Maxwell's evil

# Maxwell's_evil

Christopher Nolan's Tenet is a great movie. All the movies of Normali Nolan are awesome but it seems to me that the limit has been exceeded. It is not the purpose of this post to write about what happens in this movie. The purpose is to write a little above the two science concepts that are shown in this movie because the whole movie is based on these two concepts. One is Entropy and the other is Arrow of Time. Today's post is about entropy and arrow of time. You have to revise the previous article and submit it. If you wish, you can take a look at the entropy section of this post. If you know these two topics then maybe it will be a little useful to relate to the movie.

Before going to the post, you need to know what is a thought experiment. The matter of thought experiments can now be called a very standard practice in theoretical physics. Thought experiment can be thought of as a process. This is done because many times it may be seen that a theory has been proved in a notebook pen but the technology to prove the theory of that notebook pen experimentally has not yet been discovered. Then, since it is not possible to prove one thing by doing the physical experiment, what is the result of doing the same experiment in the mind is done and what else is discussed about the result. Just give a few examples to understand.

- As has been proven in the Hawking Radiation Book pen but we have not yet discovered the technology with which it can be proved in the lab;

- There is a type of particle called the Higgs boson. It has been proved in the lab that it was made into a large hadron collider at a cost of Rs.

There are many more examples like this. So many times when it is seen that there is no way to prove a theory, then at least the problems or advantages of a theory are done by experimenting with this thought. Einstein was the first to popularize it with his elevator thought experiment. Since then he has done many more things like running at the speed of light.

The thought experiment on today's topic is called Maxwell's Satan means in Bengali and in English you would say Maxwell's Demon or Demon as you say. The word devil is thought to have been coined by someone because Maxwell is believed not to have uttered the word.

One little thing to know before we know what this Maxwell devil is is what entropy is and where it is usually discussed.

.. Entropy.

The discussion of entropy is usually in the subject of thermodynamics so it can be said that it is taught in detail in mechanical engineering. Other engineering, of course, is given a little touch. Basically the second law of thermodynamics is entropy related. This formula says that the more you move forward in a system, the more the entropy of that system will increase and it will never be restored to its original state. Without going into the details of entropy, just remember that entropy means confusion, chaos, disorder, random. Chaos and confusion in one thing means more entropy.

Let me give you an example. Suppose you have a cup of coffee in your hand. So the coffee molecules here are probably arranged a little better, which means there is less confusion or chaos, so there will be less entropy. The moment the cup falls down from your hand and breaks, the molecules scatter around and the molecules create a kayotic situation from the arranged state i.e. the amount of confusion or chaos increases so it will be assumed that the entropy has increased. And if you think about it, you can't get the molecules back to normal. You can try, you can bring it closer, but you can never get it right. This is basically the second law of thermodynamics. This same entropy concept people use to determine the direction of time. This means that the entropy at the beginning of the Big Bang was zero because everything was together in one small space so the amount of chaos was less. But the chaos that followed the Big Bang is still going on, and that's why the value of entropy is only increasing. With this matter, many people actually determine the direction of time. If in the initial condition when entropy is zero and time and zero, but after the Big Bang, entropy is increasing and time is moving forward. Since entropy is not decreasing, the combination of time with entropy indicates that time is actually a one-way matter and only moving forward.

.. Temperature.

Suppose you let water heat up in two pots. After a while he touched the water and said that the water temperature in pan 1 is higher than the water temperature in pan 2. Notice what you are saying?

Water is made up of numerous molecules. This means that water is made up of H2O molecules. When you say the temperature of a pot of water, you are not saying the temperature of a water molecule, but you are saying the average temperature. That is, if there are 10 water molecules in that pan, then you add the temperature of those 10 molecules and divide by 10 to get the temperature. If you said one molecule, you would say it a little differently.

That's because if you could see the temperature of a molecule, you might see that the temperature of a molecule is 10 degrees and one is 15 degrees, and one might be 2 degrees or so. For this temperature, those molecules actually move inside the whole pan. This means that if the temperature is 10 degrees, it is running a little faster, and if the temperature of one is 2 degrees, then it is running a little slower. So in this run, one collides with another, one goes from one side to the other and the other pushes together and goes from one side to the other.

