There is a particularly bad section under electrical units where the failure of computers to register special characters correctly has made a paragraph virtually incomprehensible. (There may be other bad paragraphs, too. I do not plan on searching for them or reporting them to you on this list. If you are forewarned that there are problems, it should be possible to find them and figure them out for yourselves if you have any familiarity with the subject.)
If you might ever need to refer to the information about electric and magnetic field equations in Nelson's article, you should note the errors and my corrections. For some of you who may never need it, please skip the rather lengthy and technical description below.
Regards,
Bill Hooper
========================
I repeat the erroneous paragraph, here below, just as I received it. Below that, I repeat it again with corrections noted. It is the ninth paragraph under heading Electrical Units in Dr. Nelson's article.
Error laden copy:
---------------------------
In 1901, Giorgi demonstrated that the practical electrical units and the MKS mechanical units could be incorporated into a single coherent system by (1) selecting the meter, kilogram, and second as the base units for mechanical quantities; (2) expanding the number of base units to four, including one of an electrical nature; and (3) assigning physical dimensions to the permeability of free space 0, with a numerical value of 4 x10<x-tad-smaller>7</x-tad-smaller>
in a “rationalized” system or 10<x-tad-smaller>7</x-tad-smaller>
in an “unrationalized” system. (The term “rationalized,” due to Heaviside, concerned where factors of 4 should logically appear in the equations based on symmetry.) The last assumption implied that the magnetic flux density B and magnetic field H, which are related in vacuum by the equation B = <x-tad-smaller>0</x-tad-smaller>
H, are physically distinct with different units, whereas in the Gaussian system they are of the same character and are dimensionally equivalent. An analogous situation occurs for the electric fields D and Ethat are related by D = <x-tad-smaller>0</x-tad-smaller>
E, where <x-tad-smaller>0</x-tad-smaller>
is the permittivity of free space given by c<x-tad-smaller>2</x-tad-smaller>
= 1 / <x-tad-smaller>0 0</x-tad-smaller>
.
As in my earlier message, I will again note that some of your computers may have received this with the CORRECT symbols. If so, pardon me for bothering you with this long description of the errors I received on my computer.
Copy with errors noted and corrected:
-------------------------------------------------------
In 1901, Giorgi demonstrated that the practical electrical units and the MKS mechanical units could be incorporated into a single coherent system by (1) selecting the meter, kilogram, and second as the base units for mechanical quantities; (2) expanding the number of base units to four, including one of an electrical nature; and (3) assigning physical dimensions to the permeability of free space 0,The previous character should be the Greek letter lower case epsilon with a subscript zero. Apparently the letter was lost and only the zero remained. When spoken, the symbol is usually pronounced "epsilon zero" or "epsilon sub-zero".
with a numerical value of 4 x10<x-tad-smaller>7</x-tad-smaller>The preceding number should be 4 pi times 10 to the seventh power. The pi is missing and the 7 is not in a superscript as needed.
in a “rationalized” system or 10<x-tad-smaller>7</x-tad-smaller>The preceding number should be 10 to the seventh power.
in an “unrationalized” system. (The term “rationalized,” due to Heaviside, concerned where factors of 4Preceding number should be 4 pi.
should logically appear in the equations based on symmetry.) The last assumption implied that the magnetic flux density B and magnetic field H, which are related in vacuum by the equation B = <x-tad-smaller>0</x-tad-smaller>
H,The symbol preceding H in the above equation should be the lower case Greek letter mu with a subscript of zero. Apparently everything was lost except the zero. When spoken, the constant is usually pronounced "mu zero" or "mu sub-zero". The constant mu zero is called the magnetic permeability of free space.
are physically distinct with different units, whereas in the Gaussian system they are of the same character and are dimensionally equivalent. An analogous situation occurs for the electric fields D and E that are
related by D = <x-tad-smaller>0</x-tad-smaller>
E,The symbol before the E should be a Greek lower case epsilon with a subscript of zero ("epsilon zero", as before).
where <x-tad-smaller>0</x-tad-smaller>The preceding also should be epsilon sub-zero.
is the permittivity of free space given by c<x-tad-smaller>2</x-tad-smaller>
= 1 / <x-tad-smaller>0 0</x-tad-smaller>
.This final expression is completely destroyed by ALL of the same problems alluded to above. The left side should be the letter "c" squared. (It stands for the speed of light squared.) The right side should be a ratio with "1" in the numerator (that's OK) and mu sub-zero times epsilon sub-zero in the denominator.
(I am a bit concerned about my interpretation of the error and my subsequent correction here. The equation is surely c-squared equal one over the product of mu-zero times epsilon zero, but I'm not sure why he refers to it as an equation that "the permittivity of free space, epsilon sub zero, is GIVEN by" this equation. Perhaps I have misunderstood something here.)
I hope I have made correct corrections. For anyone to whom this information is particularly important, I would recommend you check my corrections against more authoritative sources.
Bill Hooper
