Living and dead Schrödinger's cat play. Schrödinger theory in simple words

If you are interested in an article on a topic from quantum physics, then there is a high probability that you love the TV series “The Big Bang Theory”. So, Sheldon Cooper came up with a fresh interpretation Schrödinger's thought experiment(You will find a video with this fragment at the end of the article). But to understand Sheldon's dialogue with his neighbor Penny, let's first turn to the classical interpretation. So, Schrödinger's Cat in simple words.

In this article we will look at:

• Brief historical background
• Description of the experiment with Schrödinger's Cat
• The solution to the Schrödinger's Cat paradox

Immediately good news. During the experiment Schrödinger's cat was not harmed. Because physicist Erwin Schrödinger, one of the creators quantum mechanics, just conducted a thought experiment.

Before diving into the description of the experiment, let's make a mini excursion into history.

At the beginning of the last century, scientists managed to look into the microworld. Despite the external similarity of the “atom-electron” model with the “Sun-Earth” model, it turned out that the familiar Newtonian laws of classical physics do not work in the microcosm. Therefore, a new science appeared - quantum physics and its component - quantum mechanics. All microscopic objects of the microworld were called quanta.

Attention! One of the postulates of quantum mechanics is “superposition”. It will be useful to us to understand the essence of Schrödinger's experiment.

“Superposition” is the ability of a quantum (it can be an electron, a photon, the nucleus of an atom) to be not in one, but in several states at the same time or to be in several points of space at the same time, if no one is watching him

This is difficult for us to understand, because in our world an object can only have one state, for example, being either alive or dead. And it can only be in one specific place in space. You can read about “superposition” and the stunning results of quantum physics experiments In this article.

Here is a simple illustration of the difference between the behavior of micro and macro objects. Place a ball in one of the 2 boxes. Because the ball is an object of our macro world, you will say with confidence: “The ball lies in only one of the boxes, while the second one is empty.” If instead of a ball you take an electron, then the statement that it is simultaneously in 2 boxes will be true. This is how the laws of the microworld work. Example: The electron in reality does not rotate around the nucleus of the atom, but is located at all points of the sphere around the nucleus simultaneously. In physics and chemistry, this phenomenon is called the “electron cloud”.

Summary. We realized that the behavior of a very small object and a large object are subject to different laws. The laws of quantum physics and the laws of classical physics, respectively.

But there is no science that would describe the transition from the macroworld to the microworld. So, Erwin Schrödinger described his thought experiment precisely to demonstrate the incompleteness general theory physics. He wanted Schrödinger's paradox to show that there is a science to describe large objects (classical physics) and a science to describe micro objects (quantum physics). But there is not enough science to describe the transition from quantum systems to macrosystems.

Description of the experiment with Schrödinger's Cat

Erwin Schrödinger described a thought experiment with a cat in 1935. The original version of the experiment description is presented on Wikipedia ( Schrödinger's cat Wikipedia).

Here is a version of the description of the Schrödinger's Cat experiment in simple words:

• A cat was placed in a closed steel box.
• The Schrödinger Box contains a device with a radioactive nucleus and poisonous gas placed in a container.
• The nucleus may decay within 1 hour or not. Probability of decay – 50%.
• If the nucleus decays, the Geiger counter will record this. The relay will operate and the hammer will break the gas container. Schrödinger's cat will die.
• If not, then Schrödinger’s cat will be alive.

According to the law of “superposition” of quantum mechanics, at a time when we are not observing the system, the nucleus of an atom (and therefore the cat) is in 2 states simultaneously. The nucleus is in a decayed/undecayed state. And the cat is in a state of being alive/dead at the same time.

But we know for sure that if the “Schrödinger box” is opened, then the cat can only be in one of the states:

• if the nucleus does not decay, our cat is alive
• if the nucleus decays, the cat is dead

The paradox of the experiment is that according to quantum physics: before opening the box, the cat is both alive and dead at the same time, but according to the laws of physics of our world, this is impossible. Cat can be in one specific state - being alive or being dead. There is no mixed state “the cat is alive/dead” at the same time.

Before you get the answer, watch this wonderful video illustration of the paradox of the Schrödinger's cat experiment (less than 2 minutes):

The solution to the Schrödinger's Cat paradox - the Copenhagen interpretation

Now the solution. Pay attention to the special mystery of quantum mechanics - observer paradox. An object of the microworld (in our case, the core) is in several states simultaneously only while we are not observing the system.

