(Sunday Thought) Two Temporal Paradoxes

The second installment of the SCIENCE CRIMES DIVISION series involves a murderer who remembers the future instead of the past. As I’ve been working through the plot, which is tricky, it occurred to me that there are at least two kinds of temporal paradox.

The first we’ll call a hard or cut-loop paradox. This includes the famous grandfather paradox, where you go back in time and kill an ancestor such that you can never be born to do it.

The second type, what we might call a soft or closed-loop paradox, would include closed, timelike curves, a theoretical space-time loop first proposed in 1937. Here, two or more temporally distant events can be seen as both cause and effect of each other. For example, if you went back in time and gave the scientist who invented time travel the means to do it, then your travel to the past would be both a cause and an effect of itself.

Although cut-loop paradoxes are the most commonly imagined, closed-loop paradoxes are hardly new to science fiction. Heinlein used one in a short story, and a three-point version was used in “All Good Things…”, the concluding episode of Star Trek: The Next Generation — although in that case, it was a contrivance by the omnipotent being Q and not considered part of the “real” timeline, which is a convenient plot device for sidestepping the issue!

Physicists like to think paradoxes are impossible. Stephen Hawking’s chronology protection conjecture and Igor Novikov’s self-consistency principle suggest that the universe is structured to prevent them (even while admitting they happen at the quantum scale). There’s also a version of the Fermi paradox that gets at the same skepticism by asking: if time travel is possible, where are all the time travelers?

But these are little more than thought experiments. While there is no solution to a hard paradox, strictly speaking, we don’t know that the soft variety violates the laws of physics. In fact, the possibility of closed, timelike curves was confirmed to be consistent with the theory of relativity by Einstein’s friend and famed mathematician Kurt Gödel. The history of the entire universe may be such a curve.

Whether that’s the case or not, it does seem as though local, closed-loop paradoxes could appear as tiny anomalies inside space-time, eddies that exist as both cause and effect of themselves, a possibility I will be exploring here on earth in the second SCIENCE CRIMES DIVISION novel, where it will pose a thorny challenge to Nio and the team. How do you catch a man who already remembers your every attempt to do so?


Speaking of temporal paradoxes, you may wonder how it is a Sunday Thought appears on a Monday. The world may never know…

But while you’re pondering that, go vote! Someone nominated THE ZERO SIGNAL for Goodreads’ Best Books of 2021but it needs votes!

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