The last time-related thread I made here on GameDev ended up in flames. Hopefully, I can get a better response this time around. Say, for instance, that a scientist is taking a walk in a field and stumbles across a worn-out time machine. The travel through space-time has rendered it almost completely inoperable. Fifteen years later, the man finally fixes the machine, takes it to the field, and sends it fifteen years in the past. This creates a loop. To me, there's only two ways this could happen: A) Someone or something other than the scientist put the original damaged time machine in the field. When the scientist fixed it and activated it, he created the loop. B) In the original timeline, the scientist never found the time machine, but still created on. Again, by activated it and sent it to the past, he created the loop. And here's why: The original damaged time machine couldn't have came from nowhere. Somewhere in or outside of time, someone had to have put though into, designed, and engineered the machine. If neither A nor B are true, where did the original time machine come from?

Maybe there is a third.

C) there is no such thing as an original timeline.

At some point, something or someone had to put that there. Like everything else, this happened in some form of a time frame. There has to be an "original timeline."

You don't know that a time machine can't come from nowhere. We might live in a universe where time machines spontaneously pop into existence. Who knows?

You might say it's a silly answer, but it's no worse than your two guesses. Basically, we're postulating about something we don't know anything about. We don't know if time machines are possible, we don't know if it's possible to create a loop like that, so we obviously don't know either *how* it could be created.

So in that context, the assumption that "The time machine must have come from somewhere" is actually pretty far-fetched, and not at all logical.

Other than that, you have to be pretty damn sure of what you mean by things like "the original time line", or "somewhere in or outside of time".
What is the original time line? The one that happened first? How do you sort timelines in chronological order then? [lol]
How can there *be* an original time line? Are they stacked on top of each other, somehow?

And how can you be outside time? How? What exactly does it mean to be "inside" time? And which time is that, exactly?

That said, have it occurred to you that maybe it couldn't happen. He sends his time machine back to a time and place where another one already existed. Then presumably there will be two of them, right? Because the "original" one came from, well, somewhere else, so it won't be affected by him sending it back again. So "now" there will be two time machines at that time and place. (Unless of course one materializes in the exact same space as the other, in which case, well, who knows. Maybe they swap places, so he gets the "original" one back to his own time (15 years in the future). Maybe it just triggers a big explosion? (But then, wouldn't we get that too if it materialized on top of anything else, say, some air, which would be hard to avoid)

But if time travel is possible, does it matter whether the timemachine was made 'later'.
And theoretically in quantum mechanics a time machine COULD pop into existence spontaneuosly.

If you can explain time travel, and explain how a time machine would work, THEN perhaps you can start creating logical explanations for how the time travel machine came to be.

Your trying to assume something as true that you can neither explain nor reason. If no one has been able to time travel, and we can't create even a good theory as to how to achieve it, how can you make that assumption? A and B are moot because there's no such thing as time travel.

And what's wrong with the loop, anyway?

The easy way out is to say it doesn't matter if it's A or B, it leads to the same result: the scientist fixes a machine that's only capable of going back to its original (from the scientis's point of view) time and state.

You could add more complexity in saying he made multiple jumps with it before something happened and it ended up in the past, broken, but then you start getting into issues of free will and the ability to affect anything and time travel is messy enough as it is. : )

Who's to say that events have to cause and effect, maybe they can run effect and cause to, in which future events impact the past. Or maybe time is circular? So, if the scientist tried to create the time machine in one lifetime and sent it into the past for his younger self to finish?

That actually could be a interesting idea for a game, effect before cause. The earth is on the brink of destruction but a time rift allows the player to travel into the distant future. As the player travels era by era back to their own time the world gets progressivly worse as a result of the players actions in the future.

The player uses their time powers to change the fate of woman dying of a terminal disease, which causes a war to start in the past. Since the only way for a cure to be devloped in time to save the womans life is if a war occurs in the past.

It would also be very interesting to have an online simulation game in which the first bunch of players start off at a certain "time" and have to develop the ability for time travel. Once that is developed, anyone in the game after that can use time machines to travel back/fourth through time and what they do can change the future.

It would be pretty hard to code a system to keep track of everything at different points in time (i think) but if it were done well would give a pretty good idea of what time travel would ultimatley cause. Then perhaps the game can be redone with different restrictions on how time travel works or could be used.

Basically think of The Sims with time travel that can effect everyone.

I suppose there would be many situations in which people will not have been born, so your player could just stop existing as you're playing it... so that would suck. Any ideas on how to tackle that?

If he sent the machine into the past would there then not be 2 machines, the one he sent back and the broken one?

Malal