Discussion in 'General Science & Technology' started by Reiku, Dec 28, 2011.
You mean like when they become a Law?
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I think he means when the theory has enough supportive evidence and accuracy to declare it true (i.e. the correct choice, as opposed to other theories).
That's what I mean though.
I seem to recall from somewhere once upon a long time ago that we have (in terms of a heirachy):
Hypothesis < Theory < Law
I think in science a law refers to something thought to be an objective immutable constant / sequence; whereas, a theory is a model that may make use of several laws.
i don't think that is a good definition of what a theory is. theories are just models that depict a bit of reality fairly well and from which you can make predictions. they have nothing to do with "truth".
Well, I agree with Mister here, how do you know that only galaxies are not moving away from each other in a steady, non-expanding space?
A good reason is the redshift itself. When space is added, it has the side effect of stretching out the wavelength of photons. The stretch observed is huge and directly corresponds with expanding space. If only galaxies were moving away from each other then the redshift would be very tiny or absent.
Another good reason is that the rate of galaxy separation often exceeds the speed of light (significantly). It is impossible for matter to reach the speed of light let alone exceed it; however, it is very possible for more space to be added between galaxies at a rate greater than C.
CC #27: "however, it is very possible for more space to be added between galaxies at a rate greater than C."
What is the MECHANISM for formation (creation?) of 'more space' at >c? Just curious.
Nobody knows yet.
. . . one might look at some 'alternative hypotheses" for unproven "clues" (Members NOTE: I have changed my avatar)
What part in the big bang theory, precisely, do you think neccessitates the creation of more space, as opposed to the stretching of what's already there?
Something that I have read (could not find a source for exact numbers sorry) is that the vast majority of galaxys are moving away from us. If it was random motion it should closer to 50/50, 50% coming closer 50% moving away but its much higher then that. (not to be taken exactly but I believe its well over 90%). This would not be possible if it was all expanding from a central point because then a larger amount of galaxys would appear to be stationary to us, or perhaps catching up to us if their speeds slowed further from the source due to gravity.
This is not the observation however, it is happening in every direction at the same time which suggestes that the space between the galaxys is expanding.
How it happens is a mystery but it's essentially adding nothing (not even energy as the galaxys are not actually moving faster, the expansion is happening faster but it just adds or stretches empty space) to the uninverse so it seems probable.
. . . .O.K. . . . .just what is the 'stretching' MECHANISM?
You're trying to put something non-mechanical in terms of mechanical analogies. For example, in a sheet of rubber there's loads of tangled macromolecules. When you pull on the sheet these straighten out, allowing the material to stretch. Space-time isn't like that, it isn't a material.
What precisely are you looking for the answer to involve?
A MECHANISM . . .as I originally stated!!..BTW I was querying Trippy, based on his previous post, not you . . .AN, methinks you are 'trolling' here just to stir-up the pot!
AN just asked the same question I would have.
It's a perfectly reasonable question, and AN is probably in a better position to answer your question than I am.
And I asked a perfectly civil question (remember how you asked for more civility?) of what kind of response you're after. I could give a mathematical one involving general relativity's space-time metric but you probably wouldn't accept, or understand, it. I could give a quantum field theoretic description of graviton polarisations but you probably wouldn't accept, or understand, that. I was attempting to gain information to tailor my response somewhat.
Remember how you asked for people to be more civil? You have just demonstrated considerable hypocrisy in that regard with your reply.
If you wanted just a reply from Trippy then you could send him a PM. This is an open discussion and people join and leave as they see fit. Your first post in this thread was replying to Trippy, who'd replied to someone else. He didn't say "Go away, I was talking to someone else!", he replied to you to integrate you into the thread.
Clearly you aren't so daft as to think only those you have already replied to may reply to your posts, else no one would be able to reply to any new thread! Instead it seems you are trying to wield that axe you have to grind with me and tried to say "Shove off" in a less than subtle manner.
No, I was trying to engage you in discussion. This is a discussion site you know? It is your post, not mine, which is trolling because you couldn't answer a straight forward question in a civil manner, despite complaining about a lack of civility on this site in the last week.
Now, if you can manage to be civil I'll ask my question again. What sort of answer are you looking for? To help you along I'll give some suggestions. One involving the mathematical point of view from current mainstream theories like GR? One from the point of view of the hypothetical gravity in string theory, which correctly limits to the GR effective theory point of view? Are you looking for a pop-science vague answer without justification? Or perhaps some analogy which doesn't really explain the specifics?
AN: "What precisely are you looking for the answer to involve?"
I am looking for the MECHANISM(S) - probably your option #2 (from the POV of hypothetical gravity in string 'theory') by which space is purportedly expanding at >c (CC's original statement. which piqued my interest). Close and accurate mechanism-specific analogies would be an added benefit - no balloon-skin analogies, please. One or two paragraphs will likely be sufficient.
Redshift may have other answers.
Separate names with a comma.