At some time or another, it seems, every
SF writer has to do a time-travel book. I decided that I wanted to try one which
at last faces up to the paradoxes and tackles them, without such cop-outs as characters
religiously making sure that everything is set up and left the way it "happened,"
magical, mysterious forces compelling them to act in ways that keep everything
consistent, masking the paradoxes by burying them far in the distant past, and
that kind of thing.
The other thing I wanted to do was get
away from those conjurors' boxes, introduced in whatever disguise, that we read
about all the time. I certainly wouldn't start by jumping hopefully into one
to be launched off to who-knows-where--or, quite possibly or more probably,
depending on one's degree of natural cynicism--to simply vanish without trace.
I'd want to send a few monkeys or some such through first, and make sure they
came back okay. In other words, if this ever became a real issue being investigated
by real scientists, it seemed to me that they'd handle it very differently than
as depicted in a lot of the stories we've seen.
Come to think of it, if this kind of physics
ever became a reality, would it be likely to emerge immediately at a sufficient
level of sophistication to permit the sending and reconstitution of structured
objects, or even of matter? A more plausible beginning might be the ability
to send just a whiff of energy. Now, if you can send energy, you can modulate
it, for example by switching it on and off according to some kind of code, which
means you can send information. If you can send information, you can cause events
at the other end to be changed, hence introducing all the familiar paradoxes
of time travel, but perhaps in a more plausible setting. The result was THRICE
UPON A TIME, which deals with a group of scientists and others trying to make
sense out of experimental results derived from the discover of being able to
propagate signals back through time--in other words, figuring out the rules.
Obviously, I had to know the rules in
order for the characters to discover them. Trying to work them out tends to
be difficult when they're entangled with the complexities of plot situations.
So to separate them out and simplify things, I reduced everything to a model
consisting of a button and a lamp. When the button is pressed, the lamp comes
on. You can't get much simpler than that. Now, add in a black box that sends
the signal back through time so that the lamp comes on thirty seconds before
the button is pressed. Two questions arise:
- The lamp comes on. Thirty seconds later it's time to press the button.
I won't. What happens?
- Thirty seconds ago the lamp didn't come on, but I press the button anyway.
Every time-travel paradox is a variation
of one or the other of these two situations. When you can answer the above two
questions, you can resolve all of them.