# Edge of the Universe?

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

1. ### Boris2Valued Senior Member

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1,106

The problem with all these analogies is the we cannot visualise the true nature of the universe ie its curvature or expansion without there being anything for it to expand into, so we try with such things that we know such as the surface of a balloon, the raisin bread etc.

This leads us to see these analogies existing in our space, therefore we can "see' the other dimensions. Which causes confusion.

3. ### CrispGone 4everRegistered Senior Member

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1,339
Hi Pollux V,

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

The theory of general relativity (which works with a curved spacetime) is so incredibly succesful in explaining experiments that most people will say that it indeed describes reality, i.e. that spacetime is indeed curved. And furthermore there are some experimental data that all speak in favour of a curved & expanding spacetime (I am thinking of gravitational lensing, receeding galaxies here)...

That does not exclude the possibility that we are all wrong ofcourse, and that it is indeed possible that spacetime is not curved. But then again, I like playing the devil's advocate...

Bye!

Crisp

5. ### IggDawgRegistered Senior Member

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Hawking, in "universe in a nutshell," has a good analogy of how "curved space" can make up a boundless universe. He does it when he's talking about imaginary numbers. he doesn't mean to be doing just that at the time, but it's a good analogy. I'll stop confusing you all now. go out and buy the book.

-IggDawg

7. ### ProsoothusRegistered Senior Member

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1,973
Crisp,

Just because the math is correct, doesn't mean that the model is correct. There can be multiple models that give the same math results. "Curved space" is just one of these models.

Tom

8. ### cassius1802Registered Member

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10
Edge of the Universe

technically, the universe does have an "edge". that "edge" is the extent of how far we can look. when you stare into the night sky, you are actually looking back in time. light only travels so fast. so if you could potentially look far enough into the stars, you would see the Big Bang. that does not mean that the universe ends there, though. there is much more "beyond" the Big Bang. our view is just limited by time itself. but he universe hets older every nanosecond. thus, we have the ability to see more of the universe every nanosecond. but no matter how far we look, we will never see all of it. that "edge" will always be in our way.

the edge of the universe is Big Bang itself.

9. ### chrootCrackpot killerRegistered Senior Member

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2,350
Re: Edge of the Universe

The horizon of our observable universe certainly does have an edge. The entire universe, however, does not need to have one.

- Warren

10. ### chrootCrackpot killerRegistered Senior Member

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2,350
Most scientists would say the model is independent of the physics until the final answer is cranked out of the machine. You certainly can express any system you want in a variety of mathematical formalisms -- and all of those formalisms will be equivalent. Which one is physically "real?" The question is moot: they all produce the same experimental predictions. You're welcome to choose the one you like best.

- Warren

11. ### cassius1802Registered Member

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true.

it is true that the actual universe does not have an edge. i was merely stating that the universe does have edges. such as that of our limited view.

12. ### awebbRegistered Member

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hey

i'd say its more of a 4d curve than a 3d one as some theories sugest that out universe is a 4 dimentional shape

13. ### ProCopValued Senior Member

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re:cassius1802

Birth/death mean then a crossing of a non existing border of the universe. (eg. by death, your were here, now you not: thus your are out of universe, thus there is a border to cross and there is one more dimenssion in this model, "the dimension of death" which "surrounds" the curved space.)

14. ### blobranaRegistered Senior Member

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@awebb
Yes there are theories that say that we live on a 4 dimensional macro universe with 6 other dimensions compacted (micro) + time.

What i think we may find is that the hyper-balloon is not a balloon shape at all but flat...

And of course we are part of the universe so if there was an edge to this universe how would we be aware of it? By the very nature of observing it it would recede away from our sight...

New space/time would be created.

15. ### Sal-ManRegistered Senior Member

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Thanks to all of you for takin the time to answer my question...