Random thoughts, —explaining why we never see time travelers…
You can only travel forward. And never back. If you go forward-only, we all have to wait until they invent a time machine. And that hasn’t happened yet. When it does…everybody piles up in future ages, increasing the population of really lost disaffected people…
Wait, I believe I wrote that book…
or at least the short story that used to preface it.
Ummmmm……wasn’t that Stonehenge…..wait I mean gates! 😉 8)
Always seemed to me that the biggest problem with time travel is space travel: to quote from 19 Feb’s handy New Scientist article on The Strange Science of Everyday Life:
So if I want to move even one second back (or forward) in time, and end up in “the same place”, rather than in space or in the middle of a rock somewhere, I have to not only work out how to play with all those tau particles or whatever I’m using as a transporter, I have to work out the 3D-movement consequences of a multi-spiralled path that “the same place” is following …
… so, possibly we’re constantly leaving a wake of experimental time travellers who missed a digit at the 20th decimal place and thus missed the Earth’s surface by a few thousand/million/billion k’s …
You got it; if you don’t aim at the planet where it WILL be, you’re going to be real unhappy when you land—and if you haven’t calc’ed planetary spin velocity, you’re going to get hammered when you set a foot down. Ask a figure skater how it is when you’re moving and the surface isn’t.
One of the best takes on the latter was—lord, the author’s name escapes me, but if you teleported, you’d better land in a specially made tank or convenient pond, because the uncompensated momentum was a killer. It was a DAW book. I thought it a brilliant notion.
A little Googling brings up Larry Niven (though, of course the fact that the blogosphere thinks that’s the answer has no evidential weight)
A peace website I used to run had, for a while, this quote in the heading: “Our lives begin to end the day we become silent about things that matter.” If you Google it, you will find 381,000 sites that attribute this to Martin Luther King. However, a complete and exhaustive search of the MLK archives does not bring up a source (I’m a fiend for primary sources). Maybe twenty thousand sites attribute the quote to Desmond Tutu: a very few of those spot that he said it as a paraphrase (not quote) of a key passage from MLK’s Letter from Birmingham Jail. SO, (probably) incorrect attributions outweigh (probably) correct ones by between 20:1 and 2000:1, depending on rigour.
Like others wrote there is no there there, no permanent firmament. If you could go back in time by even one day you’d find yourself trying to breathe vacuum.
Every day the Earth moves 1 million miles in its orbit around the sun. If you think we could travel from let’s say March 6, 2011 to March 6, 2010 think again. The sun and its solar system travels at 600,000 miles per hour around the center of the Milky Way taking about 225-250 million years to complete one orbit (a galactic year). Plus the Milky Way and its satellite galaxies are heading toward what’s called the Shapley Supercluster at about 600 miles per second. Everything is in motion out there – it’s just that it makes so little impact on us here on Earth that we overlook it.
To be able to move around in time means we must also be able to move around in space. One of the few science fiction time machines that takes this into account is Doctor Who’s TARDIS which is an acronym for Time And Relative Dimension(s) In Space. It utilizes coordinates for both space and time when it travels. So until the day we can build spaceships capable of moving to where a planet might have been or will be on any given day (and the computing ability to figure all this out) we’ll keep slowly moving forward in time as we have always done, moment by moment.
Drat, somebody beat me to the TARDIS reference.
Besides, we all know that if you try the slingshot effect, you either end up with whales in your cargo hold, crashing into the San Francisco Bay, or you wind up with a jet fighter pilot hitching a ride in your transporter room. Either way, it’s rather awkward explaining to the neighbors.
Or else you’re zip ping around in a DeLorean….
Or getting chased by Morlocks with bad table manners….
I wondered if the real reason that time travelling guests didn’t arrive at Dr. Stephen Hawking’s time travellers’ dinner party was they didn’t like the menu. 😉
Kidding aside, I liked the solution to the astronaut twin problem posed in Finity’s End, with Fletcher and Jeremy. Real incentive not to miss your ride. If that happens with regularity, it could mean ship spacers tend to carry an older state of the culture and tend to span longer real-time lives.
Ah, now, all they have to do is build a spacestation with zero motion relative to… er, something! Galactic zero? The origin point of the big bang? But then how do we know without trial and error that the UNIVERSE isn’t rotating around something.
I can just see it, a station getting farther and farther from everything where people pop into existence with just enough time to travel to a historic event, and the locals have no clue whats happening (unless someone has already come back and given them a timeline) until a mob shows up looking for tickets to Planet X. So a giant central area with no gravity, people popping in and out with hand held remotes… ugliness happens when someone misses their mark, or maybe the remotes have an automatic sensor that nudges the mark a few feet to the left if the original mark is occupied… So, no time travelers until the station is built! I think we’re safe for a bit yet.
Project Pendulum was an interesting time travel story (with twins from memory). Can’t think of the author right now.
The Centurion’s Empire is another interesting one – spanning Roman Britain to a little bit past now. Sean McMullan, I think.
Hmm, and the one going forwards thing sounds familiar – time to comb bookshelves I think. (Or am I just thinking of the song Star Trekking…?)
Having effective time travel to the past (or, equivalently, FTL) would imply P==NP. A proof that P!=NP would imply no FTL.
Having effective time travel to the past may also run into problems with the Second Law of Thermodynamics. This is not clear, though, if running a time machine increases the universe’s entropy appropriately.
I remember that short story, if it’s the same one you’re thinking of. The one that’s kind of a prequel to the Morgaine books, where people start piling up at a certain point, afraid to go any further forward in time, and then reality begins to shred.
That’s the one; Threads of Time. 😉
That explanation is in the beginning of the first Morgaine book, too – I’m guessing it’s a paraphrase of that story?
Demetri Martin says he has a time machine in his bedroom that he made out of a cardboard box. Of course, it only goes forward at normal speed… 😛