Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content,

check out go.nebola.tv slash Isaac Arthur and use my code, Isaac Arthur.

So a few months back, I finally got talked to trying out some short-form content, and after

we did a bunch, folks started asking if we could make a compilation of them to watch on

YouTube or over on Nebula and our audio-only podcasting platforms.

I figured we would release them in groups of 20, so unlike the solo shorts, you might

want a drink and a snack. I'll talk more about it at the end, but by popular demand,

and without further ado, here's the first 20 shorts we produced in summer of 2023.

A solar moth is a type of solar thermal rocket that uses a parabolic mirror, or wing-like

pairs of them, to focus light from a nearby star on a tank of future propellant, the

tank likely being half silver to allow light in and keep it bouncing around to heat the gas

inside the tank.

This superheated gas then makes for an excellent propellant. We may also use this

in conjunction with laser beaming or microwaves or any other type of energy beaming to achieve a higher

thrust. This approach allows for a higher thrust in a simple solar sail or laser sail,

though that thrust comes to an end when the propellant runs out, and then it will simply

be a solar sail, the one

moving faster sooner and bearing less cargo and payload. It may be very useful for for

deploying laser beaming equipment to new star systems. Like a laser sail, it can be used in conjunction

with a matter beam to replenish propellant too. A solar moth is a very simple design with few failure modes,

...