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Re: How can the universe be infinite?

Anonymous — Tue, 20 Aug 2013 00:08:25 GMT

Author: Anonymous

Posted: 08/20/2013 04:08

tekin wrote:

If "the universe is shaped exactly like the earth, and if you go straight long enough you end up where you were" then you would know that it's finite but it isn't because it's been proved that it's flat meaning that it's expanding and it will expand infinitely just to approach a stillness as it's limit. This results have been established through observing Type Ia Supernovae and nuances in Cosmic Microwave Background radiation and calculations of space curvature in Euclidean system (presupposed geometrical system of a global geometry as opposed to local one which can be explained consistently in Minkowskian system through general relativity) which itself results in a flat universe and Nobel Prize in physics was awarded to Saul Perlmutter, Brian P. Scmidt and Adam Reiss two years ago partly for this discovery.

It's true that the universe has been measured to be flat, at least to the precision we can measure right now, but inflation muddies the waters about the finite/infinite question. Also, the current model of the universe has the universe accelerating its expansion indefinitely into the future (rather than eternally decelerating). There's still a lot we don't understand about the energy components of the universe, though, so this picture could change.

Re: How can the universe be infinite?

AlexZangari — Wed, 14 Aug 2013 14:46:18 GMT

Author: AlexZangari

Posted: 08/14/2013 18:46

swedenman wrote:

Hm. Well, I'm not sure the best way to explain it. I'll put it this way: Imagine you have an infinite hotel with an infinite number of occupants. Now let's pretend like you have an infinite number of such hotels. Now fuse all of them together into one super-infinite hotel.

Okay, well that hotel's number of occupants would actually have the same cardinality as the number of occupants in the original hotel, but it has still "grown" in a sense.

Okay, here's a better explanation: If you have a hotel with an infinite number of occupants and one more person shows up, the hotel will "expand" or "grow" in a sense. The number of occupants will be the same as far as we're concerned, but it's also gotten "bigger".

I'm sorry if that makes no sense. The concept of "infinity" is a very ambiguous one.

Oh yeah, this sounds familiar now. Igotchu.

Re: How can the universe be infinite?

Anonymous — Wed, 14 Aug 2013 11:02:45 GMT

Author: Anonymous

Posted: 08/14/2013 15:02

The universe can only be finite if it's closed (Like a sphere or sth) because in any other scenario there will be so-called edges and because space is presupposed in our understanding of universe (and it exists because of the universe) then space is determined by extension of universe so that space is present when there is universe and because that's our boundary then it's infinite; if you don't understand this I can make it clear with an example that uses our arbitrary boundaries (which was, I think, first provided by Hawking): when you ask if universe is infinite, the question is equivalent of another more analysed question: "Is there anything beyond universe?" You may think that universe could still be finite if there wasn't anything beyond it; but that's only a mistake of grammar. Universe is all that there is and space is one of its properties (well if we're talking conventionally and not in terms of general relativity) so to say that space is finite is to say that it ends somewhere and to say that it ends somewhere requires that something else begins where it ends but universe is all that there is so nothing begins after universe so it doesn't end anywhere and anything that doesn't end and have no edges is infinite. To think otherwise is just failing to understand the meaning of words and that's just an illusion of common sense; like you wouldn't ask "what is south of the south?". If "the universe is shaped exactly like the earth, and if you go straight long enough you end up where you were" then you would know that it's finite but it isn't because it's been proved that it's flat meaning that it's expanding and it will expand infinitely just to approach a stillness as it's limit. This results have been established through observing Type Ia Supernovae and nuances in Cosmic Microwave Background radiation and calculations of space curvature in Euclidean system (presupposed geometrical system of a global geometry as opposed to local one which can be explained consistently in Minkowskian system through general relativity) which itself results in a flat universe and Nobel Prize in physics was awarded to Saul Perlmutter, Brian P. Scmidt and Adam Reiss two years ago partly for this discovery.

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 19:14:32 GMT

Author: Anonymous

Posted: 08/13/2013 23:14

Or maybe I can reinterpret what I said and think outside the box a little more. Maybe our universe is actually extremely small. We just think it's big because we think of our universe relative to us. Maybe there are things seemingly infinitely bigger than our universe. Or maybe our universe is actually some kind of computer simulation. Maybe our universe is just somebody's snowglobe of some kind. And what do they live in? You know, the things controlling or building our simulation of whatever kind? Do they live in a universe? Or maybe something totally different? And these things... creatures or whatever... maybe their intelligence is so big, they can instantly know and understand everything that ever happened in our universe as easily as we can answer 2 + 2, which is their "normal", meaning it's not that they are really smart, it's that we aren't as special as we think of ourselves.

heh...

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 19:00:37 GMT

Author: Anonymous

Posted: 08/13/2013 23:00

Robert Anton Wilson wrote:

You mean, like a president or a prime Minister?

Uhh... if this a reference to something... I'm clueless, if not, I'm not sure why a president (on earth?) would know more than some high minded scientist of some kind.

But anyway, I guess what I was originally thinking of was maybe some kind of robot race that can evolve and improve itself unimaginably fast. Or maybe it's something beyond machine. Or maybe I'm wrong and humans can actually solve this thing. We're at least self important enough to fancy ourselves doing it.

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 17:25:00 GMT

Author: Anonymous

Posted: 08/13/2013 21:25

AlexZangari wrote:

Well colour me hornswaggled and paddle me with a frozen beaver. I thought I was at least right about that part. 🫢 Now I need someone to explain to me how something that can still get bigger is somehow not finite.

Re: How can the universe be infinite?

