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So I just finished reading L. Ron Hubbard's novel To the Stars and noticed a rather glaring issue. The plot in the beginning speaks of a ship capable of near-light-speed travel which makes a return trip to Alpha Centauri and returns to Earth probably around 60 or even more years later. The exact number is never given, but 60 is a good guess, and it's certainly more than 40 which is still good enough for my argument.

The thing is that the ship constantly travels with a speed of at least 296000 km/s, which is a speed at which they will, for an outside observer, travel the 4.367 light years to Alpha Centauri in no more than 4.42 years. Even giving them 0.6 years extra, they should return at worst 10 years after leaving.

Note: there is no need to explain time dilation to me. I know how it works, but it does not apply here. The question is not how much time passed inside the super fast ship, and I agree that the answer is "much less than outside".

The point is that from the standpoint of Earth, people looking up would see a ship traveling at 296000km/s, and the ship would reach its destination after about 5 years (of course, we would only see the ship reach its destination after 9 years, but that makes no difference, the clock on earth would still show five years at the time the ship made it to AC)

Is there any in-story explanation why the time dilation was so much bigger in the story?

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    I've not read it, but does the ship immediately travel at top speed and then throughout the journey until it suddenly comes to a crash-stop or is there decades of speeding up and slowing down? – Valorum Sep 9 '15 at 11:28
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    @Richard Well, there is some vagueness there, but not that much. The story makes it clear that only the first couple of days are troublesome because the ship is accelerating, and that it gets easier later. – 5xum Sep 9 '15 at 11:30
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    Where does the figure of 296000 km/s come from? Is it stated in the book or did you deduce it from other things? Also, when you say the journey took over 40 years, is that from the perspective of people on Earth or people on the ship? And is it specifically said that this time is because the journey there and back took over 40 years, as opposed to a shorter journey but with a long stay on Alpha Centauri before returning? – Hypnosifl Sep 9 '15 at 13:49
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    @Hypnosifl The book specifically says 296000. Also, the journey takes over 40 earth years because upon return, people who were young at the beginning are now old. As far as I understand the book, there was a trip to there and a couple of weeks stay before returning. There is no indication of anything else. – 5xum Sep 9 '15 at 13:59
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    Please restrict comments to the question at hand, not Hubbard's association with Scientology. – Valorum Sep 10 '15 at 19:44
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The numbers make no sense.

Using this, assuming an acceleration/deceleration of only 1g, and a maximum velocity of 0.987c, and a distance of roughly 4.4 light years, and ignoring time dilation so it's only the outside observer's measurement, it takes about 6 years to get to Alpha Centauri, with about 349 days of acceleration on each end, so about 4.1 years coasting, then the same coming back. So just a touch over 12 years.

Even dropping the acceleration down to 0.1g gives a round-trip time of only 27.6 years.

I think the problem simply comes down to one factor not in the text: Writers Can't Do Math.

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    It appears at such a low (0.1g) acceleration, the spaceship doesn't even reach 0.6c by the halfway point at which time it starts slowing down... – DavidW Mar 26 '19 at 21:42
  • So basically the only way this makes any sense at all is if they accelerated quicker than 0.1g, but also for some reason they did not just accelerate to a coasting speed then decelerate for the end. They would have had to accelerate to near light speed, then pump the brakes hard and coast at some lower speed, or spend the entire trip slowing up and speeding down. Basically, whatever this book describes would be horribly inefficient for space travel. – JMac Mar 27 '19 at 11:12
  • I'm not about to accuse Hubbard of being able to do math, but he didn't make the specific error alleged in the question. He actually stated that a round trip between Earth and Alpha Centauri would take 9 years of Earth time. The 60-year trip included visits to several other stars, and should have taken much more than 60 years. See my answer for details. – user14111 Mar 28 '19 at 11:32
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As @ Richard and @ Hypnosifl suggested, the "extra" time comes from acceleration and deceleration on the way out and on the way back.

The OP says that "The story makes it clear that only the first couple of days are troublesome because the ship is accelerating, and that it gets easier later." This is unclear to me. If the ship took "only the first couple of days" to accelerate to the speed of light, the occupants would be squashed flat. If the ship took 3.5 days to accelerate to a mere 0.1 speed of light, that would be an acceleration of 10g. That is more than "troublesome."

