Mike Wladyka
Supporting Actor
- Joined
- Jul 24, 2003
- Messages
- 630
"Hypothetically speaking, if you head off into space you can travel in a straight line and come back to the starting point,"Hmmm.. so the Asteroids video game is looking pretty realistic now, eh?
In the case of the soccer ball model, remember that big bang theory states there is no center of the universe; it all started from the same point and from anywhere it appears to be expanding away from that point.wouldnt that suggest that the point where the big bang originated IS the center? since everything is expanding away from that point, i would think that could be considered the center.
CJ
The expansion of the universe means that the container gets larger, so the distance you would have to travel before you returned to your origin would increase.right, but isn't that true of the "old" model of the universe? How is this a new concept, then? I always thought of the universe expanding in every direction, wouldn't that be theoretically a sphere if it were to start from one point as the big bang depicts. What am i missing? i took the article to mean that the universe has a finite boundary, which implies being able to travel around as an "ant on a balloon" I am not seeing why you would be able to do this if the universe is expanding, theoretically you would never be able to come back to the point where you started if the universe was expanding because the diameter would be expanding in either direction which would make the circumference bigger yet.
well, dare i ask what they think is outside of the boundary of the soccer ball shaped universe?Italy
Andy brings up a good point, though. The very item we are trying to observe in two different places may not have been in existence sufficiently long and in the right place for us to see the light, as it were, in the second place.
This has interesting possibilities...
Mike
right, but isn't that true of the "old" model of the universe? How is this a new concept, then?The old model was an expanding sphere with an edge and we're contained within the sphere. If you travelled in one direction in the old model you would eventually reach the edge of the universe.
This model suggests that that sphere is "looped" in all directions, meaning if you travelled in a straight line you would eventually come back to where you started.
All of this will be proven true when Voyager comes crashing back to Earth.
It would if the universe had boundaries. Once you take the boundaries away... there's no center.right, but it still has a point of origin. if you dont think of it as finding the center of a sphere as the midpoint between two opposite tangent planes, then it works. something with no boundaries can have no mathematical center, but that point is certainly closer than any other point. but i see what you are saying as well. its not like we as humans have a definitive answer to how big the universe is, so much of this is semantics. i am, however, impressed with how much we are able to determine in a relatively short period of studying the skies.
CJ
Everything would be on the inside. The "edges" don't really exist; the transition from one side to the other wouldn't appear any different from traveling internally. So the expansion model still works, and galactic doppler shift is still valid. It's a topology that's both infinite and bounded.Are you sure you don't mean finite and unbounded?
I don't know where the dodecahedron comes in... why couldn't be some other polyhedron?I don't know either, but I think I can guess. Like so many things in cosmology theory, the data probably fit the model best when the variable N for number of sides was 12. As to why 12 sides works, that's a new line of study.
I'll definitely be looking for more info on this. Particularly the rebuttals and counter arguments.
Andy
but there has to be a centerOh, yes. The expanding balloon does have a centre of expansion: but it's outside the surface of the balloon. So in this 3-D reality, the centre of the universe exists, but it's situated outside the universe. In fact we immediately need a 4-D model (like the balloon, with its 2-D surface, really is a 3-D structure). If you add time as another dimension, we would need a 5-D model.
Cees
Lots of very interesting repercussions from this kind of topologyAndy, like what? wormhole travel?
If the universe is closed, though, then what is beyond the universe? Weeks took his best shot at answering this confounding question:
"The universe is finite," he said, "but there's no boundary to it," implying that there is no beyond, or that if there is, then its nature is left to your imagination and is outside the closed system that astronomers can ever hope to see.Andy, being kept honest by Brian
Andy, like what? wormhole travel?Actually, I was thinking of more mundane things, like being able to accurately measure cosmic distances if you can triangulate on multiple images of the same object. Or using the relative positions of multiple images to determine the exact flatness of space. Also, whether or not this geometry changes the calculations for an infinitely expanding (current consensus) or eventually collapsing universe. What kind of manifold this dodechahedral surface describes (flat, stretched, wrinkled, are the vertices smooth or are there holes, etc) and how its incorporation into spacetime fits with the standard model of particle theory. I'm sure there are a lot more.
Andy