In the new tv-series Devs, Lindon, a young coding prodigy, questions whether the quantum computer they are working on, is really a succes. ‘We see Christ on the cross,’ another researcher responds.
What the second researcher means is that their device allows them to see the actual Christ. They can see the Crucifixion the way it actually happened. (They also watch Joan of Arc, burning at the stake. I find these scenes very disturbing. But that is another story.) With their machine they can look into the past. For Lindon that is not good enough: ‘We see him through a blizzard of variances.’ The images of the past they conjure, are blurry. That is because much of what happens could have gone differently. Instead of writing this I could be staring at the screen, talking to the person next to me, write some other text, look at something on the internet … If one would look at what I was doing with the quantum computer of Devs, then they would see me in a ‘superposition’ of those possibilities.
The reality of the past cannot be blurry, our physical world view tells us. The physical variables have to be definite. Everything that happens has to be definite; otherwise it cannot take place. Something blurry cannot take place. If it appears so, then this is only perception. It is only in our heads that things are indefinite, because we lack knowledge about that thing.
For that reason the past cannot be indefinite. Lindon articulates what most physicists think. This principle of definiteness is no longer valid in QM. One can find some info on The Stanford Encyclopedia of Philosophy. (It should not be confused with determinism, which also runs into trouble in QM.)
Where does this idea come from? One of the first mathematical structures we discovered was Euclidean space. Physics began from the presupposition that it would only deal with things that have a definite and unique position in space. Because of the success of this approach, definiteness and spatiality became a key presupposition of our whole world view. Unexpectedly it was physics itself that undermined it: quantum objects do not have all their properties definite at all times. For example, quantum entities can be indefinite with respect to position. (Which begs the question: does they at all times exist in space?)
But is this such a revolution? What is a point anyway? What is a set of point? What is an infinite set of points? Why should we panic when one cannot make all things explicit to the exact and very last point?
Quantum mechanics rediscovered something obvious. Real things are definite to a certain degree. Beyond that there are variances. Thosse are real too. The possible ways things could have been, the possible ways things can be, define that thing. Lindon calls this ‘voodoo’. But there is nothing voodoo about it. The real Jesus is not definite, because he never was, not completely. Nor am I, nor are you. We all exist, all the time, in clouds of variances. The Belgian philosopher Leo Apostel proposed some formal models to describe the texture of possibilities surrounding everything that happens and everything that has happened, in his Matière et Forme. But one can also find it in the work of Aristotle, Leibniz, Bergson, Whitehead and Deleuze.