Is the universe infinite?

[Science Guy]

?

[Eclogite]

If we accept the BIg Bang theory then space wasn't always there.

 

There are topologies that allow for a finite universe that has no edge. It doesn't matter that you (or I) don't understand the maths - it is possible, so your argument for infinity based on incredulity won't stand.

[Science Guy]

?

[Eclogite]

why would I believe in something that hasnt been proven..... string theory proves other wise, you should definitely look into that, if you believe time as another dimension, plus the other 10 dimensions and parallel universes, which string theory inclines to pursue the point, that the universe is in fact infinite....

String theory does not prove otherwise. String theory would better be described, in my view, as string hypothesis, since no evidence has been brought forward to support it. I am not even sure that all versions of string theory call for an infinite universe. your argument just doesn't wash, since it isn't an argument.

[modest]

To have something be finite it would need to end or be boxed off, per say.

 

Not necessarily. A spatially closed universe, like Einstein's model, is spatially finite yet unbound. It's like the surface of a balloon. An ant can walk around the surface of the thing forever and never bump into a boundary... but it has only so much space.

 

~modest

[borgius]

You guys (and/or gals) trying to explain the Universe is like ants, or rather amoebas, trying to explain how computers work.

[maddog]

As Modest says, the analogy of a balloon in 3-space is the best I can think of. The universe being infinite in extent has nothing to do with any string theories.

There actually may something here to consider -- Does the "edge of the universe" extend beyond what is the "visible universe" (the one we see). This has

not been "officially" corroborated. Somewhere around 12+ billion light years out seems to get very dim. Even for the Hubble telescope.

 

Another comment on the universe is if closed then this would be very similar to a balloon. Alternatively, what if the the universe were to be shaped like a

saddle surface. This would then be unbounded and infinite.

 

maddog

[borgius]

Does the "edge of the universe" extend beyond what is the "visible universe" (the one we see). --- maddog

.

 

EDGE OF THE UNIVERSE? And what is beyond that "edge"?

 

......................

 

12 billion lightyears as the visible Universe?

.

 

Just think of a balloon with a, let's say, 999 trillion lightyears radius, and Earth in its center. Well, this relatively huge balloon is nothing but a speck of dust, or not even that much, when compared to the rest of the Universe. You can think of a balloon of any size, e.g. with a radius of 900,000,000,000,000,000,000,000,000,000,000,000,000,000,000 times 900,000,000,000,000,000,000,000,000,000,000,000,000,000,000 times 900,000,000,000,000,000,000,000,000,000,000,000,000,000,000 lightyears, and get

900,000,000,000,000,000,000,000,000,000,000,000,000,000,000 of these ballons... and the total volume of all these unimaginably large ballons is still nothing more than a speck of dust

when compared to the rest of the Universe.

 

Although, the Universe could be nothing more than a simple trick. Why do I say this? Look at empty space - somewhere between two galaxies where the void is almost completely empty, no

matter of any kind (other than the max. 10 Hydrogen atoms per cubic-meter). As we understand it, in the void there is nothing. More exactly, in the void between the few Hydrogen atoms, and the few massless photons that might be passing through, there is absolutely nothing. This means the void is nothing. Well, THIS VOID, THIS

NOTHING IS THE UNIVERSE ITSELF (with the galaxies in it here and there). THIS VOID, THIS N O T H I N G, HAS DIMENSIONS IN ANY POSSIBLE DIRECTION !!!

 

HOW CAN NOTHING HAS DIMENSIONS ?

 

What is the VOID made of if it is nothing?

 

I'd better stop right here...

[modest]

Just think of a balloon with a, let's say, 999 trillion lightyears radius, and Earth in its center. Well, this relatively huge balloon is nothing but a speck of dust, or not even that much, when compared to the rest of the Universe.

Certainly, if the universe is spatially infinite then the 999 trillion lightyears sphere is vanishingly small in comparison. The question, however, is if the universe is infinite.

 

General relativity tells us that there is a critical density, [math]\Omega[/math] beyond which the universe is closed like a four dimensional sphere. We can measure the curvature by measuring the density of space. Measurements tell us that the universe is very nearly flat (Omega is very nearly equal to unity). However, measurements are not yet accurate enough to know if Omega is exactly equal to one or slightly more or less.

 

If Omega is slightly more than one (let's say 1.01) then the radius of curvature will be about 140 billion lightyears (a circumference of about 800 billion lighyears). The universe will not be infinite and the sphere of r = 999 trillion lightyears would be larger than the universe.

 

You can read how the shape of the universe is related to its size here: Shape of the Universe -- Global Geometry

[Vox]

 

NOTHING IS THE UNIVERSE ITSELF (with the galaxies in it here and there). THIS VOID, THIS N O T H I N G, HAS DIMENSIONS IN ANY POSSIBLE DIRECTION !!!

