What's the Fabric of space made out of?

I concur with Nosy's recommendation to listen to the first lecture from the 20 minute mark to the 26 minute mark. If you listen to nothing else, at least listen to that much, here's the link: http://vegaserver1.hpc.susx.ac.uk:8080/...eynman/feynman1.rmFrom your Message 63: The better theory is the one that more closely describes what is actually observed. Perhaps someone can think of tests that would differentiate between your model and the one currently accepted within science.--Percy

RAZD has some good suggestions, but there's a much simpler one to try first. The lecture may be downloading to your computer at roughly the same rate you're listening to it. Everytime you catch up you get a brief pause while the RealPlayer buffer accumulates some more lecture. Try starting the lecture, hitting pause, then walking away or reading your email or something for five minutes (don't walk away for an hour, you'll lose your channel). When you come back there will be enough lecture buffered that it won't stutter anymore.RAZD's suggestion of playing with the bandwidth settings is the better way to address this problem, but there are some sites that seem immune to this setting. In other words, the videos at some sites, even though they let you choose between high, medium and low, and even though you play with your bandwidth settings, still stutter no matter what. These Feynmann lectures aren't prone to this problem on my computer, but different computers and OS versions and ISP connections may experience things differently.--PercyThis message has been edited by Percy, 03-13-2005 08:26 AM

Science chooses between competing theories based on which best explains observations. In his reply to this message, Sylas mentioned expansion as a measured property of space. Does your model of space take expansion into account?--Percy

It might help if we stay focused on the specifics. Concerning the unknowns, the geometry of space isn't one of them. Like anything in science our theories may be wrong, but we have much evidence supporting our view of space. As Sylas has explained, most recently in Message 108 but also in numerous previous messages, your view of space has already been observationally falsified.Nosy is trying to make a different point, but one that is at the core of your problems with science. The universe is under no compulsion to conform to human standards of logic and common sense. We have to take it as it is. As Feynman says between minutes 20 and 26 in that first lecture, a lot of very bright people have worked very hard gathering the observations about the way the universe really is, and if it doesn't make sense to you and you reject the observations because they violate your sensibilities or your theological notions, then too bad for you, the observations still stand. You can try to fit them into a different theoretical framework, but you're obligated to account for them if your theory is going to be anything other than personal fancy.As Galileo is rumored to have muttered under his breath as he left the Inquisition, "But still, it moves," this of course about his view that the earth orbited the sun and not vice-versa. You can refuse to accept the nature of space all you like, but the universe doesn't care. Whether you accept it or not, the evidence strongly suggests that space is non-Euclidian and expanding into nothing.--PercyThis message has been edited by Percy, 03-14-2005 12:33 PM

I think a reasonable question for Buzz to address is the nature of the "something" that he believes space is expanding into. If space is like a fabric draped across some underlying foundation like a rug over a floor or a sheet over a couch, then what is the nature of that underlying foundation?--Percy

I think there may be a misunderstanding about the purpose of analogies. Analogies are used not to prove a point, but to make clear a point. They are used to make more easily understood something that is hard to understand by likening it to something familiar.Analogies are for helping with understanding, not with persuasion. Analogies should not be used to persuade someone, only to help them understand, but it's a conumdrum when you're trying to help someone understand something that they don't accept.A common mistake is to rebut a position that has been argued using an analogy by attacking the analogy. No analogy is perfect. Space is not an expanding balloon and galaxies are not buttons, but the analogy of buttons remaining unchanged in size while the balloon expands is a very helpful mental image. Arguing that the buttons would fly off because of the glue holding them to the balloon completely misses the point of the analogy. You cannot argue that space isn't expanding because glue won't hold buttons onto an expanding balloon. It's only an analogy to create a helpful mental image of how we think about space. Understanding how we think about space doesn't mean you're conceding a point in the discussion.I think Sylas raised some good points in Message 120 that you haven't yet responded to.--Percy

