could be something like a finite region of space with matter within an infinite region of space with emptiness surrounding the matter.

I'm no physicist, or highly educated. So if this sounds ridiculous, you know why! :D

13. Mar 15, 2009

### Nick89

I think a good analogy is to step back one dimension.

Imagine a piece of paper lying in front of you on the table, where you drew a person, in 2D. This person is completely 2D, and so is his world / universe (the paper).

Now, if you leave the paper lying flat on the table, it is immediately apparent that his universe is finite and 'has edges'.

However, if you take the paper and bend it around into a sphere, it no longer has any edges! But because our paper guy has no idea of 3D, he will notice nothing different. He is living in his 2D world which is curved in 3D. His universe is closed and finite, but there are still no edges.

I think the same happens to us, except one dimension higher.

14. Mar 15, 2009

### Nanyang

What about a larger sphere surrounding the sphere that the 2D guy is on? Since his sphere is not infinitely large, a larger sphere can exist. Hence it is also a possibility that we might be living in a universe inside another universe...

Again, I'm just an amateur. So if my ideas seem wrong, that's why...

15. Mar 15, 2009

### v2kkim

Suppose that there are other universes, but we do not interact with them, then what can we do about it ? Scientifically nothing, but still we can write a good SciFi story with some added imagination.

16. Mar 15, 2009

### DaveC426913

The more common analogy is a balloon. We are living on the surface of the balloon. The surface of the balloon is not finite in extent, yet has no boundaries.