Universe expansion

General physics and astronomy discussions not directly related to Celestia
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JamesC
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Universe expansion

Post #1by JamesC » 13.09.2009, 14:33

A rambling and naive set of questions about universe expansion folks:

- The big bang: This creates 3D space and time - and occurred in nothing.
Therefore: Is it correct to say that the big bang occurred at every point in our current space - time?

- The cosmic microwave background: Similarly, this is isotropic and homogeneous: It suggests no origin, that is, it comes from everywhere with equal frequency and intensity for the same reason: It was created at the big bang, at every point in the (expanding) space-time ?

- And similarly: The vacuum energy or zero-point energy (identically the same thing incidentally?) - is this also completely isotropic, in which case, is it not also somehow linked to the origin of everything being everywhere?

And finally: a shot in the dark from a neophyte (me : ) who am ignorant re. general relativity:
The expansion of the universe, and resulting reduction in gravitation, means an increase in the rate of space-time expansion right?
Because space-time becomes bunched up where gravity is strong: Things are heavier, and time goes slower.
Dilute the matter - and time accelerates, and the rate of expansion increases: You observe an accelerating universe expansion because of space-time dilation through lower mass density.

And the mysterious "dark energy", which is still no more than a "deus ex machina" at present, that nobody has described in experimentally verifiable terms, becomes an irrelevance: We can do way with it.

But that explanation too obvious ... someone here can probably tell me why space-time expansion doesn't allow us to do away with this deus-ex-machina nasty "dark energy" problem.

So incidentally, I looked around and found a recent Russian theoretical paper by Minkevich along these lines:
doi:10.1016/j.physletb.2009.06.050
or
http://www.sciencedirect.com/science?_o ... rticle.pdf

which I don't understand much, but that seems to suggest something similar. As Minkevich says:
"Terms related to dark matter and dark energy ... are connected in considered theory with the change of gravitational interaction provoked by spacetime torsion."

which seems to be saying: Effects described by darn energy and dark matter can be ascribed to space-time torsion - and you can do away with "dark matter" and "dark energy" concepts entirely whilst remaining in a consistent picture.

Any cosmological experts around who can cast light on this?

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Fenerit M
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Re: Universe expansion

Post #2by Fenerit » 13.09.2009, 21:55

Just my two cents in these matters, then I leave out.

JamesC wrote:A rambling and naive set of questions about universe expansion folks:

- The big bang: This creates 3D space and time - and occurred in nothing.
Therefore: Is it correct to say that the big bang occurred at every point in our current space - time?

.

.

.


Nope, because into "nothing" cannot be something as "every"; for your question the more appropriate reply is to say that there isn't a preferential point. Your posit seem to assume "every point" as the same. One consequence of your assumption should be that all things moves itselves faster than the speed of light. (approx. the same reply is for the remnant questions)

For what concern the so-called "dark energy" or "dark matter" they are instruments philosophically equal to "phlogiston theory", "caloric theory" or "aether luminiferous" alike. They are put as "reasearching paths" they are Medieval concepts (quintessentia), IMHO. Note how in the string theory there are as much dimensions as were the "sphaere" in the medieval cosmology. They "save the phaenomena", no?
Never at rest.
Massimo

Topic author
JamesC
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Location: Spain

Re: Universe expansion

Post #3by JamesC » 19.09.2009, 09:52

Fenerit wrote:
JamesC wrote:A rambling and naive set of questions about universe expansion folks:

- The big bang: This creates 3D space and time - and occurred in nothing.
Therefore: Is it correct to say that the big bang occurred at every point in our current space - time?

Nope, because into "nothing" cannot be something as "every"; for your question the more appropriate reply is to say that there isn't a preferential point. Your posit seem to assume "every point" as the same. One consequence of your assumption should be that all things moves itselves faster than the speed of light. (approx. the same reply is for the remnant questions)

For what concern the so-called "dark energy" or "dark matter" they are instruments philosophically equal to "phlogiston theory", "caloric theory" or "aether luminiferous" alike. They are put as "reasearching paths" they are Medieval concepts (quintessentia), IMHO. Note how in the string theory there are as much dimensions as were the "sphaere" in the medieval cosmology. They "save the phaenomena", no?

Hi there - I didn't mean "every point is the same", that is, that there is no such thing as space, that would be silly.
I didn't mean "There is no such thing as distance" - I was wondering about the location of the big bang, and wondering if that question has meaning.

More clearly, perhaps, this is what I meant:
The universe has no beginning or end - only a maximum distance or maximum space-time volume from any point in that space-time.
So the rest of space-time loks the same from any point in space - and the question "Where did the universe start" is therefore meaningless - You could say 'it started everywhere at once' because the zero-dimensional singularity where the big bang kicks off is coincident with every four dimensional space-time point.
You could also say "it started nowhere and everywhere - the question has no meaning" which, I guess, might be the best way to think of it.
To conclude: Is there any cosmoligist about who can either
A) explain why the question "where did the big bang occur" is meaningless
or
B) let us know where this business kicked off, if it's not meaningless.

I reckon it's a meaningless question - and interesting all at once.


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