- #1
- 498
- 34
Hi.
If I turn on an antenna, it starts sending out radiation. If I turn it off again, the radiation doesn't instantly disappear but dies out smoothly (exponentially?). But this also means the radiation is never completely gone.
This looks time-asymmetric, which is weird for electrodynamics. It would also mean that the EM field needs to be described by a non-analytic function at the time it's turned on. Do they really occur in nature?
Another way out might be looking closer at the moment the antenna is turned on. No switch is instantaneous, bringing the contacts closer together will already have some impact on the antenna circuit, so the radiation might also be analytical backwards in time. But this would also mean that it was already there when the copper of the circuit was still in the mountains, which is also weird.
Or is there another way out of this?
If I turn on an antenna, it starts sending out radiation. If I turn it off again, the radiation doesn't instantly disappear but dies out smoothly (exponentially?). But this also means the radiation is never completely gone.
This looks time-asymmetric, which is weird for electrodynamics. It would also mean that the EM field needs to be described by a non-analytic function at the time it's turned on. Do they really occur in nature?
Another way out might be looking closer at the moment the antenna is turned on. No switch is instantaneous, bringing the contacts closer together will already have some impact on the antenna circuit, so the radiation might also be analytical backwards in time. But this would also mean that it was already there when the copper of the circuit was still in the mountains, which is also weird.
Or is there another way out of this?