Unless I'm missing the point Sylas was trying to make, I think you've misunderstood the analogy. The balloon is space, the buttons are galaxies. The buttons do not represent regions of space that don't expand, but rather groupings of matter that remain the same size while space expands through them.Asgara's analogy makes the same point in a 3D way. The nuts and raisons are not areas of space that don't expand. They're groupings of matter that remain the same size while space expands.Both these analogies are imperfect, for many reasons, but probably the biggest is that the balloon material doesn't run through the buttons, and the bread dough doesn't extend into the nuts and raisons, so here's another analogy, this one 1-dimensional. Imagine beads strung on an elastic string. As you stretch the string it expands within the beads, but the beads remain the same size. The string is space, the beads are groupings of matter held together gravitationally.As I said earlier, I think Sylas raised some good points in Message 120 that you haven't yet responded to.--Percy

I guess I'd answer in this way. About the Bible, Webster says: And so I'm free to conclude that the Bible is not inerrant and is not the Word of God, because Webster doesn't say so.Is any more discussion about the inadequacy of dictionary definitions for specialized fields necessary?Space *does* have a geometry. This is from http://www.wfu.edu/~brehme/space.htm: I suggest reading the entire article. It's pretty much what Sylas has been telling you.--Percy

You've lost me. I see a vague resemblance to the Lorentz coefficient, but I don't really know what this is.The plane and earth agree they are traveling relative to each other at 900 km/hr. The people on the plane see an eagle flying down the corridor from the rear of the plane toward the cockpit at 100 km/hr. They believe that the speed of the eagle relative to the ground is 900 km/hr + 100 km/hr = 1000 km/hr.But the people on the ground see an airplane shorted in the direction of motion, and so would see the eagle taking longer to travel, say, a meter as determined from the ground versus a meter as determined on the plane. I would have simply calculated the Lorentz coefficient (sqrt(1-v²/c²)) using the airplane's speed relative to the ground and used that as the proportion of the 100 km/hr speed of the eagle to add to the speed of the airplane. Doing this I get 1, which shows the precision limits of Google. Moving to a different calculator (which unfortunately unlike Google doesn't do automatic units conversion for me) I get .99999999999965230, and applying this to the the 100 km/hr of the eagle I get a velocity of the eagle as measured from the ground of 999.999999999965230 km/hr, which is somewhat slower than your 999.999999999999923 km/hr by 0.000000000034693 km/hr.I'm probably doing something wrong, but I can't figure out what. Do you see the error?--Percy

Thanks, Sylas. I can see that you're right, but I feel uncomfortable with not having an intuitive grasp for where t’ = γ (t + vx/c²) comes from. There's an appendix in Einstein's Relativity that covers derivation of the Lorentz transformation, and I'll work through it when I have a spare moment.--Percy

I'm not actually sure what you're trying to say here, but space *does* expand. "Expanding space" is not just another way of saying objects in the universe are moving away from each other. Space really is expanding.One of the most effective ways of convincing yourself of this is to contrast motion through space with motion due to the expansion of space. If you're an observer watching someone whiz by at .866 times the speed of light (.866c), then you'll see the second hand of his watch ticking off the seconds at half the rate of your own. But if you observe a watch in a distant galaxy receding from us at the same rate of .866c then you'll see the second hand ticking off seconds at the same rate as your own.This is because Einsteinian relativity only applies to relative motion through space. It does not apply to relative motion due to the expansion of space. The distant galaxy's motion through space relative to us is negligible compared to c, and so its clock appears unaffected. Its apparent motion due to expanding space is large, and so there is a red shift of the arriving light, but its motion through space relative to us is small, and so its clock runs at roughly the same rate as our own. If our nearby speedster's motion of .866c were away from us, his red shift would equal the distant galaxy's *and* has watch would run half as fast.This difference between motion through space and motion due to the expansion of space confirms that space *does* expand.--Percy

