Wouldn't that defeat the whole purpose?

A student at MIT is hosting a Time Traveler Party this week with the hope that people from the future will show up...too bad people from the future already know the party sucked!

- Tina Fey, Saturday Night Live

More on time travel - in the past couple of years there have been a couple of unsuccessful time travel experiments, one in Australia and one at MIT in the States, both of which were done in the simplest and cheapest way possible: advertise that you would like time travellers to show up at a specific place at a specific time. (As experiments go, this is pretty cost effective, since all you need is a little advertising and an empty piece of ground.)

Sadly, in neither case did the experiment result in a flash of light and the appearance of a modified Delorean, a blue police box, or a Victorian steampunk time chair. However, organizers were oddly unconcerned by this, since it was their contention that time travellers could easily be attending incognito. Sigh...guys, if the purpose of the experiment was to prove that time travel existed, what kind of cruel and unusual punishment would it be for a time traveller to show up and hide in the crowd? And even then, it would be surprising to have a small group of people attend. My god, if time travel were possible and even the smallest fraction of a nearly infinite future population of time travellers hears about one of the parties...actually, come to think of it they're lucky that some comedian didn't make an appearance disguised as a giant mutant ant or something similar.

However, all of this silliness addresses the one of the basic questions of time travel: if it were going to become possible, why aren't we knee-deep in visitors from the future? Isaac Asimov's Science Fiction Magazine ran a story in 1979 entitled The Merchant of Stratford by Frank Ramirez, wherein the first time traveller goes back to visit Shakespeare, only to discover that time travellers have been visiting Shakespeare for his entire life:

"I've been getting visitors from the future as far back as I can remember. My mother, being a good Christian woman, had the hardest time giving me suck, because the documentary team from the thirty-third century wanted to film it all. I barely survived childhood."

The punchline is that the first time traveller begins to receive a similar treatment from other time travellers because he's the FIRST time traveller, and as such an historical figure.

Presumably, if time travel were possible, then history would be full of visits from time travellers. (In Robert Silverberg's The Time Hoppers, a future police department is charged with ensuring that time travellers leave on schedule in order to conform with historical records.) Does this take us to the conclusion that time travel is not going to happen? Ah, this takes us to the Doctor Who quote that starts the last entry - only from the linear viewpoint is that the case. If time is in fact "a big ball of wibbly-wobbly, timey-wimey stuff", then it's equally possible that once time travel is invented, then historical documents will obligingly change themselves in order to conform to the new state of affairs, and that will be the way that things have always been...and this post will never have existed.

- Sid

"Wibbly-wobbly, timey-wimey stuff."

People assume that time is a strict progression of cause to effect, but actually, from a non-linear, non-subjective viewpoint, it's more like a big ball of wibbly-wobbly, timey-wimey stuff.

The Doctor, Blink

Time travel stories, I love a good time travel story. Obviously this would make me a strong candidate to be a Doctor Who fan, although I freely admit to having been in and out over the years. Recently I've been downloading episodes of the current season that have been posted by English fans, and in spite of a couple of shaky concepts they're doing some quite nice stories. (Hopefully this blatant confession won't result in a lightning raid by BBC copyright commandos. Given that I'm in Vancouver, British Columbia, which is damn near the other side of the planet from England, I should be safe unless they have some kind of agreement with the CBC black ops teams. But I digress...)

The most recent Doctor Who episode is entitled Blink, and deals with the sort of time travel opportunities that are parodied in Bill and Ted's Bogus Journey - decide to use your time machine to go into the past to set up things so that you win a fight in the present, then go back to set things up after you win the fight. In this case the Doctor gets sent back in time without the TARDIS, but sends messages to someone in our time to get it back - and then gets the information he needs to set things up after everything is resolved, but before it takes place in his personal timeline.

This directly addresses the real question of time travel: can you change the course of events? The two basic philosophies here are that you can't change things in the past because you didn't - commonly known as the Grandfather Paradox - or that it's an open field, in which future events exist in an indeterminate state. (For those unfamiliar with the concept, the Grandfather Paradox is as follows: build a time machine, go back to the past, kill your grandfather at the age of ten. As a result, your father is never born, you're never born, and you don't build a time machine. So you DON'T go into the past, you DON'T kill your grandfather, your father IS born, you're born, you build a time machine... It's easier to assume that the gun must have jammed when you tried to shoot the little bugger, or, in the big picture viewpoint, if you went back in time to kill Hitler before he starts the Nazi party, you'd fail, because history records that he did start it.)

Both of these philosophies have given rise to some interesting stories, although the approaches required are wildly different. The landmark story for the open field approach is Ray Bradbury's A Sound of Thunder. All you need to do is to step on a butterfly while trying to shoot a dinosaur that's going to die anyway, and the result is a slightly but significantly changed future. (This begs a bigger question, which is why anyone with a time machine would waste their, ah, time running tours into the past so that people can shoot T. Rex. If things were at the point where it was that popularized, I would think that flattened butterflies would be the least of your worries.)

The cast-in-stone position is less obviously interesting, simply because it's less exciting. Going back in time with an anthill and coming back to find out that the ants have evolved into the dominant species and destroyed humanity is a bit more of a climactic ending than coming back and finding out that they haven't. The predestination stories tend to read a bit like inverted detective stories, with the characters running around like mad making sure that all the clues are in place to ensure that the crime happens. There's often a loose thread that miraculously weaves back in at the end, just to ensure that all's well historically. A good example of this would be Connie Willis' To Say Nothing of the Dog, which is rather like the time travel version of The Importance of Being Earnest.

- Sid