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Author Topic: Ok, the universe. Infinite in size or what?  (Read 7033 times)

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Offline KennyR

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Re: Ok, the universe. Infinite in size or what?
« on: July 02, 2004, 09:44:29 PM »
@PMC

Space can expand faster than light. The edge of the universe which should be 14 billion ly away is around 27 billion ly away.

Consider the expansion of the universe as a sequence of phase transitions, like that which occur to water. As water cools and looses energy, it turns from vapour to water to ice. As the universe expanded and cooled, certain fundamental forces and effects 'froze out'; before these instants the universe's contents were too chaotic and high energy to make these forces felt individually. The expansion of space faster than the speed of light may have been possible during one of the earlier phases, but froze out and stopped after a certain point. It may be that the velocity of light actually changed to allow this effect to happen.
 

Offline KennyR

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Re: Ok, the universe. Infinite in size or what?
« Reply #1 on: July 03, 2004, 12:00:22 AM »
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T_Bone wrote:
If this is the case, I wonder what happens when universes start expanding into each other?


By definition, they can't. A universe is a universe; once a big bang happens there's no longer the conditions within that universe for it ever to happen again.

Besides which, the laws of physics are finely tuned and we would be able to detect the presence of other big bangs in our universe even if possible by mathematical analysis of fundamental properties.
 

Offline KennyR

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Re: Ok, the universe. Infinite in size or what?
« Reply #2 on: July 03, 2004, 04:40:53 PM »
Such as: the velocity of light. This is proportional to the energy 'stored' in the vacuum of the universe in the form of transient energy. If energy was to condense again from the vacuum catastrophically enough to cause another big bang, the main result would be a drop in the speed of light. (Which would probably destroy physics as we know it, and certainly make all current life processes stop).

At all other times, the speed of light and the energy contained in the vacuum form an equilibrium which prevent the universe 'exploding' into expansion the way it did just after the big bang.

Every particle in the universe effects every other. You couldn't not notice if there was another big bang outside our sphere of possible observation, even if it was possible for there to be another one (and it ain't).
 

Offline KennyR

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Re: Ok, the universe. Infinite in size or what?
« Reply #3 on: July 05, 2004, 04:01:03 PM »
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Dandy wrote:
What makes you so sure that the physical properties of the universe itself prevent anything travelling beyond the speed of light?


Because it would break all known physical and mathematical laws to do so.

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Especially by the given background, that just last week it was in the news, that scientists succeeded in "beaming" (dematerialisation, transport, rematerialisation) single atoms over a short distance.


No, they did not. They teleported the properties of atoms over a short distance, or teleported single photons. There is no point where a whole atom was ever 'teleported'.

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If the gravitation of an black hole is really that big that even its own light can't escape from it, then it seems logical to me, that, if you're caught by the gravitation of this black hole, you will be accelerated in the direction of the centre of this gravity.

As this gravity is that strong, that even light can't escape from it, it is logical that you will be accelerated so much , that you exceed light speed before reaching the surface of this black "hole".


No, that's not right. Firstly, light speed is constant and can't be accelerated or decelerated - not by gravity, not by anything. It can't escape a black hole simply because there is a point where the incident light beam is curved towards the singularity so much, instead of getting back out it just spirals inwards and is gone. Never once during this process does it change speed.

And to accelerate mass to light speed would require all of the energy in the universe - including the energy contained in the mass you're trying to accelerate. As you can see this is quite impossible. Not even a black hole can ever do this.

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In my point of view (if I understood everything right) exceeding the lightspeed means that you leave the 4-dimensional space-time continuum and enter the next (fifth?) dimension.


Actually you're already present in 11 dimensions according to String Theory. Many of these hidden ('compactified') dimensions are closer to you than your clothes.
 

Offline KennyR

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Re: Ok, the universe. Infinite in size or what?
« Reply #4 on: July 05, 2004, 04:46:06 PM »
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Cymric wrote:
I'm sure you know that this reason in itself is not a valid one, but I cannot resist adding a little clarification for those who might not know: laws of nature are not written in stone.


I disagree. They're absolute and changeless, the maths from which the fractal pattern of the universe is drawn. Only humanity's understanding of them can possibly be 'broken'.