Fundamentals of quantum physics: concepts, laws, connection with consciousness. Quantum physics for dummies. What is quantum physics: the essence in simple words

If you suddenly realized that you have forgotten the basics and postulates quantum mechanics or you don’t even know what kind of mechanics this is, then it’s time to refresh your memory of this information. After all, no one knows when quantum mechanics may be useful in life.

It’s in vain that you grin and sneer, thinking that you will never have to deal with this subject in your life. After all, quantum mechanics can be useful to almost every person, even those infinitely far from it. For example, you have insomnia. For quantum mechanics this is not a problem! Read a textbook before going to bed - and you will sleep soundest sleep It's already on the third page. Or you can call your cool rock band that. Why not?

Jokes aside, let's start a serious quantum conversation.

Where to begin? Of course, starting with what quantum is.

Quantum

Quantum (from the Latin quantum - “how much”) is an indivisible portion of some physical quantity. For example, they say - a quantum of light, a quantum of energy or a quantum of field.

What does it mean? This means that it simply cannot be less. When they say that some quantity is quantized, they understand that this quantity takes on a number of specific, discrete values. Thus, the energy of an electron in an atom is quantized, light is distributed in “portions”, that is, in quanta.

The term "quantum" itself has many uses. Quantum of light ( electro magnetic field) is a photon. By analogy, quanta are particles or quasiparticles corresponding to other interaction fields. Here we can recall the famous Higgs boson, which is a quantum of the Higgs field. But we are not going into these jungles yet.

How can mechanics be quantum?

As you have already noticed, in our conversation we mentioned particles many times. You may be accustomed to the fact that light is a wave that simply propagates at speed With . But if you look at everything from the point of view of the quantum world, that is, the world of particles, everything changes beyond recognition.

Quantum mechanics is a branch of theoretical physics, a component quantum theory, describing physical phenomena at the most elementary level - the level of particles.

The effect of such phenomena is comparable in magnitude to Planck's constant, and Newton's classical mechanics and electrodynamics turned out to be completely unsuitable for describing them. For example, according to classical theory An electron, rotating at high speed around the nucleus, must radiate energy and eventually fall onto the nucleus. This, as we know, does not happen. That is why quantum mechanics was invented - the discovered phenomena had to be explained somehow, and it turned out to be precisely the theory within which the explanation was the most acceptable, and all experimental data “converged”.

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A little history

The birth of quantum theory occurred in 1900, when Max Planck spoke at a meeting of the German Physical Society. What did Planck say then? And the fact that the radiation of atoms is discrete, and the smallest portion of the energy of this radiation is equal to

Where h is Planck's constant, nu is the frequency.

Then Albert Einstein, introducing the concept of “quantum of light”, used Planck’s hypothesis to explain the photoelectric effect. Niels Bohr postulated the existence of stationary energy levels in the atom, and Louis de Broglie developed the idea of ​​wave-particle duality, that is, that a particle (corpuscle) also has wave properties. Schrödinger and Heisenberg joined the cause, and in 1925 the first formulation of quantum mechanics was published. Actually, quantum mechanics is far from a complete theory; it is actively developing at the present time. It should also be recognized that quantum mechanics, with its assumptions, does not have the ability to explain all the questions it faces. It is quite possible that it will be replaced by a more advanced theory.

During the transition from the quantum world to the world of things familiar to us, the laws of quantum mechanics are naturally transformed into the laws of classical mechanics. We can say that classical mechanics is special case quantum mechanics, when the action takes place in our familiar and familiar macroworld. Here bodies move calmly in non-inertial frames of reference at a speed much lower than the speed of light, and in general everything around is calm and clear. If you want to know the position of a body in a coordinate system, no problem; if you want to measure the impulse, you’re welcome.

Quantum mechanics has a completely different approach to the issue. In it, the results of measurements of physical quantities are probabilistic in nature. This means that when a certain value changes, several results are possible, each of which has a certain probability. Let's give an example: a coin is spinning on the table. While it is spinning, it is not in any specific state (heads-tails), but only has the probability of ending up in one of these states.

