Praxus Posted June 12, 2008 Report Share Posted June 12, 2008 (edited) In a pinch, I will take the reality of technology over the illusion of understanding. People who held the caloric theory of heat really believed they understood heat. They were wrong. People who believed that electric charge was a continuous fluid were wrong (that includes Ben Franklin, Michael Faraday and James Clerk Maxwell). They took the fluid notion so seriously that the first capacitors were called Leyden -jars- after the place at which they were invented. A good deal of what we call understanding is, in reality heuristic, and plausible metaphor. What is essential to our survival is that we understand reality at man scale, under the conditions in which our intelligence evolved. Einstein's goal of reading the Mind of the Old One, was a tad over the top. I would say the human race understands the world at man scale quite well. Proof: we survive. And we survived when we did not have fancy science too. Somehow the pyramids were built and ships sailed around the earth before we developed a comprehensive science of mechanics. Compasses were in use long before Oestead revealed the nature of magnetism. What you call understanding is actually omniscience and that demand on any finite being - that is to say any being whatsoever - no matter how intelligent is ridiculous. All we can aspire to is contextual knowledge, which is still knowledge and a great achievement; this is to say that based upon a certain set of observed facts this conclusion x is true in the context of those facts. Thus if we discover new facts that disprove relativity it would be right to call it invalid because we have a larger context, even though it was previously correct to call it valid. Edited June 12, 2008 by Praxus Quote Link to comment Share on other sites More sharing options...
yadid Posted June 26, 2008 Report Share Posted June 26, 2008 Well, once they were derived, you didn't have to derive them again, did you? What Einstein gave was (in part, at least) an interpretation of the Lorentz equations, and--to answer your question-- --it is that interpretation that I am calling a fruit of bad philosophy. I'd rather not get any prize Al Gore has received! 1) Wow! Al Gore received the Noble prize for physics? I didn't kow... 2) Assuming your quotations are accurate (I have no reason to doubt this), can you be more concrete and specific about what therein is bad philosophy? 3) SR-71 forever Quote Link to comment Share on other sites More sharing options...
Xall Posted October 27, 2010 Report Share Posted October 27, 2010 More or less related to this, I have a question of my own: have there been any (valid) attempts at an explanation for why gravity is so pervasive (over immense distances that would make it seem as if it's acting at speeds faster than light - although this might just be convenience-naming)? Quote Link to comment Share on other sites More sharing options...
avgleandt Posted October 27, 2010 Report Share Posted October 27, 2010 More or less related to this, I have a question of my own: have there been any (valid) attempts at an explanation for why gravity is so pervasive (over immense distances that would make it seem as if it's acting at speeds faster than light - although this might just be convenience-naming)? Yeah the theory of general relativity. Gravity doesn't not act faster then light, it acts at light speed. If the sun would suddenlty vanish. Both gravity and light would go out at the same time on earth, approximatly 8 minutes after the sun vanishes. Quote Link to comment Share on other sites More sharing options...
Xall Posted October 27, 2010 Report Share Posted October 27, 2010 Gravity doesn't not act faster then light, it acts at light speed. Must've misunderstood, though it makes sense Quote Link to comment Share on other sites More sharing options...
icosahedron Posted October 28, 2010 Report Share Posted October 28, 2010 Yeah the theory of general relativity. Gravity doesn't not act faster then light, it acts at light speed. If the sun would suddenlty vanish. Both gravity and light would go out at the same time on earth, approximatly 8 minutes after the sun vanishes. This is not yet experimentally verified. If true, the gravitational force will be mediated by mass-less particles called gravitons. Gravitons have not been shown to exist yet. I doubt they will be. Why must gravity be temporally lagged? Unlike electromagnetic potentials, gravitational potentials are scalar. Because it is non-directional, gravitational potential cannot be affected by the direction of travel of the masses that determine it. If the gravitational force were transmitted radially at finite speed, then the inter-attraction of masses under gravity would be affected by their relative state of motion. This appears to be a contradiction. - ico Quote Link to comment Share on other sites More sharing options...
