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Author Topic:   The infinite space of the Universe
IamJoseph
Member (Idle past 3668 days)
Posts: 2822
Joined: 06-30-2007


Message 31 of 380 (467338)
05-21-2008 1:19 AM
Reply to: Message 15 by Agobot
05-19-2008 4:45 PM


Einstein supported a finite universe. This is logical - else we would have no cnstant measurements of any kind. Space is also finite and post-universe. We know there was a beginning, aka BB, and when a single point existed - there was no space around it, but emerged later, as expansion occured.
Because a finite entity cannot contain anything infinite, all within the universe did not exist before the BB, including space, energy, matter, particles, heat, expansionism, forces, etc, etc.
Thus there is no scientific alternative to creationism and monotheism. I have always been a firm believer that science would be the best venue to prove this.

This message is a reply to:
 Message 15 by Agobot, posted 05-19-2008 4:45 PM Agobot has replied

Replies to this message:
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Agobot
Member (Idle past 5530 days)
Posts: 786
Joined: 12-16-2007


Message 32 of 380 (467341)
05-21-2008 3:02 AM
Reply to: Message 31 by IamJoseph
05-21-2008 1:19 AM


quote:
Einstein supported a finite universe. This is logical - else we would have no cnstant measurements of any kind. Space is also finite and post-universe. We know there was a beginning, aka BB, and when a single point existed - there was no space around it, but emerged later, as expansion occured.
Because a finite entity cannot contain anything infinite, all within the universe did not exist before the BB, including space, energy, matter, particles, heat, expansionism, forces, etc, etc.
Thus there is no scientific alternative to creationism and monotheism. I have always been a firm believer that science would be the best venue to prove this.
  —IamJoseph
The is a very very big difference between the material universe being finite(well proven) and the empty space(which so far appears to be infinite and which happens to be the topic here).
Speaking of gods, magic, voodoo, ghosts and the like in serious threads is rather childish.
Edited by Agobot, : No reason given.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 33 of 380 (467348)
05-21-2008 6:39 AM
Reply to: Message 23 by Agobot
05-20-2008 4:16 AM


Re: Is it infinite?
How do you know space is finite
We don't, yet. It may be finite, it may be infinite. What you call the material content is just another aspect of space-time, and is as finite or infinite as the space.
even if the universe has a spherical shape - which is just a hypotesis by all means now
No, it is not a hypothesis. It is a (eventually) verifiable prediction of General Relativity, should the density of the Universe be above a critical value.
So if the empty space of the universe is finite, as you claim, when do we reach the boundery
There is no boundary - if the Universe is finite it is topologically compactified into a hyper-sphere, or possibly some other more complex topological object (e.g. hyper-torus) Again, there are no *last*galaxies. All of space is filled with matter, whether the Universe is finite or infinite.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 34 of 380 (467352)
05-21-2008 7:20 AM
Reply to: Message 30 by onifre
05-20-2008 6:10 PM


So it is mass that curves spacetime
Yes
through the percieved forces of gravity
** NO **
Common misconception. "Gravity" is a perceived effect of the curved space-time. It has nothing to do with the generation of the curvature itself. That is a completely local effect: the curvature at a point in space-time is a function of the energy density at that point and the immediately surrounding space-time curvature.
if we traveled in one direction of spacetime we could technically end up in the same place we started from however, do to the universe expanding at a rate faster that the speed of light this is impossible because we could never reach that speed?
Yes, although the 'expanding faster than the speed of light' is a very imprecise concept and doesn't actually have to be true to still prevent someone from returning to their starting point.
Is this what is meant by infinite spacetime? The fact that it could never be caught up with so its basically an infinite journey?
No - this is still finite. Infinite means infinite.
how exactly is the expantion rate measured
extra distance generated per unit distance per unit time - so say an extra 10 metres for every 10^8 metres every year. However, we often swap this round to give km per second per Mega-Parsec, which ends up giving the cumulative recession velocity (km/sec) per unit (mega-parsec) distance. So at 10 km/sec/Mpc, an object 10 MPc away will be receeding at a velocity of 100km/sec. This recession velocity can exceed the speed of light becasue it is not a true velocity - it is simply a measure of how much distance is being generated between two objects (galaxies). There is no actual local movement of either galaxy, although observations of each from the other certainly show recessional movement.

