With the development of artificial intelligence, virtual reality, etc., the amount of data to be processed is increasing, but the limits of integrated circuits are approaching. So instead of gates made of transistors, quantum computers that use quantum as their operational rules are emerging as an alternative. What exactly is quantum, and what can we do with it as an alternative? A reporter who has no connection with science takes a close look at everything from quantum to quantum computers, which are a recent issue, with a learning heart.


Schrodinger's cat
A cat is locked in a box. The box is connected to a machine containing a radioactive nucleus and a canister containing poison gas. At the beginning of the experiment, the probability of the nucleus decaying within an hour is adjusted to 50%. If the nucleus decays, the poison gas is released and the cat dies. Schrödinger criticized the expression of the wave function in this situation as a combination of the cat's alive and dead states, and thought that quantum mechanics was incomplete and unrealistic because a "cat that is both dead and alive" does not actually exist. Since the cat must be either alive or dead, the proton must also have either decayed or not decayed.


To understand Schrödinger's cat
The Schrödinger's cat thought experiment was presented to show how nonsensical the Copenhagen interpretation is. However, contrary to Schrödinger's intention, scientists who explain the uncertainty of quantum mechanics have been using the cat metaphor over and over again. Naturally, this metaphor only compares the microscopic world to the macroscopic world, and does not express the macroscopic world. In the macroscopic world, there is no such thing as Schrödinger's cat.
Why is that? Let's take Schrödinger's cat as an example again.

If you want to know where a cat is, you have to look at the cat. Seeing a cat means that some of the light that hits the cat enters the observer's eye. According to quantum mechanics, light is also a particle. So all particles that are hit by light are shocked. A being that is much larger than light, like a cat, may feel a little hot when hit by light, but it is not shocked. Particles are different. Small particles like electrons are shaken when hit by light. If you want to know where an electron is, you have to use light with a short wavelength, and the shorter the wavelength, the greater the shock that an electron receives. Shock changes momentum.
In the microscopic world, the act of measuring affects physical quantities such as position and velocity. Therefore, position and momentum cannot be measured accurately together. Since the value changes each time you measure, you can measure it multiple times and find the probability of what will come out. The world of quantum mechanics is too small for measurements to have any effect. Since we do not know both position and momentum at the same time, it is impossible to predict the future based on classical mechanics. Since we have no choice but to use probability, indeterminism was introduced.

Einstein denied quantum mechanics by saying, “God does not play dice,” but Bohr denied Einstein’s denial of quantum mechanics by saying, “Do not interfere with what God does with dice.”


Another interpretation, many worlds interpretation
Hugh Everett III proposed the 'many-worlds interpretation' in 1957, which is different from the Copenhagen interpretation. The many-worlds interpretation claims that there are not different states that overlap, but rather different worlds. Therefore, measurement is a process of selecting one world among many.

According to the many worlds interpretation, the cat in the box is not a superposition of dead and alive cats. There are both alive and dead cats. The moment the observer opens the box and checks the cat's condition, the universe is split into two universes: one with a living cat and one with a dead cat.

A living cat and a dead cat cannot exist at the same time. The moment an observer observes a cat, the observer either forms one universe with the cat alive, or another universe with the cat dead. There is no interaction between the two universes.


Quantum mechanics beyond common sense
What on earth does this mean? Let's just think about it. Quantum mechanics has succeeded in explaining what happens in the microscopic world. Now, many scientists are moving away from the philosophical interpretation of quantum mechanics and are conducting experiments to solve and confirm equations related to quantum mechanics. If a theory can explain the experimental results, then it is a correct theory. For practical physicists, interpretation is good, but it is not necessary.
Quantum mechanics mercilessly revised the idea that “we now know almost everything” that had dominated physics until the 19th century. Physicists explained all the difficult quantum mechanics in formulas even to specialists. This is because human language is based on common sense, and it is impossible to explain the absurd quantum mechanics in words. Mathematics also expressed the phenomena of the universe in numbers, but it is still possible to express things that cannot be done in human language.

The problem of interpreting quantum mechanics has moved from the physics world to the world of philosophy and culture. In the cultural world, quantum mechanics is being used quite a bit. While there are contents that are just nonsense, there are also contents like 'Ant-Man and the Wasp' that try to balance dramatic effects with actual science. This weak 'Quantum Exploration Series' started its first episode with Ant-Man and the Wasp. Fans are predicting that quantum mechanics, which is an important subject in the Ant-Man series, will have a big impact on the Marvel Cinematic Universe itself. If you are curious about how quantum mechanics will be handled in 'Avengers 4', go to the movie medium.

We have learned about the general history and content of quantum mechanics. From the next episode, we will learn about quantum computers that utilize quantum mechanics.