I'm not a professional physicist, nor have I ever pretended to be one.

just fyi i wasn't trying to be joking with my question, i was just making sure i understood, as the idea that space could work like me going along the surface of the earth works makes no intuitive sense to me at all, but i guess i've spent all of 2 seconds thinking about it.

I don't think anyone took your question as a joke, wahoo. And the answer to it is yes, a "straight" line comes back around to it you from the other side... and no, that's not easy to get on an intuitive level.

Re the shape (jakelamotta's question), the curvature isn't the same everywhere, but as far as we know it is "closed" (or so I am led to understand by those who study such things), meaning it's like the balloon in that it has a finite size even though it has no edge. I believe the cosmologists make the assumption that the curvature is similar in far-distant parts of the universe to what we see here, but it might be otherwise and whether it is is unknowable (because they can't be observed, as they're too far away, or at least they are if they exist).

I think it's technically wrong to say you could travel around the universe in a straight line and arrive at the other side of the Earth, because it's expanding fast enough that you'd never get back. (Pros, tell me if that's wrong.) So we have another oddity: there's no edge, but if you started out now you could travel in a line for an infinitely long time, because of the expansion. But the direction you'd be going would be toward where you started.

Now, I was under the impression that the curvature of the universe was still under debate, and that it was looking to be open actually, but most likely near-flat.

Are all closed universes really the same? In other words, in all closed universes a straight line will, given no other interference, lead back to itself after one complete "circling"? A universe where the angles of a triangle add up to 180.01 will behave the same as one where it's 360.02 in this sense?

Assume there is four objects. There is one at North Pole, South Pole, 0 degrees long., and 180 degrees long. Each object is launched in straight lines. Are you guys saying that none of them will ever get to the "edge" of the universe?

Among other things, "straight line" is very problematic here.

True. But the answer to his question is still that none of the objects will get to the edge because there's no edge to get to.

Obviously a straight line cannot lead back to it self, if you can see the back of you head them if you look to the side you can see the size of your head, thus you head will appear to be the size on the universe.


Only a complete simpleton could possibly believe that!!!


Hands up the simpletons!!!!!!!!

why is this thread not locked yet?

does this mean if i travelled the universe going in the same direction for infinity i would just circle the universe?

Good question.

My guess is that it is impossible to "go in the same direction" for the same reason straight lines are problematic, but then again, i have no understanding of topology, but the question is interesting because i was wondering the same.

Our universe is inside a larger universe.
Check out Nikodem Poplawski's (theoretical physics from Indian U) recent paper "Radial motion into an Einstein–Rosen bridge" published in Physics Letters B, Volume 687, Issues 2-3, 12 April 2010 (has been available online)

Why have you not stopped being disruptive?

Also entitled "Something I dreamt up whilst taking a dump".

That is possible. Similar to how geodesics work on the 2 dimensional surface of a sphere. You might initially think that that phenomenon only works because the surface of the sphere is embedded in higher dimensions, but it turns out a similar thing can happen even without embedded the space in some other dimension.

The brick wall of ignorance, bull**** artists notwithstanding.

I was going to delete or edit some responses but will leave them as evidence of either uncivil behavior, willful ignorance, or as something not worth responding to in the first place. If you have nothing worthwhile to contribute to the thread then please refrain from posting here, or in SMP in general, and go elsewhere. Consider this a warning.

-Zeno

Too late to edit now, but I meant Indiana U obviously, not Indian.

Also, we can't meaningfully say the edge of the Earth because we live on the 'edge'. If we lived in the centre of the Earth, we could travel in any one direction and come to the 'edge' of what we called the Earth (since it would be a sphere all around us, as the universe appears to be), and go further into the universe, thereby having gone past the edge of the Earth. Since we live within (instead of on the surface of) the universe, we can conceivably reach its edge, so the edge-of-Earth edge-of-universe comparison doesn't make sense.

For those who live inside the Earth, however, it does, but I think that population is probably quite small.

The truth is that for all their fancy made up maths the scientists have no more idea than stone age man, getting them to admit to that is a slightly different matter.

lol pen15 haven't you given up your trolling yet. They know the universe is 13.7 billion years old give or take a little, yet they don't know more than stone age man.

That's an unproven theory.

Hey pen, if you're interested in this topic, you might want read about some of the methods used to measure the age of the universe.


NASA's Wilkinson Microwave Anisotropy Probe, is a good start.

Yes interesting stuff no doubt, I have looked at similar stuff before but forgot most of it - lol.
I think you can come up with some interesting stuff, such as you can prove the earth (or indeed yourself) is at the center of the universe, perhaps. (very profound).
I would say though that for all these things you perhaps have to make certain assumptions. I mean basically they say the universe expanding now and back track it I think, but was the point they reach the start of everything?



Also if we are receiving radiation traveling at the speed of light, then how can that be if it started from a point? because if that were the case then the light would be traveling away from us as we were at that point.

So perhaps a pecularity rather than a singularity - lol.