For example, the famous experiment with 2 slits and an observer. When a beam of electrons was directed onto an opaque plate with 2 vertical slits, the electrons painted a “wave pattern” on the screen behind the plate—vertical alternating dark and light stripes. But when the experimenters wanted to “see” how electrons fly through the slits and installed an “observer” on the side of the screen, the electrons drew not a “wave pattern” on the screen, but 2 vertical stripes. Those. behaved not like waves, but like particles.

It seems that quantum particles themselves decide what state they should take at the moment they are “measured.”

Based on this, the modern Copenhagen explanation (interpretation) of the “Schrödinger’s Cat” phenomenon sounds like this:

While no one is observing the “cat-core” system, the nucleus is in a decayed/undecayed state at the same time. But it is a mistake to say that the cat is alive/dead at the same time. Why? Yes, because quantum phenomena are not observed in macrosystems. It would be more correct to talk not about the “cat-core” system, but about the “core-detector (Geiger counter)” system.

The nucleus selects one of the states (decayed/undecayed) at the moment of observation (or measurement). But this choice does not occur at the moment when the experimenter opens the box (the opening of the box occurs in the macroworld, very far from the world of the nucleus). The nucleus selects its state at the moment it hits the detector. The fact is that the system is not described enough in the experiment.

Thus, the Copenhagen interpretation of the Schrödinger's Cat paradox denies that until the moment the box was opened, Schrödinger's Cat was in a state of superposition - it was in the state of a living/dead cat at the same time. A cat in the macrocosm can and does exist in only one state.

Summary. Schrödinger did not fully describe the experiment. It is not correct (more precisely, it is impossible to connect) macroscopic and quantum systems. Quantum laws do not apply in our macrosystems. In this experiment, it is not “cat-core” that interacts, but “cat-detector-core”. The cat is from the macrocosm, and the “detector-core” system is from the microcosm. And only in its quantum world can a nucleus be in two states at the same time. This occurs before the nucleus is measured or interacts with the detector. But a cat in its macrocosm can and does exist in only one state. That's why, It’s only at first glance that it seems that the cat’s “alive or dead” state is determined at the moment the box is opened. In fact, its fate is determined at the moment the detector interacts with the nucleus.

Final summary. The state of the “detector-nucleus-cat” system is NOT associated with the person – the observer of the box, but with the detector – the observer of the nucleus.

Phew. My brain almost started boiling! But how nice it is to understand the solution to the paradox yourself! As in the old student joke about the teacher: “While I was telling it, I understood it!”

Sheldon's interpretation of Schrödinger's Cat paradox

Now you can sit back and listen to Sheldon's latest interpretation of Schrödinger's thought experiment. The essence of his interpretation is that it can be applied in relationships between people. To understand a good relationship between a man and a woman or bad - you need to open the box (go on a date). And before that they were both good and bad at the same time.

Well, how do you like this “cute experiment”? Nowadays, Schrödinger would get a lot of punishment from animal rights activists for such brutal thought experiments with a cat. Or maybe it wasn’t a cat, but Schrödinger’s Cat?! Poor girl, she suffered enough from this Schrödinger (((

See you in the next publications!

I wish everyone a good day and a pleasant evening!

P.S. Share your thoughts in the comments. And ask questions.

P.S. Subscribe to the blog - the subscription form is located under the article.

The article describes what Schrödinger's theory is. The contribution of this great scientist to modern science, and also describes a thought experiment he invented about a cat. The scope of application of this kind of knowledge is briefly outlined.

Erwin Schrödinger

The notorious cat, who is neither alive nor dead, is now being used everywhere. Films are made about him, communities about physics and animals are named after him, there is even a clothing brand. But most often people mean the paradox with the unfortunate cat. But people usually forget about its creator, Erwin Schrödinger. He was born in Vienna, which was then part of Austria-Hungary. He was the scion of a very educated and wealthy family. His father, Rudolf, produced linoleum and invested money, among other things, in science. His mother was the daughter of a chemist, and Erwin often went to listen to his grandfather’s lectures at the academy.