Robert Anton Wilson — Tue, 13 Aug 2013 16:49:13 GMT

Author: Robert Anton Wilson

Posted: 08/13/2013 20:49

The Poe wrote:

Meh, maybe there is a higher being than us somewhere that has the answer

You mean, like a president or a prime Minister?

Re: How can the universe be infinite?

GeevyDallas — Tue, 13 Aug 2013 16:33:28 GMT

Author: GeevyDallas

Posted: 08/13/2013 20:33

Seen the title, knew it was an_outlaw's thread

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 15:25:29 GMT

Author: Anonymous

Posted: 08/13/2013 19:25

Re: How can the universe be infinite?

them — Tue, 13 Aug 2013 13:49:51 GMT

Author: them

Posted: 08/13/2013 17:49

This thread has caused my brain to blow a fuse. Now I'm not sure that I can count to 10 anymore let alone give some kind of answer 🤡

Re: How can the universe be infinite?

AlexZangari — Tue, 13 Aug 2013 13:36:28 GMT

Author: AlexZangari

Posted: 08/13/2013 17:36

swedenman wrote:

Well, I'm not going to deal with the rest of the topic, since it's late and I'm too tired to give anything resembling an insightful response, but no. There are different magnitudes of infinity, so an infinitely large entity could very plausibly continue to grow.

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 05:13:00 GMT

Author: Anonymous

Posted: 08/13/2013 09:13

Meh, maybe there is a higher being than us somewhere that has the answer, but relating it to us would probably be like explaining what color is to a blind person. Maybe, I dunno. I guess I take the apathetic approach to these things. I'm not sure if I really care at all about finding these sort of answers. I'm more in awe at how... big... things... are. And existing in the first place.

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 03:53:58 GMT

Author: Anonymous

Posted: 08/13/2013 07:53

SilverWalrus wrote:

So what you're saying is that the universe is shaped exactly like the earth, and if you go straight long enough you end up where you were?

😁

I laughed too hard at this one.

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 03:40:27 GMT

Author: Anonymous

Posted: 08/13/2013 07:40

MrFrogger wrote:

Good one Chris

I can see that!

Okay, that was enough of my pretentious jargon anyway. I think the real solution to this thread is to listen to "Piper at the Gates of Dawn." It won't answer any of your questions, but it will make them seem cooler.

Re: How can the universe be infinite?

MrFrogger — Tue, 13 Aug 2013 02:01:41 GMT

Author: MrFrogger

Posted: 08/13/2013 06:01

sp4cetiger wrote:

Not really, I was just using the earth as an analogy. The similarity is that when you're on the earth, it seems flat, as if it could go on infinitely in any direction. However, if you traveled far enough, sooner or later you'd get back to where you started. This would tell you that the earth is not flat, but really a finite object.

Similarly, the universe *could* be a closed object. The difference is that we're no longer talking about a closed surface, like the earth is, but a closed manifold in three spatial dimensions. A finite universe wouldn't have to be spherical, it could be any shape if you allow for a large enough manifold.

But the universe could be infinite, we just don't know.

Haha, he was referencing this

Link

Good one Chris

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 02:00:14 GMT

Author: Anonymous

Posted: 08/13/2013 06:00

SilverWalrus wrote:

So what you're saying is that the universe is shaped exactly like the earth, and if you go straight long enough you end up where you were?

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 01:45:58 GMT

Author: Anonymous

Posted: 08/13/2013 05:45

sp4cetiger wrote:

If it were finite and closed, then there would be no boundary; that is, if you started going in one direction, then eventually you would come back to where you started. Much like what would happen if you started walking along the earth in some random direction, you would eventually come back to where you started.

So what you're saying is that the universe is shaped exactly like the earth, and if you go straight long enough you end up where you were?

Re: How can the universe be infinite?

Anonymous — Tue, 13 Aug 2013 01:25:41 GMT

Author: Anonymous

Posted: 08/13/2013 05:25

AlexZangari wrote:

And it can't get bigger if it's already infinite, right?

Re: How can the universe be infinite?

AlexZangari — Tue, 13 Aug 2013 00:09:17 GMT

Author: AlexZangari

Posted: 08/13/2013 04:09

It's expanding, so it's getting bigger, right? And it can't get bigger if it's already infinite, right? So it must be finite, or am I thinking about this in completely the wrong way? 🤡

Re: How can the universe be infinite?

Anonymous — Mon, 12 Aug 2013 18:35:24 GMT

Author: Anonymous

Posted: 08/12/2013 22:35

an_outlaw wrote:

If it was finite then what would the end be? If it finite what could be outside?

I actually do this stuff for a living, so hopefully I can help clarify some of these things. Your main question is more of a philosophical one, but the above can be answered more precisely.

When astronomers talk about the "size of the universe," we usually mean "what's the furthest thing we can see?" This is the observable universe and it has a finite size because the universe has a finite age. Light can only have traveled so far in that amount of time.

However, when a non-astronomer asks about the size of the universe, they usually mean something quite different. They want to know about all that "is", even if we can't see it. This question has to do with the topology of the universe.. At the moment, we can't say anything meaningful about the topology -- the universe could be finite or infinite. If it were finite and closed, then there would be no boundary; that is, if you started going in one direction, then eventually you would come back to where you started. Much like what would happen if you started walking along the earth in some random direction, you would eventually come back to where you started.

This sounds like it would be impossible and in normal "Euclidean" space, it is. This is the classical three-dimensional space that everyone's intuition is developed in. Since Einstein, however, the universe has been cast in terms of a four-dimensional space-time in which such things can occur. Don't bother trying to visualize it, we're simply not built to do that.

As for what's "outside" of a finite universe, then the answer is nothing! In such a scenario where the topology is closed, the universe would be all that there is.

I'll give my thoughts on the rest later (my son is screaming).