Are other things impossible too?

Of course no one can say how technology will evolve - it may very well be possible to manipulate gravity. A lot of things about gravity are poorly understood.

Here is a sci.physics.research post where the derivation of the Lorentz transformation is given, based only on the simplest possible assumptions of isotropy and homogeneity:

\n From: Danny Ross Lunsford (mail)\nSubject: Re: Unification of Electromagnetism and Gravity \n\n Newsgroups: sci.physics.research\nDate: 2001-12-22 09:38:07 PST \n\nBrian J Flanagan wrote:\n\n> "Danny Ross Lunsford" wrote:\n> \n>>Relativity theory is independent of the nature of particular forces.\n> \n> I'm not sure what you mean by "independent", here. Surely the special\n> theory has much to do with EM (in re: the constancy of c), just as the\n> general theory has much to do with gravitation?\n\nNot at all. In fact the framework of relativity is derives from a \ngroup-theoretic analysis based on very basic and simple assumptions about \nspace, time, and motion, taken from experience. The conclusion is that the \nallowed transformations depend on parameter with the dimensions of a \nvelocity that is either finite or not. In the real world, it turns out to \nbe finite. Of course, it is c. That light goes at this speed is incidental \nto the analysis, which would still be correct if light went at some other \nspeed. Light happens to go at c because the photon is massless.\n\nTo give this derivation, we assume\n\n1) The allowable transformations are linear between frames in uniform \nrelative motion, so that they depend on the relative (vectorial) velocity V\n\n2) That time can enter into the transformations in an essential way, that \nis we do not assume t' = t.\n\n3) That space and time are isotropic, that is, time flows evenly and there \nare no preferred directions.\n\nSpatial isotropy eliminates the directional character of V and so we can \nconcentrate on the simple case of one spatial dimension.\n\nTemporal isotropy implies that what is true of frame A in relation to frame \nB for V, is true of frame B in relation to frame A for -V.\n\nNow, writing\n\nx' = a(V) x + b(V) t\nt' = c(V) x + d(V) t\n\nx = a(-V) x' + b(-V) t'\nt = c(-V) x' + d(-V) t'\n\nso\n\na(V) a(-V) + b(-V) c(V) = 1\nd(V) d(-V) + b(V) c(-V) = 1\na(-V) b(V) + b(-V) d(V) = 0\na(V) c(-V) + c(V) d(-V) = 0\n\nand of course we can replace V -> -V and these still hold. So\n\na(V) b(-V) + b(V) d(-V) = 0\na(V) c(-V) + c(V) d(-V) = 0\n\nso b(V) = c(V).\n\nNow\n\na(V) a(-V) + b(V) b(-V) = 1\na(V) b(-V) + b(V) d(-V) = 0\n\nthus\n\nb(V) [ b(-V)^2 - a(-V)d(-V) ] = b(-V)\n\nand this also holds for V -> -V, which implies either\n\na(V) d(V) - b(V)^2 = 1, b(V) = -b(-V)\n\na(V) d(V) - b(V)^2 = -1, b(V) = b(-V)\n\nThe latter is ruled out by letting V=0 in which case\n\nx = x'\nt = t'\n\nWe can solve the equations now with\n\na(V) = d(V) = a(-V) = d(-V)\n\nand so\n\na(V)^2 - b(V)^2 = 1\n\nand \n\na(0) = 1, b(0) = 0\n\nThe origin x=0, which moves at speed V in the other frame, transforms as\n\nx' = b(V) t\nt' = a(V) t\n\nso\n\ndx'/dt' = V = b(V)/a(V)\n\nso\n\na(V) = 1 / sqrt(1 - V^2)\nb(V) = V / sqrt(1 - V^2)\n\nFinally we dimensionalize time vs. space and replace\n\nV -> V/C\nt -> Ct\n\nand write\n\nx' = 1/sqrt(1 - (V/C)^2) ( x + (V/C) Ct )\n\nCt' = 1/sqrt(1 - (V/C)^2) ( Ct + (V/C) x )\n\nIf we let C go to infinity,\n\nx' = x + Vt\nt' = t\n\nSo either C is finite, or not. Experience shows that it is finite.\n\nOf course, historically relativity emerged from the contradictions in \nelectron theory implied by the tacit, wrong assumptions about the nature of \nsimultaneity.\n\n-drl\n\n

Implicit in this is the assumption of homogeneity, which I should have stated. (All points are equivalent - doesn't matter if you're here or there.)

