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The permittivity of a vacuum and the permeability of a vacuum


geordief

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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?

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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

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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 2×107newtons per metre of length."

Which requires that the magnetic permeability is, by definition exactly 4 x pi x 10^-7 Henries per metre.

 

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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.

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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.

 

 

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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.

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