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Is the Universe infinite?


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7 hours ago, dordle-loddle said:

Is the Universe infinite or just really, really big?

As MigL has said the observable universe is certainly finite, and around 96 billion L/years in diameter. The  WMAP  probe showed the universe to be very nearly flat within small error bars, and that in the main points to an infinite universe, although a universe shaped like a torus which is also flat, is obviously finite.                                                                                     The other point to remember  is the "flatness" as per WMAP did have error bars, albeit small, which in effect could mean that the flatness measured is simply an arc of a much larger closed universe. In any respect though the universe is pretty big or as I like saying [and have been taken to task over it] near infinite in extent and content. :P

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15 hours ago, dordle-loddle said:

Is the Universe infinite or just really, really big?

You should specify what you meant by that.

Infinite volume of the Universe.. ?

Infinite quantity of protons in the Universe.. ? (therefor infinite mass)

Infinite lifetime of the Universe.. ? (f.e. never ending expansion)

Infinite quantity of versions of the Universe.. ? (Parallel Universes, Multiverses)

 

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The question is was our big bang everything?  Or are there adjacent big bangs that are far beyond our visual horizon?  OUR universe is probably finite in size simply because it is "easier" for a finite big bang to happen than an infinite one.  Infinity is a very special animal.  If the creation of the universe is comparable to pulling a rabbit out of a hat, an infinite universe is like pulling a unicorn out of that hat.  Which is more likely?   Of course I could be wrong, but this is something nobody can prove or disprove, until an adjacent big bang impacts the visual horizon of our big bang.

Edited by Airbrush
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If string theory/superstring theory/M-theory or any of those variants is correct then our universe could be part of a much much larger multi-verse. In fact our universe could be a grain of sand in something much much bigger.

The problem is that we don't yet have a theory of everything (we don't even have a theory of quantum gravity) so from the perspective of physics we can't yet really know if universe is finite or infinite.

I believe the universe is really infinite in extent but because of the laws of special relativity we will never be able to travel to another galaxy.

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  • 2 weeks later...
On ‎8‎/‎4‎/‎2017 at 4:04 AM, seriously disabled said:

If string theory/superstring theory/M-theory or any of those variants is correct then our universe could be part of a much much larger multi-verse. In fact our universe could be a grain of sand in something much much bigger........

I believe the universe is really infinite in extent .......

What makes you think the universe is infinite in extent when you previously said the universe could be "part of a much larger multiverse", which means our universe is finite, the multiverse is infinite, and we could be only one of many, maybe one of an infinite number of other big bangs?

Edited by Airbrush
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7 minutes ago, Airbrush said:

What makes you think the universe is infinite in extent when you previously said the universe could be "part of a much larger multiverse", which means our universe is finite, the multiverse is infinite, and we could be only one of many, maybe one of an infinite number of other big bangs?

Being part of a multiverse does not mean our universe must be finite.

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On ‎8‎/‎12‎/‎2017 at 5:19 PM, swansont said:

Being part of a multiverse does not mean our universe must be finite.

How can a universe that has infinite size be contained within an infinite sized multiverse?

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21 minutes ago, Airbrush said:

How can a universe that has infinite size be contained within an infinite sized multiverse?

There are an infinite number of rational fractions between 1 and 2. And between 2 and 3. And so on for an infinite number of integers.

More surprisingly, perhaps, there are an infinite number of real numbers between each pair of integers. And this infinity is larger than the infinity of integers.

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26 minutes ago, Airbrush said:

How can a universe that has infinite size be contained within an infinite sized multiverse?

This will mess you up most likely but it is possible to divide an infinite quantity an infinite number of times and each portion will still be infinite.

The theoretical multiverse could be the same, so could our own universe.

Edited by Mordred
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I'm still baffled, because on the scale of the universe, I don't see how you can stuff more than one infinite-sized universe into a multiverse.  An infinite number of rational fractions between 1 and 2 is interesting but not a realistic model for universes within multiverses.  The scale must remain constant.  You cannot have tiny-sized universes (between numbers 1 and 2) that are also infinite in size.

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A question worthy of a thousand books trying to prove either side. The only way to concretely say yes or no is to have a view of the entire universe, and unless you happen to be capable of "Leaving Hotel California" (The universe), I am afraid that there is no answer that is true or false except one: Perhaps it is, Perhaps it isn't.

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1 hour ago, DanTrentfield said:

A question worthy of a thousand books trying to prove either side. The only way to concretely say yes or no is to have a view of the entire universe, and unless you happen to be capable of "Leaving Hotel California" (The universe), I am afraid that there is no answer that is true or false except one: Perhaps it is, Perhaps it isn't.

Or perhaps the Hotel Hilbert in this particular case.

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3 hours ago, Airbrush said:

I'm still baffled, because on the scale of the universe, I don't see how you can stuff more than one infinite-sized universe into a multiverse. 

If the universe is infinite, then "on the scale the universe"doesn't really mean anything. (Apart from the fact you seem to be basing your conclusions on what you can imagine or what "feels" right. Neither of which have much chance of working in this context.)

Quote

An infinite number of rational fractions between 1 and 2 is interesting but not a realistic model for universes within multiverses. 

Why not?

Quote

You cannot have tiny-sized universes (between numbers 1 and 2) that are also infinite in size.

You can if they are infinite. The number line is an almost perfect analogy for this.

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2 hours ago, beecee said:

The best one can say is that the Universe is at least near infinite in extent and content.

How exactly would you define "near infinite"? That sounds a lot like "a little bit pregnant". 

 

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34 minutes ago, zapatos said:

How exactly would you define "near infinite"? That sounds a lot like "a little bit pregnant". 

I believe it describes a state that is probably finite, but also humongously big and in realty beyond  human measuring capabilities. I have been taken to task over it before, but I also believe the definition I gave, would be obvious to most people. 

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7 hours ago, Mordred said:

This will mess you up most likely but it is possible to divide an infinite quantity an infinite number of times and each portion will still be infinite.

That does mess me up. I thought each portion was finite. Or infinite.

 

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