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The Critique Crypt => General writing chat => Topic started by: delboy on October 13, 2009, 04:19:18 AM



Title: Sci-Fi Question Around Relativity
Post by: delboy on October 13, 2009, 04:19:18 AM
Recently read Joe Halderman's "The Forever War" and it struck me that I couldn't recall any other books where the idea of time dilation (if that's the right phrase) as a result of relativity takes on such significance. Assuming, Einstein was right  and if we travel at, or approaching the speed of light, then time (for the traveller, compared to people left at home) will slow down, wouldn't such time issues be crucial to masses of sci-fi? If so, why haven't I come across it before in plots, or am I simply reading the wrong books?

Del


Title: Re: Sci-Fi Question Around Relativity
Post by: Rev. Austin on October 13, 2009, 09:58:13 AM
This sounds intriguing Del.  How does the time dilation figure in the plot to 'The Forever War'?  I haven't read much time-travel sci-fi myself, and anything I have read with time travel seems to fall into the Back To The Future category of avoiding paradoxes  :grin:


Title: Re: Sci-Fi Question Around Relativity
Post by: delboy on October 13, 2009, 11:43:20 AM
If you leave earth to go and fight a (very) distant war and, in doing so spend a fair bit of time - several years - travelling at super fast speeds, jumping through wormholes, and almost hitting the speed of light (all that great sci-fi stuff) by the time you come home to earth you'll find that maybe twenty years has passed earthtime, compared to your two or three years. So your mother will be older, your girlfriend will be married with another man's kids, etc etc.

Go back on a second mission, hit the speed of light again, go and fight in a distant galaxy, etc etc, when you come home again the entire world may be a hundred years older and totally different.

Damn, I'm not doing it justice... have a look here: http://en.wikipedia.org/wiki/The_Forever_War (http://en.wikipedia.org/wiki/The_Forever_War)

The book isn't about time travel, it' sjust the first one I've read where such impact of near light speed travel is incorporated. I wonder if other SF authors just ignore the issue in their space operas, or if I've just read the wrong books.

It's got a great opening too: "Today we're going to show you eight silent ways to kill a man."

As an aside, the non-fiction book I'm reading related an experiment done on earth to prove Einstein's theory that the faster you go the slower time passes. They took two super dooper atomic clocks - perfectly in synch -, the most accurate clocks ever made, and they put one on a plane and left the other on the ground. Then they flew the one around the world very quickly... When the compared the two afterwards the one from the plane had gone slower than the one on the ground. Only by a tiny bit, like a fraction of a nano-second, but it matched exacly what Einsteins equations predicted. Now imagine that instead of being on a plane you were on a rocket ship... and instead of doing a lap of the earth you were travelling across the universe... great stuff!

Derek





Title: Re: Sci-Fi Question Around Relativity
Post by: Caz on October 13, 2009, 02:06:01 PM
I read The Forever War a few years back and  loved it. The follow up book Forever Free is also cool.

I've not read a lot of sci-fi, more into horror and supernatural, but I do watch a lot of movies with the sci-fi theme and the time dilation problem seems to be largely ignored, or the idea of wormholes is used and these transport people around the galaxy in the blink of an eye.

I read a book once about time dilation, Here's what I remember of the theory. If an atom is bounced between two stationary mirrors it takes a second to do this. As soon as the mirrors start to move it takes the atom longer to bounce between the centre point of the bottom mirror and the centre point of the top mirror as it now has to travel a diagonal path as opposed to a straight up and down path. The faster the mirrors move the further the atom has to travel. For a person travelling with the mirrors it is still only a second that has passed regardless of the distance that the atom has to travel. In essence their time has slowed down though they are not aware of it. For anyone not travelling with the mirrors time passes at its normal rate.

And now my head hurts.

