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:rolleyes:

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

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...:rolleyes: )

Hi Sal-Man,

Exactly.

Bye!

Crisp

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.

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 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?

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

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.

Originally posted by ProCop
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.
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.
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.
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

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.


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.

Originally posted by ProCop
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.
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

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?

:confused: help! :confused:

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.

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).

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.:D

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.

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 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.

Originally posted by ProCop
Thus the curving of the space is a subjective observation of an insider, while for the Universe to exist objectively 4th dimension is necessary.
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

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

Originally posted by pfcgrogan
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.

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

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

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

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.

Since the planets are moving in different directions from the Big Bang in a finite curved space they will collide at some point.

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.

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?


<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.

but in the opposite direction the inner circle of the tunnel is getting smaller

Forget about this part. No part of the universe is getting smaller.

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.

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... :D

Bye!

Crisp

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

Crisp,

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.

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

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.

Originally posted by cassius1802
the edge of the universe is Big Bang itself.
The horizon of our observable universe certainly does have an edge. The entire universe, however, does not need to have one.

- Warren

Originally posted by Prosoothus
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.
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

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.

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

the edge of the universe is Big Bang itself.

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.)

@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.

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

"The human mind is not capable of grasping the Universe. We are like a little child entering a huge library. The walls are covered to the ceilings with books in many different tongues. The child knows that someone must have written these books. It does not know who or how. It does not understand the languages in which they are written. But the child notes a definite plan in the arrangement of the books - a mysterious order which it does not comprehend, but only dimly suspects."

Albert Einstein