# Edge of the Universe?

Discussion in 'Physics & Math' started by Sal-Man, Jan 13, 2003.

1. ### Sal-ManRegistered Senior Member

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Hi, as someone has recently posted on a recent thread, the most accepted theory for the origin of the universe is The Big Bang theory.
I for one accept this theory, since it has scientific data to back it up, but one thing i have always wondered, is that this theory along with others('Big Bang' suggests the univers is expanding, other theorys suggest that that expansion is now slowing down [maybe even reversing]) the thing is that these imply that the universe has a limit, the 'edge of the universe', so i've always wondered if these theorys prove to be true, what happens if you reach the edge of the universe, is there like a sign that says "Edge of universe, you may go no further", or a huge wall or what,, maybe you guys can help me out, or if i'm wrong on something, point out where, because it really bugs me

3. ### chrootCrackpot killerRegistered Senior Member

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Space is thought to be curved in on itself, and has finite volume with no boundaries.

The most common analogy presented is that of an orange: an orange's surface is two-dimensional and finite in area, yet has no boundaries. An ant walking on the surface of the orange will never encounter an "edge," yet his world is finite in extent.

If you extend the concept to curved space in three dimensions, you can see that universe is finite in size, yet without any edge.

- Warren

5. ### Sal-ManRegistered Senior Member

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ok chroot, let me see if get this.

If we go in a 'straight line' far into the depts of the universe and get to the boundries of it, is it like going on a really really slight curve so you never really notice it (sorta like walking on this planet??):bugeye:

(Sorry i'm a bit slow on understanding certain things...

)

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Hi Sal-Man,

Exactly.

Bye!

Crisp

8. ### pfcgroganRegistered Member

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If you were to go a strait line toward 'what would be the end of the universe' you would just end up on the other side. Which suggests a 3d curve exists. Since outside the known universe (or everything in existence even outside of our known universe) exists a nothingness, which doesn’t really exist because that would suggest that the nothingness is something, which it is not. We can never go there because it is not a place, and we can only exist within existence. Therefore you would not see the edge because you cannot see nothingness because it doesn’t exist.

Last edited: Jan 13, 2003
9. ### ProCopValued Senior Member

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RE:chroot

If there was a second ant walking around the orange smoking a cigaar the first ant would had seen the smoke before he saw the smoking ant. If the space was curved inversely to the orange wouldn't the ligth curve at great distances? And how about the middle of this "space". Where would the curving begin? If the light would be approaching the "edge" how would the stupid light know that is should curve?

Well as you put it it has boundaries (it must end in some way or other in your proposal) but we cannot see them. Because if it has no boundaries it is endless.

10. ### chrootCrackpot killerRegistered Senior Member

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Re: RE:chroot

The orange is 2D analogy for 3D space. In the orange-surface space, there is no dimension of "altitude" by definition, just as there is no 4th spatial dimension in 3D space, by definition. The analogy deals only with the surface itself, which is a 2D non-euclidean space. The fact that you're used to viewing oranges in 3D, with a concept of space outside the orange is inconsequential.
Hell, I'll just repeat it: An orange's surface is a 2D space without boundaries, with finite area. The universe is a 3D space without boundaries, with finite volume.

- Warren

11. ### ProCopValued Senior Member

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re:chroot

Paint the orange blue and leave one centimeter wide line out. That wil be the boundary.

Fill the space with blue baloons leave a strip of 1 m unbalooned through it and follow the strip. You will walk the edge of the universe.

12. ### chrootCrackpot killerRegistered Senior Member

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Re: re:chroot

Jesus tap-dancing Christ, I hope you're not stupid enough to think that a line on the ground is equivalent to the "edge of the universe."

- Warren

13. ### ClaudeaRegistered Member

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i think i must just be seeing this the wrong way... but if we're looking at space in terms of a big bubble of some sort... wouldn't you come back to where you started if you continued in one direction for long enough? In 3 dimensions, if the space is finite, there has to be an edge somewhere... :bugeye: doesn't there?

help!

14. ### ProCopValued Senior Member

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RE:chroot

You indeed need to step one dimension up to see through it. But there is no 4th spatial dimension so you actually cannot do a step out of it. But, on the other hand, if there is no 4th dimension the 3d space cannot curve (objectively). Thus the curving of the space is a subjective observation of an insider, while for the Universe to exist objectively 4th dimension is necessary. So we can conclude that the universe does not objectively exist, it is more or less subjective experience: I never realised that you were coming so close to my <a href=http://www.sciforums.com/showthread.php?s=&threadid=10209> DvD theory </a>(or that you have read that <b>that</b> carefully).

15. ### VacuiRegistered Senior Member

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TIME IS FOURTH DIMENSION .
Edge of universe...

universe is much more complicated.
btw. universe is created by God.Science answers on when and how,Bible says who and why
Einstein said that he only wants to know how did God created universe.

16. ### James RJust this guy, you know?Staff Member

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I wish I had a dollar for every time somebody says "Time is the 4th dimension" in one of these discussions. Time is <b>a</b> 4th dimension, but need not be <b>the</b> 4th dimension.

When you're discussion orange analogies, you're talking spatial dimensions. Time doesn't enter the picture.

17. ### pfcgroganRegistered Member

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If you are going to use an orange in your analogy you should say that the and is walking around inside a hollowed out orange not on the outside.

18. ### chrootCrackpot killerRegistered Senior Member

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Re: RE:chroot

This is why the orange is just an analogy, ProCop. Real 3D space is curved into the time dimension. It's pretty tough visualize 3D space curving, period -- and it's even tougher to visualize it curving into time -- which is why people explain the concepts using low-dimensional, purely spatial analogies.

- Warren

19. ### Pollux VRa Bless AmericaRegistered Senior Member

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Is it possible that space is not curved? Do we know for sure? Please explain...

20. ### ClaudeaRegistered Member

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But then there is an edge. The ant cannot go through the skin...

:bugeye: my poor braaaiiiinnn... :bugeye:

21. ### ProCopValued Senior Member

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Re: Chroot

Since the planets are moving in different directions from the Big Bang in a finite curved space they will collide at some point. Now the time trick (sorry, dimension) will come, I hope.

22. ### Boris2Valued Senior Member

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No.

I am in Western Australia, you are in some other place, lets say the USA. If the Earth was getting bigger, we will say "magically" for arguments sake, when will we meet?

We wont but the distance between us will increase.

Same with the universe.

23. ### ProCopValued Senior Member

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RE:Boris2

<b>If</b> I got it right then the 3D curved space can be compared to a sideless circular tunnel. If somewhere in this tunnel BB explosion took place then from that point the planets are spreading while the tunel encreases in size. The planets, which are moving in different directions in the circulair tunnel are going one day to collide, because if the tunnel encreases in size, than in one direction it is getting bigger (direction out) but in the opposite direction the inner circle of the tunnel is getting smaller which means that the tunnel wil itself merge with itself and will became uncurved.