Please, all you science types don't lynch me I'm just a bricklayer.      :hidin:    


Title: Re: Sci-Fi Question Around Relativity
Post by: Rev. Austin on October 13, 2009, 02:29:07 PM
I think I start to see the implications of such a thing...if you're millions ad millions of miles away on another planet, you'd expect time to pass at the same rate as you're used to (depending on the size of the planet of course) so travelling back home you'd expect...aarghhh my brain! I get what future shock is now too   :cheesy:


Title: Re: Sci-Fi Question Around Relativity
Post by: Geoff_N on October 13, 2009, 03:04:06 PM
Two scifi novels that depend on time dilation come to mind - L Ron Hubbard  Return to Tomorrow abd
Poul Anderson Tao Zero

Sorry, in a rush or I'd scour my shelves.

Geoff


Title: Re: Sci-Fi Question Around Relativity
Post by: MumblingSage on October 13, 2009, 07:01:43 PM
It might be you're not reading the 'right' books, so to speak. Dan Simmons' Hyperion novels use time dialation, or ways to avoid it, to drive plot, it's also been addressed in several stories I've read (Ursula K. LeGuin and Orson Scott Card both use communication devices called 'ansibles' to get around it, in a way; that's the most interesting play with it I've seen). And I'm not a big sci-fi fan.


Title: Re: Sci-Fi Question Around Relativity
Post by: delboy on October 14, 2009, 02:56:02 AM
Cheers Sage. I've got the first of the Hyperion books on my shelf to be read. I'll have a crack at that soon. I guess I'm trying to get a feel for how this knowledge is applied in fiction - and being surprised at coming across it so rarely.

Derek


Title: Re: Sci-Fi Question Around Relativity
Post by: Ed on October 14, 2009, 03:28:25 AM
I can't imagine politicians having the longevity or the stomach for a war that lasted decades. Interesting premise.


Title: Re: Sci-Fi Question Around Relativity
Post by: delboy on October 14, 2009, 06:27:31 AM
The book's well worth a read.

I can just about get my head around the physics of it, and Halderman's done a great job of extrapolating the knowledge and implication far into the future.

I guess my underlying concern is that were I to write a story in which somebody or something went off at the speed of light from point A to point B, and later returned, can I get away with ignoring relativity, or now that's it's an understood phenomenon would I have to take account of it? I assume the latter (rather like you can't avoid mobile phones in thriller plots these days), but that's why it  puzzles me that I've come across it so rarely. Especially as the theories predate the golden age of science fiction.

Derek


Title: Re: Sci-Fi Question Around Relativity
Post by: Rev. Austin on October 14, 2009, 07:01:58 AM
Is it maybe 'ignored' because it's easier on the brains of the average reader?  Of course that supposes the general (sci-fi) reading public are idiots...but wouldn't the person who picked up one of these books have the brains to comprehend/appreciate the idea in the first place? 

I don't know.  I'm so confused!  Maybe it's simply not popular?  But then, I'm not particuarly knowledgable when it comes to sci-fi authors...  ;)


Title: Re: Sci-Fi Question Around Relativity
Post by: Caz on October 14, 2009, 02:02:07 PM
I'm no expert here but most sci-fi seems to ignore the problems that arise for a spaceship travelling between the stars. Our nearest neighbour is, I think, 2.4 light years away. So even travelling at near the speed of light it will take two and a half years to get there and it will take decades and centuries to reach the further stars. In all sci-fi tales I've read or watched the characters zoom around the galaxy in a matter of months, though I vaguely remember an old episode of Space 1999 were a group of colonists had been asleep and travelling for centuries.

As far as I know faster than light travel is not possible, so there is no way that the crew of a spaceship could reach and return from the majority of stars in our galaxy in their own life time. It seems to me that most, if not all, writers of the genre ignore this problem or invent unproven theories to get around it. It's what I would do if I were writing a sci-fi tale.

If people played by the rules then we really would've missed out on some great stories.       


