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alien life possibility is pathetic

Lonewulf said:
But if space WERE infinite, outside of where matter is... what is space expanding into, then?
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The usual analogy is to draw two dots on a balloon and then expand it some more and note that the two dots are now further apart. I don't like it because it doesn't address the idea that the balloon is actually expanding into 3-D space that already exists around it. For the analogy to work, just think of the surface of the balloon as "space". (For the analogy, space is just 2-D.) It's actually new space coming into being between the two dots (galaxies).
 
Lonewulf said:
The definition of the universe, as far as I know it, is wherever there is space (not necessarily matter), and the matter can only exist inside the space (and cannot travel outside it). The problem is (correct me if I'm wrong), the Big Bang *created* Space/Time, which expands.

There's a few theories, but the common one now (I may be wrong), is that if you traveled beyond the edge of the universe, you'd just end up on the other side, much as if you would if you ran around the globe. This has to do with the universe having four physical dimensions, and we can only see into the third (much like a 2-dimensional creature couldn't really perceive us as anything but a shadow of ourselves).

Keep in mind, I'm relying entirely on my own self studies, and an Introduction to Astronomy course at Del Mar College.
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I read a book by Einstein on relativity that said something along the lines (that I interpreted) that space didn't curve into something extra dimensional so much as it just curves. So the universe could be finite yet unbounded, yet there is no need (in terms of relativity, not saying it doesn't exist) for a ... spacious 4th non temporal dimension. But I must admit I was a little lost.
 
Mitchell314 said:
But I must admit I was a little lost.
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Since I've still got my Douglas Adams out, try this for understanding the topology of the universe:

"You get this bath, see? Imagine you've got this bath. And it's ebony. And it's conical."
"Conical?" said Arthur, "What sort of ..."
"Shhh!" said Ford. "It's conical. So what you do is, you see, you fill it with fine white sand, alright? Or sugar. Fine white sand, and/or sugar. Anything. Doesn't matter. Sugar's fine. And when it's full, you pull the plug out ... are you listening?"
"I'm listening."
"You pull the plug out, and it all just twirls away, twirls away you see, out of the plughole."
"I see."
"You don't see. You don't see at all. I haven't got to the clever bit yet. You want to hear the clever bit?"
"Tell me the clever bit."
"I'll tell you the clever bit."
Ford thought for a moment, trying to remember what the clever bit was.
"The clever bit," he said, "is this. You film it happening."
"Clever."
"That's not the clever bit. This is the clever bit, I remember now that this is the clever bit. The clever bit is that you then thread the film in the projector ... backwards!"
"Backwards?"
"Yes. Threading it backwards is definitely the clever bit. So then, you just sit and watch it, and everything just appears to spiral upwards out of the plughole and fill the bath. See?"
"And that's how the Universe began is it?" said Arthur.
"No," said Ford, "but it's a marvellous way to relax."
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Here is our message to fellow aliens somewhere out there.
Hope they like the music we put on it.


Kind of looks like the symbols in crop circles.

Maybe the aliens are trying to tell us something here. Sending back
what they may consider incoherent and silly symbols and
sending these symbols back in spades. :D
I still think SETI is worth a shot, we might actually hear something someday.
Better than not listening. I can just picture some alien watching our old broadcasts of
television and not being able to switch channels.
We should shoot a TV remote out into space, as a friendly gesture of course.
 
Lonewulf said:
But of course, if the universe was infinite with an infinite amount of matter -- including stars -- then that would make one wonder why we don't see an infinite amount of light in the sky?

But if space WERE infinite, outside of where matter is... what is space expanding into, then?
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Theoretically ? Itself.
 
Mitchell314 said:
I read a book by Einstein on relativity that said something along the lines (that I interpreted) that space didn't curve into something extra dimensional so much as it just curves. So the universe could be finite yet unbounded, yet there is no need (in terms of relativity, not saying it doesn't exist) for a ... spacious 4th non temporal dimension. But I must admit I was a little lost.
Click to expand...

Einstein was great, but there were some discoveries they had yet to make at the time; for instance, he believed that the universe would eventually collapse into itself, culminating into a new Big Bang, and then collapse into itself again for another Big Bang, and everything would be remade just the way it was (a sort of an infinite loop).

However, new evidence has been brought to light, demonstrating that the universe doesn't have the critical mass required, based on observations, to collapse in on itself. Further, galaxies are all moving away from one another (like in the balloon analogy, of which I'm well aware of), and are *accelerating* in their speed away from each other.

A little off topic, though. I'm not sure how right he is on this one. I'll need to take another astronomy course :)
 
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JoeTheJuggler said:
The usual analogy is to draw two dots on a balloon and then expand it some more and note that the two dots are now further apart. I don't like it because it doesn't address the idea that the balloon is actually expanding into 3-D space that already exists around it. For the analogy to work, just think of the surface of the balloon as "space". (For the analogy, space is just 2-D.) It's actually new space coming into being between the two dots (galaxies).
Click to expand...