Since one of the scientist’s grandmothers was English, he was interested in foreign languages and mastered English perfectly. It is not surprising that at school Schrödinger was at the top of his class every year, and at university he asked difficult questions. Early twentieth-century science had already identified inconsistencies between the more understandable classical physics and the behavior of particles in the micro- and nanoworld. I threw all my strength into resolving the emerging contradictions

Contribution to science

To begin with, it is worth saying that this physicist was involved in many areas of science. However, when we say “Schrödinger’s theory,” we do not mean the mathematically harmonious description of color he created, but his contribution to quantum mechanics. In those days, technology, experiment and theory went hand in hand. Photography developed, the first spectra were recorded, and the phenomenon of radioactivity was discovered. The scientists who obtained the results interacted closely with the theorists: they agreed, complemented each other, and argued. New schools and branches of science were created. The world began to sparkle with completely different colors, and humanity received new mysteries. Despite the complexity of the mathematical apparatus, to describe what Schrödinger’s theory is, in simple language Can.

The quantum world is easy!

It is now well known that the scale of the objects being studied directly affects the results. Visible to the eye objects are subject to the concepts of classical physics. Schrödinger's theory is applicable to bodies measuring one hundred by one hundred nanometers and smaller. And most often we are talking about individual atoms and smaller particles. So, each element of microsystems simultaneously has the properties of both a particle and a wave (wave-particle duality). From the material world, electrons, protons, neutrons, etc. are characterized by mass and associated inertia, speed, and acceleration. From the theoretical wave - parameters such as frequency and resonance. In order to understand how this is possible at the same time, and why they are inseparable from each other, scientists needed to reconsider their entire understanding of the structure of substances.

Schrödinger's theory implies that, mathematically, these two properties are related through a construct called the wave function. Finding a mathematical description of this concept brought Schrödinger Nobel Prize. However, the physical meaning that the author attributed to it did not coincide with the ideas of Bohr, Sommerfeld, Heisenberg and Einstein, who founded the so-called Copenhagen interpretation. This is where the “cat paradox” arose.

Wave function

When it comes to microcosm elementary particles, the concepts inherent in macroscales lose their meaning: mass, volume, speed, size. And shaky probabilities come into their own. Objects of this size are impossible for humans to capture - only indirect ways of studying are available to people. For example, stripes of light on a sensitive screen or film, the number of clicks, the thickness of the film being sprayed. Everything else is the area of ​​calculations.

Schrödinger's theory is based on the equations that this scientist derived. And their integral component is the wave function. It unambiguously describes the type and quantum properties of the particle under study. It is believed to show the state of, for example, an electron. However, it itself, contrary to the ideas of its author, has no physical meaning. It's just a convenient mathematical tool. Since our article presents Schrödinger's theory in simple terms, let's say that the square of the wave function describes the probability of finding a system in a predetermined state.

Cat as an example of a macro object

The author himself did not agree with this interpretation, which is called the Copenhagen interpretation, until the end of his life. He was disgusted by the vagueness of the concept of probability, and he insisted on the clarity of the function itself, and not its square.

As an example of the inconsistency of such ideas, he argued that in this case the microworld would influence macro objects. The theory goes as follows: if you place a living organism (for example, a cat) and a capsule with a poisonous gas in a sealed box, which opens if a certain radioactive element decays, and remains closed if decay does not occur, then before opening the box we get a paradox. According to quantum concepts, an atom of a radioactive element will decay with some probability over a certain period of time. Thus, before experimental detection, the atom is both intact and not. And, as Schrödinger’s theory says, for the same percentage of probability the cat is both dead and otherwise alive. Which, you see, is absurd, because when we open the box, we will find only one state of the animal. And in a closed container, next to the deadly capsule, the cat is either dead or alive, since these indicators are discrete and do not imply intermediate options.

There is a specific, but not yet fully proven, explanation for this phenomenon: in the absence of time-limiting conditions to determine the specific state of a hypothetical cat, this experiment is undoubtedly paradoxical. However, quantum mechanical rules cannot be used for macro-objects. It has not yet been possible to accurately draw the boundary between the microworld and the ordinary one. However, an animal the size of a cat is undoubtedly a macro object.

Application of quantum mechanics

As with any, even theoretical, phenomenon, the question arises of how Schrödinger’s cat can be useful. The Big Bang theory, for example, is based precisely on the processes that relate to this thought experiment. Everything that relates to ultra-high speeds, the ultra-small structure of matter, and the study of the universe as such is explained, among other things, by quantum mechanics.

Yuri Gordeev
Programmer, game developer, designer, artist

"Schrödinger's Cat" is a thought experiment proposed by one of the pioneers of quantum physics to show how strange quantum effects look when applied to macroscopic systems.

