Odd Thoughts on Universe's Expansion

[dgavin]

I had one of those disturbing thoughts last night that an amature vulcanologist/geologist shouldn't be even pondering.

I was sitting there thinking 'Why did the universe after some half it's life start expanding and the expansion accelerates?'

Then I remember something in a sci article about the universal constants might be changing, (i wish i could remember where i read this though) and jumped to this.

"What if the Gravitational constant degraded to the point where expansion could not be contained? The universe would Expand again, addiationally as the gravitational constant degraded more, the expanstion would seem to accelerate would it not?"

Which led me to this hypothetical answer. "The gravitational constant of the universe is (may be) inversly (square or cube) related to the energy distribution by the size of the the universe itself. As the universe and space expands and the energy density decreases, the gravitational constant also decreases."

And one hypothetical prediction:
"The rate of the gavitational constants degradation and it's relation to the expanstion, if valid, should be determinable by reversing the process from it's current value, back in time to the point expansion began."

So what do you all think, may I have stumbled upon a possible explanation? Or like am I just barking up the wrong expansion tree?

[Vermonter]

Could be, but I like to say, "We don't have enough data yet...we're not sure yet!"

[dgavin]

Thats sort of what i figured. Which is why i only posted the one prediction of the hypothisis, that might be verifiable or disproven at this point.

I'd like to work on that except, i'd need some assistance with the math, as this is a bit beyond finding the epicenter and magnitude of a quake.

Any pointers or suggestions that way?

[Cougar]

I was sitting there thinking 'Why did the universe after some half it's life start expanding and the expansion accelerates?'
Well, it's always been expanding. Observations indicate that until the universe was about half its current age -- when everything was closer together -- the gravity of all the mass in the universe was slowing the expansion. But when the expansion passed a certain point, the vacuum energy (or dark energy) of the now more voluminous space began to dominate the slowing effect of the gravity. Strange thing about the vacuum energy: as space expands, its inherent energy content does not get diluted, as one might naturally think. That energy content was always there, but it only started coming into play when the amount of space in the universe got to be large enough. After that, the expansion stopped slowing, and then it slowly started speeding up. It's remarkable that observations confirm this!

Then I remember something in a sci article about the universal constants might be changing... "What if the Gravitational constant degraded to the point where expansion could not be contained? The universe would Expand again, addiationally as the gravitational constant degraded more, the expanstion would seem to accelerate would it not?"... Which led me to this hypothetical answer. "The gravitational constant of the universe is (may be) inversly (square or cube) related to the energy distribution by the size of the the universe itself. As the universe and space expands and the energy density decreases, the gravitational constant also decreases."... So what do you all think, may I have stumbled upon a possible explanation? Or like am I just barking up the wrong expansion tree?
Woof! I'm afraid this forest has been explored.

[Tony Rothman] has investigated this problem for at least one choice of variable-G theory and found that at three minutes after the Big Bang, G must have been essentially what it is now.

The Brans-Dicke [variable-G] theory has been constrained so much by observations of the binary pulsar's orbital period that it is virtually the same as special relativity. Probably the last believers in the Brans-Dicke theory died at the Port Authority Bus terminal [in 1984]." :o

See Science a la Mode, Physical Fashions and Fictions [1989] -- Tony Rothman (General Relativity professor at Harvard)

[dgavin]

Thanks for the information. Seems i'm only 22 years out of date, Guess I'll stick to dog'ing volcanoes:lol: