[extropy-chat] Re: Space Elevators

[Adrian Tymes]

--- Damien Broderick <thespike at satx.rr.com> wrote:
> So consider: I'm sitting in my geo-station, spooling out
> bucky 
> thread. Mysteriously, it's going straight away from me toward the
> surface. 
> After a while, the far end is hovering one inch above the ground.
> Even more 
> mysteriously, it's travelling at only a thousand miles an hour, while
> I'm 
> hurtling overhead at five miles a second. What's causing the lag?

Rotation...assuming you adjust your angular velocity accordingly while
spooling out the cable (an easy trick to do, especially if you're
careful to spool out an exact same amount straight away from the
surface at the same time).  The entire structure then spins 360 degrees
every 24 hours - which means the far ends of the cable traverse quite a
lot of distance in that time.  Your center of mass may be going five
miles a second, but the far end is travelling somewhat under five miles
a second backwards thanks to rotation; the net velocity relative to the
Earth's core happens to be about the same as the velocity of a certain
point on the Earth's surface (namely, the point it's hovering over).

Meanwhile, the end of the cable above you is travelling faster than
five miles per second: where the rotation opposed velocity below, it
adds to velocity above.  Fortunately, it's doing so through vacuum -
and, again, velocity is relative.  (How fast is Voyager going?  And yet
it's in little imminent danger of catastrophic collision.)