Surely you have heard many times about the inexplicable mysteries of quantum physics and quantum mechanics. Its laws fascinate with mysticism, and even the physicists themselves admit that they do not fully understand them. On the one hand, it is curious 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 inquisitive people type in the search line: “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 post is 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 is quantum entanglement (or quantum teleportation for dummies)? (see article)
• What is the Schrödinger's Cat thought experiment? (see article)

Quantum mechanics is part of quantum physics.

Why is it so difficult to understand these sciences? The answer is simple: quantum physics and quantum mechanics (a 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 macro- and microworlds: in our macrocosm, if you put a ball into one of the 2 boxes, then one of them will be empty, and the other - a ball. But in the microcosm (if instead of a ball - an atom), an atom can be simultaneously in two boxes. This has been repeatedly confirmed experimentally. Isn't it hard to put it in your head? But you can't argue with the facts.

One more example. You photographed a fast racing red sports car and in the photo you saw a blurry horizontal strip, as if the car at the time of the photo was from several points in space. Despite what you see in the photo, you are still sure that the car was at the moment when you photographed it. in one specific place in space. Not so in the micro world. An electron that revolves around the nucleus of an atom does not actually revolve, but 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 small digression into history. For the first time, scientists thought about the quantum world when, in 1900, the German physicist Max Planck tried to find out why metals change color when heated. It was he who introduced the concept of quantum. Before that, 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 only a wave. Sometimes it 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) .

In order to make it easier to understand the laws of quantum physics and mechanics (Wikipedia), it is necessary, in a certain sense, to abstract from the laws of classical physics familiar to us. And imagine that you dived, like Alice, down the rabbit hole, into Wonderland.

And here is a cartoon for children and adults. Talks about the fundamental experiment of quantum mechanics with 2 slits and an observer. Lasts only 5 minutes. Watch it before we delve into the basic 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 slots. And in the case when discrete particles (for example, pebbles) are “shot” at the plate, they fly through 2 slots and hit the screen directly opposite the slots. And "draw" on the screen only 2 vertical stripes.

Light interference- this is the "wave" behavior of light, when a lot of alternating bright and dark vertical stripes are displayed on the screen. And those vertical stripes called an interference pattern.

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

So, it's not all that difficult! 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 consider the 2nd experiment. This is the famous Stern-Gerlach experiment (which was carried out in the 20s of the last century).

In the installation described in the cartoon, they did not shine with light, but “shot” with electrons (as separate particles). Then, at the beginning of the last century, physicists around the world believed that electrons are elementary particles of 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 they are “thrown” into 2 slots, like pebbles, then on the screen behind the slots we should see 2 vertical stripes.

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

You may remember that at school we were told in physics about "particle-wave dualism"? It means that when we are talking about very small particles (atoms, electrons) of the microworld, then they are both waves and particles

It is today that you and I are so smart and understand that the 2 experiments described above - shooting with electrons and illuminating slots with light - are the same thing. Because we're firing quantum particles at the slits. Now we know that both light and electrons are of quantum nature, 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 on our slits with a stream of photons (electrons) - and we see an interference pattern (vertical stripes) behind the slits on the screen. It is clear. But we are interested to see how each of the electrons flies through the slit.

Presumably, one electron flies to the left slit, the other to the right. But then 2 vertical stripes should appear on the screen directly opposite the slots. Why is an interference pattern obtained? Maybe the electrons somehow interact with each other already on the screen after flying through the slits. And the result is such a wave pattern. How can we follow this?

We will throw electrons not in a beam, but one at a time. Drop it, wait, drop the next one. Now, when the electron flies alone, it will no longer be able to interact on the screen with other electrons. We will register on the screen each electron after the throw. One or two, of course, will not “paint” a clear picture for us. But when one by one we send a lot of them into the slots, we will notice ... oh horror - they again “drawn” an interference wave pattern!

We start to slowly 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. Fantasy! We will return to the explanation of 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 (let's call them photons for simplicity from now on).

As a result of the experiment, when we threw 1 photon into 2 slits, we realized that it flies as if through two slits at the same time. How else to explain the interference pattern on the screen?

But how to imagine a picture that a photon flies through two slits at the same time? There are 2 options.

• 1st option: 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 have arrived at the "path integral". This is Richard Feynman's formulation of quantum mechanics.

By the way, exactly Richard Feynman belongs to the 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 we know that a photon can behave both as a particle and as a wave. That he can fly through 2 slots at the same time in some way that is incomprehensible to us. 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 care that we don't understand them. This is the point.

