Well, let's start with a simple mental game, you woke up not remembering anything, you found yourself sitting on a white chair, in front of a white table, in a completely white room, closed on all sides, on the table is a coin, and in one of the walls up there is a loudspeaker and to Next to it is a screen, for a moment you think about what brought you here, or what happened before that moment, but no matter how you blow your mind, you find nothing.

A few minutes pass, and while you are sitting on your chair, someone speaks from the loudspeaker saying: “Welcome, I have sinned a lot in your life, and I am here to save you from your sins. From you and him to “roll the coin” up, then when it falls on the table you will record a reading, either “king” (picture) or “writing”, you will survive the game if it happens only once and you agree to read the coin between you and your friend, the screen will display the result of your friend After each lap, you have 45 minutes."

Immediately on the screen the counting begins, but you don't get worried even though you already realize that you are now in a situation similar to the heroes of the "SAW" series, you know that the natural rules of probability theory make it normal that some results are similar and others different in cases of coin rolls, so you will You get out safely from the game, but when the game starts, and after fifty rewinds, the tension begins to seep into your depths, the results of each time differ on the two tables, but the real horror will begin after two hundred laps, as it did not happen - not even once - that the results of your currencies were similar. You will ask yourself: What is going on?

How are these two currencies related together?

By the end of time you know someone is messing with you and intending to kill you.

The trio: "Anton Zeilinger" (right), "John F. Clauser" (center) and "Alan Asp" received the Nobel Prize in Physics 2022. (Social networking sites)

It is not normal in our ordinary life for distant things to be interconnected with each other momentarily, and without knowing how they are interconnected, so I felt strange about what happened in the previous example, but for the world of quantum mechanics, this is possible, and it is amazing at the same time, and that is precisely why it happened Trio John F.

John F. Clauser (America), Anton Zeilinger (Australia), and Alain Aspect (France) were awarded the 2022 Nobel Prize in Physics for their achievements in the field of quantum mechanics, or as the Nobel Committee said: for their experiments with quantum entangled photons, demonstrating the potential to breach the Bell inequality, and pioneering quantum information science.”

quantum entanglement

To understand it, let's start with quantum entanglement.

One of the fundamental properties of subatomic particles is spin. It's like the Earth's spin, but not exactly;

It is only the closest example we know, with an important difference that the Earth rotates because it was pushed to rotate at the beginning of the formation of the solar system, while the rotation of subatomic particles is an intrinsic property specific to it, it does not rotate because someone pushed it to rotate, but it always continues to do so, it is like your voice or Your laugh, it's part of your human makeup, and so for particles, each particle has a specific spin pattern that never changes.

The rotation of the particle is either up or down.

Quantum entanglement refers to the presence of instantaneous correlation between two subatomic particles, at any distance between them, whether we place each particle (say a photon) in a different room from the other, or even if we decide to place each particle on one side of our galaxy, the Milky Way, or even When we put them on both sides of the same universe.

This effect will occur momentarily between them as if one of them - an analogy for the purpose of approximation only - knows what is going on in the mind of the other.

When we read the rotation of particle “A” at a certain moment, when reading the rotation of particle “B” that is entangled with it quantitatively at the same moment, it will be opposite. Super conductive.

Of course, this contradicts one of the important physical foundations, which is that no effect can occur faster than the speed of light. Let us, for example, suppose that the sun has disappeared from existence at the moment you read this sentence, here on Earth we will not feel it until after 8 full minutes, because The effect of their attraction to us will not suddenly disappear, but rather it takes time, at the maximum speed of light, to occur.

In physics, this is called the locality principle.

A particle that reads an opposite rotation with its companion at the other end of the galaxy breaks that principle.

Therefore, Einstein imagined that quantum entanglement must contain what he called hidden variables, that is, a set of conditions unknown to us that make the results appear to have a momentary effect. Something, this thing is hidden variables.

Read also: When Einstein was wrong

deceptive particles

To understand it easier, let's suppose, for example, that each of "Abdul Rahman" and "Rahaf", two children who are not yet ten years old, have claimed that they can communicate with each other telepathically, in order to prove their claim wrong we will ask each of them to enter a toy store Different from the other, at the same moment, and buying a “car” game, provided that they leave the two toy stores every time we repeat the experience with a car of a different color from each other, either red or green.

At that point, the two children may actually go out every time with cars of opposite color, but you will ask yourself: What if Abdel Rahman and Rahaf had agreed before the experiment?

What if they wrote a long list, and hid it in their pockets, for the situations that each of them would choose, so Rahaf chooses a red car for the first time for the experiment, a green for the second and third, and a red for the fourth, and so on, while Abdul Rahman knows that he will do the opposite, and so the experiment continues. How many times, this list that they wrote and each of them put a copy of in his pocket, is - to a large degree of simplification of course - the "hidden variables" that Einstein meant.

