“Tenet” Physicist thoroughly examines! What was this “retrograde” world? *Spoiler alert [CINEMORE ACADEMY Vol.9]

What is entropy?

Editorial Department: First of all, how should we interpret entropy?

Yamazaki: Well, I'll give you a textbook answer. Let's say you drink coffee first. Then put the cream in there. Then, the cream will spread out and the coffee will end up being a bit whitish. So, if you take a video of the process up to this point and play it backwards, the whitish coffee becomes fuzzy and separates into coffee and cream. But this never happens naturally.

A useful word to explain why this doesn't happen is entropy. When coffee and cream are separated, there is order, so entropy is said to be low. On the other hand, if you stir coffee and cream together, it will be chaotic, so we say it has high entropy. ``It is easy to mix up two parts, but a mixed object will never be separated into two.'' The law that ``entropy always increases'' ( Note: This is the second law of thermodynamics .

Also, using Chinjao loin as an example, I actually don't like green peppers and bamboo shoots. So, the state where green peppers, bamboo shoots, and beef are mixed together is a state of high entropy. However, if we had a technology like ``Tenet'', the entropy would decrease and the meat would be separated into green peppers, bamboo shoots, and beef. But naturally, that will never happen.

Editorial Department: So, does entropy have nothing to do with the flow of time, but does it mean order or disorder?

Yamazaki: Ah, this is very closely related to the flow of time, and some even say that ``the flow of time is the direction in which entropy increases.'' This is because in the laws of physics, it seems that there is no flow of time. For example, if you record a video of a pendulum's movement and play it backwards, it won't look unnatural. That's why the laws of physics don't seem to distinguish between the past and the future.

However, many people say that entropy is the only exception. Therefore, some people say that entropy determines the direction of time, such as ``the direction in which entropy increases is the future, and the direction in which it decreases is the past.'' So there is maximum relationship.

In the movie, Nolan uses the phrase "reversing the direction of entropy increase" to refer to going backwards in time, and it's clear that entropy is the main focus of his work.

Oguchi: It was last year. The news broke that a quantum computer had been used to confirm a decrease in entropy .

Yamazaki: Oh, did you know? I also took a quick look.

Physical accuracy and visual interest