It remains for us to simply accept as an axiom that the "superposition" of a quantum object means that it can be on 2 or more trajectories at the same time, at 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 used 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 are 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"?

It remains for us a little - to understand what is "measurement" and what is "collapse of the wave function".

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 indeterminate state, its spin is directed both up and down at the same time. We need to measure his condition.

Let's measure with 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 will deviate in the other direction. Photons can also be sent to a polarizing filter. If the spin (polarization) of a photon is +1, it passes through the filter, and if it is -1, then it does not.

Stop! This is where the question inevitably arises: before the measurement, after all, the electron did not have any particular spin direction, right? Was he in all states at the same time?

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 its own angular momentum vector - spin). But at the moment when you measured his state, he seems to be deciding which spin vector to take.

This quantum object is so cool - it makes a decision 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 decides 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 " wave function collapse". The wave function before the measurement was indefinite, i.e. the electron spin vector was simultaneously in all directions, after the measurement, the electron fixed a certain direction of its spin vector.

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

Spin a coin on the table like a top. While the coin is spinning, it has no specific meaning - heads or tails. But as soon as you decide to "measure" this value and slam the coin with your hand, this is where you get the specific state of the coin - heads or tails. Now imagine that this coin decides what value to "show" you - heads or tails. The electron behaves 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 the scientists wanted to fix (measure) the moment when photons passed through the slit and put an “observer” behind the screen, the photons began to behave not like waves, but like particles. And “drawn” 2 vertical stripes on the screen. Those. at the moment of measurement or observation, quantum objects themselves choose what state they should be in.

Fantasy! Is not it?

But that's not all. Finally we got to the most interesting.

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.

And now, do you want the information to be put on the shelves? look documentary prepared by the Canadian Institute for Theoretical Physics. In it, in 20 minutes, very briefly and in chronological order You will be told about all the discoveries of quantum physics, starting with the discovery of Planck in 1900. And then they will tell you what practical developments are currently being carried out on the basis of knowledge of quantum physics: from the most accurate atomic clocks to super-fast calculations of a quantum computer. I highly recommend watching this movie.

See you!

I wish you all inspiration for all your 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?

P.S.3 Subscribe to the blog - the subscription form under the article.

29.10.2016

Despite the sonority and mystery of today's topic, we will try to tell What does quantum physics study in simple words , what sections of quantum physics have a place to be and why quantum physics is needed in principle.

The material offered below is accessible to anyone for understanding.

Before ranting about what quantum physics studies, it would be appropriate to recall how it all began ...

By the middle of the 19th century, mankind had come to grips with the study of problems that could not be solved by using the apparatus of classical physics.

A number of phenomena seemed "strange". Some questions were not answered at all.

In the 1850s, William Hamilton, believing that classical mechanics is not able to accurately describe the movement of light rays, offers its own theory, which entered the history of science under the name of the formalism of Hamilton-Jacobi, which was based on the postulate of the wave theory of light.

In 1885, after arguing with a friend, the Swiss physicist Johann Balmer derived empirically a formula that made it possible to calculate the wavelengths of spectral lines with very high accuracy.

At that time, Balmer could not explain the reasons for the revealed patterns.

In 1895, Wilhelm Roentgen, while investigating cathode rays, discovered radiation, which he called X-rays (later renamed rays), which was characterized by a powerful penetrating character.

A year later, in 1896, Henri Becquerel, studying uranium salts, discovered spontaneous radiation with similar properties. The new phenomenon was called radioactivity.

In 1899, the wave nature of X-rays was proven.

Photo 1. The founders of quantum physics Max Planck, Erwin Schrödinger, Niels Bohr

The year 1901 was marked by the appearance of the first planetary model of the atom, proposed by Jean Perrin. Alas, the scientist himself abandoned this theory, not finding confirmation of it from the standpoint of the theory of electrodynamics.

Two years later, a scientist from Japan, Hantaro Nagaoka, proposed another planetary model of the atom, in the center of which there should have been a positively charged particle, around which electrons would orbit in orbits.

This theory, however, did not take into account the radiation emitted by electrons, and therefore could not, for example, explain the theory of spectral lines.

Reflecting on the structure of the atom, in 1904 Joseph Thomson was the first to interpret the concept of valence from a physical point of view.

The year of birth of quantum physics, perhaps, can be recognized as 1900, associating with it the speech of Max Planck at a meeting of the German Physics.