Here we are gradually approaching Schrödinger equation And Heisenberg uncertainty principle.

According to legend, Erwin Schrödinger, in 1926, speaking at a scientific seminar on the topic of wave-particle duality, was criticized by a certain senior scientist. Refusing to listen to his elders, after this incident Schrödinger actively began developing the wave equation to describe particles within the framework of quantum mechanics. And he did it brilliantly! The Schrödinger equation (the basic equation of quantum mechanics) is:

This type equations - the one-dimensional stationary Schrödinger equation - the simplest.

Here x is the distance or coordinate of the particle, m is the mass of the particle, E and U are its total and potential energy. The solution to this equation is the wave function (psi)

Wave function– another fundamental concept in quantum mechanics. So, any quantum system that is in some state has a wave function that describes this state.

For example, when solving the one-dimensional stationary Schrödinger equation, the wave function describes the position of the particle in space. More precisely, the probability of finding a particle at a certain point in space. In other words, Schrödinger showed that probability can be described by a wave equation! Agree, we should have thought of this before!

But why? Why do we have to deal with these incomprehensible probabilities and wave functions, when, it would seem, there is nothing simpler than just taking and measuring the distance to a particle or its speed.

Everything is very simple! Indeed, in the macrocosm this is indeed the case - we measure distances with a certain accuracy with a tape measure, and the measurement error is determined by the characteristics of the device. On the other hand, we can almost accurately determine by eye the distance to an object, for example, to a table. In any case, we accurately differentiate its position in the room relative to us and other objects. In the world of particles, the situation is fundamentally different - we simply physically do not have measurement tools to accurately measure the required quantities. After all, the measuring instrument comes into direct contact with the object being measured, and in our case, both the object and the instrument are particles. It is this imperfection, the fundamental impossibility of taking into account all the factors acting on the particle, as well as the very fact of changing the state of the system under the influence of measurement, that underlies the Heisenberg uncertainty principle.

Let us give its simplest formulation. Let's imagine that there is a certain particle, and we want to know its speed and coordinate.

In this context, the Heisenberg Uncertainty Principle states that it is impossible to accurately measure the position and velocity of a particle at the same time. . Mathematically it is written like this:

Here delta x is the error in determining the coordinate, delta v is the error in determining the speed. Let us emphasize that this principle says that the more accurately we determine the coordinate, the less accurately we will know the speed. And if we determine the speed, we will not have the slightest idea of ​​where the particle is.

There are many jokes and anecdotes on the topic of the uncertainty principle. Here is one of them:

A policeman stops a quantum physicist.
- Sir, do you know how fast you were moving?
- No, but I know exactly where I am.

And, of course, we remind you! If suddenly, for some reason, solving the Schrödinger equation for a particle in a potential well does not allow you to sleep, contact professionals who were raised with quantum mechanics on the lips!

Hello dear readers. If you do not want to lag behind life, to be a truly happy and healthy person, you should know about the secrets of quantum modern physics, at least have a little idea to what depths of the universe scientists have dug today. You don’t have time to go into deep scientific details, but want to comprehend only the essence, but see the beauty of the unknown world, then this article: quantum physics for regular teapots or you can say for housewives just for you. I will try to explain what quantum physics is, but in simple words, to show it clearly.

“What is the connection between happiness, health and quantum physics?” you ask.

The fact is that it helps answer many unclear questions related to human consciousness and the influence of consciousness on the body. Unfortunately, medicine, based on classical physics, does not always help us to be healthy. But psychology cannot properly say how to find happiness.

Only a deeper knowledge of the world will help us understand how to truly cope with illness and where happiness lives. This knowledge is found in the deep layers of the Universe. Quantum physics comes to our aid. Soon you will know everything.

What quantum physics studies in simple words

Yes, quantum physics is indeed very difficult to understand because it studies the laws of the microworld. That is, the world in its deeper layers, at very short distances, where it is very difficult for a person to see.

And the world, it turns out, behaves there very strangely, mysteriously and incomprehensibly, not as we are used to.

Hence all the complexity and misunderstanding quantum physics.