I’ll try to explain in really simple words: gentlemen of physics, don’t blame me. The phrase "roughly speaking" is implied further before each sentence.

On a very, very small scale, the world is made up of things that behave in very unusual ways. One of the strangest characteristics of such objects is the ability to be in two mutually exclusive states at the same time.

What is even more unusual from an intuitive point of view (some would even say creepy) is that the act of purposeful observation eliminates this uncertainty, and the object, which was just in two contradictory states at the same time, appears before the observer in only one of them, as if in nothing never happened, looks to the side and whistles innocently.

At the subatomic level, everyone has long been accustomed to these antics. There is a mathematical apparatus that describes these processes, and knowledge about them has found the most various applications: For example, in computers and cryptography.

At the macroscopic level, these effects are not observed: objects familiar to us are always in a single specific state.

Now for a thought experiment. We take the cat and put him in a box. We also place a flask with poisonous gas, a radioactive atom and a Geiger counter there. A radioactive atom may or may not decay at any time. If it disintegrates, the counter will detect radiation, a simple mechanism will break the flask with gas, and our cat will die. If not, the cat will remain alive.

We close the box. From this moment, from the point of view of quantum mechanics, our atom is in a state of uncertainty - it decayed with a probability of 50% and did not decay with a probability of 50%. Before we open the box and look inside (make an observation), it will be in both states at once. And since the fate of the cat directly depends on the state of this atom, it turns out that the cat is also literally alive and dead at the same time ("...smearing the living and dead cat (pardon the expression) in equal parts..." writes the author of the experiment). This is exactly how quantum theory would describe this situation.

Schrödinger could hardly have guessed how much noise his idea would make. Of course, the experiment itself, even in the original, is described extremely crudely and without any pretense of scientific accuracy: the author wanted to convey to his colleagues the idea that the theory needs to be supplemented with clearer definitions of processes such as “observation” in order to exclude scenarios with cats in boxes from its jurisdiction.

The idea of ​​a cat was even used to “prove” the existence of God as a superintelligence, whose continuous observation makes our very existence possible. In reality, “observation” does not require a conscious observer, which takes some of the mysticism out of quantum effects. But even so, quantum physics remains today the frontier of science with many unexplained phenomena and their interpretations.

Ivan Boldin
Candidate of Physical and Mathematical Sciences, researcher, MIPT graduate

The behavior of microworld objects (elementary particles, atoms, molecules) differs significantly from the behavior of objects with which we usually have to deal. For example, an electron can simultaneously fly through two spatially distant places or be simultaneously in several orbits in an atom. To describe these phenomena, a theory was created - quantum physics. According to this theory, for example, particles can be smeared in space, but if you want to determine where the particle is located, then you will always find the entire particle in some place, that is, it will seem to collapse from its smeared state to some specific place. That is, it is believed that until you have measured the position of a particle, it has no position at all, and physics can only predict with what probability you can detect a particle in which place.

Erwin Schrödinger, one of the creators of quantum physics, wondered: what if, depending on the result of measuring the state of a microparticle, some event occurs or does not occur. For example, this could be implemented as follows: take a radioactive atom with a half-life of, say, an hour. An atom can be placed in an opaque box, a device can be placed there that, when the radioactive decay products of the atom hit it, breaks an ampoule with poisonous gas, and a cat can be placed in this box. Then you will not see from the outside whether the atom has decayed or not, that is, according to quantum theory, it has both decayed and not decayed, and the cat, therefore, is both alive and dead at the same time. This cat became known as Schrödinger's cat.

It may seem surprising that a cat can be alive and dead at the same time, although formally there is no contradiction here and this is not a refutation of quantum theory. However, questions may arise, for example: who can collapse an atom from a smeared state into a certain state, and who, with such an attempt, himself goes into a smeared state? How does this collapse process occur? Or how does it happen that the one who performs the collapse does not himself obey the laws of quantum physics? Whether these questions make sense and, if so, what the answers are, is still unclear.

George Panin
graduated from Russian Chemical Technical University named after. DI. Mendeleev, Chief Specialist research department (marketing research)

As Heisenberg explained to us, due to the uncertainty principle, the description of objects in the quantum microworld is of a different nature than the usual description of objects in the Newtonian macroworld. Instead of spatial coordinates and speed, which we are used to describing mechanical movement, for example, a ball on a billiard table, in quantum mechanics objects are described by the so-called wave function. The crest of the “wave” corresponds to the maximum probability of finding a particle in space at the moment of measurement. The movement of such a wave is described by the Schrödinger equation, which tells us how the state of a quantum system changes over time.