It was Planck who proposed a theory that united many hitherto disparate physical concepts, formulas and theories, including the Boltzmann constant, linking energy and temperature, Avogadro's number, Wien's displacement law, electron charge, Boltzmann's law of radiation ...

He also introduced the concept of the quantum of action (the second - after the Boltzmann constant - the fundamental constant).

The further development of quantum physics is directly connected with the names of Hendrik Lorentz, Albert Einstein, Ernst Rutherford, Arnold Sommerfeld, Max Born, Niels Bohr, Erwin Schrödinger, Louis de Broglie, Werner Heisenberg, Wolfgang Pauli, Paul Dirac, Enrico Fermi and many other remarkable scientists, created in the first half of the 20th century.

Scientists managed to understand the nature of elementary particles with unprecedented depth, study the interactions of particles and fields, reveal the quark nature of matter, derive the wave function, explain the fundamental concepts of discreteness (quantization) and wave-particle duality.

Quantum theory, like no other, brought mankind closer to understanding the fundamental laws of the universe, replaced the usual concepts with more accurate ones, and made us rethink a huge number of physical models.

What does quantum physics study?

Quantum physics describes the properties of matter at the level of micro-phenomena, exploring the laws of motion of micro-objects (quantum objects).

The subject of quantum physics are quantum objects with dimensions of 10 −8 cm or less. This:

• molecules,
• atoms,
• atomic nuclei,
• elementary particles.

The main characteristics of micro-objects are rest mass and electric charge. The mass of one electron (me) is 9.1 10 −28 g.

For comparison, the mass of a muon is 207 me, a neutron is 1839 me, and a proton is 1836 me.

Some particles have no rest mass at all (neutrino, photon). Their mass is 0 me.

The electric charge of any micro-object is a multiple of the electron charge equal to 1.6 · 10 −19 C. Along with the charged ones, there are neutral micro-objects, the charge of which is equal to zero.

Photo 2. Quantum physics forced to reconsider the traditional views on the concepts of waves, fields and particles

The electric charge of a complex micro-object is equal to the algebraic sum of the charges of its constituent particles.

Among the properties of micro-objects is spin(literally translated from English - "to rotate").

It is customary to interpret it as the angular momentum of a quantum object that does not depend on external conditions.

The back is difficult to find an adequate image in real world. It cannot be represented as a spinning top due to its quantum nature. Classical physics cannot describe this object.

The presence of spin affects the behavior of micro-objects.

The presence of spin introduces significant features into the behavior of objects in the microcosm, most of which - unstable objects - spontaneously decay, turning into other quantum objects.

Stable micro-objects, which include neutrinos, electrons, photons, protons, as well as atoms and molecules, can only decay under the influence of powerful energy.

Quantum physics completely absorbs classical physics, considering it as its limiting case.

In fact, quantum physics is - in a broad sense - modern physics.

What quantum physics describes in the microcosm cannot be perceived. Because of this, many provisions of quantum physics are difficult to imagine, in contrast to the objects described by classical physics.

Despite this, new theories have made it possible to change our ideas about waves and particles, about dynamic and probabilistic description, about continuous and discrete.

Quantum physics is not just a newfangled theory.

This is a theory that has managed to predict and explain an incredible number of phenomena - from the processes occurring in atomic nuclei, to macroscopic effects in outer space.

Quantum physics, unlike classical physics, studies matter at a fundamental level, giving interpretations to the phenomena of the surrounding reality that traditional physics is not able to give (for example, why atoms remain stable or whether elementary particles are really elementary).

Quantum theory gives us the ability to describe the world more accurately than was accepted before its inception.

The Significance of Quantum Physics

The theoretical developments that make up the essence of quantum physics are applicable to the study of both unimaginably huge space objects and extremely small elementary particles.

quantum electrodynamics immerses us in the world of photons and electrons, focusing on the study of interactions between them.

Quantum theory of condensed matter deepens our knowledge of superfluids, magnets, liquid crystals, amorphous bodies, crystals and polymers.

Photo 3. Quantum physics has given humanity a much more accurate description of the world around us

Scientific research in recent decades has focused on the study of the quark structure of elementary particles within the framework of an independent branch of quantum physics - quantum chromodynamics.