But after reading this article, you will expand the horizons of your knowledge and look at the world in a completely different way.

Brief history of quantum physics

It all started at the beginning of the 20th century, when Newtonian physics could not explain many things and scientists reached a dead end. Then Max Planck introduced the concept of quantum. Albert Einstein picked up this idea and proved that light does not travel continuously, but in portions - quanta (photons). Before this, it was believed that light had a wave nature.

But as it turned out later, any elementary particle is not only a quantum, that is, a solid particle, but also a wave. This is how wave-particle dualism appeared in quantum physics, the first paradox and the beginning of discoveries mysterious phenomena microworld.

The most interesting paradoxes began when famous experiment with two slits, after which there were many more mysteries. We can say that quantum physics began with him. Let's look at it.

Double slit experiment in quantum physics

Imagine a plate with two slits in the form of vertical stripes. We will place a screen behind this plate. If we shine light on the plate, we will see an interference pattern on the screen. That is, alternating dark and bright vertical stripes. Interference is the result of the wave behavior of something, in our case light.

If you pass a wave of water through two holes located next to each other, you will understand what interference is. That is, the light turns out to be of a wave nature. But as physics, or rather Einstein, has proven, it is propagated by photon particles. Already a paradox. But that’s okay, wave-particle duality will no longer surprise us. Quantum physics tells us that light behaves like a wave but is made up of photons. But miracles are just beginning.

Let's put a gun in front of the plate with two slits that will emit electrons rather than light. Let's start shooting electrons. What will we see on the screen behind the plate?

Electrons, after all, are particles, which means that a flow of electrons, passing through two slits, should leave only two stripes on the screen, two traces opposite the slits. Imagine pebbles flying through two slits and hitting the screen?

But what do we actually see? The same interference pattern. What is the conclusion: electrons travel in waves. So electrons are waves. But this is an elementary particle. Again, wave-particle dualism in physics.

But we can assume that at a deeper level, the electron is a particle, and when these particles come together, they begin to behave like waves. For example, a sea wave is a wave, but it consists of drops of water, and at a smaller level of molecules, and then of atoms. Okay, the logic is solid.

Then let's shoot from a gun not with a stream of electrons, but release electrons separately, after a certain period of time. It’s as if we were not passing a sea wave through the cracks, but were spitting out individual drops from a child’s water pistol.

It is quite logical that in this case different drops of water would fall into different cracks. On the screen behind the plate one would see not an interference pattern from the wave, but two clear stripes from the impact opposite each slit. We will see the same thing: if you throw small stones, they, flying through two slits, would leave a mark, like a shadow from two holes. Let's now shoot individual electrons to see these two streaks on the screen from the electron impacts. They released one, waited, the second, waited, and so on. Quantum physics scientists were able to do such an experiment.

But horror. Instead of these two bands, the same interference alternations of several bands are obtained. How so? This could happen if an electron were flying through two slits at the same time, and behind the plate, like a wave, it would collide with itself and interfere. But this cannot happen, because a particle cannot be in two places at the same time. It either flies through the first gap or through the second.

This is where the truly fantastic things of quantum physics begin.

Superposition in quantum physics

With a deeper analysis, scientists find out that any elementary quantum particle or the same light (photon) can actually be in several places at the same time. And these are not miracles, but real facts microworld. Quantum physics says so. That's why, when we shoot a single particle from a cannon, we see the result of interference. Behind the plate, the electron collides with itself and creates an interference pattern.

The objects of the macrocosm that are common to us are always in one place and have one state. For example, you are now sitting on a chair, weigh, say, 50 kg, and have a heart rate of 60 beats per minute. Of course, these readings will change, but they will change after some time. After all, you cannot be at home and at work at the same time, weigh 50 and 100 kg. All this is understandable, it is common sense.

In the physics of the microworld, everything is different.

Quantum mechanics states, and this has already been confirmed experimentally, that any elementary particle can simultaneously be not only in several points in space, but also have several states at the same time, for example, spin.

All this boggles the mind, undermines the usual understanding of the world, the old laws of physics, turns thinking upside down, one can safely say drives you crazy.

