My first post revisited.

Rye · Post by **Rye** » 2003-06-22 11:44am

Just remembering back to my first post when i asked about how the universe was speeding up in it's expansion.

Well apparently it's because of gravity's long-range repulsive effect, but that's not important.

What i want to know is : If the universe is continuing to speed up, when the matter starts to be accellerated towards c, will it gain almost infinite mass and cause a big crunch?

I remember that the big crunch theory has gone out of fashion recently because the universe is speeding up, but it can't speed up forever, as eventually ordinary matter will reach c.

So will there be a big crunch or will something i've not quite thought through happen?

Kuroneko · Post by **Kuroneko** » 2003-06-22 12:08pm

Rye wrote:What i want to know is : If the universe is continuing to speed up, when the matter starts to be accellerated towards c, will it gain almost infinite mass and cause a big crunch?

Of course not. The mass increase, by a factor γ=1/sqrt(1-v²), means the gravitational force will be increased by that amount. However, the higher mass also means that the momentum p=mv=γm0v is increased by that amount as well, so that the net effect is precisely zilch--the increase in force precisely cancels out the increase in momentum.

Meanwhile, their distance will continue to increase, so that the net gravitational effect will go down to zero.

Hamel · Post by **Hamel** » 2003-06-22 02:17pm

One theory states that eventually everything will get ripped apart from the sheer speed

Kuroneko · Post by **Kuroneko** » 2003-06-22 02:23pm

Hamel wrote:One theory states that eventually everything will get ripped apart from the sheer speed

That makes no sense--speed is irrelevant unless there is an impact with something else (which is not the case here). You probably mean that the acceleration difference between one part of an object and another will be enough to rip apart anything.

Hamel · Post by **Hamel** » 2003-06-22 03:21pm

Kuroneko wrote:
Hamel wrote:One theory states that eventually everything will get ripped apart from the sheer speed
That makes no sense--speed is irrelevant unless there is an impact with something else (which is not the case here). You probably mean that the acceleration difference between one part of an object and another will be enough to rip apart anything.

That was probably it. Sorry.

NapoleonGH · Post by **NapoleonGH** » 2003-06-22 03:21pm

remember also that it isnt the matter in the universe that is being accelerated it is the universe itself. THe space around the galaxies is speeding up in exansion making the galaxies move themselves because the space they occupy is moving.

Enforcer Talen · Post by **Enforcer Talen** » 2003-06-22 09:33pm

woah. that is a deep thought.

cool sig btw. I just saw that episode.

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My first post revisited.

My first post revisited.

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