12 Nov 09
Originally posted by AThousandYoungLoopholes are an acceptable term I think. But my experience in games (which is extensive) has found that gamemasters (or DMs in D&D and other role-playing games) are by definition "God"; they make the rules, and all the decisions. They have to--they keep the story moving. Now if they are arbitrary and change their rules on a whim, word will get 'round, no one will play with them and Bob's your uncle---problem solved. I happen to prefer boardgames (as oposed to rpgs) because there is no subjective ruling--if it ain't in the rulebook, ya can't do it. Everything from Scrabble to Advanced Third Reich have no loopholes to exploit.
I got your joke. I just think that the link between scientists and rules lawyers is so profound that I wanted to expand on it. I like to compare the rules of reality to the rules of games. I find tabletop gaming annoying because there are too many "miracles" - the GM overriding the rules.
OK, so we don't like the word "loophole". I was using it ...[text shortened]... "loophole" may not have been the most formally correct way to express my point.
12 Nov 09
Originally posted by PinkFloydI made the same point to Alan Guth who gave a talk at Bell labs I was lucky enough to attend. He made a statement (Guth was one of the originators of inflation theory in the big bang, I should make that clear) during his talk, this was in around the year 1986 or so, anyway he said the universe expanded from a little mostly point source close enough to zero volume for my back of the envelope calculation, to something the size of a football in a very small instant of time, I forget, maybe 1E- 43 second, so I put those #'s together and did the math and came up with a number of 10 to the 22nd order times the speed of light for the expansion of the universe at that epoch in the universes creation according to big band and inflation theory.
So space has no mass (this point was not expounded upon, probably because we were supposed to know that already 😀 ) but still, his point was that space (massless though it is) can and does exceed the speed of light, and this I did not know was possible.
When I mentioned that number 22 orders faster than the speed of light, the first thing he said was " Well you did you arithmetic right!" And then went on to say there is no relativistic speed limit for the expansion of space, and in fact although severely slowed down (assuming inflationary theory is correct, of course), the universe is still expanding at several times the speed of light.
I imagine you have heard the expanding balloon analogy where dots on a balloon separate when the balloon is blown up, but in real space it (I think) is more like individual points of space are being pumped in between other points of space in a 4 dimensional reference point, like you have a minimum distance between two points in space as being the plank limit of space, something like 10 to minus 35th meter, something like that but a magic hand of expansion puts another point in between what previously was the minimum distance and now you have two separate spaces where there were one, of course on a three dimensional platform. I use that as my own private analogy to help me visualize the effect. Does that make any sense?
12 Nov 09
As much sense as I'm able to contemplate, yes 🙂 I always had a hard time with the "space as an expanding balloon" thing, where we are points on said balloon, but I always chalked it up to being a firm Newtonian with almost no grasp of the whole quantum deal. Spheres in space are like big balls on a blanket?? I just can't wrap my head around it. I WANT to, mind you--I'm just not able to. It's like that Schroedinger/cat thingy--if you put a cat in a box and close the lid, is the cat there? Of course it's there! I'll never understand how simple observation of a thing somehow contaminates or has an effect on that thing--unless the thing is Paris Hilton, or some other thing that KNOWS it's being observed and enjoys it. 😀
12 Nov 09
2 edits
Originally posted by PinkFloydSpace isn't "moving". To move is to change positions in space. What space is doing is much different.
So space has no mass (this point was not expounded upon, probably because we were supposed to know that already 😀 ) but still, his point was that space (massless though it is) can and does exceed the speed of light, and this I did not know was possible.
Try reading here:
http://en.wikipedia.org/wiki/Metric_expansion_of_space
Space is stretching, as if it were made of rubber and being pulled on from all directions. There is no "end to space" that we know of which is getting farther and farther away from some central point. As far as we know the universe has infinite space in it, with no end to the space. However that space is stretching.
13 Nov 09
Originally posted by AThousandYoungSo when one says the universe is expanding, that's not really true? I just can't help but imagine an "edge" to the universe, and if that edge keeps moving (by stretching or getting bigger or whatever), then SOMEthing is moving, right? That edge was at point A, and a second or two later it's at, what, A+100 light years? I think I need an astronomy course AND a physics course 🙂
Space isn't "moving". To move is to change positions [b]in space. What space is doing is much different.
Try reading here:
http://en.wikipedia.org/wiki/Metric_expansion_of_space
Space is stretching, as if it were made of rubber and being pulled on from all directions. There is no "end to space" that we know of which is getting f ...[text shortened]... verse has infinite space in it, with no end to the space. However that space is stretching.[/b]
Thanks for the link though.
