I like the book's example of simple frag with the beer.
So the setup is that you and your time travelling buddy are watching the big Sportsball match on TV in both of your relative presents.
You want a beer so you go to the fridge and there isn't any. So you jump Downstream a couple of minutes, grab a brew and jumps up. Uh oh, don't drink and Span because you just fragged your friend as you are both drinking the same beer.
Your friend is naturally peeved and tells you to fix it. So, what you do is:
* Buy a pack of the same brand of beer and put it in the fridge
* Put a note on one of the bottles telling yourself and your friend not to touch it
* Span (Jump) Upstream a few hours so it's cold then jump back to just after you took the beer from the fridge yourself and put the new beer (the one that was cooling in the present -> future) in so your friend can grab it when he wants a beer.
* You also have to not run into yourself so you jump back up to after the point where you left for the future so as punisment you miss the big sportspile. However all is well because you friend just fills you in regularly and you both enjoy your tasty beverages.
So the setup is that you and your time travelling buddy are watching the big Sportsball match on TV in both of your relative presents.
You want a beer so you go to the fridge and there isn't any. So you jump Downstream a couple of minutes, grab a brew and jumps up. Uh oh, don't drink and Span because you just fragged your friend as you are both drinking the same beer.
Your friend is naturally peeved and tells you to fix it. So, what you do is:
* Buy a pack of the same brand of beer and put it in the fridge
* Put a note on one of the bottles telling yourself and your friend not to touch it
* Span (Jump) Upstream a few hours so it's cold then jump back to just after you took the beer from the fridge yourself and put the new beer (the one that was cooling in the present -> future) in so your friend can grab it when he wants a beer.
* You also have to not run into yourself so you jump back up to after the point where you left for the future so as punisment you miss the big sportspile. However all is well because you friend just fills you in regularly and you both enjoy your tasty beverages.