Nonrelativistic quantum mechanics(the one that is beyond the scope of Einstein's theory of relativity) studies microscopic objects moving at a relatively low speed (less than), the properties of molecules and atoms, their structure.

quantum optics engaged in the scientific study of the facts associated with the manifestation of the quantum properties of light (photochemical processes, thermal and stimulated radiation, photoelectric effect).

quantum field theory is a unifying section that incorporates the ideas of the theory of relativity and quantum mechanics.

Scientific theories developed within the framework of quantum physics have given a powerful impetus to the development of quantum electronics, technology, quantum theory of solids, materials science, and quantum chemistry.

Without the emergence and development of the noted branches of knowledge, it would be impossible to create spacecraft, nuclear icebreakers, mobile communications and many other useful inventions.

Ecology of knowledge: Quantum physics frightens the unprepared listener from the very beginning of acquaintance. It is strange and illogical, even for the physicists who deal with it every day. But she's not incomprehensible

Quantum physics frightens an unprepared listener from the very beginning of acquaintance. It is strange and illogical, even for the physicists who deal with it every day. But she is not incomprehensible. If you are interested in quantum physics, there are actually six key concepts from it that you need to keep in mind. No they are not related with quantum phenomena . And it's not thought experiments. Just wind them around your mustache and quantum physics will be much easier to understand.

Everything is made of waves - and particles too

There are many places to start this discussion, and this is as good as the others: everything in our universe has the nature of both particles and waves at the same time. If one could say about magic this way: "All these are waves, and only waves," that would be a wonderful poetic description of quantum physics. In fact, everything in this universe has a wave nature.

Of course, also everything in the universe has the nature of particles. It sounds strange, but this is an experimental fact.

Describing real objects as particles and waves at the same time would be somewhat inaccurate. Strictly speaking, the objects described by quantum physics are not particles and waves, but rather belong to the third category, which inherits the properties of waves (frequency and wavelength, along with propagation in space) and some properties of particles (they can be counted and localized to a certain degree ). This leads to a lively debate in the physics community about whether it is even correct to speak of light as a particle; not because there is a contradiction in whether light has a particle nature, but because calling photons "particles" and not "excitations of a quantum field" is misleading students. However, this also applies to whether electrons can be called particles, but such disputes will remain in purely academic circles.

This "third" nature of quantum objects is reflected in the sometimes confusing language of physicists who discuss quantum phenomena. The Higgs boson was discovered as a particle at the Large Hadron Collider, but you've probably heard the phrase "Higgs field", such a delocalized thing that fills all of space. This is because under certain conditions, such as particle collision experiments, it is more appropriate to discuss excitations of the Higgs field than to characterize the particle, while under other conditions, such as general discussions As to why certain particles have mass, it is more appropriate to discuss physics in terms of interactions with the quantum field on a universal scale. It's simple different languages describing the same mathematical objects.

Quantum physics is discrete

Everything in the name of physics - the word "quantum" comes from the Latin "how much" and reflects the fact that quantum models always include something that comes in discrete quantities. The energy contained in a quantum field comes in multiples of some fundamental energy. For light, this is associated with the frequency and wavelength of the light—high-frequency, short-wavelength light has a huge characteristic energy, while low-frequency, long-wavelength light has little characteristic energy.

In both cases, meanwhile, the total energy contained in a separate light field is an integer multiple of this energy - 1, 2, 14, 137 times - and there are no strange fractions like one and a half, "pi" or the square root of two. This property is also observed in the discrete energy levels of atoms, and the energy bands are specific - some energy values ​​are allowed, others are not. Atomic clocks work thanks to the discreteness of quantum physics, using the frequency of light associated with the transition between two allowed states in cesium, which allows you to keep time at the level necessary for the "second jump".

Ultra-precise spectroscopy can also be used to search for things like dark matter, and remains part of the motivation for the institute's work on low-energy fundamental physics.

It's not always obvious - even some things that are quantum in principle, like blackbody radiation, are associated with continuous distributions. But upon closer examination and with the connection of a deep mathematical apparatus, quantum theory becomes even more strange.

Quantum physics is probabilistic

One of the most surprising and (at least historically) controversial aspects of quantum physics is that it is impossible to predict with certainty the outcome of a single experiment with a quantum system. When physicists predict the outcome of a particular experiment, their prediction is in the form of the probability of finding each of the particular possible outcomes, and comparisons between theory and experiment always involve deriving a probability distribution from many repeated experiments.