Title: Re: Sci-Fi Question Around Relativity
Post by: Ed on October 14, 2009, 05:45:25 PM
I dunno. We're all used to the concept of travelling in straight lines between points at the speed of whatever, but wormhole theories and the concept of distorting space, or folding it so that two distant places are able to practically touch one another lets us off the hook where time is an issue. As long as you can postulate a plausible theory that makes is possible, it is so - we are speculating, which is what speculative fiction is all about, surely? :smiley:


Title: Re: Sci-Fi Question Around Relativity
Post by: JonP on October 14, 2009, 07:27:20 PM
I'm sure that Stanlslaw Lem's Return from the Stars deals with something like this issue, although I can't remember the details (or even if I've got the name of the book right).


Title: Re: Sci-Fi Question Around Relativity
Post by: Loki on October 15, 2009, 12:13:55 PM
As has been pointed out above, interstellar travel is effectively impossible in our universe using any sort of conventional drive other than by way of generational ships - huge spaceships which take decades or centuries to get to where they're going.  (See Gene Wolfe's Long Sun series as one example of this type of travel.)  Even at %99.999 of the speed of light, the journey will take years to get to the closest stars.  The only way around this is some sort of FTL - faster than light travel.  It's usually called a warp drive or hyperspace or something similar. 

If you postulate FTL, then you're no longer traveling through our universe at Relativistic speeds, and so time dilation can be generally ignored.  This brings up some serious technical issues.  If you can travel "instantly" from point A to point B, you're effectively establishing simultaneity between distant sites, which violates Relativity.  Relativity states that it is impossible to determine that two events are simultaneous if they occur in different inertial frames of reference.  Some observers will see A happening before B, some B before A, and some will see the event as simultaneous.  Each of those viewpoints is correct from the point of view of that observer. (1)  Instantaneous travel violates that law. 

Because of the myriad problems it introduces, most science fiction simply hand-waves the issues away.  Realistic treatment of such effects is possible in fiction, but it's difficult and you'd better know your physics (or consult with someone who does) or you'll end up getting it wrong.  It's highly counter-intuitive and even experts sometimes gets things wrong.  (I was recently involved in a discussion which included a couple of physics professors arguing about whether a satellite in geostationary orbit experienced time dilation due to velocity or only due to gravity/inertia.)  If any of the above is confusing to you, you're probably better off doing some hand-waving.  That being said, if you want to use Relativistic effects in your story, don't let me discourage you.  Just be prepared to do some serious research.
 

(1) In some cases, all observers will see event A happening before event B.  If there is a causal effect - that is, if A causes B to happen, all observers will see A happen before B.  But there are no cases where all observers will see two events as simultaneous if the events occur in different inertial frames.


Title: Re: Sci-Fi Question Around Relativity
Post by: delboy on October 15, 2009, 02:00:31 PM
Great stuff, thanks Loki. The idea that I'm contemplating involves someone being able to travel x amount of light years away, and then, later, come back (*). My concern was, if in the process everyone he left behind will have aged considerably, then the plot fails. But if it's acceptable to simply ignore the time dilation issue, then the plot could work. The story mightn't, but the plot would. So if I come up with Del's Patented FTL Methodology, and lots of handwaving, I might get away with it...

Derek

(*) The story is a little bit more than this. To simply go away and come back would, after all, be a rip off of Lord Of The Rings  ;)


Title: Re: Sci-Fi Question Around Relativity
Post by: digitaldeath on November 09, 2009, 05:45:56 AM
I find it difficult trying to make scifi believable. It the speed of light it takes at least 30 m ins Mars to Jupiter, when they are closest. Sirius is 4 light years. If the take the kids on holiday that is a lot of 'are we nearly there yet'. You need to indroduce an X factor [in Mars I used subspace, in the Skydreamer series I warped time 'surfing'.] Star Trek distort time and space. That is what is baffling over real UAT/UFO s, time/distance. If you are using another dimension or surfing boundaries Einstein is spinning in his grave. Naturally the greatest anomaly is communication and a signal should not be able to travel faster than light. Am I boring anyone?


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