[ExI] The tools humanity will need for living in the year 1 trillion

[Adrian Tymes]

On Sat, Jul 14, 2018 at 7:57 AM, John Clark <johnkclark at gmail.com> wrote:
> Feynman said place two beads on a sticky rigid rod, the beads can slide
> freely but there is a small amount of friction between the beads and the
> rod. If the rod is placed transversely to the direction of propagation of
> the gravitational wave then atomic forces will hold the length of the rod
> fixed, or almost fixed, but the proper distance between the two beads would
> be free to oscillate. So the beads would have to rub against the rod, and
> the friction from that would produce heat, and with heat you could run a
> steam engine and get work out of it.
>
> Why couldn’t the same argument also be used to show you could get work out
> of the expansion of the universe?

Static friction, though this may work against Feynman's idea too.

In short, there is a certain minimum impulse needed to start movement,
when one object is resting upon another such that there is friction
between them.  If a gravitational wave is too weak to overcome this,
it's not a small amount but literally zero movement that is imparted.
Expansion of the universe seems likely to remain substantially weaker
than most detectable gravitational waves.