Are there any conjectures or theories of the "shape" of the universe?

Question

In my last question I did not intend to put forth a theory. I am trying to understand, and to distinguish what we know, and what theories there are.

So I say, it seems to me (not that I am holding to any of my assumptions, but for the purpose of questioning), that the universe can not have a shape because then photons would curve through space. Perhaps I am wrong. But then does the universe have a shape? If not then is it true that the universe has an envelope?

Actually we can not see 40 billion light years into space, such is based on assumptions. We can see 4 parsecs, and up to about 30 or 35 parsecs, but beyond that we can not tell distance.

Answer 1

Good question. Not because I know the answer, but because I find it interesting. I don't think there is a shape to the universe. If it’s everything that exists, do you think that it would be possible to leave it and view it from the outside? And it would be impossible to view it from the inside. If there were a shape to the universe (I'm not saying there is but...) it would most likely be round or oval. Everything in space seems to be round or oval; the sun, the planets, others stars. It's very subtle place with no sharp or sudden edges. (Except for meteors and their overall shape is roundish)

Answer 2

Photons like all objects do curve through space! Einstein showed 100 years ago that the Universe is not flat. Rather Space-time is very dynamic and its curvature manifests the gravitational force. Our planet is not moving along a curved path. Rather it is moving in a straight line through a curved space (curved by the suns presence). So its motion appears to be curved.

The Universe is believed to have a well defined shape. Conventional cosmology holds that the Universe is a 3 dimensional surface wrapped around a 4 dimensional sphere. This is easy to picture using a lower dimenional analog. Much like the surface of a sphere the universe has no boundries meaning it is infinte in spatial extent. You can walk around the surface of a sphere forever without running into a boundry or reaching the end. However the sphere has a finite size. So does the Universe. The Universe is said to be infinte in spatal extent but finite in size.

What about expansion? Well, draw a bunch of little dots on a ballon. Then inflate it. The dots all move away from each other because the space that their confined to is expanding.

Yep your right the observable universe is 40 billion light years across. We can't see father than 13.5 billion liht years becuase light has not had enough time to travel any farther. Why then is it 40 billion light years? becuas the light we are observing from the most distant objects is 13.5 billion years old. The Universe is expanding faster than the speed of light. So by now, those distant objects are much much further.

Answer 3

I admire your curiosity. I was struck by your last comment--"beyond that we can not tell distance." How do we measure distances when we are speaking of distances in terms of billions of light years? Before we conjecture about shape, wouldn't it be nice if we could be absolutely certain as to distances beyond a billion light years.

I am familiar with the measuring yardsticks. Close in, we can calculate distances by measuring the apparent motion of a star as we orbit the sun. Farther out, we can measure the relative brightness with a certain variable star whose luminosity is known. But what do we use when we get out to a billion light years and beyond? The redshift of galaxies' light? And that is the basis for my quandary.

The more distance an object, the greater the red shift of its radiation. But why is it that no matter what direction we look out into deep space, the furthest objects are racing away from us? Are we that unique that we are located in the center of the universe? I think not. Something is amiss here.

What if the universe was the shape of a curved surface or spherical? And do you accept the theory that electromagnetic radiation can be bent? What if we are observing distance objects racing along this curved boundary and we are seeing the radiation after is has been bent. The apparant position and the real position would be different. And it is this bending that is stretching the radiation toward the longer wavelength end of the spectrum. No matter in what direction we look, we will see this red shift and assume the distances are great. But what if they aren't at those great distances?

Answer 4

If I remember right, a parsec is about 3 light years. I am sure that telescopes can do much better than that. I'm sure that photons can curve through space; they would have to approaching a black hole, which would put them into a spiral orbit.

Let's just hope, a la Truman, that there just isn't a door at the end of the universe and someone with a camera on the other side. That would be a bummer!!

Answer 5

I may be and am probably completely wrong but I think that the "edge" of the universe is and will always be where light would have reached had it started at the big bang point. This would be the limit of where matter could be, applying einstein's relativity theories. This is what is meant by an expanding universe. By my interpretation of "shape", I think it would be spherical, since light would travel the same speed from the point of origin.