I wanted to keep it simple, but I've been assuming there are really two contributions. One is the effect of recession, the other is the effect of relativity. Relativity doesn't care about the direction of relative motion, only the magnitude. With recession/approach effects the direction matters a great deal. Does that sound right to you? This was a confusing paragraph for me. I've been assuming that we couldn't reach any conclusions based on supernova light curves without knowing the relative contributions to the red shift of both relativity and recession . I'm having trouble figuring out, on an intuitive level, how studying supernova in distant galaxies, even at many different distances, and even given that one effect is linear and the other isn't, could enable one to conclude expanding space if we didn't have a pretty good handle on distances. These distances are measured by other means, such as studying supernova of a type which produce a standard brightness.--Percy

You're right, but you're probably thinking of Green's description of the dramatic impact of relative motion on our perception of "now", particularly for distant objects. My point was more about the relative pace of observed time of a moving object, which shouldn't be a function of the direction of relative motion. In other words, the clock of someone moving at .866c through space relative to us will tick half as fast, whether they're receding, approaching or moving in a perpendicular direction. Of course, you have to adjust for Doppler (for want of a better word) effects.If I understand this correctly (always questionable), then there are a couple interesting effects. A distant galaxy with no red shift and therefore neither receding from nor approaching us would be moving through space at high speed and should therefore experience severe relativistic effects, like clock slowing (I think Sylas was questioning this conclusion, but I'll await confirmation). If the galaxy actually were approaching us then there would be a speed relative to us where the Doppler and relativistic effects cancelled as far as red shift, though that speed would be a function of distance due to the expansion of space and therefore the amount of expanding space between us and the galaxy.Of course, I never underestimate my ability to bollux this kind of thing completely. I'm just trying to make clear how I see this, and any corrections are welcome.--Percy

Until Sylas chimes back in take this all with a grain of salt, but the way I'm looking at this is that distant galaxies have only small relative motions relative to us through space. That's because their apparent motion away from us is due to the expansion of all the intervening space, not because they're really moving relative to us through space. Because relativity only applies to objects moving relative to us through space, the relativistic effects are very tiny.If we were to see a distant galaxy with no red shift, one that was neither receding or approaching, it would mean that it would have a hefty relative velocity toward us through space. This is because while it maintains a constant distance from us, the intevening space is expanding and zipping past it at high velocity. There is a bit of similarity to the Red Queen. Though dx/dt is 0 for us and the distant galaxy, the distant galaxy would have to "run" as fast as it could toward us just to maintain that distance.The elastic band analogy works pretty well here. Imagine that our galaxy and the distant galaxy are far apart on an elastic band which is infinitely stretchable (the elastic band could also be infinite in length, but since we're only considering the portion of the elastic band between our two galaxies it isn't important). The elastic band is being continually stretched longer and longer by the forces of darkness, and so our galaxies not only become separated by a greater and greater distance, but our speed of recession grows larger and larger, too.One curious thing about this situation is that neither our galaxy nor the distant galaxy is moving with respect to the local piece of elastic band to which it is attached, and so though the distant galaxy is receding away from us at great speed, our relative motion as measured against the elastic band, i.e., our relative motion through space, is 0. With no relative motion through space there can be no measurable relativistic effects.In order for the distant galaxy to maintain the same distance from us, it would have to begin moving toward us along the elastic band at the same rate that the elastic band is stretching in its region of the elastic band. If the galaxies were instead little radio controlled cars and the elastic band were actually one of those elastic ace bandages oriented so the cars could rest on it, then the distant car would have to really rev up its engines and go for broke in order to maintain the same distance from us.--Percy

Before you click on the "Gen Reply" button to reply to this message, just position your mouse over that button and let it hover there. A little hover box should appear. The text in the box says, "Please do not use this button unless making a general reply. Instead use the small reply button beneath each message."Now move your mouse over the little reply button at the bottom of this message and click on that. There, much better. This allows both forward and backward links between messages and replies. I think Lyx2no suggested you read a book because your messages seemed to display a great deal of unawareness of science in general and modern cosmology in particular.Concerning Lyx2no's one word answer of "gravity" and your clarification that the question was only rhetorical, either you don't know what rhetorical means or you don't know how to form a rhetorical question. What your question about why Earth's air isn't sucked off into space seemed to indicate is that you're not very familiar with science. If you read a book or two (hundreds of books is best) then you'll be better able to formulate questions that make sense.--Percy