Spider Star
The human colony on the planet Argo has long explored and exploited the technology left behind by an extinct alien race. But then an archaeology team accidentally activates a terrible weapon...
Read More.Praise for Star Dragon
"Seldom does a storytelling talent come along as potent and fully mature as Mike Brotherton. His complex characters take you on a voyage that is both fiercely credible and astonishingly imaginative. This is Science Fiction."
-- David Brin"Star Dragon is terrific fare, offering readers a fusion of hard science and grand adventure."
-- Locus Magazine"Star Dragon is steeped in cosmology, the physics of interstellar travel, exobiology, artificial intelligence, bioscience. Brotherton, author of many scientific articles in refereed journals, has written a dramatic, provocative, utterly convincing hard science sf novel that includes an ironic twist that fans will love."
-- Booklist starred review"Readers hungry for the thought-provoking extrapolation and rigorous technical detail of old-fashioned hard SF are sure to enjoy astronomer Brotherton's first novel."
-- Publishers Weekly"Mike Brotherton, himself a trained astrophysicist, combines the technical acuity and ingenuity of Robert Forward with the ironic, postmodern stance and style of M. John Harrison. In this, his debut novel, those twin talents unite to produce a work that is involving on any number of levels. It's just about all you could ask for in a hardcore SF adventure."
-- Paul di Fillippo, SCI-FI.COM
Search
Science and Science Fiction: Time Travel
September 23rd, 2008
In my post about Ten Things I Hate About Science Fiction I wrote:
4. Inconsistent or illogical time travel. It seems like writers just make up rules for time travel that make no sense a lot more often than other types of stories. I mean, WTF was with that fading photograph in Back to the Future? Don’t try to make too much sense of it, please, or your brain will hurt. And while I’m talking about this, bad history or irrational projection of today’s morals/beliefs on other peoples.
I stand by that (and I understand that while it made no sense, the photograph was an effective storytelling device for most viewers).
While I’m a bit of a time travel grinch because it’s done so illogically in so much science fiction, there are a number of ways that science is open and supportive of real time travel.
And I just took a moment to see what wikipedia says about time travel. It’s pretty good, actually. I recommend it for people interested in more details and links. I’ll continue with a brief summary from the point of view of a hard science guy.
First of all, relativity already allows for “easy” travel into the future through time dilation effects. Fly around at close to light speed and when you return to Earth much more time has passed. Or, hang out near the event horizon, as close as you can manage without getting torn apart (supermassive black holes have minimal tidal effects near their event horizons and are suggested), and when you climb out of the gravity well again much more time has passed.
But what about the past? How do you make a time machine in physics?
You need wormholes, which might or might not be feasible in practice, but are an allowed solution to the equations of general relativity. Then you put one end of the worm hole someplace, and the other deep in the gravity well of a black hole where time moves more slowly. You can get the two ends to exist at different times.
So then, how do physicists deal with the paradoxes?
Easy. They don’t have them.
Only self-consistent solutions are allowed, and there are plenty of them. You treat time as another variable like space and find the consistent solution. Any attempt to create a paradox, by shooting your grandfather, perhaps, cannot happen. Related to this idea of a self-consistent solution is that you have only one possible set of events that occur and they never change, and, in fact, cannot be changed. No free will in effect.
Like your freewill or like your time travel then. Not so easy to have both and have things make sense. See Heinlein’s By Your Bootstraps for a nice example of how this can work and work well in science fiction.
Keep in mind that faster than light travel is the same as traveling into the past. G. David Nordley has a nice article explaining this (doc file, some math required). If you use FTL, you really should have time travel and deal with the paradoxes in some consistent way.
There might be one way to give yourself some wiggle room on this issue: multiverses. This is what John Scalzi invokes for his FTL in his very entertaining debut novel Old Man’s War, although I’m not sure it’s entirely self-consistent.
If you accept a contentious interpretation of quantum mechanics, that an infinite number of universes exist branching apart every moment, then you just skip out on all the paradoxes and you’re really not traveling into your own history at all. I personally think this is kind of cheating on the whole time travel thing myself, but it would irritate me less than things that don’t make sense.
Anyway, that’s my take on rational, physics-based time travel in science/science fiction. There may be some variations of these I’ve skipped here, but I don’t generally think some popular types of time travel make any sense whatsoever (sorry, Back to the Future) even if they make for fun, entertaining stories. I classify them as fantasy.
