geordief Posted November 4, 2017 Share Posted November 4, 2017 I understand that both these constants are experimentally observed . Can I deduce from that that there is no particular reason why the numbers noted should be what they are? Is there a close relation between those two constants and the speed of a massless object in a vacuum? Link to comment Share on other sites More sharing options...
studiot Posted November 4, 2017 Share Posted November 4, 2017 30 minutes ago, geordief said: I understand that both these constants are experimentally observed . Can I deduce from that that there is no particular reason why the numbers noted should be what they are? Is there a close relation between those two constants and the speed of a massless object in a vacuum? Yes, http://scienceworld.wolfram.com/physics/SpeedofLight.html Link to comment Share on other sites More sharing options...
John Cuthber Posted November 5, 2017 Share Posted November 5, 2017 Actually, one of the numbers is a consequence of the definition of the ampere. "The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed one metre apart in vacuum, would produce between these conductors a force equal to 2×10−7newtons per metre of length." Which requires that the magnetic permeability is, by definition exactly 4 x pi x 10^-7 Henries per metre. Link to comment Share on other sites More sharing options...
swansont Posted November 5, 2017 Share Posted November 5, 2017 14 hours ago, geordief said: I understand that both these constants are experimentally observed . Can I deduce from that that there is no particular reason why the numbers noted should be what they are? Yes, there is a reason. As JC implied, it's because we have chosen a particular set of units in the SI system. If you went to another unit system, the values would be different. Link to comment Share on other sites More sharing options...
geordief Posted November 5, 2017 Author Share Posted November 5, 2017 1 hour ago, swansont said: Yes, there is a reason. As JC implied, it's because we have chosen a particular set of units in the SI system. If you went to another unit system, the values would be different. But the relation of the 2 constants to to c would be the same,I suppose,. It seems interesting to me that ,if the permeability was equal to the permittivity (obviously ridiculous a la "apples and oranges") the form of the relation between the three components would reduce to c is inversely related to permittivity (or permeability). simply by the form of the equation. I am not sure if that has any significance. Link to comment Share on other sites More sharing options...
swansont Posted November 5, 2017 Share Posted November 5, 2017 6 minutes ago, geordief said: But the relation of the 2 constants to to c would be the same,I suppose,. It seems interesting to me that ,if the permeability was equal to the permittivity (obviously ridiculous a la "apples and oranges") the form of the relation between the three components would reduce to c is inversely related to permittivity (or permeability). simply by the form of the equation. The square root of their product will be c. But that might not nail down either value, only their product. Link to comment Share on other sites More sharing options...
John Cuthber Posted November 5, 2017 Share Posted November 5, 2017 4 hours ago, swansont said: The square root of their product will be c. 1/c Link to comment Share on other sites More sharing options...
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