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Parker Solar Probe
The Eugene Parker Solar Probe has just launched
to investigate close up solar magnetic and electric fields. In his book: "Conversations on Electric and Magnetic Fields in the Cosmos" Dr Parker notes: a SI charge non 'mass, length and time' definition as coulomb is a limitation for dimensional analysis of such EM problems. One wonders if his 'mass, length and time' analysis of such EM problems in cgs units system provided him with scientific reasoning in regards to solar EM fields deemed crazy by his peers at the time 50 years ago but which are currently accepted as true and the basis for his named solar probe. Richard D Saam [[Mod. note -- Actually, there's very little dimensional analysis in Parker's 1958 paper. That paper can be read online (open-access!) at http://adsabs.harvard.edu/full/1958ApJ...128..664P -- jt]] |
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Parker Solar Probe
| [[Mod. note -- Actually, there's very little dimensional analysis in
| Parker's 1958 paper. That paper can be read online (open-access!) at | http://adsabs.harvard.edu/full/1958ApJ...128..664P | -- jt]] When I was a student we learned from Cosmical magnetic fields: Their origin and their activity E N Parker Oxford, Clarendon Press; New York, Oxford University Press, 1979 which was just out then! Unfortunately it is 250 USD and up on Amazon -- ciao, Bruce drift wave turbulence: http://www.rzg.mpg.de/~bds/ |
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Parker Solar Probe
On 8/13/18 11:48 AM, Richard D. Saam wrote:
The Eugene Parker Solar Probe has just launched to investigate close up solar magnetic and electric fields. In his book: "Conversations on Electric and Magnetic Fields in the Cosmos" Dr Parker notes: a SI charge non 'mass, length and time' definition as coulomb is a limitation for dimensional analysis of such EM problems. One wonders if his 'mass, length and time' analysis of such EM problems in cgs units system provided him with scientific reasoning in regards to solar EM fields deemed crazy by his peers at the time 50 years ago but which are currently accepted as true and the basis for his named solar probe. Richard D Saam [[Mod. note -- Actually, there's very little dimensional analysis in Parker's 1958 paper. That paper can be read online (open-access!) at http://adsabs.harvard.edu/full/1958ApJ...128..664P -- jt]] Thanks for Parker's paper. His paper actually has a (mass(M), Length(L) Time(T) dimensional point of view: Dimensional energy m*v^2 and k*T M^1*L^2*T^-2 gravitational force G*M*M/r^2 M^1*L^1*T^-2 = (M^-1*L^3*T^-2)(M^2*L^0*T^0)(M^0*L^-2*T^0) thermal conductivity M^1*L^0*T^-3 appear throughout his paper but consider the last equation (bottom of page 674) that describes the torque caused by spiraling waves from the sun's magnetic field (B) with the physically descriptive equation: Torque(M^1*L^2*T^-2) = force(M^1*L^1*T^-2)*distance(M^0*L^1*T^0) =(9/15)*b^4(M^0*L^1*T^0)^4*omega((M^0*L^0*T^-1)*(1/v)(M^0*L^-1*T^1) *B^2(M^1/2*L^-1/2*T^-1)^2*(1+b/r(M^0*L^0*T^0) This conceptually reduces to Torque ~ space volume containing magnetic field * magnetic field squared or Torque (in units of energy) = volume * energy/volume The magnetic field B definition as M^1/2*L^-1/2*T^-1 makes everything dimensionally flow. Parker probably assumed the B and H field were equal (vacuum) having the same M^1/2*L^-1/2*T^-1 units where B = mu*H and permeability(mu) = 1 Of course, this all can be done in SI with the Coulomb addition but my mind hurts to think how to make physical sense of it, the finer points to which Parker addressed in his book. One note: Parker's secretary left out the '/sec' after the angular velocity 2.7 x 10^-4 at the top of page 674. Such a simple (and certainly not crazy) scientific pen and paper reasoning thing done by Parker in part resulting in the Solar Probe in his name. RDS |
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