One more thing needs to be noticed here. Although the temperature of pan 1 is higher, this does not mean that the temperature of each molecule in pan 1 is higher than that of the molecule in pan 2. Let me give you an example. Maybe the average temperature of pan 1 is higher than that of pan 2 but maybe the temperature of a molecule in pan 2 is higher than that of a molecule in pan 1. So basically if you calculate one molecule at a time without calculating the average, it can be a little complicated to say temperature.

.. The devil of Maxwell.

The above two things will be needed in this Maxwell's Devil Thought Experiment. Basically Maxwell wanted to prove with this thought experiment that the second law of thermodynamics may not be true. That is, as this formula says, the entropy of a system will continue to increase over time. This may not be true because the entropy in a system can decrease over time.

The experiment was like this.

He said, "Suppose someone has two boxes and these two boxes are full of gas." Suppose a box has a high temperature and a box has a low temperature. Let's say you bring the two boxes closer together so that one box and one box stick to each other. Now if you let it stay like this for a while then the hot box will get a little cold after a while and the cold box will get a little hot and at a time both the boxes will be at the same temperature. And think about the condition of the molecules of that gas. Like the pot of water. One molecule will go this way and one molecule will go that way, one will collide with another, and so on and so forth. In doing so, at some point the molecules will get an equilibrium and the temperature at that equilibrium will be less than the temperature of the hot box and a little higher than the temperature of the cold box. So to bring the temperature evenly, these molecules in the box will go through a chaos process and if we calculate it, we can see that the amount of entropy has actually increased. So the second law of thermodynamics is correct.

But now if you do one thing it might be a little different. All you have to do is imagine a door between these two boxes through which a molecule can go from one side to the other. Now let's assume that a devil is controlling this door. What this devil is doing is closing the gate only when a high temperature molecule wants to move from its box to a low temperature box, i.e. it does not allow any high temperature molecule to move from a high temperature box to a low temperature box but if a low temperature molecule What was in the high temperature box is opening the door for him if he wants to go to the low temperature box.

Again he is doing the opposite for the low temperature box. There are some molecules in this low temperature box which are a little higher temperature. So when a high temperature molecule wants to go from a low temperature box to a high temperature box, he opens the door and lets them go, but if a low temperature molecule wants to go from a low temperature box to a high temperature box, he doesn't let it go.

Maybe you feel hospitable. Read slowly again. Then think about what is happening now.

- The box with the higher temperature is getting the higher temperature molecules from the lower temperature box;

- The low temperature box is getting the low temperature molecules from the high temperature box;

And if this is the case, then the higher temperature box will be hotter and the lower temperature box will be colder.

And if this is the case then the second law of thermodynamics is no longer valid because this law says that the entropy in a system will only increase with time but since the low temperature box is getting a low temperature molecule then its temperature decreases which means the entropy actually decreases. And if this is true, then of course the second law of thermodynamics will always be correct. It is not true.

There has been a lot of discussion about this thought experiment since then and many have tried to create this Maxwell devil in the lab to see what really happens. Finally, it has been observed that the entropy of the system does not decrease but increases with Maxwell's thought experiment.

This is because of this. Take a look at what's going on in the whole system as the devil lets the molecules go from one side to the other.

- A completely new system is being added because this devil was not in the previous system but is in this new system;

- The devil must first know exactly how many molecules are in the two boxes. To know this, he has to spend time counting each molecule;

- The devil has to build a system so that he can know the temperature of each molecule because if he does not know the temperature, he will not be able to understand in any way which direction the molecule has to go;

- Next you need to know exactly how hot the box is called hot. And not only does he have to know which molecules in the low heat box he has to consider as hot because if he doesn't know this information he can't determine exactly which molecule he has to let go;

- Knowing the information of each molecule, he has to do some analysis with the result;

- He must add a mechanism to open and close the door;

- He has to do extra work.

- etc.

- etc.

And when these things are being done, he has to design a different system and attach it to these boxes so that he can get this information and work that way. And when so much is being added, the entropy in that system is not decreasing but increasing over time. And the entropy that is increasing in a system is increasing the entropy of this universe over time.

In other words, the second law of thermodynamics really exists and still exists. This is a very famous formula in science.

.. Mango experiment.

Geniuses do thought experiments and mangoes do mango experiments. People float in thought experiments and people drown in mango experiments. In the mango experiment, a mango not only drowns itself but also drowns everything that comes next. What else to do. Talk about mango.