Michael Ikeda <mmikeda@erols.com> wrote or quoted:It varies.
:Yes, but one could argue the science in science fiction is supposed
:to be somewhat plausible.
I've been annoyed for a while that "Science Fiction" is basical-
ly never scientifically accurate. But I gotta say you can read the
word "Science" in Science Fiction a few different ways. It could
mean, like I used to think, "based on scientific findings," or it
could just mean "pulling in ideas from science." Often words like
"wormhole" get used as a motif, but then a wormhole is what the au-
thor imagines, not what science actually says about it. By the way,
I recently watched a talk (as a video) where Professor Susskind
talks about how two black holes, formed from entangled particles far
apart, make a wormhole. If Jack and Jill each jump into one of those
holes, they'd meet inside. So science isn't always boring, I think.
The video was "The Quantum Origins of Gravity" (Oscar Klein Memorial
Lecture 2018) by Leonard Susskind.
Heinlein's /The Rolling Stones/ has a lot about trajectories for
traveling from the Moon to Mars with a fly-by of the Earth to get a
push. I suspect it is accurate in the sense that it was what was
thought to be correct at the time. It may also be accurate in an
absolute sense, who can say?
Paul S Person <psperson@old.netcom.invalid> wrote:
Heinlein's /The Rolling Stones/ has a lot about trajectories for
traveling from the Moon to Mars with a fly-by of the Earth to get a
push. I suspect it is accurate in the sense that it was what was
thought to be correct at the time. It may also be accurate in an
absolute sense, who can say?
It's pretty close in an absolute sense, although I am not sure that
you can get sufficient precision from mechanical cams. And of course
you can't control your course once you have it set in, without
getting new cams machined by the big computer on Earth. That's a
problem if something goes wrong halfway there and you have to change
your thrust level.
Heinlein's /The Rolling Stones/ has a lot about trajectories for
traveling from the Moon to Mars with a fly-by of the Earth to get a
push. I suspect it is accurate in the sense that it was what was
thought to be correct at the time. It may also be accurate in an
absolute sense, who can say?
On Sun, 1 Mar 2026 12:31:55 -0500 (EST), Scott Dorsey wrote:It's not entirely clear whether, when they all try to compute
Paul S Person <psperson@old.netcom.invalid> wrote:
Heinlein's /The Rolling Stones/ has a lot about trajectories for
traveling from the Moon to Mars with a fly-by of the Earth to get a
push. I suspect it is accurate in the sense that it was what was
thought to be correct at the time. It may also be accurate in an
absolute sense, who can say?
It's pretty close in an absolute sense, although I am not sure that
you can get sufficient precision from mechanical cams. And of course
you can't control your course once you have it set in, without
getting new cams machined by the big computer on Earth. That's a
problem if something goes wrong halfway there and you have to change
your thrust level.
Imagine trying to calculate a slingshot orbit, getting gravity assists
from various planets along the way, sometimes multiple times, as so
many space probes are routinely doing these days. No analog computer
could achieve enough accuracy for that, I donAt think.
By the way, BabbageAs old steam-powered oDifference Engineo did
calculations with a precision of 30 decimal digits. Even with todayAs >advanced digital computers, thatAs still pretty unusual.
On Sun, 1 Mar 2026 21:49:07 -0000 (UTC), Lawrence D|OliveiroThe last chapter I read introduced a "flat cat", and the title of the
<ldo@nz.invalid> wrote:
On Sun, 1 Mar 2026 12:31:55 -0500 (EST), Scott Dorsey wrote:
Paul S Person <psperson@old.netcom.invalid> wrote:
Heinlein's /The Rolling Stones/ has a lot about trajectories for
traveling from the Moon to Mars with a fly-by of the Earth to get a
push. I suspect it is accurate in the sense that it was what was
thought to be correct at the time. It may also be accurate in an
absolute sense, who can say?
It's pretty close in an absolute sense, although I am not sure that
you can get sufficient precision from mechanical cams. And of course
you can't control your course once you have it set in, without
getting new cams machined by the big computer on Earth. That's a
problem if something goes wrong halfway there and you have to change
your thrust level.
Imagine trying to calculate a slingshot orbit, getting gravity assists
from various planets along the way, sometimes multiple times, as so
many space probes are routinely doing these days. No analog computer
could achieve enough accuracy for that, I donAt think.
By the way, BabbageAs old steam-powered oDifference Engineo did >>calculations with a precision of 30 decimal digits. Even with todayAs >>advanced digital computers, thatAs still pretty unusual.
It's not entirely clear whether, when they all try to compute
solutions for a given maneuver (the trip to Mars turns out to be more >exciting than planned), they are using anything more than
pencil-and-paper (or perhaps stylus-and-erasable pad).
But I didn't claim that /how they computed it/ was necessarily
correct. It is the description of how such maneuvers work (burn here,
coast there, relative velocity with neighboring ships -- Newtonian
mechanics at its finest).
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