anyone know anything about astrophysics? i have a question about the universe

Spectral emitters (like stars and galaxies) that are most distant from us show a spectral 'shift'. Just like a train that races by with the whistle blowing, it seems to emit a different pitch racing away from us, to that heard when the train was approaching. Just so, spectral emitters can be shown to be racing away from us based on measurable parts of the spectra that are 'absent'. These absent portions of spectra are wavelengths that are absorbed by the elements of which the stars/galaxies/quasars etc are made. By mapping the 'absent' regions, we can calculate the velocity of the emitter. Studies have shown the the more distant emitters have higher red-shifts in their spectra, and therefore higher velocity away from us. Hence the theory of the expanding Universe.

The recent claims that the Universe is not only expanding, but accelerating defies all the known laws to humankind. One other possibility is this:

If our relative time-space is decelerating, then any observations made from our point of view will appear as though they are accelerating, yet they may just be travelling at constant velocity or even decelerating, (in keeping with big-bang theory).

Think of it this way: if you make a tape recording of the train whistle, then play it back very loud on the speeding train it sounds the same as we would normally expect, but lets say now we play back the sound of the whistle at half speed on the same speeding train. The whistle now sounds more like a low moan, yet the train still travels at the same speed. If we could re-calibrate our observations to adjust for the change in frequency of the playback, so that it sounded like it should at normal speed, then it would appear as though the train was moving at double the speed it was originally.

So the real question is this: What is causing our time/space to decelerate (remember, this is unobservable by us since we are integral parts of that time/space).

Stay tuned for more revelations. (or dumb ideas).

Asymmetrical expansion implies that there would be other forces at work that we are unaware of, or maybe the possibility of multiple Universes, of which ours would only be a subsection.

(i had two hrs sleep last night so even i don't know what i'm talking abt) (on the upside roger penrose wz my lecturer in non-euclidean whatever)

An essential element.

God currently being seen as a relaxed individual, the universe gets more study in some quarters, and little surprise if preconceptions are projected onto it. I actually take comfort in the fact that it'll just keep ticking over somehow regardless of us.

It's hard to even know where to start with this, Donna. Your two questions are both misunderstandings: the Big Bang theory incorporates starting time as well as space, so there is no concept of before, since that relies on time. Similarly, there is no edge and no outside, since that relies on space extrinsic to the universe. I'm not offering this as proof, just saying that the theory accounts for these in as complete a way as is possible.

More generally, physics has gone beyond believing that it is describing the underlying laws and structures of the universe. The meaning of scientific truth is that the theory is not contradicted by the facts and has proved fruitful in predicting things. For some physical theories, it is extraordinarily difficult to even imagine how a proof could be constructed. Any of the sub-subatomic physics theories (superstrings, m-branes), for instance. I'd mention the multiple universes theory, but those working on quantum computing believe that they may prove that one, since methods they plan rely on performing calculations simultaneously in a countless (possibly infinite, dammit) number of universes.

Or something.

Personally, I'm not going to be entirely hapy with any of the BIG explanations until someone successfully reconciles relativity with quantum mechanics in a way that also explains where mass comes from. This is what all this superstring/m-brane stuff is aimed at. I'm not sure how well this work is going, because it is beyond me - 26-dimensional maths is at least 23 more than I know how to do.

Obviously I don't know what your personal beliefs are, Donna, and how they might fit with any particular theories, but scientific truth is a pretty objective thing - i.e. some given aspect of science is 'true' in proportion to how completely it describes the facts as we know them, and how useful it is in predicting things. None of this can affect religious beliefs as they are commonly constructed - the Christian God, for instance, is beyond any scientific ideas, because he can be said to have created any and all of them, and to exist in a realm beyond the reach of science.

You are right, this is far bigger than our meager intellect will ever be able to fathom.
I would love to discuss any theory.
My own 'spiritual' type beliefs have trouble accepting a 'creation' point. I am more inclined to go with some kind of 'eternal existence' theory.

it's all about weird geometry

You must allow for the creative properties of entropy.

I have a few questions, but am feeling too stupid at the moment to ask. It is, after all, 5.50am here and I haven't slept yet. The mission got me entranced.

yeah Im pretty interested in this stuff, even if it isn't useful or complete as a theory yet. Quantum physics um....I sorta know the basics and have an understanding of the deal.
Obviously not an expert though and I can't make intelligent, coherent paragraphs discussing any of it! I have more of an 'in my minds eye' understanding.

-- the extra dimensions are "curled up" so small that we don't ordinarily see them. The usual explanation for this, as you have probably heard, the example of a long cylinder. If you look at the cylinder from up close, you can clearly see that it is three-dimensional, but if you looked from far away, then it would appear to be a line (i.e. one-dimensional).

-- what we perceive as "mass" is the tension in a string. Therefore, heavier particles are strings that are pulled more taut than lighter ones.

-- why do we need the 11 dimensions in the first place? That's due to a mathematical formalism called group theory ... the general idea is that you can (maybe) describe all particles in the universe with one consistent theory provided you are working in an 11-dimensional framework. Don't worry too much about group theory though, only people working in group theory understand much about it. Most physicists (including this one) don't know shit about it beyond the most basic concepts.

xposts

Still, if you ask a string theorist, they'll say "STRING THEORY IS THE BEST, IT'S THE ONLY POSSIBLE THING THAT WILL EXPLAIN EVERYTHING" but the thrill is gone for most people and they're content to let the string theorists work in their own microworld.

hey thanks, that helped clear the picture a bit.

One stupid question before I leave this alone - dense matter such as say, wood, has particles that vibrate faster or slower ( higher rate or whatever the proper expression is ) than less dense matter?

I used to know this, but it has gone and the logic of both possibilities is sounding ok to me now, depending on which way I think about it all.

The vibrations you are thinking about may be thermal vibrations ... that is, molecules at higher temperature vibrate faster than ones at lower temperature.

This is all classical stuff, nothing to do with string theory, of course.

thanks by the way, for answering.

If you want a good book on string theory for a clever but non-expert reader, I'd suggest Superstrings And The Search For The Theory Of Everything, by F. David Peat.

(I will now go back and read this thread and see if it answers my question.)

I find String Theory somewhat easier to wrap my brain around than Quantum Theory (probably because it's somewhat more intutitive to the point of view of a musician's brain used to vibrating strings on her guitar and easier to conceptualise and visualise in a way that Quantum theory is just counterintuitive) but I've still not got to the chapter on How M Theory Will Save Us All!

As an interested observer to all of this - I have an engineering/science background - I'e always found it interesting that the things non scientist think sound obvious - y'know energy, mass charge etc. are actually the things that cutting edge physics seems to have the most problems with.

The original questioner mentioned the the apparent acceleration of expansion of the universe - there are two things that come to mind about this question Einstein's Cosmological Constant and Inflation - gien the Inflationary era is probably over..I'm wondering about the status of thought on the Cosmological Constant and whether that might sere as an explanation for "anomolous" results involving the Hubble Constant.