The mathematical description of a quantum system, as a rule, takes the form of a "wave function", represented in the equations of the Greek beech psi: Ψ. There are many discussions about what exactly the wave function is, and they have divided physicists into two camps: those who see the wave function as a real physical thing (ontic theorists), and those who believe that the wave function is solely an expression of our knowledge (or lack thereof) regardless of the underlying state of a particular quantum object (epistemic theorists).

In each class of the underlying model, the probability of finding a result is not determined directly by the wave function, but by the square of the wave function (roughly speaking, it is still the same; the wave function is a complex mathematical object (and therefore includes imaginary numbers like the square root or its negative variant), and the probability operation is a little more complicated, but "the square of the wave function" is enough to get the basic gist of the idea). This is known as the Born rule, after the German physicist Max Born, who first calculated it (in a footnote to a 1926 paper) and surprised many people with its ugly implementation. There is active work in trying to derive the Born rule from a more fundamental principle; but so far none of them has been successful, although it has generated a lot of interesting things for science.

This aspect of the theory also leads us to particles that are in many states at the same time. All we can predict is probability, and before measuring with a particular result, the system being measured is in an intermediate state - a superposition state that includes all possible probabilities. But whether the system is really in multiple states or is in one unknown depends on whether you prefer an ontic or epistemic model. Both of them lead us to the next point.

Quantum physics is non-local

Last Einstein's great contribution on to physics was not widely accepted as such, mainly because he was wrong. In a 1935 paper, along with his young colleagues Boris Podolkiy and Nathan Rosen (the EPR paper), Einstein made a clear mathematical statement of something that had been troubling him for some time, what we call "entanglement."

EPR's work claimed that quantum physics recognized the existence of systems in which measurements made at widely separated places could be correlated so that the outcome of one determined the other. They argued that this meant that the results of the measurements had to be determined in advance by some common factor, since otherwise the result of one measurement would have to be transmitted to the site of another at a speed faster than the speed of light. Therefore, quantum physics must be incomplete, an approximation of a deeper theory (the “hidden local variable” theory, in which the results of individual measurements do not depend on something that is farther from the measurement site than a signal traveling at the speed of light can cover (locally), but rather is determined by some factor common to both systems in an entangled pair (hidden variable).

The whole thing was considered an incomprehensible footnote for more than 30 years, since there seemed to be no way to verify it, but in the mid-60s, the Irish physicist John Bell worked out the consequences of EPR in more detail. Bell showed that you can find circumstances under which quantum mechanics will predict correlations between remote measurements that are stronger than any possible theory like those proposed by E, P, and R. This was experimentally tested in the 70s by John Kloser and Alain Aspect in the early 80s. x - they showed that these intricate systems could not potentially be explained by any local hidden variable theory.

The most common approach to understanding this result is to assume that quantum mechanics is non-local: that the results of measurements made at a particular location can depend on the properties of a distant object in a way that cannot be explained using signals traveling at the speed of light. This, however, does not allow information to be transmitted at superluminal speeds, although many attempts have been made to circumvent this limitation using quantum nonlocality.

Quantum physics is (almost always) concerned with the very small

Quantum physics has a reputation for being weird because its predictions are drastically different from our everyday experience. This is because its effects are less pronounced the larger the object - you will hardly see the wave behavior of particles and how the wavelength decreases with increasing momentum. The wavelength of a macroscopic object like a walking dog is so ridiculously small that if you magnified every atom in a room to solar system, the wavelength of a dog would be the size of one atom in such a solar system.

This means that quantum phenomena are mostly limited to the scale of atoms and fundamental particles, whose masses and accelerations are small enough that the wavelength remains so small that it cannot be observed directly. However, a lot of efforts are being made to increase the size of a system that exhibits quantum effects.

Quantum physics is not magic

The previous point quite naturally brings us to this point: however strange quantum physics may seem, it is clearly not magic. What it postulates is strange by the standards of everyday physics, but it is severely constrained by well-understood mathematical rules and principles.

So if someone comes to you with a "quantum" idea that seems impossible - infinite energy, magical healing power, impossible space engines - it's almost certainly impossible. This doesn't mean that we can't use quantum physics to do incredible things: we are constantly writing about incredible breakthroughs using quantum phenomena, and they have already quite surprised humanity, it only means that we will not go beyond the laws of thermodynamics and common sense .