 

HOW CAN NOTHING HAS DIMENSIONS ?

 

What is the VOID made of if it is nothing?

 

I'd better stop right here...

 

 

Why should you , please do continue...I have always been interested of nothing.

[maddog]

EDGE OF THE UNIVERSE? And what is beyond that "edge"?

Simply something we don't see. What I mean it is beyond the flight time/[distance] for light to get to us.

HOW CAN NOTHING HAS DIMENSIONS ?

You can define a coordinate system in any finite dimension. If with confines of the metric you set nothing is contained then you have

a void. Coordinate systems are "critters" we ascribe as a tool for measuring something.

 

What Modest was telling you about Omega is how close to closure is the universe (below 1 - Closed, above 1 - Open, Exactly 1 - Flat).

What is the VOID made of if it is nothing?

According to Quantum Mechanics (QM), a Void is Never Exactly Empty. This is because of Vacuum Fluctuations.

Because of the Heisenberg Uncertainty Principle you can have something created from nothing.

I'd better stop right here...

Carry on as you see fit.

 

maddog

[borgius]

According to Quantum Mechanics (QM), a Void is Never Exactly Empty. - maddog

 

.

 

I am not talking about what is or isn't in the void. i AM TALKING ABOUT THE VOID ITSELF. Let's suppose for a moment that there is absolutely nothing there, not even the very few Hydrogen atoms (per cubic-meter), no photons, no radiation, nothing at all. The void (space) is still there. So, WHAT IS THE VOID (THE ABSOLUTELY EMPTY SPACE) MADE OF?

[Little Bang]

If we accept the BIg Bang theory then space wasn't always there.

 

 

wclog, do we have proof that time and space are inseparable? If we do then that excludes all other possible scenarios. Does a beginning constitute proof? I can imagine others, maybe the possibility of bigger and smaller universe's separated by the rate at which time moves and space being infinite. The Big Bang has no before the Big Bang, no time, no matter, no nothing. Regardless of who you are, scientist, engineer, layman or preacher, it’s got to bother you. No explanation can be given other than the famous ,“ It was a Quantum event. “, colliding brane’s or dimensions. That’s kind of like having to leave a good movie before the end. Surely there are some ideas out there to explain the BB and fit one or more of the observations we see today. I’ll start with my own science fiction tale.

 

A few weeks ago there was a discussion that started talking about photons. I tried to think of ways to better understand the photon. A low energy collision between two molecules or atoms seemed like a good place to start since that is where infrared photons are created. In a high energy collision at the instant just before the two atoms start to accelerate away from each other the energy density at the nearest point of contact should be enormous. Somewhat analogous to the Big Bang. Is it possible that a tiny Universe is created here, where clocks of this tiny Universe run trillions and trillions of times faster than our clocks? The expanding electric field would cause this tiny Universe to experience an accelerated expansion. This idea would suggest an infinite number of tiny Universes below the size of ours and an infinite number of larger Universes above the size of ours. Science fiction? Maybe not.

[HydrogenBond]

An infinite universe is a good mind expanding concept. But science can not prove an infinite universe with hard data. Between is a creative gap.

[modest]

i AM TALKING ABOUT THE VOID ITSELF

It looks like you're screaming about it. All caps are usually taken as shouting.

 

I am not talking about what is or isn't in the void..... Let's suppose for a moment that there is absolutely nothing there

 

The second sentence seems to contradict the first.

 

So, WHAT IS THE VOID (THE ABSOLUTELY EMPTY SPACE) MADE OF?

 

I don't see how it's related to the topic. Maddog's point is valid. Empty space, according to quantum field theory, is never truly empty. It has a vacuum expectation value. If this is unsatisfying then you might ponder a quote from Einstein on the subject, "People before me believed that if all the matter in the universe were removed, only space and time would exist. My theory proves that space and time would disappear along with matter." But, I really don't see how it's related to the topic.

 

~modest

[modest]

In a high energy collision at the instant just before the two atoms start to accelerate away from each other the energy density at the nearest point of contact should be enormous. Somewhat analogous to the Big Bang. Is it possible that a tiny Universe is created here, where clocks of this tiny Universe run trillions and trillions of times faster than our clocks?

 

No, that would be a false analogy. It's like saying, "bats and people are analogous because they have exactly the same internal body temperature. Therefore: people can fly". Colliding atoms may be like the universe in the sense that galaxies move away from each other and the atoms move away from each other but the atoms are not a universe.

 

~modest

[Little Bang]

Hydro, there is nothing supporting my fictional story except the inferred dark energy which I could claim is my expanding electric field that created our Universe in the first place. Also the fact that there is no limit on how fast or slow time can move. It can move infinitely slow or infinitely fast.