In this blog I’ve written up some of the non-fiction speculations behind my stories, and I was interested to see that a new publisher, Sci Phi Journal (Science Fiction and Philosophy) makes the connection explicit by adding “Food for Thought” sections after the stories and including essays that discuss philosophical aspects of spec fic.
Time travel is a spec fic standard that has never gone away, and in the sometimes real world, a lot of questions about the nature of time—physical, philosophical and neurological—still have no clear answer.
The questions about the direction of time, or time’s arrow, are some of my favourites. One way to find an arrow of time is to look at successive snapshots of a scene and see if they can be put in the right order. If it’s easy, as in the shots above, you have an arrow. If it’s difficult, a chicken and an egg say, then you don’t have an arrow.
The spec fic movie Time Lapse features a camera that photographs the future, and it’s a lot of fun, but to really photograph the future, you need to see what an ordinary camera does and reverse it in time.
Since it’s difficult, if not straight out impossible, to handle anything too complicated, I won’t consider time-reversing a digital SLR, instead I’ll re-design a simple photographic plate, starting with the way things usually work.
what happened in the dark room
In your dark room under the red light, you see black bits on a photographic plate, and you deduce that at some time or times in the past, light shone on those places and turned the photosensitive silver iodide to silver, blackening the plate.
“Aha!” you think, “I’ve discovered photography,” and you text your friends, but unfortunately you’re a hundred years too late.
the full time reversal
Running the scenario backwards in time, the past becomes the future, and chemical reactions take place at future times in various places on the plate. But there is another key difference—the direction of the light must also be reversed. Instead of hitting the plate and causing a reaction, the light or radiation must actually be emitted by reactions on the plate.
One hypothetical way you could do this would be to make a plate with lead atoms in some places and atoms of the medical radioisotope technetium-99m in others. You know that x-rays will be emitted at some point in the future by the technetium, and you know it with the same level of certainty that you knew light struck the dark areas on the ordinary photographic plate.
So that’s how to get a real photograph of the future. It’s nowhere near as interesting as the camera in Time Lapse, but on the other hand, it doesn’t suffer from the logical inconsistencies that would arise if information really could be sent backwards from the future to the past. And thought experiments like this one serve a purpose, because they help to unravel the mysteries of time.