On 09/12/2015 08:43, gareth wrote:
The impedance of Free Space is given as 377 ohms.

Surely if there's nothing there, that should be unity, suggesting that our
systems of units, newtons, volts, etc. are arbitrary and just plain wrong.

No.
Firstly, for the same reason that in a vacuum the speed of light is not
infinite.
Secondly, if there is nothing there, why 1? Why not .05 or 100 ohms? 0
ohms makes more sense for a vacuum, nothing there, nothing to oppose.

Should we change, as we do for circular measure, now using Radians and
neither
Degrees nor Grads?

Radians is simply more convenient as an angular measure because the use
of pi makes the calculation and manipulation simpler and more intuitive.

Andy