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Re: Electrostatic shielding

I guess I should qualify the response of my last post a bit. I wrote:

.... But *if* the spacelike sections of spacetime
are topologically compact (so that the universe is spatially closed) it
is a easily provable theorem that the universe must be charge-neutral
(for essentially the reason illustrated by Bill) because all electric
flux lines must stop & start on opposite charges and there is no
spatial infinity for any excess such lines to escape to.

I should point out that I phrased the sentence badly. I meant to say
that all flux lines that happen to have an endpoint must also possess
an oppositely charged endpoint, and this guarantees global charge
neutrality, because any flux line that had one endpoint must either have
another endpoint (of necessarily opposite charge) or it must escape to
asymptotic spatial infinity. If there is no such asymptotic spatial
infinity for the excess one-ended flux lines to go to, there can be no
such excess.

It is always possible to have E field flux lines that have no endpoints
at all by simply having them form a loop (such as when such loops are
induced by Faraday's law or when they might globally loop the entire
universe if it is compact).

David Bowman