13 Nov 09
Originally posted by PinkFloydThe universe is definitely expanding, getting bigger, and the part we can see, which goes out to about 14 billion light years is not the whole size because it is expanding at a 'velocity' of several times the speed of light as we speak so the estimates of the actual size is around 50 billion light years 'across'. The only thing about that is we can never visit those parts of the universe because we can't go faster than light, only get very close with the best spacecraft we can ever build. The only way we can visit that part of the universe is if we develop some kind of space warp/wormhole drive which I wouldn't hold my breath waiting for.
So when one says the universe is expanding, that's not really true? I just can't help but imagine an "edge" to the universe, and if that edge keeps moving (by stretching or getting bigger or whatever), then SOMEthing is moving, right? That edge was at point A, and a second or two later it's at, what, A+100 light years? I think I need an astronomy course AND a physics course 🙂
Thanks for the link though.
Did you get my idea of space points being pumped in between existing space points?
Where there was two points between the plank distance of 1E-35 meters, a new point gets installed by some means we have not figured out yet? That is my own visualization analogy.
13 Nov 09
2 edits
Originally posted by sonhouseWhere did that figure of 50 billion light years come from? Is that how far the Bang has reached?
The universe is definitely expanding, getting bigger, and the part we can see, which goes out to about 14 billion light years is not the whole size because it is expanding at a 'velocity' of several times the speed of light as we speak so the estimates of the actual size is around 50 billion light years 'across'. The only thing about that is we can never vi installed by some means we have not figured out yet? That is my own visualization analogy.
EDIT - Found it. That's the distance to the particle horizon, which is the farthest we can theoretically gather information about. It is NOT the end of the universe - not unless we abandon the Copernican Principle that Earth is not the center of the Universe.
14 Nov 09
Originally posted by AThousandYoungAs far as I know, we can't get information past the distance of 13.7 billion LY, and anything beyond that would require a journey faster than C to get there and certainly not with just looking through telescopes because telescopes are also time machines in that it is looking at light at most 13.7 billion years old. Remember when they take the red shift and pronounce a number, IE, redshift of 6.8 means the source is say, 10 billion LY away, the redshift goes up to essentially infinity as you approach the BB, since we are talking about a lengthening of all the EM wavelength as time goes by, so as time approaches zero hour, the size of the whole universe might be only the size of a tennis ball, well you take the ratio of the size of the universe now and if it was the size of a tennis ball, the redshift would also be that same number, trillions or something more, didn't bother with the math, it is pretty apparent just looking at it.
Where did that figure of 50 billion light years come from? Is that how far the Bang has reached?
EDIT - Found it. That's the distance to the particle horizon, which is the farthest we can theoretically gather information about. It is NOT the end of the universe - not unless we abandon the Copernican Principle that Earth is not the center of the Universe.
14 Nov 09
4 edits
Originally posted by sonhouseI'm not sure I understand your post. I got my information from Wiki, so it could be wrong, but it doesn't sound like you really put much time into this either.
As far as I know, we can't get information past the distance of 13.7 billion LY, and anything beyond that would require a journey faster than C to get there and certainly not with just looking through telescopes because telescopes are also time machines in that it is looking at light at most 13.7 billion years old. Remember when they take the red shift and ...[text shortened]... ions or something more, didn't bother with the math, it is pretty apparent just looking at it.
However, let's keep in mind - the universe doesn't come to an end just because it's impossible for us to gather information about distances (or times) beyond some theoretical limit.
The comoving distance from Earth to the edge of the visible universe (also called the particle horizon) is about 14 billion parsecs (46.5 billion light-years) in any direction.[4] This defines a lower limit on the comoving radius of the observable universe, although as noted in the introduction, it's expected that the visible universe is somewhat smaller than the observable universe [which is not the entire universe itself unless we abandon Copernicus' Principle]
Misconceptions
Many secondary sources have reported a wide variety of incorrect figures for the size of the visible universe. Some of these are listed below.
