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|    sci.physics.research    |    Current physics research. (Moderated)    |    17,520 messages    |
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|    Message 15,706 of 17,520    |
|    rockbrentwood@gmail.com to J. J. Lodder    |
|    Re: Mathematics of physical units and di    |
|    19 Jul 17 01:13:08    |
      It is not so much the question of what *additional* axioms are       needed, but which ones need to be removed. Physical quantities are       not numbers, so that not all the infrastructure of a field (or more       generally: of the number system) has physical meaning with them;       both rather only a substructure thereof.              The dimensions associated with the quantities are connected with       constraints on which ways they may be combined; namely that for       quantities of different physical dimensions, addition and subtraction       are not meaningful operations.              On Saturday, July 15, 2017 at 3:54:00 PM UTC-5, J. J. Lodder wrote:       > Before going on it is necessary to understand       > that dimensions have no physical reality.              Quite the contrary: they are deeply connected with the operational       meaning of the various quantities involved. The most notable example       being E and B whose "variability" of dimensions "in different       systems" is grounded in a confusion of concepts; namely the confusion       of E and B with D and H.              This is particularly important when the fields are non-abelian       because in that case, E and B aren't even the same KIND of quantity       as D and H (in particular, the former pair are Lie-vector valued       while the latter are Lie-CO-vector valued!) So the conflating of       them not only worsens the confusion but Sapir-Worfs matters of great       physical relevance (which later get put back in "by hand" under the       guise of moduli and coupling constants).              This is something that gets almost universally ignored in contemporary       liteature -- for which reason, the literature itself is also subject       to the same criticism. Your standpoint and its fallacious nature       is basically just an echo-chambering the contemporary literature,       which is just as wrong, so this needs to be addressed to them as       well.              E and B arise from the Lorentz force law; and as such are 2-form       valued:        F = (E_x dx + E_y dy + E_z dz) ^ dt        + B^x dy ^ dz + B^y dz ^ dx + B^z dx ^ dy.       This is actually how Maxwell originally presented the relevant       quantities (apart from the joining up of the E 1-form with dt, that       is). Because of their involvement in the force law, the 2-form must       have dimensions conjugate to that of electric charge. Calling the       dimensions of charge Q, and the dimensions of action H, (and using       L for length and T for time) that gives (E_x,E_y,E_z) the dimensions       of H/(QLT) and (B^x,B^y,B^z) the dimensions of H/(QL^T).              For both Maxwell and non-abelian fields, the field is derived from       the potential 1-form A = (A_x dx + A_y dy + A_z dz) - phi dt (and       again, Maxwell himself used this form originally for the 3-vector       A before using vector notation). That makes the dimensions of       (A_x,A_y,A_z): H/(QL) and of phi: H/(QT).              All of the foregoing is universally the case for ALL field theories       that can be cast in Lagrangian form, not just electromagnetism or       gauge theory. Corresponding to (A,phi) are the field configuration       variables; corresponding to (E,B) are the field gradients or       combinations thereof; together comprising the field kinematics.              They are always conjugate to the quantities that comprise the field       dynamics -- which (in a Lagrangian theory) are connected to the       respective derivatives of the Lagrangian density.              So, here, the Lagrangian (as a 4-form) would be        S = L dt ^ dx ^ dy ^ dz;       and the and would have the units of action H. Out of the total       differential: dS = dA ^ J - dF ^ G comes the conjugate field --       which comprise the field dynamics.              The respective forms are what give us the (D,H) fields:        G = D^x dy ^ dz + D^y dz ^ dx + D^z dx ^ dy        - (H_x dx + H_y dy + H_z dz) ^ dt;       while J gives us the source terms        J = rho dx ^ dy ^ dz - (J^x dy ^ dz + J^y dz ^ dx + J^z dx ^ dy) ^ dt;       where rho is the charge density and J the current density.              The units of G and Q are those of electric charge, so one has the       dimensions (H_x, H_y, H_z): Q/(LT), (D^x, D^y, D^z): Q/L^2;       (J^x,J^y,J^z): Q/(L^2 T) and rho: Q/L^3              All systems for (E,B,D,H) have these dimensions. Appearances otherwise       are rectified by bringing back out the various quantities that the       respective system has Sapir-Worfed away (and making explicit again       the *relevant* Physics it omitted by doing so!)              --- SoupGate-Win32 v1.05        * Origin: you cannot sedate... all the things you hate (1:229/2)    |
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