While coded signals would be fascinating to librarians and scientists alike, it’s always more fun to have a live alien in the foreground, too. So I supplied Poul’s Ythri.

Poul was a major player of the game among hard SF writers, a collegial challenge: see if these ideas pass muster, and see what I’ve done with them. I knew Poul since 1963 and treasured the many times we met, dined, and drank together. I miss him greatly, and it’s been a pleasure to play in one of his imagined worlds.

The true lore of science fiction is that it is, like science itself, at its very best—a continuing conversation about matters broad and deep.

The Ythri chronicles appear mostly here:

The People of the Wind, London, 1977, p. 7, notably “The Problem of Pain.”

The Earth Book of Stormgate, New York, 1978, and others.

Following are the pages Poul sent (handwritten notes hard to see).

ORBITFALL? REALLY?

Is this stunt possible?

As often, there’s a site for that: https://www.quora.com/Could-a-person-survive-falling-from-space-to-Earth-Assume-the-person-doesnt-have-to-worry-about-freezing-or-breathing-in-space.

From 100 kilometers up, the first 75,000 meters of fall is going to have very little atmospheric resistance. You are going to hit the thicker part of the atmosphere below 25,000 meters going mach 3.5. A 100 kg person falling at that speed has a kinetic energy of 72,000,000 joules. You are not going to survive this free fall.

You are going to hit the dense part of the atmosphere at Mach 3.5. Once you hit the thick atmosphere (assuming the turbulence has not shredded you to pieces yet), you need to immediately start to decelerate. You must slam on the brakes at 25,000 meters. It will take you 42 seconds at 3 g’s to go from 1200 m/s down to 2 m/s at ground level. You will have to dissipate 1,714,285 watts of energy for 42 seconds.

The SR-71 [Blackbird airplane] at 25,000 meters going Mach 3.5 saw the temperature rise on the leading edges of the wing to 1100°F. [So] he may become the first human shooting star.

For a 100 kg man his final temp would be 239°C or 463°F.

These temperatures are confirmed with the results of Scaled Composites SpaceShipOne. The 100 km altitude free fall hit speeds in excess of 1000 m/s. The actual skin temperature was greatly reduced by the vertical tail drag structure by design but even with this the aircraft experienced skin temperatures of 500°F.

Dead as a doornail unless you can find a way to transfer the heat to something else other than the person falling… and without killing them from intense g force shock!

So I’ve included some tech fixes for my characters. This is the distant future, after all. Still, I wouldn’t do the orbitfall. But Fraq and Rachel do.

TOROIDAL WORMHOLES

General relativity allows wormholes, and they can spin. Pass spinning matter through them, and through coupling this transfers to the spacetime warping that follows.