If the above points are not enough for you, consider this only a useful starting point for further discussion. published

Join us at

Hello dear readers. If you do not want to lag behind life, to be a truly happy and healthy person, you must know about the secrets of quantum modern physics, at least have a little idea of ​​​​what depths of the universe scientists have dug out today. You have no time to go into deep scientific details, but you want to comprehend only the essence, but to see the beauty of the unknown world, then this article: quantum physics for ordinary dummies or, one might say, for housewives, is just for you. I will try to explain what quantum physics is, but in simple words, to show clearly.

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

The fact is that it helps to answer many incomprehensible questions related to human consciousness, the influence of consciousness on the body. Unfortunately, medicine, relying on classical physics, does not always help us to be healthy. And psychology can't properly tell you how to find happiness.

Only 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 the rescue. Soon you will know everything.

What does quantum physics study in simple words

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

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 of 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.

Briefly about the 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 propagate continuously, but in portions - quanta (photons). Prior to this, it was believed that light has 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 duality appeared in quantum physics, the first paradox and the beginning of discoveries mysterious phenomena microworld.

The most interesting paradoxes began when the famous double-slit experiment was carried out, after which the mysteries became much more. We can say that quantum physics began with him. Let's take a look at it.

Double slit experiment in quantum physics

Imagine a plate with two slots in the form of vertical stripes. We will put a screen behind this plate. If we direct light onto 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 side by side, you will understand what interference is. That is, the light turns out to be sort of like it has a wave nature. But as physics, or rather Einstein, has proven, it is propagated by photon particles. Already a paradox. But it's okay, corpuscular-wave dualism will no longer surprise us. Quantum physics tells us that light behaves like a wave but is made up of photons. But the miracles are just beginning.

Let's put a gun in front of a plate with two slots, which will emit not light, but electrons. Let's start shooting electrons. What will we see on the screen behind the plate?

After all, electrons are particles, which means that the flow of electrons, passing through two slits, should leave only two stripes on the screen, two traces opposite the slits. Have you imagined pebbles flying through two slots and hitting the screen?

But what do we really see? All the same interference pattern. What is the conclusion: electrons propagate in waves. So electrons are waves. But after all it is an elementary particle. Again corpuscular-wave dualism in physics.

But we can assume that at a deeper level, an 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 is made up of water droplets, and on a smaller level, molecules, and then atoms. Okay, the logic is solid.

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

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

But horror. Instead of these two fringes, the same interference alternations of several fringes are obtained. How so? This can happen if an electron flies through two slits at the same time, but behind the plate, like a wave, it collides with itself and interferes. But this cannot be, because a particle cannot be in two places at the same time. It either flies through the first slot 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. This is what quantum physics says. That is why, when shooting a separate particle from a cannon, we see the result of interference. Behind the plate, the electron collides with itself and creates an interference pattern.

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

In the physics of the microcosm, everything is different.

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

All this does not fit into the head, undermines the usual idea of ​​​​the world, the old laws of physics, turns thinking, one can safely say it drives you crazy.

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

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

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

Wave function collapse in physics in simple terms

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

But in the end, the result stunned everyone.

As soon as we start looking through which slit an electron passes through, it begins to behave not like a wave, not like a strange substance that is located at different points in space at the same time, but like an ordinary particle. That is, it begins to show the specific properties of a quantum: it is located only in one place, it passes through one slot, it has one spin value. What appears on the screen is not an interference pattern, but a simple trace opposite the slit.

But how is that possible. As if the electron is joking, playing with us. At first, it behaves like a wave, and then, after we decided to look at its passage through a slit, it exhibits the properties of a solid particle and passes through only one slit. But that's the way 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 collapse of the wave function appeared in quantum physics.

When an electron flies towards the gap, it is in an indefinite state or, as we said above, in a superposition. That is, it behaves like a wave, it is located simultaneously at different points in space, it has two spin values ​​\u200b\u200b(a spin has only two values). If we didn’t touch it, didn’t try to look at it, didn’t find out exactly where it is, if we didn’t measure the value of its spin, it would fly like a wave through two slits at the same time, which means it would create an interference pattern. Quantum physics describes its trajectory and parameters using the wave function.

After we have made a measurement (and it is possible to measure a particle of the microworld only by interacting with it, for example, by colliding another particle with it), then the wave function collapses.

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

One can say that an elementary particle is like a ghost, it seems to exist, but at the same time it is not in one place, and with a certain probability it can be anywhere 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. Sure, but the wonders of quantum physics are just beginning. The most incredible is yet to come. But let's take a 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 at a deeper level. Do we still think we live in a 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 experiment with two slits, everything is also told there in an understandable, 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:

How did you not know about this before?