This is how we come to understand the term “superposition” in quantum mechanics.

Superposition means that an object of the microworld can simultaneously be in different points of space, and also have several states at the same time. And this is normal for elementary particles. This is the law of the microworld, no matter how strange and fantastic it may seem.

You are surprised, but these are just the beginnings, the most inexplicable miracles, mysteries and paradoxes of quantum physics are yet to come.

Wave function collapse in physics in simple words

Then the scientists decided to find out and see more precisely whether the electron actually passes through both slits. All of a sudden it passes through one slit and then somehow splits and creates an interference pattern as it passes through it. Well, you never know. That is, you need to place some kind of device near the slit that would accurately record the passage of an electron through it. No sooner said than done. Of course, this is difficult to do; you need not a device, but something else to see the passage of an electron. But scientists did it.

But in the end, the result stunned everyone.

As soon as we begin to look through which slit the electron passes, it begins to behave not like a wave, not like a strange substance that is simultaneously located in different points of space, but like an ordinary particle. That is, the quantum begins to exhibit specific properties: it is located in only one place, passes through one slit, and has one spin value. It is not an interference pattern that appears on the screen, but a simple trace opposite the slit.

But how is this possible? It’s as if the electron is joking, playing with us. At first it behaves like a wave, and then, after we decided to watch it pass through a slit, it exhibits the properties of a solid particle and passes through only one slit. But this is how it is in the microcosm. These are the laws of quantum physics.

Scientists have seen another mysterious property of elementary particles. This is how the concepts of uncertainty and wave function collapse appeared in quantum physics.

When an electron flies to the slit, it is in an indeterminate state or, as we said above, in a superposition. That is, it behaves like a wave, is simultaneously in different points of space, and has two spin values ​​at once (spin has only two values). If we had not touched it, if we had not tried to look at it, if we had not found out exactly where it was, if we had not measured the value of its spin, it would have flown like a wave through two slits simultaneously, which means it would have created an interference pattern. Quantum physics describes its trajectory and parameters using the wave function.

After we have made a measurement (and you can measure a particle of the microworld only by interacting with it, for example, by colliding another particle with it), then the collapse of the wave function occurs.

That is, now the electron is located exactly in one place in space and has one spin value.

You can say an elementary particle is like a ghost, it seems to exist, but at the same time it is not in one place, and can, with a certain probability, end up in any place within the description of the wave function. But as soon as we begin to contact it, it turns from a ghostly object into a real tangible substance that behaves like ordinary objects of the classical world that are familiar to us.

“This is fantastic,” you say. Of course, but the wonders of quantum physics are just beginning. The most incredible is yet to come. But let's take a little break from the abundance of information and return to quantum adventures another time, in another article. In the meantime, reflect on what you learned today. What can such miracles lead to? After all, they surround us, this is a property of our world, albeit on a deeper level. And we still think that we live in boring world? But we will draw conclusions later.

I tried to talk about the basics of quantum physics briefly and clearly.

But if you don’t understand something, then watch this cartoon about quantum physics, about the double-slit experiment, everything is also explained there in clear, simple language.

Cartoon about quantum physics:

Or you can watch this video, everything will fall into place, quantum physics is very interesting.

Video about quantum physics:

And how did you not know about this before?

Modern discoveries in quantum physics are changing our familiar material world.

In this article we will give useful tips on studying quantum physics for dummies. Let us answer what should be the approach in learning quantum physics for beginners.

The quantum physics- This is a rather complex discipline that not everyone can easily master. Nevertheless, physics as a subject is interesting and useful, which is why quantum physics (http://www.cyberforum.ru/quantum-physics/) finds its fans who are ready to study it and ultimately get practical benefits. To make it easier to learn the material, you need to start from the very beginning, that is, with the simplest quantum physics textbooks for beginners. This will allow you to get a good basis for knowledge, and at the same time well structure your knowledge in your head.

