Following on from all of the talk of interstellar trade, Glen Whitman explores the economics of time travel [HT: Tyler Cowen]. His argument is that if wages rise in the future, future society will use time travel to import cheaper labour from the past. So there will be intertemporal migration and wage equalisation. Really? You think that is what we are going to get if someone invents a time machine. This is about as convincing as Michael Crichton’s continual plot line that inventing things like time machines or dinosaur resurrection would be funded off the basis of theme parks.
Let’s get serious, for a moment, about the possibilities of time travel. When it comes down to it, the primary reason for someone to spend money inventing a time machine is to go back into the past, possessing future knowledge, and to exploit that knowledge either by inventing something (e.g., MS-DOS before Bill Gates) or trading on financial markets (e.g., airline stocks before late 2001). That is, on the face of it, a sound commercial rationale especially if time travel is Terminator rather than Back to the Future style.
The question is: if you think about the full equilibrium, will the investment in a time machine pay off? You see, you go back in the past and make a fortune. The problem is, even if you can patent or keep secret your time machine, someone in the future is going to duplicate your innovation. It only takes time. Then, they will target the maximum wealth generating opportunity in the past. If that was for you inventing something in particular, it will likely be the same for them. They will just go back in time and pre-empt your investment. The end result will be that you will find yourself going back in time but with the past already altered. All cost and no return. You would then have to go into the future to work out what you need to do but, and you can see where I am going here, that would have to be pretty much to the end of time at which point, the knowledge you need may not be so transparent.
A savvy (potentially evil) would be expropriator of future knowledge cannot possibly recoup all of the R&D costs on inventing a time machine. Hence, it won’t be done.
So if you are wondering why we haven’t seen time travellers from the future, you don’t need some elaborate theory of physics whose main purpose is to make science fiction really fiction. All you need is some economics: there is no incentive to invent time travel (unless you want to stick to historical theme parked tourism that is). That said, didn’t someone invent MS-DOS before Bill Gates?