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

Empty space is not empty

Modern research has shown that empty space is not empty. It is filled with enormous energy. In each cubic centimeter of absolute vacuum there is as much of this energy as is not contained in all material objects of our Universe!

What if we dig even deeper? Thousands of years before Democritus, Indian sages knew that beyond the reality that is perceived by our senses, there is another, more "important" reality. Hinduism teaches that the world of external forms is only maya, an illusion. It is not at all the way we perceive it. There is a "higher reality" - more fundamental than the material universe. All the phenomena of our illusory world come from it, and it is somehow connected with human consciousness.

In essence, nothing has any meaning - everything is absolutely illusory. Even the most massive objects are all immaterial matter, very similar to thought; in general, everything around is concentrated information. — Jeffrey Satinover, MD

Quantum physics has come to the same point today. Its provisions are as follows: the basis of the physical world is an absolutely "non-physical" reality; it is the reality of information, or "probability waves," or consciousness. More specifically, it should be expressed as follows: at its deepest levels, our world is a fundamental field of consciousness; it creates information that determines the existence of the world

Scientists have found that the atomic system - the nucleus and electrons - is not a collection of microscopic material bodies, but a stable wave pattern. Then it turned out that there was no need to talk about stability: an atom is a short-term mutual superposition (condensation) of energy fields. Add to this the following fact. The ratio of the linear dimensions of the nucleus, electrons and the radii of the electron orbits is such that we can safely say that the atom consists almost entirely of emptiness. It's amazing how we don't fall through a chair when we sit down on it - after all, it is one continuous emptiness! True, the floor is the same, and the earth's surface ... Is there anything in the world that is "filled" enough so that we do not fail?!

What is more real - consciousness or matter?

Andrew Newberg, M.D., explored the spiritual experiences of different people, as a neurologist and described the results of his work in the books “Why Doesn't God Leave? The Science of the Brain and the Biology of Belief” and “The Mystical Mind. A Study in the Biology of Faith". “A person who has experienced spiritual insight,” he writes, “feels that he has touched the true reality, which is the foundation and cause of everything else.” The material world is a kind of superficial, secondary level of this reality.

“We need to carefully examine the relationship between consciousness and the physical universe. Perhaps the material world is derived from the reality of consciousness; perhaps consciousness is the basic material of the universe.” Dr. Newberg

Is reality the result of choice?

Or maybe our moment-to-moment interpretations of reality in everyday life are simply the result of the choice of the “democratic majority”? Or, to put it another way, is what most people think is real? If there are ten people in a room and eight of them see a chair and two of them see a Martian, which one of them is crazy? If twelve people perceive the lake as a mass of water closed in its shores, and one considers it to be a solid solid body on which one can walk, which of them is delirious?

Returning to the concepts of the previous chapter, we can now say that a paradigm is simply a generally accepted model of what is considered real. We vote for this model with our actions and it becomes our reality. But then the Great Question arises: "Can consciousness create reality?" Is it because no one has ever given an answer to this question, because reality itself is the answer?

Emotions and perception of the world

There is purely anatomical evidence that information about the world is given to us by the brain, not by the eyes. In that place eyeball where the optic nerve passes to the back of the brain, there are no visual receptors. Therefore, one would expect: if we close one eye, we will see a black spot in the center of the “picture”. But this does not happen - and only because the “picture” is drawn by the brain, not the eye.

Moreover, the brain does not distinguish between what a person really sees and what he imagines. It seems that he does not even see the difference between the performed and the imaginary action.

This phenomenon was discovered in the 1930s by Edmund Jacobson, M.D. (the creator of the gradual relaxation technique to relieve stress). He asked subjects to imagine certain physical actions. And I found that in the process of visualization, their muscles contracted subtly, in exact accordance with the movements that were performed mentally. Now athletes all over the world use this information: they include visual training in their preparation for competitions.

Your brain does not see the difference between the outside world and the world of your imagination. — Joe Dispenza

Research by Dr. Perth from the National Institutes of Health (USA) suggests that a person's perception of the world is determined not only by his ideas about what is real and what is not, but also by his attitude to information supplied by the senses.

It largely depends on the latter whether we perceive something, and if we perceive it, then how. The doctor says: “Our emotions determine what is worth paying attention to ... And the decision about what will reach our consciousness, and what will be discarded and remain at the deep levels of the body, is made at the moment when external stimuli affect the receptors.”

