From: Randall Randall (randall@randallsquared.com)
Date: Mon Jun 09 2003 - 21:10:02 MDT
On Monday, June 9, 2003, at 03:02 PM, Hal Finney wrote:
> Randall wrote:
>> If this were true, wouldn't it follow that one could build an FTL
>> communications device consisting of a sufficiently precise detector
>> and a movable highly charged object? For this reason alone, it seems
>> implausible that electric fields behave as perfectly rigid objects, as
>> you describe.
>
> Sorry, I wasn't completely clear. The electric and gravitational
> fields
> move along with the star only while it is moving uniformly. If the
> star
> gets bumped, the *change* in the field propagates outward at c. At
> time
> t after the bump there is an expanding sphere of size c*t, where inside
> the sphere the field has changed due to the bump, but outside the
> sphere,
> nothing has changed yet. Outside of the sphere, the field points to
> where the star would have been at that moment if it hadn't been bumped.
> This part of the field doesn't know yet about the bump.
So since two orbiting stars are continually being "bumped" by each
other, your explanation seems to imply that each star is orbiting
around a location which trails the actual star. As long as orbits
work anyway, this is fine, but wasn't the Flandern (sp?) fellow
saying that in this event orbits couldn't be stable? I don't know
anything like enough math to work this out myself, so I'll eventually
take someone's word for it, I suppose, for the time being.
-- Randall Randall <randall@randallsquared.com> "Not only can money buy happiness, it isn't even particularly expensive any more." -- Spike Jones
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