21

A colleague of mine explained this concept in the early 1990s; he sounded like he read it in a (printed) sci-fi story: whether novel, novella, short story or radio-drama script I have no idea.

The premise is, a lightweight drive has made slower-than-light travel feasible over interstellar distances (couple of l-yrs, say): the ship incurs tremendous acceleration on the first half of the voyage (hundreds or thousands of G's, say), followed by tumbling and equally tremendous deceleration until it get captured around the target star.

Such an acceleration would make it impossible to embark a crew: they would be squashed to red pulp against the floor of their cabin. The solution is to also embark a portable black hole and to adjust the position of the cabin relative to it, constantly keeping the gravitational field of the black hole within +/- 1g of the propulsive acceleration around the cabin.

Things we did not discuss:

  • how the black hole and the cabin are kept fixed w/resp. to the drive;
  • protection of the crew against ageing by relativistic effects: time dilation and twin paradox.

What story was this (author/title) and was it published in print? Note, the publishing must be before the end of the 1st Gulf war (mid-1991, latest). My then-colleague could have read it, or its translation, in French, English or Russian.

Added after accepting the answer.
The McAndrew Chronicles differ markedly from my understanding of my colleague's exposition. I believe this arises from failed recollection and the accepted answer really was his source.

The McAndrew drive is the "lightweight drive which has made slower-than-light travel feasible" over interplanetary, not interstellar, distances; basically, it uses portable black holes for energy storage, pretty much like we use flywheels instead of batteries to power electromagnetic guns.

At least in Moment of Inertia, the anti-G system which enables interstellar travel(?) with the drive and motivated my question balances ~50G of propulsive acceleration (not thousands of G's) with the gravity of a circular plate of condensed matter, not with that of a black hole.

6
  • 1
    Nearly same question and same answer as scifi.stackexchange.com/questions/73294/… Commented May 8 at 0:32
  • @dave_thompson_085 Same answer indeed; I would not have guessed it from just comparing the questions. Commented May 8 at 17:06
  • With thanks to all the editors, by the way. Commented May 8 at 17:47
  • 1
    @FrançoisJurain On your edit - if you don't think this is the correct answer, you don't need to mark it correct. There's still a possibility that someone else remembers another story that might be closer to your recollection.
    – DavidW
    Commented May 8 at 18:01
  • @DavidW I am aware of that possibility, which I dismiss as utterly unbelievable: only a mathematician could independently come up with the concept and if they were also active in SF, they would know of Sheffield's works. If anyone published anything alike, it would only be as a tribute to him. So he must have the priority & you must accept the kudos, sorry :-). Commented May 9 at 10:31

1 Answer 1

26

This sounds like the "McAndrew drive" from a couple of Charles Sheffield's stories, starting with "Moment of Inertia" (1980). "Moment of Inertia" was originally published in Analog, October 1980, and collected in Hidden Variables (1981) and The McAndrew Chronicles (1983), which was translated to French as Les chroniques de McAndrew (1985).

The (mini) black hole (called a "kernel") provides power for acceleration, but the mass that balances the acceleration is a large disk of collapsed matter.

"See the plate on the bottom? It's a hundred-meter-diameter disk of compressed matter, electromagnetically stabilized and one meter thick. Density's about eleven hundred and seventy tons per cubic centimeter—pretty high, but nothing near as high as we've worked with here at the Institute. Less than you get in anything but the top couple of centimeters of a neutron star, and nowhere near approaching kernel densities. Now, if you were sitting right at the center of that disk, you'd experience a gravitational acceleration of fifty gees pulling you down to the disk. Tidal forces on you would be one gee per meter—not enough to trouble you. If you stayed on the axis of the disk, and moved away from it, you'd feel an attractive force of one gee when you were two hundred and forty-six meters from the center of the disk. See the column growing out from the disk? It's four meters across and two hundred and fifty meters long."

I looked at it through the scope. The long central spike seemed to be completely featureless, a slim column of grey metal.

"What’s inside it?"

"Mostly nothing." Wenig picked up a model of the Dotterel and cracked it open lengthwise, so that I could see the interior structure. "When the drives are off, the living capsule is out here at the far end, two hundred and fifty meters from the dense disk. Gravity feels like one gee, towards the center of the disk. See the drives here, on the disk itself? They accelerate the whole thing away from the center column, so the disk stays flat and perpendicular to the motion. The bigger the acceleration that the drives produce, the closer to the disk we move the living capsule, up the central column here. We keep it so the total force in the capsule, gravity less acceleration, is always one gee, towards the disk."

The story is currently available on the Baen website.

2
  • 1
    Sure does read like you're spot on. Author's a physicist, story translated to French in 1985, mentions "efficient use of Kerr-Newmann BH's"... Thx, must read. Commented May 7 at 15:28
  • 1
    @user14111 Correct, the series started in 1978, but the "McAndrew drive" spacecraft in question didn't appear until "Moment of Inertia."
    – DavidW
    Commented May 7 at 15:45

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.