Rahaf and Abd al-Rahman are two entangled quantum particles. Einstein assumes that these particles have something like a hidden list of all possible states, but John Stewart Bell, a diligent American physicist, in the sixties of the last century, was alerted because the idea of ​​the list containing On those hidden variables are not possible.

To understand this, let's change the rules of the game for the two children.

This time we will ask them to enter two stores that not only offer cars, but offer cars, planes or ships randomly, meaning that each of the two children will enter his toy store and ask for a toy, so the seller enters a closed and dark room to grab the first box he meets, and he comes out and gives it to the child The box contains two copies of the same game, green and red, and the two children have to choose between them with new conditions:

  • First:

    They must come out of the two toy stores with a toy of a different color, either red or green.

  • Second:

    But only if they come up with two similar toys, here the two toys must be the same color.

At that point, the problem begins. Abdel Rahman and Rahaf can write a previous list specifying the color of the game each time, but what about the similarities of the game?

In a random sample, the two children will come up with a similar game in only one third of the cases, so Abdul Rahman and Rahaf can be right through the list method in only two thirds of the cases, and accordingly, in the case of telepathy, Abdul Rahman and Rahaf must succeed in coming up with a game that agrees with the new rule in more Of the two-thirds (66.6%) times we repeat the experiment.

Trio Nobel

Now let's stop for a while and talk about particles, the two children are quantum particles, the color of the toy is the spin of each particle, and the type of the toy is the way in which this spin can be measured, and regardless of the mechanism of measurement and its direction, all that is required to understand is that this is possible To change it at random!

Like the previous game, Bell's theorem, or Bell's inequality, says that we can design a set of experiments in which researchers, such as shopkeepers, randomly choose between measurement directions, thus proving that "there cannot be Any hidden variables can predict the results of quantum theory.

Quantum teleportation can be achieved by sharing the entanglement state of a larger number of particles.

Over the years following the theorem, beginning with the experience of this year's first Nobel laureate John F.

Clauser in 1972, the hypothesis of hidden variables was tested, and each time the results confirmed that there are no hidden variables, the two particles cannot agree on anything previously, because the results of the predictions exceed two-thirds each time.

Even when some researchers questioned Bell's theorem itself and assumed that there was some kind of communication by tricking particles into scientists' measurement methods, under the name "loopholes", subsequent experiments emerged that confirmed that this was not true, including the experiments of this year's second Nobel Prize winner Alain Aspe Central in the 1980s, and the experiments of the third Nobel man, Anton Zeilinger, in the 1990s and onwards.

During more than 20 major experiments in this range, the last of which was Bell's Great Experiment in 2018, which bridged a gap called "free will" by using 100,000 random players to participate in the experiment, it appeared that there are no hidden variables, it's just the nature of the quantum world to be like this strangeness.

The revolution brought about by quantum physicists in that period from the seventies to the eighties opened the door to the development of amazing new technologies, as it represented the nucleus of quantum computers, quantum cryptography that prevents penetration, and other areas that Nobel scientists contributed to this year, and on top of this revolution appeared in the nineties Zellinger With his experiments in the domain of quantum teleportation, a process by which "quantum information" (not ordinary information) is transferred from one location to another using traditional communication media in the manner of quantum entanglement that is shared between the transmitting site and the receiving site, it is a promising range today.

Read also: For the first time in history, did Google create a super quantum computer?

quantum world

Well, when the hidden variables gaps are filled, quantum mechanics puts us in front of only two possibilities imposed by the so-called “Copenhagen interpretation” of the nature of the world and the universe around us. Either we intervene to influence the reality of the universe, and we change it every time we look at it, or there is a relationship that cannot be So far, imagine its nature between quantum entangled particles, or perhaps both together, and to understand those previous heavy sentences, let us return to the world of examples.

If we only had an orange and an apple in a room, and everyone knew it, including you, and while you were busy talking to a friend of yours, someone put the apple in your bag and the orange in his bag, then you traveled to Siberia, and he traveled to South Africa, when you arrive it will open Your bag and you see the apple, here you will know right away that your friend's bag contains the orange, not because you caused it in some quantum way, but because there is a "non-hidden information" that says that all we have is an apple and an orange only, so if I take the apple he takes the orange Of course, this is what happens in the real world.

