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?
'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.
I guess this paper by Westerlund and Ekstam (not Eklam) might be what is being referred to:
There's also this more recent paper, ooh boy controversy! I bet it's a hot ticket
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