Start off selfeducation you need good literature. It is literature that is the decisive factor in the process of acquiring knowledge and ensures its quality. Quantum mechanics is of particular interest, and many begin their studies with it. Everyone should know physics, because it is the science of life, which explains many processes and makes them understandable to others.

Please note that when you start studying quantum physics, you must have knowledge of mathematics and physics, as without them you simply will not cope. It will be good if you have the opportunity to contact your teacher to find answers to your questions. If this is not possible, you can try to clarify the situation on specialized forums. Forums can also be very useful in learning.

When you decide on the choice of a textbook, you must be prepared for the fact that it is quite complex and you will have to not just read it, but delve into everything that is written in it. So that at the end of your training you don’t think that this is all unnecessary knowledge, try to connect theory with practice each time. It is also important to determine in advance the purpose for which you began to learn quantum physics, in order to prevent the emergence of thoughts about the uselessness of the acquired knowledge. People fall into two categories: people who think quantum physics is an interesting and useful subject and those who don't. Choose for yourself which category you belong to and accordingly determine whether quantum physics has a place in your life or not. You can always remain at the beginner level in studying quantum physics, or you can achieve real success, everything is in your hands.

First of all, choose really interesting and quality materials in physics. You can find some of them using the links below.
And that's all for now! Study quantum physics in an interesting way and don’t be a dummie!

You've probably heard it many times O unexplained mysteries quantum physics and quantum mechanics. Its laws fascinate with mysticism, and even physicists themselves admit that they do not fully understand them. On the one hand, it is interesting to understand these laws, but on the other hand, there is no time to read multi-volume and complex books on physics. I understand you very much, because I also love knowledge and the search for truth, but there is sorely not enough time for all the books. You are not alone, many curious people type in the search bar: “quantum physics for dummies, quantum mechanics for dummies, quantum physics for beginners, quantum mechanics for beginners, basics of quantum physics, basics of quantum mechanics, quantum physics for children, what is quantum Mechanics". This publication is exactly for you.

You will understand the basic concepts and paradoxes of quantum physics. From the article you will learn:

• What is quantum physics and quantum mechanics?
• What is interference?
• What's happened quantum entanglement(or Quantum teleportation for dummies)? (see article)
• What's happened thought experiment"Shroedinger `s cat"? (see article)

Quantum mechanics is a part of quantum physics.

Why is it so difficult to understand these sciences? The answer is simple: quantum physics and quantum mechanics (part of quantum physics) study the laws of the microworld. And these laws are absolutely different from the laws of our macrocosm. Therefore, it is difficult for us to imagine what happens to electrons and photons in the microcosm.

An example of the difference between the laws of the macro- and microworlds: in our macroworld, if you put a ball in one of 2 boxes, then one of them will be empty, and the other will have a ball. But in the microcosm (if there is an atom instead of a ball), an atom can be in two boxes at the same time. This has been confirmed experimentally many times. Isn't it hard to wrap your head around this? But you can't argue with the facts.

One more example. You took a photograph of a fast racing red sports car and in the photo you saw a blurred horizontal stripe, as if the car was located at several points in space at the time of the photo. Despite what you see in the photo, you are still sure that the car was located at that second when you photographed it. in one specific place in space. In the micro world, everything is different. An electron that rotates around the nucleus of an atom does not actually rotate, but is located simultaneously at all points of the sphere around the nucleus of an atom. Like a loosely wound ball of fluffy wool. This concept in physics is called "electronic cloud" .

A short excursion into history. Scientists first thought about the quantum world when, in 1900, German physicist Max Planck tried to figure out why metals change color when heated. It was he who introduced the concept of quantum. Until then, scientists thought that light traveled continuously. The first person to take Planck's discovery seriously was the then unknown Albert Einstein. He realized that light is not just a wave. Sometimes he behaves like a particle. Einstein received Nobel Prize for his discovery that light is emitted in portions, quanta. A quantum of light is called a photon ( photon, Wikipedia) .

To make it easier to understand the laws of quantum physicists And mechanics (Wikipedia), we must, in a sense, abstract from the laws of classical physics that are familiar to us. And imagine that you dived, like Alice, into the rabbit hole, into Wonderland.