But if these two fruits are entangled in a quantum world, your closed bag will not only carry one of them, but all possible possibilities together, an apple and an orange at the same time, to understand the idea let's consider the famous Schrödinger thought experiment, we will put a cat in a closed box with a small amount Of a radioactive substance, 50% of an atom is likely to decay within a specified period. If that atom decays, it will cause the Geiger counter that measures radiation, here the counter will release a hammer and fall on the poison bottle, it spreads in the place and the cat dies.

Now you and I stand in front of that box before we open it to ask: Is the cat alive or dead?

At this point, the Copenhagen interpretation of quantum mechanics intervenes to answer with: "Both states are both alive and dead," because this atom has a "probability wave" that describes it in all cases;

That is, decomposing and not decomposing at the same time, but when we open the box, we will not find any surprises, the cat is either alive or dead, this is what happens when we try to enter a measurement or observation process in the quantum world, because the particle loses its strange quantum state - a situation where all cases exist In it together (quantum superposition) - and moves to a subjective mode, that is, one specific state.

Stranger than your strangest fantasies

Like a cat (alive/dead), there is a state (apple/orange), when you open your bag and see the apple, it means that you intervened to affect the quantum state in the bag and it changed to a normal state, and it also means that you may have affected the quantum state in The other bag, which indicates that you have an effect on a body thousands of kilometers away from you, and in an instant, which contradicts what Einstein called local realism.

Observation or experiment in Einstein's world is very similar to observing a distant galaxy through our telescopes, these telescopes cannot affect the galaxy you are observing, but in the quantum world the experience is like tasting a piece of cake, when you observe, you interact with the experience, it can be understood with a mental experiment Another, we will imagine that you are an anthropologist from a prestigious university, who would like to travel to the Anacheri region in the Bolivian rainforest to live with the Chimani, a group of 16,000 people who live in scattered villages, your goal in this trip is to study the nature of their lives.

Read also: Five books that introduce you to quantum mechanics easily

What Albert Einstein erred is to imagine that quantum theory and local realism can be combined in one crucible, and this is precisely what was proven by this year's Nobel laureates when they confirmed John Stuart Bell's theorem.

(Social Media)

When we ask: Do you really get an accurate result from your studies?

The answer will be: "Not exactly", because your goal will be to study their pure lifestyle, while they are no longer pure in your presence, they are affected by your clothes, your shoes, the music you hear, your cameras and your staff, and everything else you brought into their study, so your monitoring affects In practice, this is - to a large degree of simplification - what we encounter in the quantum case.

Local realism differs from the quantum view.

In local realism everything that can be measured has a definite value, whether we measure it or not, whether we open the box or not, if you're not looking at the moon - as Einstein once said - you're relieved that it is there in the same way you used to see it, not in A quantum state in which all its phases exist together, for example!

And if you're not looking at the apple, you know it's an apple, and if you haven't been looking at the cat, you know it's alive, safe, and eating delicious fish now.

For a deeper understanding of the problem that we face if this assumption is true, let us imagine that we have two boxes, each of which has a quantum particle connected to the other, and the winding of this particle affects a cat next to it inside the box, killing it if it is up or living if it is down, we sent a box of them to a galaxy Another, and we decided to open the box here. If we found the cat alive, this would inevitably mean that if we opened the other box, we would find it dead. Here the puzzling question arises: Was it possible for you to influence while you are here in your home a cat that is trillions of kilometers away from you because you opened the box here?

John Bell again

"For me, the real problem with quantum theory is the apparent contradiction between its strict equations and the theory of relativity," says John Stuart Bell. "A real synthesis between the two theories may require not just technical developments, but a radical renewal of concepts."

(Social Media)

Einstein, then, was wrong, but he was not exactly wrong in his opinion that quantum mechanics is right or not, or that it is incomplete. In fact, we do not know whether quantum mechanics is right or wrong. What Albert Einstein did wrong is the perception that quantum theory can be combined with realism. This is precisely what this year's Nobel laureates proved when they confirmed John Stuart Bell's theorem, who once said: "For me, the real problem with quantum theory is the apparent contradiction between its strict equations and the theory of relativity, perhaps not requiring a synthesis The real difference between the two theories is not only technical developments, but a radical renewal of concepts.

That is the genius of John Stuart Bell, then, he was able to draw the boundary between quantum theory and classical theories (led by relativity), which opened the door for later theoretical physicists to develop the quantum theory more clearly after tracing that separation point, and looking at conventions such as non-locality ( Nonlocality) and quantum entanglement in a different way and trying to develop new concepts to achieve a better understanding of them.

Quantum mechanics still fascinates us day in and day out, still makes us question what we might think of as reality, and that's why it's so amazing.

Richard Feynman once said, "I can say, with confidence, that no one understood quantum mechanics."

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Sources

  • Scientific Background

  • How entanglement has become a powerful tool