merrill@gigi.DEC (Rick GIGI::Merrill DECRITE) (08/13/84)
How do you "explain" gravity? Are gravitons sent to and fro? Why don't they cancel each other out if the masses are equal? How fast should gravity waves travel? Just the speed of light? Is mass the cause of gravity or does the movement of the gravitons create the effect of mass?
russ@ihuxi.UUCP (Russell Spence) (08/14/84)
> How do you "explain" gravity? Are gravitons sent to and fro? Why don't > they cancel each other out if the masses are equal? How fast should > gravity waves travel? Just the speed of light? > > Is mass the cause of gravity or does the movement of the gravitons create > the effect of mass? You can't "explain" gravity just like you can't "explain" any natural laws or physical phenomena. What you can do is observe the effects and assign terms like "gravity", "mass", and "gravitons" to them so that you can make statistical observations about them that will lead to a method of predicting the probable outcome of events. Some scientific systems are more successful at this than others. Modern science has progressed to the point that it can predict what will happen in most circumstances. This has led to the mis- taken belief that science can "explain" things. It can "decribe" things (and events) and can be used to make predictions about future events, but it doesn't really "explain" anything. I would think that your questions could best be answered by a good book on quantum mechanics. The mathematics required to figure out the speed of gravity waves or the movement of gravitons is probably too difficult to make a good subject for the net. If you just want to discuss their existence or what causes the effect of mass and gravity, then you will probably get either a standard textbook response or a personal opinion that has the validity of an answer to the question "which came first, the chicken or the egg?". -- Russell Spence ihnp4!ihuxi!russ AT&T Technologies Naperville, IL
dgary@ecsvax.UUCP (08/14/84)
< Quoting ... > >From: merrill@gigi.DEC (Rick GIGI::Merrill DECRITE) Mon Aug 13 08:46:28 1984 >Is mass the cause of gravity or does the movement of the gravitons create >the effect of mass? The exchange of virtual particles like gravitons for gravity, Ws and Zs and photons for electroweak, and gluons for strong (color) force are ways of dealing with the "action at a distance" of the forces of nature. Of these particles, only the electroweak ones have been detected (all but the photon this year, in fact). Making gluons would require an accelerator the size of the solar system with something like a quasar as power source, and Glashow says this seems a little much to ask from the Reagan administration. Gravitons are even more theoretical than the other particles. To my knowledge, all currently accepted theories of gravitation are geometrical in nature, with Einstein's General Theory still holding up well as the front-runner. To see how a geometric view of force works, imagine that we are at the Earth's equator and you and I begin walking north. We eventually realise that we are drawing closer together, even though we are carefully walking in a straight line. By repeating the trip with different sized loads we can determine that the "force" between us is proportional to our inertial masses, a mystery indeed (why should gravitational "charge" equal inertial mass, anyway?). But when we discover we are on a curved surface (the Earth) we understand what gives pretty quickly. Replace "north" with "forward in time" and convert the Earth's 2-dimensionasurface to a 4-dimensional one and you have a good measure of General Relativity. There's a good deal more, of course, but all that can be summed up as Einstein did, by saying that "space tells matter how to move, and matter tells space how to curve." You might wonder if the other forces of nature can be dealt with geometrically. The answer is yes, if you allow some of the coordinates to be so tightly curved that moving in a given direction returns you to your starting point in an infinitesimal distance. Such geometrical unified field theories (called Kaluza-Klein theories if my memory and spelling are right) have undergone a recent resurgance of interest. Not directly to the point I admit, but maybe that helps. And yes, this really does belong in net.sci, but I followed the original poster's newsgroup choice. D Gary Grady Duke University Computation Center, Durham, NC 27706 (919) 684-4146 USENET: {decvax,ihnp4,akgua,etc.}!mcnc!ecsvax!dgary
colonel@gloria.UUCP (George Sicherman) (08/17/84)
>> How do you "explain" gravity? Are gravitons sent to and fro? >> Why don't they cancel each other out if the masses are equal? >> How fast should gravity waves travel? Just the speed of light? >> Is mass the cause of gravity or does the movement of the >> gravitons create the effect of mass? I like this explanation, quoted in DeMorgan's _Budget of Paradoxes_: "Gravity is caused by the earth moving so fast that it draws everything to itself, like a train when you stand close to the track." -- Col. G. L. Sicherman ...seismo!rochester!rocksanne!rocksvax!sunybcs!gloria!colonel