h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I even know a better paradox: The 'Muse Paradox'. Suppose you take some Shakespeare books to the master's early years (i. e. no fame, no masterpieces), then let him have a look at his own works. Suppose he writes his own works down, then there's no way to tell who had thought of 'Hamlet' in the first place.

Funny, isn't it ?

.... I dimly recall the story of a poet who wrote wonderful poems and then some day in the future a correction-fluid company figured how nice it would have been if the poet had had the fluid. So they send someone back in time ... I think they ended up copying the texts themselves. Ah, don't quite remember, must read THHGTTG again it seems.

... not forgetting the guide entry which was copied off a cereal packet then the editor sent it back in time and sued the cereal company for copyright infringement....

See also "Back to the Future", and how the Flux Capacitor came to be invented.

Why, this isn't a paradox. When Marty told Doc Brown, it already had happened.

What you have there is a case where the information is infinitely old, and creates a causality loop.

For instance, say you meet a future self who back in time and he gives you a pamphlet detailing the events to come. They come, they pass, and you get your hands on a time machine. Taking the same pamphlet you received all those years ago, you then give it to yourself -- but where did it originally come from?

Theory predicts that during one of those loops, the pamphlet would crumble to dust, thus destroying the time continuum with it...

There's a brilliant scifi story (the author's name escapes me at the moment tho...) similar to that theory. The protagonist meets a man who forces him to go get a whole long list of very esoteric items, because the man tells our hero that it will help him rule the world in the future. The hero gathers up all the items, it shanghied into the distant future, where he waits for the guy who sent him on his treasure hunt. Turns out it was himself all along.

you know, the same guy who wrote such masterpeices as "Starship Troopers" and "Time Enough for Love"? This particular story can be found (at least)in a collection called "The Menace From Earth", and the story is "By His Bootstraps". It's really quite interesting, although a bit repetitive (seeing as how the topic is time travel).
Personally, I consider any universe in which time travel is possible to be extremely badly built, precisely because of paradoxes like the ones we're talking about. If I kept my tax records with the same kind of accounting needed to maintain matter and energy in a 5 dimensional universe (I may be confusing several conversations here, if so I apologise), the IRS would lock me up for life

a good "paradox" is one i got from dilbert by scott adams. if someone invented a time machine they would send all their garbage forward in time to themselves when a better method of waste disposal had been invented. but the best method of waste disposal was to send it all back in time and not worry about it. so at somepoint in time you would be bombarded with all your garbage from the next half century, causing you to give up and throw it out the usual way...

You'd only need a four dimensional universe to travel in time, the fifth dimension would be the possibility of alternative universes.
And badly built? What makes you think it was built?
And if it was built, would that not just increase the risk of it being flawed?
Or perhaps even be designed to selfdestruct if someone tried to manipulate time.

You'd only need a four dimensional universe to travel in time, the fifth dimension would be the possibility of alternative universes.
And badly built? What makes you think it was built?
And if it was built, would that not just increase the risk of it being flawed?
Or perhaps even be designed to selfdestruct if someone tried to manipulate time.

The best Heinlein Time Paradox story IMO, is _All You Zombies_. Look away if you don't want the plot spoiled.
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In this story the main character manages to become his own mother, father, child and recuiter.

The "Sending your own Rubbish forth and back in Time to get rid of it"-paradoxon is great.
I once read a story from Stanislav Lem, were the Director of the History-optimalisation-Institute send his incompetent departure Chefs back in Time. There they became Leonardo da Vinci, Dschingis Khan, the Greece Philosophers...

Yeah, there's a Dilbert cartoon {man, I just took a BIG step down the Ladder of Literary Taste(tm)} in which Dilbert invents a time machine, and then sends all of his garbage into the future, hoping that his future self will dispose of it in some environmentally friendly manner.
Turns out that the futuristic method of waste disposal is to send it all back in time and let it decompose.

Ah, man! I just had another idea for the Muse Paradox, based on the garbage disposal concept. Picture a future society in which people actually DO get rid of their garbage by sending it into the past. When I say the past, I'm talking way back. Think Archean Era, before any life existed on earth. Anyway, the bacteria and organic compounds of the garbage actually become the first living things on earth, and start the evolutionary process. Hey, scientists don't know HOW the first cells arose. This would basically mean that we created ourselves.

From our own filth, yes!

This kind of thing is exactly why I am convinced Time Travel, while theoretically possible, will never become practical.

That's all folks!

What about the one where the time traveller goes back to the time of the Crucifixion in biblical times. He joins the crowd shouting "free barabas". It turns out that most of the same crowd are all time travellers. So would Jesus have been crucified if they hadn't been there?

well- what if (no blasphemy intended) Jesus was the time- traveller, and he realised where he had landed, and into which role he was stuck.
Would he have to stay to ensure that society developed into the civization that it did to make sure that he had the ability to time travel, so that time didnt get messed up...
so, despite knowing his future, he'd have to stay?

Mmmm... profund.

One of my favourite time-travel stories is also the only example of this time-travel method. In the film "Somewhere In Time", Christopher Reeve is the hero, Richard. The film opens in 1972, where Richard is a college grad. just produced his own play. An old woman gives him a gift, it's a beautiful pocket-watch. She says "Come back to me"....
The film jumps 8 years to 1980, & Richard, unhappy, goes for a drive, he passes a hotel & "something" appeals to him. He books in, browses through the Hall of History whilst waiting for the restaurant to open. He sees a portrait on the wall, and instantly falls in love with the beautiful woman, Elise, played by Jane Seymour. He finds out that she'd performed in a play at the Hotel theatre, in 1912. He goes to a local library to find out information on her, and finds the last photo ever taken of her, and it was the old woman who had given him the watch! Richard goes back to his old college, to find his old philosophy teacher to ask about time travel...and the teacher tells him how to do it. Hypnotise yourself, remove all reminders of the present, so he gets himself a turn of the century suit, cuts his hair, gets old coins...and hypnotises himself back into 1912. There he meets Elise, they fall in love & spend one night together, she asks him the time, he hands her the watch, she says it's beautiful, he says it was a gift, before he inadvertently pulls a 1979 coin from his pocket, and he vanishes before her eyes. Once back in 1980, he can't get back.....and he starves himself to death.
So, in 1912, how did Elise meet Richard, when he hadn't even been born? He was a time traveller. But, in 1912, how did Richard give Elise the watch, when she gave it to him in 1972? Not an endless time-loop, as Richard goes back to 1980 & dies. Elise died the night she gave him the watch. What I would like to know is: Where did the watch *originally* come from?

Somewhere in Time, and the two Bill & Ted movies are really the only movies I have seen where the effects of non-linear travel work the way they sould.

The best part in Somewhere in Time is when Chris Reeves' character finds his signature in an old hotel registry before he traveled into the past. So, all his actions in the past have already affected the present he was living in even though in his own personal timeline he had not done them yet.

It is my belief that paradoxes do not happen with non-linear travel. We cannot change the past by time-travel because all of our doings in the past are already recorded in our history. Things just work out.

"Wow, I guess I really did steal my dad's keys!" -- Ted "Theodore" Logan

Small aside: Am I alone in thinking that Terminator was just a violent re-make of Somewhere in Time? I mean its the exact same plot, a man falls in love with a woman he sees in a picture, and travels into the past to be with her...