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    If there was a loooong acceleration and deceleration phase that could explain why it took 40 years in the Earth's reference frame, but the problem is that then it would take nearly 40 years on the ship too, but from the comments above I got the impression it was a much shorter journey for those on board. – Hypnosifl Nov 21 '15 at 4:55
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    @Hypnosifl Right. I don't think we can figure this out without actually reading the book (and maybe not even then), which I might do next week when everything interesting in my life is cancelled because of Thanksgiving. The numbers just don't add up, from what the OP tells us. Accelerating to 0.987xc doesn't make sense on a voyage of 4.367 light years -- overkill -- . Key thing to find out is what their acceleration and deceleration were. – ab2 Nov 21 '15 at 13:26
  • @ab2 Did you ever get around to reading the book? – user14111 Mar 28 '19 at 11:35
  • @user 14111 Blush. No. But it is still on my list. – ab2 Mar 28 '19 at 12:43
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First, let's note that there may be two or three somewhat different versions of that story. Quoting the ISFDB:

The story was serialized in February and March 1950 as To the Stars and first published in book form in 1954 as Return to Tomorrow and then reprinted in 2004 as To the Stars.

I suppose the 1954 book was an expanded version of the 1950 serial. I have no idea if the text of the 2004 book (the one you read, I presume) is from the 1950 serial or the 1954 book or contains further revisions. Unfortunately I don't have either of the books on hand. This answer is based on the 1950 serial, which is available at the Internet Archive, in the February 1950 and March 1950 issues of Astounding Science Fiction. Maybe some revisions in the book you read invalidate my answer, though I'm inclined to doubt that. [Never mind! See postscript below. I forgot there's a thing called "Google Books". It's the same trip in 2004 as it was in 1950.] All quotations below are from the February 1950 ASF, page references and links provided so you can view them in context.


By the way, I would also like to mention that, while L. Ron Hubbard was a good storyteller, a master of pulp fiction, and a spectacularly successful "artist" of a sort, his yarns were not especially noted for their scientific accuracy, so you should not take his math and physics too seriously. For instance, he seems to think that, if you're driving a spaceship at just under the speed of light, you'd better keep a close eye on the speedometer, or you might accidentally go over the speed limit with catastrophic results. The pilot has a gong to warn him if he gets too close.

p. 35, column 2 — p. 36, column 1:

The gong rang three times and then three times again.

Let her go. Let her edge on up to Constant. Let her flash on through zero time and explode to pure energy or let her hang as one ship had at the exact speed of light and hang there forever, impervious, unmoving, her people statues within her, locked, protected and condemned to eternity by zero time.


The answer to your question is that, at least in the original serial, Alan Corday's first voyage on the Hound of Heaven aka the Flea Circus was not a simple round trip to Alpha Centauri, and in fact the error seems to be in the other direction; with stops at Betelgeuse and "Other Ports of Call", he should have been gone for much longer than 60 years. Here the author states correctly that a round trip to Alpha Centauri would take less than 10 years Earth time:

page, 16, column 1:

Outward bound on the long passage, outward bound to the stars. He did not know the speed of this pariah nor how close it would come to light. If it was as slow as ninety-four percent it still meant that for every moment ticked by the clocks of the Hound of Heaven, hundreds passed on Earth. If the Hound spent six weeks in a round trip to Alpha Centauri, nine years would pass on Earth.

"As mass approaches the speed of light, time approaches zero." It was his sentence. A cold equation, a dispassionate mathematics, but it was Alan Corday's sentence to forever.

The run to Alpha Centauri would be the shortest trip they could make.

How old would be his people when he saw them next? How old?

Here's what it said on the paper that Alan Corday was tricked into signing.

page 11, column 1:

And he looked down and saw his name on the articles. "The Hound of Heaven. Outward Bound for Alpha Centauri, Betelguese [sic] and Other Ports of Call." He went white and lunged back. But Gow-eater and his friend still had him.

Only one landing is described in the story, on a planet called Johnny's Landing (star unnamed as far as I know), and this seems to be the last stop before the return to Earth.


P.S. The quotation

"The Hound of Heaven. Outward Bound for Alpha Centauri, Betelgeuse and Other Ports of Call."

also appears in a Google Books copy of the 2004 edition, with nothing changed from 1950 except for correcting the misspelling of Betelgeuse. So there's your in-story explanation: they did not just fly from Earth to Alpha Centauri and back.

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