Quantum time travel is very similar to Quantum suicide. Here is the recipe:
Build a conditional suicide machine that instantly kills the user unless a particular set of conditions in the environment is satisfied. With "conventional" quantum suicide these conditions could be a winning lottery ticket for example. With time travel suicide, these conditions would be that prespecified factors in the environment should match the past to which we would like to travel to. How do we prespecify these factors? By entering them into the machine computer data base, either from memory or from an existing record (movie, audio.....). The more accurate the database in depicting the past, the closer you'll get to the desired world. Of course your recording/memory is subject to Heisenberg uncertainty limit and therefore, the past you'll get to will be slightly different from the one you come from...but since the past you come from is also subject to Heisenberg limit... it doesn't matter. Just as the Quantum suicide machine, the Quantum time travel machine would have to be supremely reliable. It's failure rate would have to be orders of magnitude less then the likelihood that the part of the universe that has been recorded in the machine database matches the recorded data. But of course this is just a problem for the engineers to worry about. :-) And if you not really careful, you may end up in a future Hollywood movie, 21st Century-Park, reenacting our time period and directed by a successor to Steven Speilberg. George Levy