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Marcosll
Junior Member (Idle past 5778 days)
Posts: 25
From: Estepona, Spain
Joined: 02-14-2008


Message 35 of 380 (467353)
05-21-2008 7:45 AM


Infinite
I think the universe must be inifite for practicle purposes, otherwise it would collapse onto itself at some point.
I think we'd like to believe the universe is finite for comprehension purposes, similar to like how people in ancient times thought the earth was flat because it was easier to comprehend.
Another thing that's difficult to comprehend is the difference between "empty space" and "nothingness". Space is some "stuff" that extends infinitely in all directions around us.

Estepona Apartments - Apartments for sale and rent in Estepona, Spain

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lyx2no
Member (Idle past 4716 days)
Posts: 1277
From: A vast, undifferentiated plane.
Joined: 02-28-2008


Message 36 of 380 (467360)
05-21-2008 8:16 AM
Reply to: Message 35 by Marcosll
05-21-2008 7:45 AM


Necessary Consequence
I think the universe must be inifite for practicle purposes, otherwise it would collapse onto itself at some point.
Please explain why a finite universe must collapse upon itself and how you know this one won't.
In laymen terms, please. Not all of us can follow the advanced maths.

Kindly
A mind changed against its will is of the same opinion still.

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cavediver
Member (Idle past 3643 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 37 of 380 (467361)
05-21-2008 8:19 AM
Reply to: Message 35 by Marcosll
05-21-2008 7:45 AM


Re: Infinite
I think the universe must be inifite for practicle purposes, otherwise it would collapse onto itself at some point.
In the old cosmology, this is exactly what happens... so what? Given that the Universe is around 14 billion yesrs old and strill expanding, even if it were to recollapse, it would take >14 billion years to do so. Why is this an issue?
In modern cosmology we recognise an accelerative component to the expansion, suggesting that even if the Universe is finite, it will not recollapse.

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onifre
Member (Idle past 2951 days)
Posts: 4854
From: Dark Side of the Moon
Joined: 02-20-2008


Message 38 of 380 (467368)
05-21-2008 9:02 AM
Reply to: Message 34 by cavediver
05-21-2008 7:20 AM


Common misconception. "Gravity" is a perceived effect of the curved space-time. It has nothing to do with the generation of the curvature itself. That is a completely local effect: the curvature at a point in space-time is a function of the energy density at that point and the immediately surrounding space-time curvature.
So the energy density is the 'known' so to speak, and the effects of gravity is whats perceived, Ok. Yeah I should have read your origin responce properly.
Now, you said 'immediately surrounding space-time', is that 'immediatelty surrounding' area relative to the amount of mass on the object?
In other words, well I think im wording the question properly, every object generates its own curvature however, when we look at a galaxy, is it the total amount of mass in the galaxy that curves space-time or each individual piece of matter within the galaxy that curves it individually and it gives the effect that the entire galaxy is doing it? Or is it both?
extra distance generated per unit distance per unit time
So basically its measured by the Doppler effect?
Does this mean that the galaxies will eventually collapse in like a reverse Big Bang? I hope that kinda made sense...

All great truths begin as blasphemies

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New Cat's Eye
Inactive Member


Message 39 of 380 (467380)
05-21-2008 11:16 AM
Reply to: Message 38 by onifre
05-21-2008 9:02 AM


Does this mean that the galaxies will eventually collapse in like a reverse Big Bang? I hope that kinda made sense...
Have you heard of the Big Crunch?
In other words, well I think im wording the question properly, every object generates its own curvature however, when we look at a galaxy, is it the total amount of mass in the galaxy that curves space-time or each individual piece of matter within the galaxy that curves it individually and it gives the effect that the entire galaxy is doing it? Or is it both?
The mass of an object creates the curvature. Each individual piece of matter curves it individually and it all adds up together (probably in some kind of superposition or something) so to answer your question... it is both.

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Replies to this message:
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New Cat's Eye
Inactive Member


Message 40 of 380 (467384)
05-21-2008 11:24 AM
Reply to: Message 21 by Agobot
05-20-2008 3:56 AM


Re: Is it infinite?
LOL. You said the space in the Universe if finite but unbounded/I quoted that/. Then you gave an example with the spherical shape of the Earth as being finite and unbounded. And now you don't know what you have meant by "finite but unbounded spherical 3-dimensional empty space"?
I guess I don't understand what you are asking for...
Care to rephrase it?
You seem to view the universe as residing within something else. This is not the case. The universe is all encompasing. There is not outside of it. It isn't expanding through something. The expansion is just a result of its 4d shape.
BTW, you have a wrong idea about the theory of the unbounded but finite universe. It only applies to the material portion of the universe(galaxies). It does not apply to the seemingly infinite empty 3-dimension space of the Universe(of which we talk about here and which is beyond the last, farthest galaxies).
Umm, no I'm not. The space itself is a "material portion of the universe" in a way (depending on what you really mean by that phrase).
The last farthest galaxy!? Farthest from what? The Earth? Why does that even matter?