Addition: There’s a new documentary from National Geographic on Time Travel that may be of interest. I’m not sure that there’s often a lot of useful information in these things, but this one is new and seems to have some awesome videos that could be inspirational.
You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
Oh, this is excellent timing. I’m just starting a time-travel story.
So “By Your Bootstraps” passes the self-consistency test. I assume that “All You Zombies” abjectly fails. It doesn’t make any biological sense, either. Just thinking about it is making my brain hurt. But perhaps that is the point of the story.
The link to the Nordley article is broken (need to remove period at end of URL).
I keep meaning to get around to reading “All You Zombies” but it has escaped me until now. And yes, Bootstraps passes the self-consistency test.
Thanks, anonymous. Link fixed.
Concise plot summary of “All You Zombies” — hermaphroditic time traveler is his own mother and father.
David Gerrold did a version of that with THE MAN WHO FOLDED HIMSELF. Enjoyed the book, but not for everyone.
I love the idea that FTL is time travel to the past. It explains the Star Trek universe, where so many aliens are very Human: They are actually descendants of Humans colonists whose evolution diverged slightly once they landed on their new world and proceeded forwards in time again.
And, yeah, I enjoy the way my brain hurts when I read All You Zombies, except for the pontificating bit at the end. I don’t know why the narrator is so proud of his accident with time travel and a birth control pill.
Cheers
Morva Shepley
The problem with time travel is that you can use it for computation (see http://arxiv.org/abs/quant-ph/0502072, point 8 Time Travel Computing), which makes it possible to solve NP-complete (and even PSPACE-complete) problems. This would make computation an impossibly powerful tool. So while I can at times cut out my brain to enjoy time travel stories, I can’t take them seriously, because the existence of time travel would inevitably change everything (sadly most people who write time travel stories don’t understand the consequences for computation).
That’s a good point! Might be a good idea for a story showing how ridiculous and underexploited time travel really is in fiction.
[…] regular readers probably think I hate most time travel stories. And while I do hate many of them, a few are among my favorites. Ken Grimwood’s Replay is […]
[…] there’s the mess with the time lines and how they handle time travel on the show. This is one of my issues, so forgive a mini-rant. Apparently every time someone goes back in time they rewrite history, […]
Theres a episode of LOST IN SPACE called VISIT TO A HOSTLE PLANET WHERE THE jupiter 2 IS PROPELLED BACK INTO 1947 AFTER A MAL FUNCTION END THEM UP GOING INT THE PAST AND WHO CAN FORGET peabody AND shermin and the WALBAC machine
Hi Mike.
I love your website dedicated to hard sci-fi. I have a few questions on the subject.
The idea of time traveling into the past to prevent the time traveler’s birth which would result in changing history, as well as erasing the memories of everyone on the planet would seem to be counterproductive and ruins the possibility of time traveling into the past because nobody would even remember or know that time traveling into the past was possible. This is ridiculous, so the paradoxical theory is out. And then there is the paradox where the timeline changes which erases everybodys memories, with the time travelers the only ones who remember the original timeline, as well as the changes in the new one. Take Star Trek: First Contact. The Borg goes back through time via vortex to the year 2063 and changes history, resulting in a Borgified Earth in the future. Captain Picard, his crew and the Enterprise should have ceased to exist as well, but by some miracle, they remain unaffected. Then Data comes up with a lame explanation that the Temporal Wake must have somehow protected them from the changes in the timeline.
1. Does this make any sense to you? Why or why not?
In regards to the parallel universe theory, I don’t really subscribe to it because it violates the laws of energy of conservation whenever a time traveler changes history and another timeline branches off. The only way I can see how they don’t violate the laws of energy conservation is if these parallel universes were created at the same as ours during the big bang.
2. What do you think?
I agree with you that the self-consistency principle is the most logical kind of time traveling into the past. If you go to the past, you were always meant to go back, you can never change the past, but merely fulfill it. However, if we follow this mode of logic, then its safe to conclude that if you were not part of history, then you will never go back in time, hence, time traveling into the past is impossible.
3. Any thoughts on this?
The other type of time traveling that I would like to address is the observation principle where a time traveler goes back in time to observe the past, but can never participate in it.
4. Do you also subscribe to the observation principle, just like the self-consistency principle?
And lastly, the quantum eraser experiment has already proven that that past of a particle cannot never be altered, providing that you already know its history, but it remains to be seen if the same is true for relativity time travel.
5. Do you think the same is true for relativity time travel?
liposuction doctor…
[…]Science and Science Fiction: Time Travel[…]…