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

What's this thing in the entry about a time machine not being able to travel back to before it was created? Doesn't that only apply to wormhole based time travel? Which admittedly he claims to have used. But other types of time travel might not have that constraint.

...are there any other known forms of time travel? Tachyons or something?

Actually- using the theory of relativity, if you moved real fast there's no limit to how far back you could zip, is there?

Well, if you manage to slow down your own time by zipping around in circles everything else will pass by faster. So you could travel into the future that way. Not sure if you could travel back to the past in that same way. That would probably relate to the twin paradox which I still don't understand.

I thought that if you move fast enough you go faster than time, and therefore time passes you, and you go back. But I could be wrong.

I'm glad to see this entry recieved this kind of response . There is an idea that the best way to time travel is not to build time machines, but to create virtual worlds that can be visited.

The notion stems from the fact that those who build computer processors tend to develop processors that are twice as poweful as their predecessors every 18 months or so. Therefore sooner or later they will be able to process limitless amounts of data, which inturn will make it possible to create virtual worlds that are as detailed as real life, to the point that the virtual people who inhabit these worlds will 'think' they are real.

The worrying aspect to this is, due to the number of virtual worlds that would be created and the numbers of virtual people that would inhabit them, statisically there will be more chance of being one of these virtual people than a real person. It has also been suggested that possibly these virtual worlds have already been built and what we accept as reality is just us trapped in a virtual, pc generated world.

But that would be no more real time travel than watching a Jane Austen movie.

And if people in virtual worlds get to the point where they can create virtual worlds, then the number of worlds is infinite, and my head spins, and quite frankly, I dont beleive it.

But otherwise, its a fun theory.

besides, limitless in infinite, and infinity is a very touchy topic.

Very late entry, this subject was the basis of the movie "13th floor" I think it was called, where a virtual reality was created within a computer system, where one of the programmers started to interact as a person in this virtual reality, which was a replica of 'thirties America. At he end of the movie it transpires that the programmers reality is in itself a virtual reality created in a future world.
Titor said our worldline was 2.5% as close to his worldline, but by his intervention at any time this would surely increase from the moment he interacted with anyone, or acted within his past or our worldline, thereby creating another worldline off on its own tangent.