The edge of space

[amt7565]

How far should we go to reach the edges of Space- our Universe? 15 billion light years?

According to scientists, how will this edge look once we reach it? Everyone can say 'nothing', but how would it feel if we are able to reach it? Is there some sought of barrier?

 

 

While on the topic, is it safe to assume that our Universe has a spherical shape?

[niviene]

How far should we go to reach the edges of Space- our Universe? 15 billion light years?

According to scientists, how will this edge look once we reach it? Everyone can say 'nothing', but how would it feel if we are able to reach it? Is there some sought of barrier?

 

 

While on the topic, is it safe to assume that our Universe has a spherical shape?

 

I don't think there is an "edge" to our universe. If we knew what it looked like, that would mean we knew the boundary of the universe, and, the last I heard, we certainly didn't know anything remotely close. All we can do is speculate, for sure. However, in 1992, apparently there were some ripples discovered - temperature fluctuations - that they think are on the edge of the universe... And as far as I know, many now assume the universe to be spherical, but of course, there is no way to prove that yet.

 

Check out this link, it's neat:

http://www.damtp.cam.ac.uk/user/gr/public/cmbr_anis.html

 

And this one:

Astronomers Re-measure the universe

 

Also, check out this image, just because it's really awesome!

Horsehead Nebula

[infamous]

I don't think there is an "edge" to our universe. If we knew what it looked like, that would mean we knew the boundary of the universe, and, the last I heard, we certainly didn't know anything remotely close. All we can do is speculate, for sure. However, in 1992, apparently there were some ripples discovered - temperature fluctuations - that they think are on the edge of the universe... And as far as I know, many now assume the universe to be spherical, but of course, there is no way to prove that yet.

 

Check out this link, it's neat:

http://www.damtp.cam.ac.uk/user/gr/public/cmbr_anis.html

 

And this one:

Astronomers Re-measure the universe

 

Also, check out this image, just because it's really awesome!

Horsehead Nebula

 

Interesting links, thanks for the contribution niviene. Breathtaking view of the Horsehead Nebula.

[Turtle]

___In regard to talking of a spherical shape, this in itself implies a boundry, ie an edge.

___There is no edge as I understand it, but rather space curves back onto itself. Just as the expanding balloon example (in one of Niviene's links, & commonly cited elsewhere) points out that points on the 2-dimensional surface move apart as it expands & none has claim to center, the surface of the balloon has no edge either. Leave any point & keep going "straight" & you return to the same point. ;)

[Boerseun]

Hi

 

As far as I understand it, the Universe has been expanding at the speed of light ever since the Big Bang. Which means that Space itself is expanding at the speed of light. The extremities of the Universe defines space, so to ask what is lying outside of it is meaningless. There is nothing, not even space. And there is no way of reaching it, seeing as the speed of light is a barrier we can't cross. So, yes - it's curved in on itself, but don't even try to imagine a 2 dimensional analogy for a 3 dimensional reality. You'll just pop a vein in your brain!

[coldcreation]

the boundary condition is an old problem in cosmology. A similar problem exists for the event horizon of black holes. The singulaity can be avoided. But if you ask me the bondary of space (like the edge of the Earth when it was thought to be flat) in science fiction. Incidentaly, according to inflation theory, the universe is flat.

 

Not much has changed...

[Turtle]

___Not only is the Universe folding in on itself, not only is it flattened, it all sits on the back of a turtle. ;)

[Queso]

a very wise one at that.

[Tormod]

Incidentaly, according to inflation theory, the universe is flat.

 

I think it is important to point out that this "flatness" does not mean that the universe has a 2D shape. The flatness is derived from relativity theory and is related to whether the universe is open, closed, or flat - ie, whether it will expand forever or not.

 

Here is a page which explains it in a simple way:

http://curious.astro.cornell.edu/question.php?number=171

 

As for the second question: No, it is not safe to assume that the universe has a spherical shape. We cannot know the shape of the universe since all we can see is the observable universe.

 

The observable universe (everything we can see), however, is what has expanded at the speed of light since the Big Bang. Nobody knows what is outside the observable - although it is usually assumed that there is "more of the same". As for what is outside the *entire* universe - that depends on who you ask. I think most cosmologists would answer that the question has no meaning.

 

The observable universe appears spherical to us and we appear to be in the middle of it for obvious reasons.

[infamous]

I was just wondering if any of the membership here ever considered the questions:

 

#1; Is the speed of light determined by this universal expansion?

 

#2; If the universal expansion were slower, would it also be the same for the speed of light.

 

#3; If this is so, then what happens if the expansion comes to a halt.

 

Just a litltle food for thought, what do you think??

[Tormod]

I was just wondering if any of the membership here ever considered the questions:

 

#1; Is the speed of light determined by this universal expansion?

 

Good questions, infy.

 

No, it is the reverse: the speed of light determines how much of the universe we can see.

 

The expansion of the rest of the universe is not the same as the expansion of the observable universe.

 

#2; If the universal expansion were slower, would it also be the same for the speed of light.

 

Yes, since the expansion of the observable universe is determined by light, this could technically be true.

 

#3; If this is so, then what happens if the expansion comes to a halt.

 

Nothing, really. It would mean that there is nothing more to see...

[infamous]

Good questions, infy.

 

No, it is the reverse: the speed of light determines how much of the universe we can see.

 

The expansion of the rest of the universe is not the same as the expansion of the observable universe.

 

 

 

Yes, since the expansion of the observable universe is determined by light, this could technically be true.

 

 

 

Nothing, really. It would mean that there is nothing more to see...

 

OK I think I get it. Maybe we could understand the expansion as similar to the way a star ship could be powered with a light sail. The light energy was created by the Big Bang and the universe is the sail, so to speak. Why I havn't undestood this before, I'm at a loss to explain. Thank you Tormod

[amt7565]

Good points.

 

I have been watching the Science Channel on cable recently. They have Michiko Kaku talk alot. Excellent programs on parrallel universes and other stuff.

 

Thanks.

[infamous]

I just googled this link: http://epsc.wustl.edu/classwork/classwork_210a/pdfs/cb5_2002.pdf

I think many will find this very informative.

[Little Bang]

What reference point are we using to say the universe is expanding at C?

[bumab]

We don't know what speed the universe is expanding at. The OBSERVABLE universe is expanding at c because that's how fast light, which we use to observe, travels. Think of the light cone- expands at c.

[Boerseun]

That's the thing, see.

 

It doesn't matter what your velocity, c is always c. That's where the whole relativity bit comes in. You can travel at 90%c relative to whatever you want, as far as you're concerned (your frame of reference) light will always travel at c in your frame of reference. That's what necessitated time dilation in Einstein's famous gedenkeneksperimen.