Steven S

Ignore my earlier post. Dr. Edenwald is perfectly correct to describe the gravitational field as spacetime (otherwise how would gravitation waves work?). I'm just being stupid and I guess I've had my QFT hat on too much lately.

Steven S

[ November 18, 2002: Message edited by: Steven S ]</p>

DNAunion

DNAunion: The inflationary model would explain this. Somewhere around 10^-35 seconds after the Big Bang itself began, and lasting only for a minute fraction of a second, the Universe underwent a series of exponential expansions, with parts of it "flying apart" from other parts at speeds much greater than that of light (this superliminal expansion is the whole point of inflation - it solves several "paradoxes" of the standard Big Bang theory). This did not defy relativity because things were not flying THROUGH space at speeds greater than light - it was space itself that was expanded at speeds greater than light, carrying "matter" along for the ride. After expanding by an absolutely enormous amount (I don't know, something like 10^xxxx times), inflation ceased and regular old expansion took over.

It is the episode of exponential expansion - inflation - at the very beginning that allows the Universe to be greater than 14 billion lightyears in diameter (or even in radius) even though it is only about 14 billion years old.

DNAunion: Some form of a steady state theory is still being proposed by a couple of its longtime adherents, but I think it is basically rejected by cosmologists overall. There may be other theories - I simply don't know.


DNAunion: One of the three main possible "geometries" of the Universe is the closed one with positive curvature (the other ones are open, with negative curvature, and flat, with 0 curvature). The closed case is often times modeled in two-dimensions as a ball - the surface represents the only dimensions that exist and one can travel in any direction indefinitely and yet never come to an edge. This is an imperfect 2-D model but does demonstrate how a Universe in higher dimensions (four) could be unbounded and yet finite.

[ November 19, 2002: Message edited by: DNAunion ]</p>

joedad

Here's something different:

<a href="http://www.sciencenews.org/20010922/bob9.asp" target="_blank">http://www.sciencenews.org/20010922/bob9.asp</a>

joe

Sidian

thanks again for the introductions to new theories.

i find multiple/parallel unverses really hard to swallow. i guess the inflationary model isn't alot better though.

could it be that light wasn't around at all when the big bang occured?

maybe matter was all there was and it flew apart with such speed (not heat, just speed) that it was nothing but hydrogen gas and couldn't be liquid or solid for the sole reason that it was "singlemindedly" heading in the direction away from the bang.

because it was traveling close to the maximum speed, the "time" it would take for cooling would be stretched so that full expansion of the universe would be possible (the particles of the gas would barely be moving at all relative to each other). they continue to fly apart until things slowed down and they started grouping into stars (standard theory from here on). could it be the energy from the combination into stars is what created light for the first time? what creates light now besides stars or some other manipulation of matter.

why do we believe light was there to begin with?

is this idea far fetched or proven against? everytime we try to push against what we already know i cringe. maybe that's why i have trouble holding onto situations where "physics break down"

eh

I guess it depends on what you're saying. Everything with a temperature above absolute zero emits light, or EM radiation to be more precise. Are you saying just visible light could not form, early on?

DNAunion

DNAunion: Also, when matter and antimatter meet - as was occurring right after the Big Bang - they undergo mutual annihilation, producing gamma rays (extremely energetic electromagnetic radiation).

I can't remember this too well - or is it badly - so forgive me if I go astray.

I think that light was always produced, but that during the first 300,000 years or so it could not get very far - photons would travel only a short distance before interacting with free electrons (or other particles): I believe that since they were free there was no restriction on the light's frequency - any wavelength would interact with electrons: the Universe was opaque. At about 300,000 years, the temperature had fallen enough that the average kinetic energy of particles was small enough that stable atoms could form. Photons then had to be of just the right frequency to interact with electrons (exact quanta) so a great many of them, which were not of a correct frequency to interact with hydrogen atoms, bypassed matter and kept going their ways: the Universe became transparent.

That's a GENERAL idea - the details may be wrong. Also, there's a specific term for this early transition from opaqueness to transparency, but I can't remember it off the top of my head.

Anyway, that is why the cosmic background radiation goes back to only about 300,000 years after the Big Bang - that is the point in time at which light became free to move without its almost instantly interacting with matter.

[ November 21, 2002: Message edited by: DNAunion ]</p>

Shadowy Man

DNAunion:

It is called the time of last scattering. Current observations of various aspects of the cosmic background radiation can allow us to infer information about the state of the universe at that time.

DNAunion

DNAunion: That’s not the term I was thinking of. I remembered the term seems like a misnomer because it starts with “re” even though it refers to the first time something happened (electrons combining with protons to form stable atoms). I spent a minute and found the term: recombination.

Answerer

I was wondering how did the massless particles at the beginning of the big bang changed formed into quarks and leptons after 10*-43 sec. Does anyone have an idea?


<img src="confused.gif" border="0">

DNAunion

DNAunion: What massless particles change into quarks and leptons?

It is thought by many that the Higgs boson (or is it the Higgs field) is what gives particles their mass. But does it turn massless particles like photons into quarks and leptons? I don't think so.