13.7 billion light-years. The age of the Universe is about 13.7 billion years. While it is commonly understood that nothing travels faster than light, it is a common misconception that the radius of the observable universe must therefore amount to only 13.7 billion light-years. This reasoning makes sense only if the Universe is the flat spacetime of special relativity; in the real Universe, spacetime is highly curved on cosmological scales, which means that 3-space (which is roughly flat) is expanding, as evidenced by Hubble's law. Distances obtained as the speed of light multiplied by a cosmological time interval have no direct physical significance.
http://en.wikipedia.org/wiki/Size_of_the_universe
14 Nov 09
Originally posted by sonhouseI did--yes. It helped me to grasp the concept of infinity as well--something that has also eluded me since Calculus II. (but that was 100 yrs ago, give or take)
The universe is definitely expanding, getting bigger, and the part we can see, which goes out to about 14 billion light years is not the whole size because it is expanding at a 'velocity' of several times the speed of light as we speak so the estimates of the actual size is around 50 billion light years 'across'. The only thing about that is we can never vi ...[text shortened]... installed by some means we have not figured out yet? That is my own visualization analogy.
14 Nov 09
1 edit
Originally posted by PinkFloydThere's no edge that we know of, no. If there is one it is theoretically impossible for us to know about it because it's so far away...at least at this stage in our understanding.
So when one says the universe is expanding, that's not really true? I just can't help but imagine an "edge" to the universe, and if that edge keeps moving (by stretching or getting bigger or whatever), then SOMEthing is moving, right? That edge was at point A, and a second or two later it's at, what, A+100 light years? I think I need an astronomy course AND a physics course 🙂
Thanks for the link though.
A lot of people use the words "beginning of time", "expansion of the universe", etc a little too casually, confusing laypeople.
What they mean by that is the beginning of observable time, and the expansion of the observable universe, which does have an edge - simply because beyond that we can't see, so it's the "edge of our vision".
15 Nov 09
Originally posted by AThousandYoungAnd that limit is 13.7 billion LY, there is complete agreement on that one in the scientific community. Just think about the redshift problem for instance, the further out into space you look the closer to the beginning of the BB and the redshift would mean to see, for instance, the very first star to form, the red shift would be so large you would have to look for it in very long wave radio waves, maybe only 1 hz or less which would make it extremely difficult if not impossible to obtain any kind of spectrum from it, the entire spectrum from IR to UV might be the span of 1 hz to 1.1 hz or the like.
There's no edge that we know of, no. If there is one it is theoretically impossible for us to know about it because it's so far away...at least at this stage in our understanding.
A lot of people use the words "beginning of time", "expansion of the universe", etc a little too casually, confusing laypeople.
What they mean by that is the beginnin ...[text shortened]... e an edge - simply because beyond that we can't see, so it's the "edge of our vision".
16 Nov 09
Originally posted by sonhouseDid you read my above post which points out that 13.7 billion LY is a common misconception?
And that limit is 13.7 billion LY, there is complete agreement on that one in the scientific community. Just think about the redshift problem for instance, the further out into space you look the closer to the beginning of the BB and the redshift would mean to see, for instance, the very first star to form, the red shift would be so large you would have to ...[text shortened]... trum from it, the entire spectrum from IR to UV might be the span of 1 hz to 1.1 hz or the like.
16 Nov 09
About that red-shift thing--every time it's mentioned, the physicist on the tube says "ALMOST every galaxy is red-shifted in relation to ours." I can't help but wonder--well, what about those blue-shifted ones? If not every galaxy is racing away from the Milky Way as if it had released a massive cosmic fart, there must be some reason why some are headed our way, right? So red-shifting alone doesn't prove the expanding universe theory--right?
By the way, I'm not questioning that he universe IS expanding, nor its approx. age. I'm just trying to understand the reasons why we know them to be true.
17 Nov 09
Originally posted by PinkFloyd"So red-shifting alone doesn't prove the expanding universe theory--right?"
About that red-shift thing--every time it's mentioned, the physicist on the tube says "ALMOST every galaxy is red-shifted in relation to ours." I can't help but wonder--well, what about those blue-shifted ones? If not every galaxy is racing away from the Milky Way as if it had released a massive cosmic fart, there must be some reason why some are headed ...[text shortened]... its approx. age. I'm just trying to understand the reasons why we know them to be true.
Wrong. Yes it does.
There are two movements among the galaxies. (1) A random movement, and (2) a "movement" due to universe expanding. The further away the more (2) take place in relation to (1). So other galaxy clusters are moving away from us, but within the galaxy clusters the random movement is most important in relation to us.
There are no galaxies in other galaxy clusters that are blue shifted. But the nearest galaxies in our own cluster may be blue shifted, like the Andromda Galaxy (M31) and its satellites (M32 and others). Or red shifted, as random behaviour would be expected.
So the red shift *is* one of the most important reasons that we believe that the universe is expanding in the BigBang theory.