Earth's absolute speed

His Divine Shadow · Post by **His Divine Shadow** » 2003-07-16 08:38am

Durandal wrote:Whether or not the universe is open or closed depends upon the critical mass density versus the distribution of matter. If the mass density is not sufficient (i.e. does not meet the critical mass density), the universe is negatively curved and will expand forever. If the mass distribution of the universe is the same as the critical mass density, the universe is flat and will expand forever, which is what it's looking like. If the mass distribution exceeds the critical mass density, the universe is closed, and we'll end up seeing a Big Crunch.

Hmpf, I was looking forward to the big crunch.

Durandal · Post by **Durandal** » 2003-07-16 10:05am

kojikun wrote:
Durandal wrote:No, it's not. The universe's "shape" is determined by the net amount of spacetime curvature it has, which is in turn affected by gravity, which is in turn affected by mass. Critical mass density affecting the shape of the universe is a simple consequence of general relativity.
Been through this before. Mass cannot affect the curvature of spacetime without an external force acting upon it.

That's just the nature of mass, as far as we know. It's irrelevant whether or not there is an external force doing something. The end result is the same, space time is curved, and critical mass density still affects the shape of the universe.

The Silence and I · Post by **The Silence and I** » 2003-07-16 11:24am

This stuff is getting deep

This is what I live for sometimes.

kojikun · Post by **kojikun** » 2003-07-16 02:04pm

Durandal wrote:That's just the nature of mass, as far as we know. It's irrelevant whether or not there is an external force doing something. The end result is the same, space time is curved, and critical mass density still affects the shape of the universe.

We don't have any evidence for curved space caused by mass, however. Thats where the problem lays, theres no evidence.

Durandal · Post by **Durandal** » 2003-07-16 05:56pm

kojikun wrote:
Durandal wrote:That's just the nature of mass, as far as we know. It's irrelevant whether or not there is an external force doing something. The end result is the same, space time is curved, and critical mass density still affects the shape of the universe.
We don't have any evidence for curved space caused by mass, however. Thats where the problem lays, theres no evidence.

Please look up the general theory of relativity. Mass generates gravity, and gravity causes curves in space-time. Now, there could be a potential chicken and egg problem here -- does mass curve space-time, or does mass occur where space-time is curved? -- but that is irrelevant. What is relevant is that mass is an indication of space-time curvature.

kojikun · Post by **kojikun** » 2003-07-16 06:03pm

Durandal wrote:Please look up the general theory of relativity. Mass generates gravity, and gravity causes curves in space-time. Now, there could be a potential chicken and egg problem here -- does mass curve space-time, or does mass occur where space-time is curved? -- but that is irrelevant. What is relevant is that mass is an indication of space-time curvature.

Thats not evidence, dumb dumb, its supposition. Einstein put that into his theory because he was a very big fan of Kaluza-Klein and the attempts to turn forces into geometry. There isn't EVIDENCE, just theory that has no backing up. There is no indication of space-time curvature at all, no observation, just the theory of relativity which could have supplemented any unverified theory (build up of ether, for all i care) for space-time curvature.

Durandal · Post by **Durandal** » 2003-07-16 07:00pm

kojikun wrote:Thats not evidence, dumb dumb, its supposition. Einstein put that into his theory because he was a very big fan of Kaluza-Klein and the attempts to turn forces into geometry. There isn't EVIDENCE, just theory that has no backing up. There is no indication of space-time curvature at all, no observation, just the theory of relativity which could have supplemented any unverified theory (build up of ether, for all i care) for space-time curvature.

Yes you're absolutely right. There's not a shred of evidence to backup general relativity's prediction of gravity causing space-time curvature, just Einstein's predicted deviation of a light beam around a massive body being in line with observation, the prediction of the perihelion's placement in Mercury's orbit, global positioning satellites using general relativistic corrections for length and time dilation and achieving higher precision when doing so and countless other verified predictions, including the existence of black holes. Regardless of why Einstein originally put that postulate in there, he was absolutely correct.

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