And here is a cartoon for children and adults. Describes the fundamental experiment of quantum mechanics with 2 slits and an observer. Lasts only 5 minutes. Watch it before we dive into the fundamental questions and concepts of quantum physics.

Quantum physics for dummies video. In the cartoon, pay attention to the “eye” of the observer. It has become a serious mystery for physicists.

What is interference?

At the beginning of the cartoon, using the example of a liquid, it was shown how waves behave - alternating dark and light vertical stripes appear on the screen behind a plate with slits. And in the case when discrete particles (for example, pebbles) are “shot” at the plate, they fly through 2 slits and land on the screen directly opposite the slits. And they “draw” only 2 vertical stripes on the screen.

Interference of light- This is the “wave” behavior of light, when the screen displays many alternating bright and dark vertical stripes. Also these vertical stripes called interference pattern.

In our macrocosm, we often observe that light behaves like a wave. If you place your hand in front of a candle, then on the wall there will be not a clear shadow from your hand, but with blurry contours.

So, it's not all that complicated! It is now quite clear to us that light has a wave nature and if 2 slits are illuminated with light, then on the screen behind them we will see an interference pattern. Now let's look at the 2nd experiment. This is the famous Stern-Gerlach experiment (which was carried out in the 20s of the last century).

The installation described in the cartoon was not shined with light, but “shot” with electrons (as individual particles). Then, at the beginning of the last century, physicists around the world believed that electrons are elementary particles matter and should not have a wave nature, but the same as pebbles. After all, electrons are elementary particles of matter, right? That is, if you “throw” them into 2 slits, like pebbles, then on the screen behind the slits we should see 2 vertical stripes.

But... The result was stunning. Scientists saw an interference pattern - many vertical stripes. That is, electrons, like light, can also have a wave nature and can interfere. On the other hand, it became clear that light is not only a wave, but also a little particle - a photon (from historical information at the beginning of the article we learned that Einstein received the Nobel Prize for this discovery).

Maybe you remember, at school we were told in physics about "wave-particle duality"? It means that when we're talking about about very small particles (atoms, electrons) of the microworld, then They are both waves and particles

Today you and I are so smart and we understand that the 2 experiments described above - shooting with electrons and illuminating slits with light - are the same thing. Because we shoot quantum particles at the slits. We now know that both light and electrons are of a quantum nature, that they are both waves and particles at the same time. And at the beginning of the 20th century, the results of this experiment were a sensation.

Attention! Now let's move on to a more subtle issue.

We shine a stream of photons (electrons) onto our slits and see an interference pattern (vertical stripes) behind the slits on the screen. It is clear. But we are interested in seeing how each of the electrons flies through the slot.

Presumably, one electron flies into the left slot, the other into the right. But then 2 vertical stripes should appear on the screen directly opposite the slots. Why does an interference pattern occur? Maybe the electrons somehow interact with each other already on the screen after flying through the slits. And the result is a wave pattern like this. How can we keep track of this?

We will throw electrons not in a beam, but one at a time. Let's throw it, wait, let's throw the next one. Now that the electron is flying alone, it will no longer be able to interact with other electrons on the screen. We will record each electron on the screen after the throw. One or two, of course, will not “paint” a clear picture for us. But when we send a lot of them into the slits one at a time, we will notice... oh horror - they again “drew” an interference wave pattern!

We are slowly starting to go crazy. After all, we expected that there would be 2 vertical stripes opposite the slots! It turns out that when we threw photons one at a time, each of them passed, as it were, through 2 slits at the same time and interfered with itself. Fantastic! Let's return to explaining this phenomenon in the next section.

What is spin and superposition?

We now know what interference is. This is the wave behavior of micro particles - photons, electrons, other micro particles (for simplicity, let's call them photons from now on).

As a result of the experiment, when we threw 1 photon into 2 slits, we realized that it seemed to fly through two slits at the same time. Otherwise, how can we explain the interference pattern on the screen?

But how can we imagine a photon flying through two slits at the same time? There are 2 options.