This sort of assumes that the universe has a shape, not that it's infinite, though.
 
You're right that the answer isn't light fading. It also doesn't mean that the universe is necessarily finite. We can only see light up to about 14 billion light years away because the light hasn't had more time than that to travel. (We can't see galaxies that might be further away because that light hasn't reached us yet.) As the universe continues to expand, some of it will always be farther away than there has been time for the light to reach us.
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Makes sense.
 
That theory should be relatively easy to resolve, too, if time-intensive: If we see more and more as the years pass on, then the theory would be semi-proven.
 
Lonewulf said:
This sort of assumes that the universe has a shape, not that it's infinite, though.
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It was meant to explain expansion (not whether or not space is finite or infinite) without getting to the completely wrong idea that the expansion of the universe means it's expanding into existing space.

It's actually expanding space itself. Think of it as new space coming into being between the galaxies.
 
JoeTheJuggler said:
It was meant to explain expansion (not whether or not space is finite or infinite) without getting to the completely wrong idea that the expansion of the universe means it's expanding into existing space.

It's actually expanding space itself. Think of it as new space coming into being between the galaxies.
Click to expand...

Nonono, I already understood expansion, and how it doesn't need existing space to expand. My point was more a criticism of the infinite universe theory more than anything.
 
Lonewulf said:
That theory should be relatively easy to resolve, too, if time-intensive: If we see more and more as the years pass on, then the theory would be semi-proven.
Click to expand...
But if we don't, it doesn't disprove it because of expansion. As I said, as long as the universe keeps expanding, there will always be stuff that's farther away than there has been time for its light to reach us. (I don't know how to say that without such torturous grammar.)

When we look as far away as we can see, we see quasars (primitive galaxies, most likely). There isn't much further to see because that's about as early (after the Big Bang) as stuff was making light for us to see.

That still doesn't prove the universe must be finite. It just means we can only see about 14 billion light years in any direction.
 
Lonewulf said:
So, ultimately, it's unfalsifiable?
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What is?

Whether space is finite or infinite is beyond me. I have no idea what evidence (if any) could prove any of the models one way or another.

That we can only see some 14 billion light years away is fact. That light travels at the constant velocity is fact.

That the universe is expanding is as close to fact as you can get, I think.

My comment that the fact that we don't see an infinite amount of light in our skies doesn't prove that the universe is finite is just a logical application of known facts.

That the universe isn't expanding into existing space is based on our models of the Big Bang. Whenever someone shows an image of the Big Bang (like an animation), they always have "us" on the outside as observers as if it happened in existing space. It didn't. The Big Bang happened everywhere in the universe. There was and is no outside the universe. So in answer to your question about what the universe is expanding into (if the universe is infinite), I pointed out that it doesn't expand into anything. Expansion is rather just new space (or space-time, I suppose) coming into being between stuff (galaxies). There's not necessarily an edge or a frontier of expansion. Expansion happens throughout the universe (which is the same thing as saying the Big Bang happened everywhere in the universe not at some central point in an existing universe of space).

ETA: I'm no authority on these things. There are actual physicists in the forum who could probably give you some of the math and have more complete answers than my meager layman's knowledge.
 
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Whether or not there's actually anything out farther than we can see.
 
Lonewulf said:
Whether or not there's actually anything out farther than we can see.
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As far as I know that's not testable.

On the other hand, if they've got mathematical models (equations and what not) that describe what we can test very well, and the models say that there's no center and no edge and so on, does that constitute "evidence"? How about if those models predict that there's more than what we can see, AND something else that is testable, and that test supports the equation? That's not directly supporting the untestable prediction, but it seems to me since it gives more support to the model, it's reasonable to suspect that model is true. (Or more accurate than other models.)

At any rate, I'm not claiming the universe is infinite. I'm just saying that the argument that we'd see an infinite amount of light if it were, and that since we don't, it's not, doesn't stand up. I know it sounds silly, but the reason we don't see an infinite amount of light in the sky is simply that the universe isn't infinite within a sphere of diameter about 14 billion light years with us at the center. (That is, in this finite sphere, there aren't an infinite number of stars and galaxies.)

ETA: This is true whether the universe is infinite (there's more to beyond that 14 b.l.y radius) or finite (for example, that 14 b.l.y. radius sphere is all there is). For that matter, there could be more universe beyond that distance AND the universe could still be finite. (Meaning we're not even seeing all the light from a finite number of light sources.)
 
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Another take on expansion:

The distance from Kansas City to St. Louis is about 300 miles. Imagine that distance is getting greater. It's not because St. Louis is moving east across the Mississippi into Illinois or Kansas City is moving west into the sunflower fields in Kansas. It's because the highway itself is getting longer. (Or there's more mid-Missouri coming into being.) St. Louis is still on the eastern edge of Missouri, and Kansas City on the western edge. There's must more Missouri in between. (It's not expanding into the surrounding states either.)
 
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