Post #130,620 by Arkadiy 12/13/03 7:41:51 PM Reply	Are other things impossible too? For example, does Newton's third law precludes us from ever controlling gravity? If we learn how to do that, drives based on it will violate 3rd law. Also, could you explain to a non-phisycist (and non-matematician) what part of contemporary physics makes it certain that we will never travel faster than light? And how it is asserted? -- "There's nothing more nervous than a million dollars. It does not speak French, it does not speak English, it does not speak German and it moves very fast." -- Jean Chretien
Post #130,627 by deSitter 12/13/03 8:06:22 PM Reply	Re: Are other things impossible too? Of course no one can say how technology will evolve - it may very well be possible to manipulate gravity. A lot of things about gravity are poorly understood. Here is a sci.physics.research post where the derivation of the Lorentz transformation is given, based only on the simplest possible assumptions of isotropy and homogeneity: \n From: Danny Ross Lunsford (mail)\nSubject: Re: Unification of Electromagnetism and Gravity \n\n Newsgroups: sci.physics.research\nDate: 2001-12-22 09:38:07 PST \n\nBrian J Flanagan wrote:\n\n> "Danny Ross Lunsford" wrote:\n> \n>>Relativity theory is independent of the nature of particular forces.\n> \n> I'm not sure what you mean by "independent", here. Surely the special\n> theory has much to do with EM (in re: the constancy of c), just as the\n> general theory has much to do with gravitation?\n\nNot at all. In fact the framework of relativity is derives from a \ngroup-theoretic analysis based on very basic and simple assumptions about \nspace, time, and motion, taken from experience. The conclusion is that the \nallowed transformations depend on parameter with the dimensions of a \nvelocity that is either finite or not. In the real world, it turns out to \nbe finite. Of course, it is c. That light goes at this speed is incidental \nto the analysis, which would still be correct if light went at some other \nspeed. Light happens to go at c because the photon is massless.\n\nTo give this derivation, we assume\n\n1) The allowable transformations are linear between frames in uniform \nrelative motion, so that they depend on the relative (vectorial) velocity V\n\n2) That time can enter into the transformations in an essential way, that \nis we do not assume t' = t.\n\n3) That space and time are isotropic, that is, time flows evenly and there \nare no preferred directions.\n\nSpatial isotropy eliminates the directional character of V and so we can \nconcentrate on the simple case of one spatial dimension.\n\nTemporal isotropy implies that what is true of frame A in relation to frame \nB for V, is true of frame B in relation to frame A for -V.\n\nNow, writing\n\nx' = a(V) x + b(V) t\nt' = c(V) x + d(V) t\n\nx = a(-V) x' + b(-V) t'\nt = c(-V) x' + d(-V) t'\n\nso\n\na(V) a(-V) + b(-V) c(V) = 1\nd(V) d(-V) + b(V) c(-V) = 1\na(-V) b(V) + b(-V) d(V) = 0\na(V) c(-V) + c(V) d(-V) = 0\n\nand of course we can replace V -> -V and these still hold. So\n\na(V) b(-V) + b(V) d(-V) = 0\na(V) c(-V) + c(V) d(-V) = 0\n\nso b(V) = c(V).\n\nNow\n\na(V) a(-V) + b(V) b(-V) = 1\na(V) b(-V) + b(V) d(-V) = 0\n\nthus\n\nb(V) [ b(-V)^2 - a(-V)d(-V) ] = b(-V)\n\nand this also holds for V -> -V, which implies either\n\na(V) d(V) - b(V)^2 = 1, b(V) = -b(-V)\n\na(V) d(V) - b(V)^2 = -1, b(V) = b(-V)\n\nThe latter is ruled out by letting V=0 in which case\n\nx = x'\nt = t'\n\nWe can solve the equations now with\n\na(V) = d(V) = a(-V) = d(-V)\n\nand so\n\na(V)^2 - b(V)^2 = 1\n\nand \n\na(0) = 1, b(0) = 0\n\nThe origin x=0, which moves at speed V in the other frame, transforms as\n\nx' = b(V) t\nt' = a(V) t\n\nso\n\ndx'/dt' = V = b(V)/a(V)\n\nso\n\na(V) = 1 / sqrt(1 - V^2)\nb(V) = V / sqrt(1 - V^2)\n\nFinally we dimensionalize time vs. space and replace\n\nV -> V/C\nt -> Ct\n\nand write\n\nx' = 1/sqrt(1 - (V/C)^2) ( x + (V/C) Ct )\n\nCt' = 1/sqrt(1 - (V/C)^2) ( Ct + (V/C) x )\n\nIf we let C go to infinity,\n\nx' = x + Vt\nt' = t\n\nSo either C is finite, or not. Experience shows that it is finite.\n\nOf course, historically relativity emerged from the contradictions in \nelectron theory implied by the tacit, wrong assumptions about the nature of \nsimultaneity.\n\n-drl\n\n Implicit in this is the assumption of homogeneity, which I should have stated. (All points are equivalent - doesn't matter if you're here or there.) -drl
Post #140,256 by Arkadiy 2/6/04 10:47:19 AM Reply	Wow. I have finally been able to follow through on this. I'd have to return a few times, but I get the "why not" part, for some definition of get. I will have to go through this again looking at how assumptions are used... -- Select [link\|http://www.glumbert.com/pictures/Default.asp?index=30\|here].
Post #130,631 by boxley 12/13/03 8:18:08 PM Reply	there is 3 ways to defeat gravity gravity is a wave. There is two physical ways to defeat it and one metaphysical way. 1. provide a counter wave locally stronger than gravity. That is escape velocity. 2. Find an object or construct that is impervious to the wave so the gravitational effects flow around but do not affect the object. 3. Gravity is an artificial construct that your brain uses to maneuver in physical space, just ignore it. thanx, bill "We must face the fact that there is not a single country in the world that measures up to the lofty moral and social standards that are the hallmark of the U.S.A.: even Canada is delinquent and deserves a whiff of grape. There is not a single country in the world which, like the U.S., reeks of democracy and "human rights," and is free of crime and murder and hate thoughts and undemocratic deeds\ufffd. And so, since no other countries shape up to U.S. standards, \ufffd I make a Modest Proposal for the only possible consistent and coherent foreign policy: the U.S. must, very soon, Invade the Entire World!" Murray N. Rothbard questions, help? [link\|mailto:pappas@catholic.org\|email pappas at catholic.org]

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