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| Tags: definition, quotlorentz, transformationquot |
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#1
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Alas there is more misinformation being passed around. This time regarding
the precise definition of "Lorentz Transformation." The misinformation is that, for example, a transformation from frame S which has spherical spatial coordinates (t,r,theta,phi) to another frame S' moving relative to S and having coordinates (t',r',theta',phi') is a Lorentz transformation. That is incorrect. While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." That term has a very specific meaning. Let S have coordinates X = (t,x,y,z) and S' have coordinates X' = (t',x',y',z'). These coordinates are often refered to as "Lorentz Coordinates" or "Minkowski Coordinates." Let n = Minkowski metric = diag(1,-1,-1,-1). The correct, precise, definition of a Lorentz transformation is as follows Definition: A transformation L from X to X', i.e. X' = LX, is a transformation for which n'LL = n. Such transformations include rotations, reflections and boosts. This definition is found in most decent texts on relativity and tensor analysis. Sources - From Thorne and Blanchard's new text -- http://www.pma.caltech.edu/Courses/p...p01/0201.2.pdf - page 28 "Introducing Einstein's Relativity," D'Inverno, Oxford Univ. Press, (1992), page 109-111 "Tensors, Differential Forms, and Variational Principles," Lovelock & Rund, Dover Pub., (1989), page 53 "Electrodynamics and Classical Theory of Fields and Particles," Barut, Dover Pub., (1980), Chapter 1 Pmb |
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#2
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Subject: Definition of "Lorentz Transformation"
From: "Pmb" Date: 9/27/03 8:38 AM US Mountain Standard Time Message-id: Alas there is more misinformation being passed around. This time regarding the precise definition of "Lorentz Transformation." You were already MATHEMATICALLY PROVEN WRONG when I gave you the Lorentz transformation in spherical coordinates. |
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#3
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"Pmb" wrote in message ... Alas there is more misinformation being passed around. This time regarding the precise definition of "Lorentz Transformation." The misinformation is that, for example, a transformation from frame S which has spherical spatial coordinates (t,r,theta,phi) to another frame S' moving relative to S and having coordinates (t',r',theta',phi') is a Lorentz transformation. That is incorrect. While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." What are they referred to as? Martin Hogbin |
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#4
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"Martin Hogbin" wrote in message ... "Pmb" wrote in message ... Alas there is more misinformation being passed around. This time regarding the precise definition of "Lorentz Transformation." The misinformation is that, for example, a transformation from frame S which has spherical spatial coordinates (t,r,theta,phi) to another frame S' moving relative to S and having coordinates (t',r',theta',phi') is a Lorentz transformation. That is incorrect. While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." What are they referred to as? They don't have a name. Pmb |
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#5
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Subject: Definition of "Lorentz Transformation"
From: "Pmb" Date: 9/27/2003 2:43 PM US Mountain Standard Time Message-id: "Martin Hogbin" wrote in message ... "Pmb" wrote in message .. . While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." What are they referred to as? They don't have a name. Pmb Yes they do. They are Lorentz. |
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#6
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"Martin Hogbin" wrote in message ... "Pmb" wrote in message ... Alas there is more misinformation being passed around. This time regarding the precise definition of "Lorentz Transformation." The misinformation is that, for example, a transformation from frame S which has spherical spatial coordinates (t,r,theta,phi) to another frame S' moving relative to S and having coordinates (t',r',theta',phi') is a Lorentz transformation. That is incorrect. While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." What are they referred to as? Martin Hogbin Moller wrote a general relation between the spatial vector and the time in his text "The Theory of Relativity." This relation is found in many places such as Goldstein's "Classical Mechanics" - But that is not exactly a "coordinate transformation" since it has little, if nothing, to do with coordinates. In fact you don't even need to write coordinates down in that relation. In that view you're changing frames of reference rather changing coordinate systems - a subtle difference Pmb |
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#8
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Pmb:
[...] incorrect. While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." That term has a very specific meaning. Lorentz transforms are transforms which preserve inertial frames. Let S have coordinates X = (t,x,y,z) and S' have coordinates X' = (t',x',y',z'). These coordinates are often refered to as "Lorentz Coordinates" or "Minkowski Coordinates." Let n = Minkowski metric = diag(1,-1,-1,-1). The correct, precise, definition of a Lorentz transformation is as follows Definition: A transformation L from X to X', i.e. X' = LX, is a transformation for which n'LL = n. Thats obviously incorrect. The rotation: [ cos(A) -sin(A) ] X' = [ ] X [ sin(A) cos(A) ] Doesn't satisfy the relation you've written, since LL = L^2 != 1. Multiply it out. You also might try actually writing the equations out instead of trying to use notational shortcuts that only let you shoot yourself in the foot. Such transformations include rotations, reflections and boosts. Unfortunately, your definition only gives reflections, since the operator LLX only equals X for L = +/- 1. This definition is found in most decent texts on relativity and tensor analysis. Sources - From Thorne and Blanchard's new text -- http://www.pma.caltech.edu/Courses/p...p01/0201.2.pdf - page 28 Which doesn't agree with you. What they have written is: q_uv L^u_a L^v_b = g_ab L^u_a and L^v_b are inverses of each other. That is not what you have written. In particular, rotations are orthogonal transformations and an orthogonal transformation is defined by a matrix for which the transpose is equal to the inverse. Also, note the example they give at the top of the next page (29). Furthermore, the relations given don't _define_ lorentz transforms. What your reference says is that a transform which satisfies those relations is a lorentz transform. But, that's strictly because the transforms were derived in order to preserve the scalar product under the assumption of the minkowski metric. To wit, your reference defines the transforms by first defining X and X' as inertial frames. In order to find a transform between them, the transformation has to preserve inertial frames. |
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#9
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"Pmb" wrote in message ... "Martin Hogbin" wrote in message ... "Pmb" wrote in message ... Alas there is more misinformation being passed around. This time regarding the precise definition of "Lorentz Transformation." The misinformation is that, for example, a transformation from frame S which has spherical spatial coordinates (t,r,theta,phi) to another frame S' moving relative to S and having coordinates (t',r',theta',phi') is a Lorentz transformation. That is incorrect. While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." What are they referred to as? They don't have a name. I would have thought that calling them 'the Lorentz transformations in spherical polar coordinates' would make everyone happy. Martin Hogbin |
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#10
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(WaiteDavid137) wrote in message ...
Subject: Definition of "Lorentz Transformation" From: "Pmb" Date: 9/27/2003 2:43 PM US Mountain Standard Time Message-id: "Martin Hogbin" wrote in message ... "Pmb" wrote in message .. . While there most certainly exists transformations as suich and which leave the spacetime interval ds^2 invariant they are not refered to as "Lorentz Transformations." What are they referred to as? They don't have a name. Pmb Yes they do. They are Lorentz. No contect here. More unsubstantiated boguis claims Mr. Pmb - waite's relativity teacher |
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