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Fazor
2006-Nov-02, 06:16 PM
Okay, I was just reading on http://www.astro.ucla.edu/~wright/nocenter.html that the big bang has no center. Am I picturing it correctly then that distance in relation to each point (galaxy, solar system, whatever you want to compaire) is just growing uniformly? Heh, my struggle with the english language may be hindering what i'm trying to say (hey, it's only my native tounge, how well *should* I know it?). So i don't know if what i'm asking is clear.

I guess...instead of everything moving away from point "A", everything is moving away from everything else proportionate to it's origonal distance? "expanding" if you will. Like, if you put a bunch of dots on a half-filled balloon then filled it with more air?

astromark
2006-Nov-02, 06:44 PM
The parts of a solar system and / or galaxy are gravitationally bound. So do not share this mass expansion but other than this small glitch. Your understanding of the 'Big whomp' is right.

DaveC426913
2006-Nov-03, 06:04 PM
As is your analogy to dots on the surface of an expanding balloon.

Fazor
2006-Nov-03, 06:57 PM
Okay so i got one thing right, lets try for two.

Would it be a fair analogy to say then that the "force" of whatever that caused the expansion of the universe works on large bodies such as galaxies but not on a small scale (planets, stars, solar systems, etc still bound by gravity) i the same way that, say a bomb going off next to a brick wall may cause the bricks to scatter but (for the most part) the molecules that make up the bricks stay intact?

err, might not be the best example as the mortar being weaker than the bricks contributes.

or is it more because space, or spacetime, is expanding but matter is not?

phunk
2006-Nov-03, 07:15 PM
Expansion works on all scales, but it's such a small effect that it's only visible when added up over large distances. The local forces holding together atoms, molecules, people, planets, etc are all much stronger and keep things together as space expands 'out from under them'. But while gravity grows weaker with distance, expansion grows stronger with distance. I believe the current estimate is something like 60km/s per megaparsec. So a distance of over 3.25 million light years will expand by only 60km/s. To put that in perspective, the space occupied by the entire planet earth will expand only about 1 nanometer each second.

Ken G
2006-Nov-03, 11:27 PM
To put that in perspective, the space occupied by the entire planet earth will expand only about 1 nanometer each second.

Nevertheless, if that expansion were really happening, in the 10^17 second existence of the Earth, it would be a huge expansion. That expansion is not happening, because the Earth's own gravity prevents it. Also note: notwithstanding dark energy, there is no "force" causing the expansion, it is an initial condition of the universe. Apparently, the comoving space in our universe was expanding when it was made. No one knows how or why.

Cougar
2006-Nov-05, 03:46 AM
Apparently, the comoving space in our universe was expanding when it was made. No one knows how or why.Alan Guth (http://insti.physics.sunysb.edu/itp/OWP/talks/aguth/) does. :p

Ken G
2006-Nov-05, 05:39 AM
Actually, inflation comes after the initial condition, and is therefore part of the dynamics of the universe, not the initial cause. There is nothing even remotely resembling an explanation for the initial cause, and don't give me "colliding branes". Colliding brains, perhaps.

gzhpcu
2006-Nov-05, 06:54 AM
Actually, inflation comes after the initial condition, and is therefore part of the dynamics of the universe, not the initial cause. There is nothing even remotely resembling an explanation for the initial cause, and don't give me "colliding branes". Colliding brains, perhaps.

Yet, colliding branes is still the only thing nearest to a plausible explanation, isn't it? Yes, I know you have to accept 6 additional spatial dimensions, but heck, it is at least an attempt at an explanation....:)

Mister Earl
2006-Nov-05, 01:56 PM
Who knows what the universe is? For all we know, we're just sentient nodes in some kid's computer simulation. In ten minutes, his mother will call him to dinner, and we'll all vanish as he turns his simulator off. It's for a good cause, though, I have a feeling he's having hot turkey sandwiches. Mmmm.

Ozzy
2006-Nov-05, 02:25 PM
We are but choc chips in the universal muffin?!

Ken G
2006-Nov-06, 01:19 AM
Yet, colliding branes is still the only thing nearest to a plausible explanation, isn't it? Yes, I know you have to accept 6 additional spatial dimensions, but heck, it is at least an attempt at an explanation....:)

Saying that the Earth is carried on the back of a turtle is also an attempt at an explanation. I'll await some form of observational constraints/predictions.

Kaptain K
2006-Nov-12, 05:20 AM
Yet, colliding branes is still the only thing nearest to a plausible explanation, isn't it? Yes, I know you have to accept 6 additional spatial dimensions, but heck, it is at least an attempt at an explanation....:)
Actually, brane theory requires 7 extra dimensions.

closetgeek
2006-Nov-12, 10:58 PM
lol, can you prove we don't exist on the back of a turtle?


Saying that the Earth is carried on the back of a turtle is also an attempt at an explanation. I'll await some form of observational constraints/predictions.

Cookie
2006-Nov-13, 05:47 PM
Satellite Imagery...

Ken G
2006-Nov-14, 07:26 PM
All right, an invisible turtle then...