violation of causality by purely imaginary impedance functions

I've read that the exponential behavior predicted in e.g. RC circuits by taking the Laplace-domain impedance of capacitors to be 1/sC leads to a causality violation, and that after much testing of many capacitors some guys named Westerlund and Eklam determined that the true behavior is a probably a power law, which I guess means the dv/dt in I = C dv/dt would actually have to be some kind of fractional derivative.

Can anyone elaborate on why this is so?

Reply to
bitrex
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'T'ain't so. Just another casualty of causality.

(People, especially assistant professors, periodically announce causality violations due to mistaking group delay for true delay(*) or measuring logic transitions by output threshold crossings with a slowish input.

Cheers

Phil Hobbs

(*) I did that myself once, in this very boutique.

Reply to
Phil Hobbs

I guess this paper by Westerlund and Ekstam (not Eklam) might be what is being referred to:

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There's also this more recent paper, ooh boy controversy! I bet it's a hot ticket

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Reply to
bitrex

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