Xall Posted October 28, 2010 Report Share Posted October 28, 2010 (edited) Also, I don't think it will be shown to exist anywhere in the short to medium future of the human race, given wikipedia, "For example, a detector with the mass of Jupiter and 100% efficiency, placed in close orbit around a neutron star, would only be expected to observe one graviton every 10 years, even under the most favorable conditions. It would be impossible to discriminate these events from the background of neutrinos, since the dimensions of the required neutrino shield would ensure collapse into a black hole". Furthermore, as to gravity's "speed", I've found this: "To begin with, the speed of gravity has not been measured directly in the laboratory--the gravitational interaction is too weak, and such an experiment is beyond present technological capabilities. The "speed of gravity" must therefore be deduced from astronomical observations, and the answer depends on what model of gravity one uses to describe those observations." http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html Edited October 28, 2010 by Xall Quote Link to comment Share on other sites More sharing options...
avgleandt Posted October 28, 2010 Report Share Posted October 28, 2010 This is not yet experimentally verified. If true, the gravitational force will be mediated by mass-less particles called gravitons. Gravitons have not been shown to exist yet. I doubt they will be. Why must gravity be temporally lagged? Unlike electromagnetic potentials, gravitational potentials are scalar. Because it is non-directional, gravitational potential cannot be affected by the direction of travel of the masses that determine it. If the gravitational force were transmitted radially at finite speed, then the inter-attraction of masses under gravity would be affected by their relative state of motion. This appears to be a contradiction. - ico Yeah I don't think the speed at which gravity waves move has been verified directly yet. I was just explaining what general relativity says about gravity. General relativity is currently a well accepted theory of gravity. They are building LIGO, a gravity wave ditector, so we might get a direct expirement soon. One of the reasons that general relativity is so accepted is because a lot of its predictions have been verified experimentally. The speed of light is not all about light, its a fundemantal ultimate speed of any phsycial interaction in nature. Quote Link to comment Share on other sites More sharing options...
icosahedron Posted October 28, 2010 Report Share Posted October 28, 2010 Yeah I don't think the speed at which gravity waves move has been verified directly yet. I was just explaining what general relativity says about gravity. General relativity is currently a well accepted theory of gravity. They are building LIGO, a gravity wave ditector, so we might get a direct expirement soon. One of the reasons that general relativity is so accepted is because a lot of its predictions have been verified experimentally. The speed of light is not all about light, its a fundemantal ultimate speed of any phsycial interaction in nature. They won't detect gravitons, which may or may not render the mathematical model useless ... but will at least force re-evaluation of the assumption that gravity can be modeled as a pair-wise interaction mediated by particles. I'd put all my money on it. None of the verifiable predictions of general relativity will be altered one bit, whether or not gravitons are real, because it doesn't matter, in the context of so far valid predictions, whether or not gravity itself is explained; general relativity describes the behavior of gravity well as far as can be verified. There is evidence for another view, because it is not the speed of motion, but rate of signal transmission, and hence ability to transmit information, that is at the root of the speed limit in reality. If gravity has nothing to do with signal transmission, but is instead a global embracement that keeps systems from breaking apart due to entropic considerations, i.e., if gravity is the "force" of systemic integrity, then it is better visualized as a rubber netting around the outside and pulling inwards in all directions, like a soccer ball bag. The state of the embracement would be a function of every point in the netting, i.e., the whole netting state would need to be known to compute any stresses. This is like a quantum state of a linked collection of oscillators, and like a quantum state, must be global to the system, independent of the system's size or complexity, up to and including the whole of existence. If gravity pertains instantaneously, like a quantum state, then it has no mediating particles filling the space (that is for the electric, bi-directional forces -- and its effects pertain instantaneously. I don't think it's possible to materialize an object without its gravitational envelope already formed along with the object. - ico Quote Link to comment Share on other sites More sharing options...
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