Have you seen Tenet and you want to know more, otherwise you wouldn’t be here right now.
You have an easy comment on social media, but it is not yet clear to you if you want to write praise or insults (to Nolan, Comingsoon.it, entropy, the high school physics professor who made you spend a lot of time …) .
So, in addition to the articles on the explanation of the plot, on the finale, on the Sator square, on the volume of dialogues and effects, on the theory linked to the child, you also get this which explains why Christopher Nolan has chosen the colors red and blue to represent the two directions of time. Ah, sure, we are always in territory spoiler, therefore, be aware of it.
Tenet: the choice of red and blue has a scientific basis
Although it is always science-fiction, Tenet does not quote Matrix. The red pill and the blue pill are not the reference taken from Christopher Nolan to give colors to the two directions of time Tenet.
Undoubtedly, the fact of distinguishing them gives us a fundamental help in understanding who is doing what and in which direction. You may also have noticed the lighting inside the two rooms of the turnstile when Sator holds Kat hostage while questioning the Protagonist: rosso on the side of the normal flow, blu on the side of the inversion. Similarly, the red or blue patch on the soldiers’ shoulder makes us identify well which group is working backwards in time and which is not.
First hypothesis: as we understand, the idea of time reversal in Tenet derives frominversion of entropy. Entropy is a quantity that measures the molecular disorder of an object in an environment, which allows us to understand how natural phenomena occur that are spontaneously tending to disorder, to a non-reversible dispersion of energy. Of course, we can restore order to the molecules of a liquid, for example, by freezing them in an ice cube, but the artificial intervention of an energy-consuming freezer is necessary and therefore, in the process, contributes to disorder. It is possible that Nolan has been inspired by the theoretical experiment of Maxwell’s Imp trying to refute the second law of thermodynamics of which entropy is part.
James Clerk Maxwell, Scottish physicist father of modern theories on electromagnetism, hypothesized this experiment (photo below): two chambers filled with the same gas at the same temperature are adjacent and separated by a trap door that can only be opened by a little devil which possesses a microscopic view. When the little devil sees the faster moving molecules approaching the hatch, he opens it and lets them pass into the other chamber, and then closes everything. Doing so, i.e. moving the fast molecules from A to B, would result in an increase in temperature, as the higher the average speed of the molecules, the greater the heat. Chamber B would therefore become warmer and chamber A colder, with a consequent inversion of entropy. The colors red and blue simply identify the temperature difference where red is disorder, energy in greater movement, and blue is order caused by a reversal of the process. All this without any energy consumption.
It has not yet been possible (and probably never will be) to demonstrate the experiment in practice Maxwell, especially due to the impossibility of identifying the little devil in a real element. It is not entirely wrong to metaphorically associate the figure of the little devil, which in English it is called demon, to that of Sator, who in the film embodies the evil one who overturns the laws of physics.
Second hypothesis: red and blue find a correct correspondence with theDoppler effect, the physical phenomenon analyzed by the Austrian Christian Andreas Doppler which measures the variation of a wave emitted by a source towards an observer, whether it is a sound or electromagnetic wave (but the classification of waves is broad). The wave propagates in time and space carrying energy. Since the spectrum of colors visible to the human eye has red and blue at the extremes, it is red shift (in English redsfhit) is the phenomenon that occurs when the source of light or another electromagnetic wave is moving away (or it is the observer who is moving away). In the opposite sense, the blueshift indicates the approach with a greater intensity of the waves. In cosmological terms, and that’s where that Nolan may have been inspired, the redshift proves the continuous expansion of the universe, hence the constant direction of time and space according to our perception.
Below a Tenet processing video.