[ExI] fermi question alive and well

John Clark johnkclark at gmail.com
Sat Mar 30 17:11:14 UTC 2019

On Sat, Mar 30, 2019 at 12:06 PM Mike Dougherty <msd001 at gmail.com> wrote:

> Does this have anything to add to the ongoing discussion of "waste heat"?
> https://www.livescience.com/64995-heat-speed-of-sound-through-graphite.html

It's called "second sound" and was what I was talking about with Helium-2,
but with Helium it works for long distances but with Graphite it works for
less than .01mm

*> If heat can be focussed analogous to light in a laser, it might not be
> directed at us.*

Waste heat takes the form of low temperature Black Body radiation, it is
very diffuse, consists at many different wavelengths and moves in many
directions. A Laser beam is very concentrated, is at only one wavelength,
and moves in only one direction. So a Laser has much less Entropy than
Black Body radiation. So if you make a Laser beam you're going to create a
lot of waste heat and getting rid of that heat is the very thing you're
trying to do. So a Laser radiator makes no sense.

> *If advanced kardashev civs have learned eco-friendly engineering at
> glactic-scale, would we have evidence?*

We would unless "eco-friendly engineering at a glactic-scale" means doing
absolutely nothing to the galaxy.

> > the incredible hubris required to look at some squiggles from
> telescopes to decide the fate of the universe.

Yes, but you almost make that sound like a bad thing.

 John K Clark

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