Is the universe infinite?

Originally posted by Shakyamunison
I was told that communication using entanglement would be impossible. Don't you destroy the information as soon as you detect the spin?

That said the work is theoretical and only includes the particle clusters mentioned above as well as methods of reading the information.

What I mean is, the way you're wording you're wrong. But I'm sure you're simply misinterpreting an article. If you reference it I could clarify it for you.

Originally posted by Astner
What I mean is, the way you're wording you're wrong. But I'm sure you're simply misinterpreting an article. If you reference it I could clarify it for you.

I'm sure I am not saying it correctly, but the information was from a discussion with a physics teacher, a few years back. When I first learned about entanglement I thought "that would make the ultimate communication device". One of the engineers I work with is also a physics teacher (he has moved to another job), he popped my bubble, telling me that could never happen. I am glad to see that other people disagree. 😄

Originally posted by Astner
A complete superluminal system wouldn't be possible, because you'd need to have receptor interpreting the signals as well. That said, information wouldn't be destroyed because it's used in a binary sense, and if we detect the spin of a particle, then we know that its antiparticle will have the opposite spin. It's a matter of using it appropriately in a system.

If I understand what you've written here you're not even describing something vaguely similar to a faster than light communication device.

Originally posted by Symmetric Chaos
If I understand what you've written here you're not even describing something vaguely similar to a faster than light communication device.

Since entanglement occurs instantly, if the method stands for most of the distance in a system -- including the reception of the signals -- the mean "velocity" can well transcend light speed.

Originally posted by Astner
We're not creating a communication device, we're simply examining a certain phenomena and its applications.

Since entanglement occurs instantly, if the method stands for most of the distance in a system -- including the reception of the signals -- the mean "velocity" can well transcend light speed.

How can you be sure about the end result?

We're not. Those are just the basics.

Either way w're pretty far into the theory, and we have good communication with the doctors and docents at the Department of Fundamental Physics.

Besides most of what's left is number crunching, in the end there are a number of ways to solve partial differential equations. You don't necessarily have to solve them analytically if you're able to come up with a numeric solution, and if that doesn't work you can always take another approach and reinitialize the conditions.

Back on topic, what would it mean if the universe weren't infinite? Would there be some "edge" that could theoretically be reached? Would there be something beyond it or is that looking at it too simplistically from the human viewpoint that everything with a definite area must be contained by something that defines that area?

No. There wouldn't be an edge, it would be closed. Think of it like the surface of a ball, the area of the surface is limited but you could endlessly walk in one direction along the surface, there would be no wall there to stop you from doing so.

So there would be nothing beyond the surface of the ball that contains us if our universe is finite?

You miss the anecdote. The surface is two-dimensional. You have back/forth and left/right, but no up/down.

Contrary to the surface of the ball our universe is three-dimensional. In other words you couldn't get out of the universe by simply moving in the directions: back/forth, left/right, or up/down.

In our example of the ball "up/down" would translate to "back/forward in time". So beyond the surface you'd have the future, which technically is seen as part of the universe.

So if you discovered a fuel that would allow a vehicle to travel forever on one vector, assuming that it doesn't impact something along the way, what would happen to it? In that case would it not eventually come to the end of the universe?

Originally posted by Ascendancy
So if you discovered a fuel that would allow a vehicle to travel forever on one vector, assuming that it doesn't impact something along the way, what would happen to it? In that case would it not eventually come to the end of the universe?

If you put a model train in a loop and have it go around and around does it ever reach the "end" of the loop?
If you get in a plane and fly all over the world do you ever reach the "end" of the world?

These are easy to visualize because we have brains evolved and developed to handle those kinds of things. Mathematically its been proven that the same thing is possible with things that have more (spatial) dimensions but unfortunately there's no way to visualize that. I don't know of any indication that the universe is really shaped like that, though.

There are other ways to have a bounded universe with no edge. One of my favorites is the plate world from Flatterland. At the center of the world a box is 10 feet tall and 10 feet wide. Half way to the edge its 5 feet tall and 5 feet wide. As a result you can never reach the edge (because your stride is always too short) and you have infinite space. The same thing can be made to work in three dimensions with the same result. There's no reason to believe it happens anywhere but it is kind of neat.

Originally posted by Ascendancy
So if you discovered a fuel that would allow a vehicle to travel forever on one vector, assuming that it doesn't impact something along the way, what would happen to it? In that case would it not eventually come to the end of the universe?

Well technically that isn't possibly either because the universe is expanding at the speed of light. Meaning that you'd have to move faster than light to get back to your position, which isn't possible.

Originally posted by Symmetric Chaos
There are other ways to have a bounded universe with no edge. One of my favorites is the plate world from Flatterland. At the center of the world a box is 10 feet tall and 10 feet wide. Half way to the edge its 5 feet tall and 5 feet wide. As a result you can never reach the edge (because your stride is always too short) and you have infinite space. The same thing can be made to work in three dimensions with the same result. There's no reason to believe it happens anywhere but it is kind of neat.

Originally posted by Astner

Well technically that isn't possibly either because the universe is expanding at the speed of light. Meaning that you'd have to move faster than light to get back to your position, which isn't possible.

What's outside, ie what is (if anything) the universe expanding into while it's growing?

Originally posted by Robtard
What's outside, ie what is (if anything) the universe expanding into while it's growing?

Originally posted by Robtard
What's outside, ie what is (if anything) the universe expanding into while it's growing?

Originally posted by Lord Lucien
Other universes. Our expansion is their reduction. Eventually another universe will start expanding and begin squeezing ours, pushing in to a single point that will one day be forced to start expanding again.

Originally posted by Astner
What it's expanding into is the future, from the perspective of general relativity the future is already there we've just not reached it yet. It's not expanding in a spatial direction -- back/forward, left/right, and up down.

So you really don't know either. No worries.

Originally posted by Robtard
So you really don't know either. No worries.