A round trip returns travellers to their starting point, in Tolkien's phrase: "There and back again." A long spatial round trip with the benefit of time dilation can return interstellar explorers to a changed Solar System tens or hundreds of millennia after their departure, as in Starfarers by Poul Anderson or in A World Out Of Time by Larry Niven. To this extent, such a round trip resembles a long one way time travel journey like the "time projection" in Midsummer Century by James Blish.
A temporal round trip would be "then and back again," as in The Time Machine by HG Wells or in "Flight to Forever" by Poul Anderson. To be complete, such a round trip should return the time traveller to the moment of his departure whereas the Time Traveller re-enters his nineteenth century laboratory several hours after leaving it although he had spent several days in the future.
Did Wells and his earliest readers simply assume that a return must happen after a departure or did Wells deliberately avoid the obvious paradoxes: could the Time Traveller have returned in time to see his younger self departing? Could he even have prevented that departure? Can a younger and an older Time Traveller coexist and converse? The story is tantalizing for the questions that it implies but does not ask.
5 comments:
Kaor, Paul!
Besides Anderson's STARFARERS and Niven's A WORLD OUT OF TIME, I would have included the former's THE LONG WAY HOME. That last mentioned book shows human explorers returning "home" 5000 years after leaving Earth, without them REALIZING their still new and incompletely understood "FTL" drive had not worked as they had thought it would.
THE LONG WAY HOME was one of Anderson's earlier novels, and shows it here and there, but I liked it and thought it well written.
I'm inclined to think Wells and most of his earliest readers didn't fully understand the implications of the theme he had invented, time traveling. I would not expect pioneers like Wells to fully grasp the consequences of the ideas he came up with. I think later writers like L. Sprague De Camp, Robert Heinlein, Poul Anderson, Ward Moore, etc., would think of those implications and start working out their consequences.
Sean
Sean,
Please check the Logic of Time Travel blog and maybe later today the James Blish Appreciation blog and the Science Fiction blog. Because this is the last day of the month and Poul Anderson Appreciation has a round number of posts, 130, I am posting on other blogs but these new posts will be copied here later tomorrow - or even later today if they total 10 before the end of the day.
Paul.
Kaor, Paul!
I will look up some of your articles in the other blogs. Thanks!
Sean
Re: "THE LONG WAY HOME."
I'm disappointed there isn't more SF that uses lightspeed drives.
It is the fastest that doesn't run up against the problem that relativity tells us that FTL allows time travel & so creates all the causality paradoxes.
A lightspeed drive gives us a very interesting situation for multiple cultures in different solar systems. Nearest neighbor systems would get information & visitors from just a few years ago & so wouldn't diverge in culture all *that* much if they don't want to. Get light decades or light centuries apart and interesting divergences are inevitable.
The almost lightspeed drive of the Kith/Starfarers stories gives something very like what I am talking about, but Anderson couldn't cover all the interesting possibilities.
Kaor, Jim!
But Anderson did examine many, many possibilities using the STL or FTL hypotheses.
And not all scientists completely dismiss FTL as at least a theoretical possibility. E.g., see Alcubierre's work. It may well be the the difficulty of making FTL an engineering practicality which is the biggest hurdle.
Ad astra! Sean
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