• 1st option: a photon, like a wave (like water) “floats” through 2 slits at the same time
• 2nd option: a photon, like a particle, flies simultaneously along 2 trajectories (not even two, but all at once)

In principle, these statements are equivalent. We arrived at the “path integral”. This is Richard Feynman's formulation of quantum mechanics.

By the way, exactly Richard Feynman there is a well-known expression that We can confidently say that no one understands quantum mechanics

But this expression of his worked at the beginning of the century. But now we are smart and know that a photon can behave both as a particle and as a wave. That he can, in some way incomprehensible to us, fly through 2 slits at the same time. Therefore, it will be easy for us to understand the following important statement of quantum mechanics:

Strictly speaking, quantum mechanics tells us that this photon behavior is the rule, not the exception. Any quantum particle is, as a rule, in several states or at several points in space simultaneously.

Objects of the macroworld can only be in one specific place and in one specific state. But a quantum particle exists according to its own laws. And she doesn’t even care that we don’t understand them. That's the point.

We just have to admit, as an axiom, that the “superposition” of a quantum object means that it can be on 2 or more trajectories at the same time, in 2 or more points at the same time

The same applies to another photon parameter – spin (its own angular momentum). Spin is a vector. A quantum object can be thought of as a microscopic magnet. We are accustomed to the fact that the magnet vector (spin) is either directed up or down. But the electron or photon again tells us: “Guys, we don’t care what you’re used to, we can be in both spin states at once (vector up, vector down), just like we can be on 2 trajectories at the same time or at 2 points at the same time!

What is "measurement" or "wavefunction collapse"?

There is little left for us to understand what “measurement” is and what “wave function collapse” is.

Wave function is a description of the state of a quantum object (our photon or electron).

Suppose we have an electron, it flies to itself in an indefinite state, its spin is directed both up and down at the same time. We need to measure his condition.

Let's measure using a magnetic field: electrons whose spin was directed in the direction of the field will deviate in one direction, and electrons whose spin is directed against the field - in the other. More photons can be directed into a polarizing filter. If the spin (polarization) of the photon is +1, it passes through the filter, but if it is -1, then it does not.

Stop! Here you will inevitably have a question: Before the measurement, the electron did not have any specific spin direction, right? He was in all states at the same time, wasn't he?

This is the trick and sensation of quantum mechanics. As long as you do not measure the state of a quantum object, it can rotate in any direction (have any direction of the vector of its own angular momentum - spin). But at the moment when you measured his state, he seems to be making a decision which spin vector to accept.

This quantum object is so cool - it makes decisions about its state. And we cannot predict in advance what decision it will make when it flies into the magnetic field in which we measure it. The probability that he will decide to have a spin vector “up” or “down” is 50 to 50%. But as soon as he decides, he is in a certain state with a specific spin direction. The reason for his decision is our “dimension”!

This is called " collapse of the wave function". The wave function before the measurement was uncertain, i.e. the electron spin vector was simultaneously in all directions; after the measurement, the electron recorded a certain direction of its spin vector.

Attention! An excellent example for understanding is an association from our macrocosm:

Spin a coin on the table like a spinning top. While the coin is spinning, it does not have a specific meaning - heads or tails. But as soon as you decide to “measure” this value and slam the coin with your hand, that’s when you get the specific state of the coin - heads or tails. Now imagine that this coin decides which value to “show” you - heads or tails. The electron behaves in approximately the same way.

Now remember the experiment shown at the end of the cartoon. When photons were passed through the slits, they behaved like a wave and showed an interference pattern on the screen. And when scientists wanted to record (measure) the moment of photons flying through the slit and placed an “observer” behind the screen, the photons began to behave not like waves, but like particles. And they “drew” 2 vertical stripes on the screen. Those. At the moment of measurement or observation, quantum objects themselves choose what state they should be in.

Fantastic! Is not it?

But that is not all. Finally we We got to the most interesting part.

But... it seems to me that there will be an overload of information, so we will consider these 2 concepts in separate posts:

• What's happened ?
• What is a thought experiment?

