On Friday, July 27, 2012 7:39:28 AM UTC-5, Szczepan Bialek wrote:
From Maxwell's time all circuits are closed. So sometimes the
current must flow in the air.

Maxwell did not believe in current flowing "in the air". That's why he used the concept of "displacement current". He was ignorant of photon energy flow being the equivalent of current flow. Nowadays, we know that when it appears that coherent current is flowing in the air or indeed through any dielectric (including free space), it is actually photons that are doing the flowing, i.e. photons are accomplishing the energy transfer *as if* current were flowing through charge carriers. All EM field/wave phenomena involve quantized photons.

For those who still believe in displacement current, it is easy to prove that, under certain conditions, the displacement current would have to violate the speed of light limit in order to accomplish the energy transfer in the measured time.

Do you understand the Pointing explanation that nothing if flowing in
the conductor?

Quoting "Fields and Waves ...", by Ramo & Whinnery: "A perfect conductor is usually understood to be a material in which there is no electric field at any frequency. Maxwell's equations ensure that there is then also no time-varying magnetic field in the perfect conductor."

In the non-perfect real world, something is flowing in the skin effect depth of a conductor which is the cause of the power losses in the conductor.
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73, Cecil, w5dxp.com