Now about the cat. Everyone knows that cats love to hide in boxes (thequestion.ru). Erwin Schrödinger was also in the know. Moreover, with purely Nordic fanaticism, he used this feature in a famous thought experiment. The gist of it was that a cat was locked in a box with an infernal machine. The machine is connected through a relay to a quantum system, for example, a radioactively decaying substance. The probability of decay is known and is 50%. The infernal machine is triggered when the quantum state of the system changes (decay occurs) and the cat dies completely. If you leave the “Cat-box-hellish machine-quanta” system to itself for one hour and remember that the state of a quantum system is described in terms of probability, then it becomes clear that whether the cat is alive or not depends on this moment time, it probably won’t work, just as it won’t be possible to accurately predict the fall of a coin on heads or tails in advance. The paradox is very simple: the wave function that describes a quantum system mixes the two states of a cat - it is alive and dead at the same time, just as a bound electron can be located with equal probability in any place in space equidistant from the atomic nucleus. If we don't open the box, we don't know exactly how the cat is doing. Without making observations (read measurements) of an atomic nucleus, we can describe its state only by superposition (mixing) of two states: a decayed and undecayed nucleus. A cat in nuclear addiction is both alive and dead at the same time. The question is: when does a system cease to exist as a mixture of two states and choose one specific one?

The Copenhagen interpretation of the experiment tells us that the system ceases to be a mixture of states and chooses one of them at the moment when an observation occurs, which is also a measurement (the box opens). That is, the very fact of measurement changes physical reality, leading to the collapse of the wave function (the cat either becomes dead or remains alive, but ceases to be a mixture of both)! Think about it, the experiment and the measurements that accompany it change the reality around us. Personally, this fact bothers my brain much more than alcohol. The well-known Steve Hawking also has a hard time experiencing this paradox, repeating that when he hears about Schrödinger’s cat, his hand reaches out to the Browning. The severity of the reaction of the outstanding theoretical physicist is due to the fact that, in his opinion, the role of the observer in the collapse of the wave function (collapsing it into one of two probabilistic) states is greatly exaggerated.

Of course, when Professor Erwin conceived his cat-mockery back in 1935, it was an ingenious way to show the imperfection of quantum mechanics. In fact, a cat cannot be alive and dead at the same time. As a result of one of the interpretations of the experiment, it became obvious that there was a contradiction between the laws of the macro-world (for example, the second law of thermodynamics - the cat is either alive or dead) and the micro-world (the cat is alive and dead at the same time).

The above is used in practice: in quantum computing and quantum cryptography. A light signal in a superposition of two states is sent through a fiber-optic cable. If attackers connect to the cable somewhere in the middle and make a signal tap there in order to eavesdrop on the transmitted information, then this will collapse the wave function (from the point of view of the Copenhagen interpretation, an observation will be made) and the light will go into one of the states. By conducting statistical tests of light at the receiving end of the cable, it will be possible to detect whether the light is in a superposition of states or has already been observed and transmitted to another point. This makes it possible to create means of communication that exclude undetectable signal interception and eavesdropping.

Another more recent interpretation of Schrödinger's thought experiment is a story that Big Bang Theory character Sheldon Cooper told his less educated neighbor Penny. The point of Sheldon's story is that the concept of Schrödinger's cat can be applied to human relationships. In order to understand what is happening between a man and a woman, what kind of relationship is between them: good or bad, you just need to open the box. Until then, the relationship is both good and bad. youtube.com

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This is a cat that is both alive and dead at the same time. He owes this unfortunate condition to Nobel laureate in physics, Austrian scientist Erwin Rudolf Joseph Alexander Schrödinger.

Sections:

The essence of the experiment / paradox

The cat is in a closed box with a mechanism containing a radioactive core and a container of poisonous gas. The characteristics of the experiment are selected so that the probability that the nucleus will decay in 1 hour is 50%. If the nucleus disintegrates, it activates the mechanism, the gas container opens, and the cat dies. According to quantum mechanics, if no observation is made of the nucleus, then its state is described by a superposition (mixing) of two states - a decayed nucleus and an undecayed nucleus, therefore, a cat sitting in a box is both alive and dead at once.