Now, do you want the information to be sorted out? Watch the documentary produced by the Canadian Institute of Theoretical Physics. In 20 minutes it is very brief and chronological order You will be told about all the discoveries of quantum physics, starting with Planck's discovery in 1900. And then they will tell you what practical developments are currently being carried out on the basis of knowledge in quantum physics: from the most accurate atomic clocks to super-fast calculations quantum computer. I highly recommend watching this film.

See you!

I wish everyone inspiration for all their plans and projects!

P.S.2 Write your questions and thoughts in the comments. Write, what other questions on quantum physics are you interested in?

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Returning a car under warranty or quantum physics for dummies.

Let's say the year is 3006. You go to the “connected” and buy a budget Chinese time machine in installments for 600 years. Do you want to sneak around a week ahead to beat the bookmaker's office? In anticipation of a big jackpot, you frantically type the arrival date on the blue plastic box...

And here's the laugh: In it, the Nikadim-chronon converter burns out right away. The machine, emitting a dying squeak, throws you into the year 62342. Humanity was divided into back-heeled and shaved and scattered to distant galaxies. The sun has been sold to aliens, the Earth is ruled by giant radioactive silicon worms. The atmosphere is a mixture of fluorine and chlorine. Temperature minus 180 degrees. The ground has eroded and you also fall onto a cliff of fluorite crystals from about fifteen meters away. On your last exhale, you exercise your civil galactic right of one intertemporal call on your key fob. Call the center technical support“connected”, where a polite robot tells you that the guarantee for the time machine is 100 years and in their time it is completely functional, and in 62342 you received an amount of millions of pennies, unpronounceable by the human speech mechanism, for an installment plan that was never paid.

Bless and save! Lord, thank you that we live in this decimated bearish past, where such incidents are impossible!
...Although, no! Just most of the big ones scientific discoveries do not give as epic results as various science fiction writers imagine.

Lasers do not burn cities and planets - they record and transmit information and entertain schoolchildren. Nanotechnology does not turn the universe into a self-replicating horde of nanobots. They make the raincoat more waterproof and the concrete more durable. Atomic bomb, exploded at sea and never started a chain reaction thermonuclear fusion hydrogen nuclei and did not turn us into another sun. The Hadron Collider did not turn the planet inside out or drag the entire world into a black hole. Artificial intelligence has already been created, but he only scoffs at the idea of ​​\u200b\u200bthe destruction of humanity.
Time Machine is no exception. The fact is that it was created in the middle of the last century. It was built not as an end in itself, but only as a tool for creating one small, nondescript, but very remarkable device.

At one time, Professor Dmitry Nikolaevich Grachev was very puzzled by the issue of creating effective means protection against radio radiation. At first glance, the task seemed impossible - the device had to respond to each radio wave with its own one and at the same time not be in any way tied to the signal source (since it was an enemy one). Dmitry Nikolaevich once watched children playing “dodgeball” in the yard. The fastest player who dodges the ball most effectively wins the game. This requires coordination, and most importantly, the ability to predict the trajectory of the ball.

The ability to predict is determined by the computing resource. But in our case, increasing computing resources will lead to nothing. Even the most modern supercomputers will not have enough speed and accuracy for this. We were talking about predicting a spontaneous process with the speed of a half-cycle of a microwave radio wave.

The professor picked up the ball that had flown into the bushes and threw it back to the children. Why predict where the ball is going when it has already arrived? A solution was found: the characteristics of the unknown input radio signal are well known in the near future and there is simply no need to calculate them. It is enough to measure them directly there. But here’s the problem: it’s impossible to travel in time even for a nanosecond. However, this was not required for the task at hand. It is only necessary that the sensitive element of the device - the transistor - be at least partially in the near future. And then it came to the rescue recently open phenomenon quantum superposition. Its meaning is that the same particle can be in different places and times at the same time.

As a result, Professor Grachev created a Mass-Oriented Quantum Electron Trap - a real time machine, in which a semiconductor chip was created for the first time, some of the electrons of which are in the future and at the same time in the present. A prototype of that same TMA - a chip that controls the Grachev resonator. You could say this thing will always have one foot in the future.