So Bob didn’t understand relativity. Big deal. Neither do I. The stories are still meaningful and well-told. By now, the science is out-dated as Verne anyway.
Been a while since I read it – but that twin certainly DID accelerate when they left earth (not using magical FTL – I remember that much). So the twins aren’t identical.
That one, I can’t even claim as a mistake: There’s no reason that the crew of the Mayflower would need to know that, since the Mayflower was an in-system vessel and so wouldn’t be getting to relativistic speed anyway. So it’s just a case of character ignorance.
There’s a place to discuss misunderstood and outdated science in older sf; it’s interesting to see how things were perceived, or understood, or mis- both - by the people of the time or just the writer.
But I agree that such things are irrelevant if the story is sufficiently well told. Nearly all of sf is actually sheer moonshine fantasy, no matter how hard-nuts the writer’s aim or credentials. To diss a work because it wouldn’t pass peer review is missing the point.
But the problem is that, in the universe that Time for the Stars takes place, instantaneous telepathy is possible. In fact, to the physicist character on the ship the whole point of the expedition is to test the simultaneity of this newly discovered physical phenomenon and the “look for new planets” is just a sideshow. And the experiments on telepathy eventually lead to the FTL “irrelevant” ships that bring Tom back to earth at the end.
So…in real life, one twin is on a spaceship, one twin is on earth. The twin on the spaceship zooms away. But of course, in our universe there is no preferred frame, so it is just as valid to say that the twin on the spaceship slows down, and lets the speeding earth zoom away. So which twin is traveling at a greater fraction of c? Either twin could argue that the other is traveling, and both would be correct.
The only time they will agree as to which one travelled and which one stayed put is when they come back together and compare clocks, then they can agree that one traveled faster and one traveled slower. But until they can compare clocks, they won’t agree.
However, it seems to me that “come back together” just means “be in the same reference frame”. So Tom heads to Tau Ceti leaving Pat on Earth. While Tom is moving, it seems to Tom that Pat is moving (along with the rest of the galaxy), and it seems to Pat that Tom is moving. But then Tom stops accelerating at midpoint of the trip and decelerates and comes to rest at Tau Ceti. And Tau Ceti and Sol are both in the same reference frame–that is, they are traveling through the universe (more or less) together, just like two twins on Earth are traveling through the universe together even if one is at London and one is at New Zealand.
So, assuming no telepathy and no FTL, when Tom arrives at Tau Ceti, he sends a radio message to Pat, “Hey Bro! My clock reads YYYY.MM.DD.hh.mm.ss.μμ.” Eight years later Pat gets the message, and since Pat knows Tau Ceti is 8 light-years away at traveling at (roughly) the same velocity as the solar system, he can then tell that Tom is the younger twin and he is the older twin.
Or not?
Slight hijack:
Following along with this thread made me try to re-read The Number of the Beast (which I quite liked as a teen) when I ran across it a few days ago.
You bastards.
Unlike the rest of you (apparently) I like the World-as-Myth stuff. So I’m looking forward to reading about some hot naked geniuses.
As do I; but the incessant agruing about who is the captain. Argh!
Character ignorance by an atomic propulsion specialist in a relativistic spaceship? I doubt it.
That wasn’t Heinlein’s style anyway. He went to great effort to make sure the science was right. He famously spent days calculating orbital parameters for single-line throwaway dialog. He painstakingly engineered the details of spacesuits. He would never knowingly put a piece of scientific misinformation in a book and then write it off as the character being stupid.
That doesn’t mean he was always right. For being the considered the Dean of hard science fiction, Heinlein believed in his share of nonsense. He was a bit of a mystic, he thought ESP research showed real effects, he bought into ‘General Semantics’ and other pseudo-science of his day. But it was rare that he made basic engineering and science mistakes.
Remember that “dean” simply means “eldest” and does not necessarily confer any notion of superiority. That’s part of the reason Heinlein hated being called that.
Making errors in sciences still under development or incompletely explained to the average person - which, in this case, Heinlein was - is one thing. Bobbles like the nonsensical juggling of statistics and odds in MIAHM… sigh.
I’m afraid I can’t hear you over the sound of all the space pirates with their consarned slide rules.
I have no idea what you mean. My perfectly-maintained slipsticks are completely silent. Perhaps the space pirates used the wrong kind of stick slip.
I think he means that the pirates are noisy, not the slipsticks (some pirates though, are prone to poor sliderule maintenance, leading to an annoying squeaking sounds as they calculate).
Well, obviously someone involved in the design of a torchship at some point had to understand relativity (there must be some pretty deep physics involved in the total-conversion reaction), and such a ship could in principle reach relativistic speeds, but for just running from Earth to Jupiter, it wouldn’t, and so I wouldn’t expect the ship’s engineer to know any more relativity than the typical real-world engineer (which isn’t much). Someone can be quite competent without being omnicompetent.
And all of my slide rules (well, the seven I just checked, at least) are audible, though I confess that I’m not sure how I ought to be maintaining them. Some sort of oil?
Mind power, Chronos. That and proper thoughts.
Skull sweat 
We have a winner.
There are, of course, Android Slide Rule apps! (That’s one of several.)
Now that I know a thing or two about Reletivity, I view that scene as a guy in a “teacher” role ending the questions at the end of the tour and maybe sparking the kids’ curiousity. I assume the character knew better. For the author trying to explain why kicking in the afterburners when you’re at 99% of c won’t take you past c (just to 99.5% of c) would take another chapter, without moving the plot forward.
I think this is exactly Heinlein’s intent with all these passages, allowing that he may have had some misunderstanding of relativity in the mid-1950s. I’m not trying to go to any length to excuse his ignorance or mistakes, only pointing out that he had the same tendency as many of the best teachers I’ve had: to provoke students/readers into going out and finding their own answers. He and his characters often indicate they know the answer… but know that just telling someone the next fact is not the same as sparking them to go out hunting their own more complete answers.
Is there more to say about TFTS besides wrangling over a scientific point no more wrong or distorted than can be found in 90% of the lit?