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Fraser
2004-Jul-20, 05:15 PM
SUMMARY: The theory that the expansion of our Universe is accelerating got another boost this week by a group of researchers from Princeton University. They used data in the Sloan Digital Sky Survey to measure the light from 3,000 quasars. They weren't looking at these quasars, though, but at diffuse hydrogen gas that sits in space partially obscuring the intervening space. The light from the quasars is changed depending on how much this gas that it has to go through. The astronomers were able to get a sense of how this gas clumped together over time, and their results exactly match the inflationary model of the Universe.

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Guest
2004-Jul-20, 06:14 PM
incredible I wasn't sure they had evidence for this weird negative-energy or anti-gravity stuff but now they can see it affecting the universe, so it won't be ending in a big crunch but more like a big rip pulling galaxies and atoms apart ?

Guest
2004-Jul-20, 07:03 PM
yes, it's a wonderful area of study but I don't think the universe will be ending in a big rip anytime soon
here it is



No evidence of dark energy changing in time has emerged so far, and the possibility that the universe will be torn apart by a big rip in the future is substantially reduced by these new results


looks like we're ok for now :)

StarLab
2004-Jul-20, 11:47 PM
Still, I don't think DE would ever get a final confirmation....there's gotta be a lot more math involved, not some random observation. They just focused on one part of the sky...maybe the story is a bit different elsewhere. These people are under the assumption that this Dark Energy, this...force, is responsible for expansion. I don't follow that logic. Nothing causes expansion. Expansion just is. It is purely geometrical.

devilmech
2004-Jul-21, 09:03 AM
Originally posted by StarLab@Jul 20 2004, 11:47 PM
Still, I don't think DE would ever get a final confirmation....there's gotta be a lot more math involved, not some random observation. They just focused on one part of the sky...maybe the story is a bit different elsewhere. These people are under the assumption that this Dark Energy, this...force, is responsible for expansion. I don't follow that logic. Nothing causes expansion. Expansion just is. It is purely geometrical.
Can I have some of what you're smoking? :blink:

Expansion doesn't just happen. Let's take air for example. For air to expand, it must be heated, causing it to expand by increasing the kinetic energy of it's constituent atoms. As for expansion being geometrical, I would be glad if you could elaborate on that one for me.

String Fan
2004-Jul-21, 10:28 AM
Expansion is geometrical in so far as it's an increase in the quantifiable (or for the time being, unquantifiable in the case of our universe ;) ) size of something.
It requires an energy source for this to occur though, whatever that may be, so I don't think it "just is".
That is, unless you (devilmech) can provide an example of expansion that occurs without the need for energy.

StarLab
2004-Jul-21, 03:07 PM
I usually picture the universe as a grid, almost. The operation of gravity on this grid is almost mechanical: in my view, spacetime is a punctuated Euclidean grid.