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Agobot
Member (Idle past 5530 days)
Posts: 786
Joined: 12-16-2007


Message 41 of 380 (467390)
05-21-2008 11:45 AM
Reply to: Message 33 by cavediver
05-21-2008 6:39 AM


Re: Is it infinite?
quote:
So if the empty space of the universe is finite, as you claim, when do we reach the boundery
  —Agobot
quote:
There is no boundary - if the Universe is finite it is topologically compactified into a hyper-sphere, or possibly some other more complex topological object (e.g. hyper-torus) Again, there are no *last*galaxies. All of space is filled with matter, whether the Universe is finite or infinite.
  —cavediver
"All of space is filled with matter". How do you know that? This seems like a very bold statement for the modest stage of our development.
I would be inclined to think that empty space is empty space and matter is matter. I don't really see them as one inseparable entity. Unless you mean that prior to T=0 there had been no empty space. But there is no way you could know that.
If space and matter are one inseparable entity, as you suggest, what is the matter(substance) that the universe is expanding into? Nothingness? Nothingness doesn't exist and it would seem like a form of over-simplification to think that the universe is expanding into nothingness(especially in our material world).
Edited by Agobot, : No reason given.

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Marcosll
Junior Member (Idle past 5778 days)
Posts: 25
From: Estepona, Spain
Joined: 02-14-2008


Message 42 of 380 (467392)
05-21-2008 11:59 AM
Reply to: Message 41 by Agobot
05-21-2008 11:45 AM


Re: Is it infinite?
Empty Space isn't empty/void/null.
Current research seems to indicate that what you describe as "matter" is actually produced by some other currrently undetectable energies existing in the "empty space".
There's a reason it's often called "fabric of space".
Simple logic tells us that if "nothing" separates two things they must be adjacent. Further still, if space was "nothingness" or "empty" then fields (such as gravity) couldn't exist in it by definition.
Edited by Marcosll, : No reason given.

Estepona Apartments - Apartments for sale and rent in Estepona, Spain

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New Cat's Eye
Inactive Member


Message 43 of 380 (467398)
05-21-2008 12:54 PM
Reply to: Message 41 by Agobot
05-21-2008 11:45 AM


Re: Is it infinite?
If space and matter are one inseparable entity, as you suggest, what is the matter(substance) that the universe is expanding into?
Space, iself, is expanding... not the matter within space.
And it doesn't expand through something and it isn't expanding into something.
The universe has a four deminsional shape that is an expansion in 3d. That's all.

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Replies to this message:
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Agobot
Member (Idle past 5530 days)
Posts: 786
Joined: 12-16-2007


Message 44 of 380 (467399)
05-21-2008 12:54 PM
Reply to: Message 42 by Marcosll
05-21-2008 11:59 AM


Re: Is it infinite?
quote:
Further still, if space was "nothingness" or "empty" then fields (such as gravity) couldn't exist in it by definition.
Lots of unsupported claims in this thread. What makes you think there is gravity in the empty space of the universe(beyong where we think matter ends, say 90 billion light years away from us)? How could you state that as a fact?

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Agobot
Member (Idle past 5530 days)
Posts: 786
Joined: 12-16-2007


Message 45 of 380 (467400)
05-21-2008 1:01 PM
Reply to: Message 43 by New Cat's Eye
05-21-2008 12:54 PM


Re: Is it infinite?
quote:
Space, iself, is expanding... not the matter within space.
And it doesn't expand through something and it isn't expanding into something.
The universe has a four deminsional shape that is an expansion in 3d. That's all
This is another gross over-simplification. In the material world that we happen to live in, EVERYTHING is contained into something else(bigger).
We don't know if space is expanding(so far we know about matter expanding), let alone what space is expanding into or if the whole universe is self-contained(as you claim, which seems like an over-simplification).
Edited by Agobot, : No reason given.
Edited by Agobot, : No reason given.

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