As soon as you open the box, the experimenter should see only one state - “the nucleus has decayed, the cat is dead” or “the nucleus has not decayed, the cat is alive.” But while there is no observer in the process, the ill-fated animal remains “dead.”

Marginalized

• Misfortune never comes alone
  Not only the health of the tailed inhabitant of the box is in doubt, but also its gender: in the original experiment, Schrödinger’s cat was still a cat (die Katze).
• There are no “dead” cats
  It is important to remember that Schrödinger's experiment was not intended to prove the existence of "dead" cats (and, contrary to the statement in the second part of the game "Portal", was not invented as an excuse for killing cats). Obviously, the cat must be either alive or dead, since there is no intermediate state.
  Experience shows that quantum mechanics is not able to describe the behavior of macrosystems (which includes the cat): it is incomplete without some rules that indicate when the system chooses one particular state, under what conditions the wave function collapses and the cat either remains alive or becomes dead , but ceases to be a mixture of both.

• Nadav Katz from the University of California and his colleagues published the results of a laboratory experiment in which they were able to “return” the quantum state of a particle back, and after measuring this state. Thus, it is possible to save the cat’s life regardless of the conditions for the collapse of the wave function. It doesn’t matter whether he’s alive or dead: you can always win it back [link] .
• 06/03/2011 RIA Novosti reported that Chinese physicists were able to create eight-photon "Schrodinger's cat"[link] , which should facilitate the development of future quantum computers

Image in culture

Perhaps no one has done more to popularize quantum mechanics than the poor cat. Even people who are farthest from this complex field of knowledge, worried about the fate of the probably suffering animal, are trying to understand the intricacies of the experiment, hoping that not everything is so bad. The cat inspires artists and popular culture.
Let us mention his main achievements:

Can a cat be both alive and dead at the same time? How many exist parallel universes? And do they even exist? These are not science fiction questions at all, but very real scientific problems solved by quantum physics.

So let's start with Schrödinger's cat. This is a thought experiment proposed by Erwin Schrödinger to point out a paradox that exists in quantum physics. The essence of the experiment is as follows.

An imaginary cat is simultaneously placed in a closed box, as well as the same imaginary mechanism with a radioactive core and a container of poisonous gas. According to the experiment, if the nucleus disintegrates, it will activate the mechanism: the gas container will open and the cat will die. The probability of nuclear decay is 1 in 2.

The paradox is that, according to quantum mechanics, if the nucleus is not observed, then the cat is in a so-called superposition, in other words, the cat is simultaneously in mutually exclusive states (it is both alive and dead). However, if the observer opens the box, he can verify that the cat is in one specific state: it is either alive or dead. According to Schrödinger, the incompleteness of quantum theory lies in the fact that it does not specify under what conditions a cat ceases to be in superposition and turns out to be either alive or dead.

This paradox is compounded by Wigner's experiment, which adds the category of friends to an already existing thought experiment. According to Wigner, when the experimenter opens the box, he will know whether the cat is alive or dead. For the experimenter, the cat ceases to be in superposition, but for the friend who is behind the door, and who does not yet know about the results of the experiment, the cat is still somewhere “between life and death.” This can be continued with an infinite number of doors and friends, and according to similar logic, the cat will be in a superposition until all people in the Universe know what the experimenter saw when he opened the box.

How does quantum physics explain such a paradox? Quantum physics offers a thought experiment quantum suicide and two possible options developments of events based on different interpretations of quantum mechanics.

In a thought experiment, a gun is pointed at the participant and either it will fire as a result of the decay of a radioactive atom or it will not. Again, 50 to 50. Thus, the participant in the experiment will either die or not, but for now he is, like Schrödinger’s cat, in superposition.

This situation can be interpreted in different ways from the point of view of quantum mechanics. According to the Copenhagen interpretation, the gun will eventually go off and the participant will die. According to Everett's interpretation, superposition provides for the presence of two parallel universes in which the participant simultaneously exists: in one of them he is alive (the gun did not fire), in the second he is dead (the gun fired). However, if the many-worlds interpretation is correct, then in one of the universes the participant always remains alive, which leads to the idea of ​​​​the existence of "quantum immortality".

As for Schrödinger’s cat and the observer of the experiment, then, according to Everett’s interpretation, he also finds himself and the cat in two Universes at once, that is, in “quantum language”, “entangled” with him.

It sounds like a story from a science fiction novel, however, it is one of many scientific theories that have a place in modern physics.