Big Bang Origin?

The observation of the expansion is an experimental confirmation of consequences of GR. As I understand (I can't do the math to confirm it myself) the expansion is a predicted property of spacetime. I only found this out recently and it is very impressive as GR has been so well confirmed in many other tests.The observed expansion and then the cosmic background radiation are experimental results that are expected from GR.

I don't blame you, but it's not surprising. I told you that you were asking deep questions, and you have pushed beyond Wikipedia's ranbge of utility. I would go further and say that Wikipedia's entry is BS, but I'm not that kind of guy It is because of dubious entries like this in popular science that I am employed (on an incredibly part-time basis) to help edit the UKs best selling dictionary of science on matters of astrophysics, cosmology, quantum theory, particle physics and fundemental theoretical physics. In other words... trust me and not Wikipedia This message has been edited by cavediver, 01-03-2006 04:32 AM

You'll appreciate them all the more when you see my reply to Crash over in "When a tree falls..." in defense of you Oh no, quite the opposite. It's just teaching from the ground up. There's no need to overcomplicate things. I have said many times that the way to learn this stuff is to understand the original closed big bang model in all its 4d wonder. You are then reasy to appreciate all of the other non-finite models. It's right on the edge. Recent measurements show it to be possibly just over critical density, but I would not be surprised if that changes. Inflation drives the universe towards Criticality from either side. But the main reason we will not recollapse is the observed acceleration of the expansion driven by a cosmological constant type device.

I am not sure if it as easy to explain as I will ask for, but I will ask nonetheless.Perhaps a "General Relativity tells us there should be a beginning singularity because GR says...... which tells us there should have been a singularity because...."If it is not that simple, perhaps a somewhat similar explanation would work. Either way, I need to see just how GR relates to the Big Bang.Also, does GR tell us anything of the shape of the Universe, or is that a different thing?Trék

Oops. That was a replay to cavediver. I'm still trying to get down this reply system :s.Sorry,
Trék

cavediver will give you an actual accurate answer pretty soon I bet In the meantime it is my understanding that what GR does is to imply that the universe is infinitely more likely to be either expanding or contracting than staying still. As cavediver mentioned already, Einstein hated this, he wanted a steady-state universe, so he tried to fudge the math.But really it's pretty simple, imagine a steady state as a point on a line with expanding being that infinite distance to the right and contracting being that infinite distance to the left. Obviously one or the other will be much more likely than that little point. The reason that it is GR that opens this can of worms is because it's the first real-world use of the idea of space that can be thicker or thinner, as it were. Once it CAN do it, what's to stop it?But it's actually Hubble who produced the red-shift information that implied that expanding was what it was doing. From there it's a short leap backwards to the singularity, the singularity is just a point where the math has to stop. A careful study of the conditions that would have had to prevail shortly AFTER the singularity produces ideas like inflation and predictions like the Cosmic Microwave Background.And the CMB turns out to be exactly what was predicted. Ergo, the theories aren't moonshine anymore, people have to start fleshing them out.* Geez, how wrong am I?

I thought that NASA's WMAP site: WMAP Cosmology 101: Shape of the Universe Implied a open universe that is perpetual. The last updated Dec 05. Although I do believe what Cavediver says because he is still emersed in academia.

That's what these latest findings imply yes. Might end up being true, might not.But look a lot of people are confused about what it means if the universe is "infinite" or not. It's kind of like when the doctor says the test is "positive" that doesn't usually mean "good".What I mean is, a universe that keeps expanding and collapsing and perhaps re-expanding ad infinitum, that's the "finite" guy. The "infinite" universe keeps on shooting out into nothing until nothing is within the light horizon of anything else, even a particle, and that's the end of it, heat death. Any new universe thereafterward will have to shoot out of nothing on its own, it doesnt have the advantage of a big crunch to jumpstart it.

No, only that it looks very very flat. Which is what we expect from inflation. The question is, is it very very flat because:1) it is closed with staggeringly large radius2) it is open with vanishingly small curvature3) it is actually perfectly flat1) and 2) and what we expect from inflation, starting with a closed and an open universe respectively. 3) is the peculiar one.The flatness of the universe is a prediction of inflation confirmed by observation.

Yes, it absolutely does, and no, it is not a different thing at all. Plug in the mass distribution into GR and it tells you the shape of space-time. That is what it does. The singularity at t=0 is just the shape of the universe at that point. To put it simply, GR predicts that the universe is spherical (hyper-spherical) with a radius R and it shows us that R ranges from 0 at t=0 (the initial singularity) to some maximum value at t=0.5 and then reduces back to 0 (the final singularity) at t=1. When you see the R=0 at t=0 prediction, you say "wow, R=0 implies that there is an infinite density point at t=0"This message has been edited by cavediver, 01-04-2006 05:32 AM

Hello Cavediver,
Thanks for the reply.
I am always intriqued by nature. Everytime I think I am in understanding the "exception to the rule" clause always rears it's
head futher confounding me.I find it very amazing that the universe's self perpetuating nature allows the homeostasis that is condusive to our existance. That is the reason I am interested in the ultimate picture of what will eventually happen to all this stuff.

My question would to this would be....Where did they first universe come from?? I haven't read the entire converstaion sooooooooooooooo someone could have alread posted that!! lol oh well

clearly, you're doing a great deal of posting without reading threads. part of the discussion on this board is understanding what has been said. then, after you have read the whole thread and become aware of what the discussion has become, then you post something meaningful and not a sentence saying you haven't read the thread. further, i would suggest you check your spelling and grammar prior to posting since the posts of yours that i have read have been rather... well, they've needed work. (please don't mention my lack of capitalization, we've been through this. it's a style issue. my grammar is usually pristeen.)oh god i'm turning into a mod.This message has been edited by brennakimi, 01-29-2006 02:07 AM

ouch. =(couldn't my grammar be a style issue? =) =) so its not okay to reply to the original message? whoops! sorry I didn't know that...I'll read all of it next time. I was just curious as to what the original poster would say.This message has been edited by pianoprincess*, 01-24-2006 09:22 PMThis message has been edited by pianoprincess*, 01-24-2006 09:23 PMThis message has been edited by pianoprincess*, 01-24-2006 09:26 PM

i would suggest you check your spelling and grammar -------------------------------------------------------------- we've ben through this.ouch!