So, the essence of the matter is more or less clear. We ourselves create the world that we perceive. When I open my eyes and look around, I see not reality "as it is", but the world that my "sensory equipment" - the sense organs - can perceive; the world that my faith allows me to see; a world filtered by emotional preferences.

Fundamentals of quantum mechanics

The known meets the unknown

Over the next century, an entirely new science emerged, known as quantum mechanics, quantum physics, or simply quantum theory. It does not replace Newtonian physics, which perfectly describes the behavior of large bodies, i.e. objects of the macrocosm. It was created to explain the subatomic world: Newton's theory is helpless in it.

The universe is a very strange thing, says one of the founders of nanobiology, Dr. Stuart Hameroff. “There seem to be two sets of laws governing it. In our everyday, classical world, everything is described by the Newtonian laws of motion, discovered hundreds and hundreds of years ago... However, upon transition to the microcosm, to the level of atoms, a completely different set of "rules" begins to operate. These are quantum laws.”

Facts or fiction? One of the deepest philosophical differences between classical and quantum mechanics is this: classical mechanics is built on the idea that it is possible to passively observe objects… quantum mechanics has never been wrong about this possibility. — David Albert, PhD

Facts or fiction?

A particle of the microworld can be in two or more places at the same time! (One of the most recent experiments showed that one of these particles can be in 3000 places at the same time!) One and the same "object" can be both a localized particle and an energy wave propagating in space.

Einstein postulated that nothing can move faster speed Sveta. But quantum physics has proven that subatomic particles can exchange information instantly - being at any distance from each other.

Classical physics was deterministic: given initial conditions like the location and speed of an object, we can calculate where it will move. Quantum physics is probabilistic: we can never say with absolute certainty how the object under study will behave.

Classical physics was mechanistic. It is based on the premise that only by knowing the individual parts of an object can we ultimately understand what it is. Quantum physics is holistic: it paints a picture of the universe as a single whole, the parts of which are interconnected and influence each other.

And, perhaps most importantly, quantum physics has destroyed the idea of ​​a fundamental difference between subject and object, observer and observed - and yet it dominated the minds of scientists for 400 years!

In quantum physics, the observer influences the observed object. There are no isolated observers of the mechanical Universe - everything takes part in its existence.

Observer

My conscious decision about how to observe the electron will, to some extent, determine the properties of the electron. If I am interested in him as a particle, then I will get an answer about him as a particle. If I take an interest in it as a wave, I will get an answer about it as a wave. Fridtjof Capra, physicist, philosopher

The observer influences the observed

Before an observation or measurement is carried out, an object of the microworld exists in the form of a probabilistic wave (more strictly, as a wave function).

It does not occupy any definite position and has no speed. The wave function is simply the probability that, when observed or measured, an object will appear here or there. It has potential coordinates and speed - but we won't know them until we start the observation process.

“Because of this,” writes theoretical physicist Brian Greene in The Fabric of the Cosmos, “when we determine the position of an electron, we are not measuring an objective, pre-existing property of reality. Rather, the act of measurement is tightly woven into the creation of the measurable reality itself.” Fridtjof Kapr's statement logically completes Green's reasoning: "The electron has no objective properties independent of my consciousness."

All this blurs the line between the "outside world" and the subjective observer. They seem to merge in the process of discovery - or creation? - the world around us.

Measurement problem

The idea that the observer inevitably influences any physical process he observes; that we are not neutral witnesses of what is happening, simply observing objects and events, was first expressed by Niels Bohr and his colleagues from Copenhagen. This is why these provisions are often referred to as the Copenhagen Interpretation.

Bohr argued that Heisenberg's uncertainty principle implies something more than the impossibility of precisely simultaneously determining the speed and position of a subatomic particle.

This is how Fred Alan Wolf describes his postulates: “It's not just that you can't measure something. This "something" does not exist at all - until you start observing it.

Heisenberg believed that it exists on its own.” Heisenberg hesitated to admit that there was no "something" before the observer was involved in the process. Niels Bohr not only asserted this, but also decisively developed his assumptions.

Since particles don't come into being until we start observing them, he said, reality doesn't exist at the quantum level until someone observes and measures it.

Until now, there is a heated debate in the scientific community (it should rather be called a fierce debate!) About whether it is the human consciousness of the observer that causes the “collapse” and the transition of the wave function to the state of a particle?

Writer and journalist Lynn McTaggart expresses this idea in this way, avoiding scientific terms: “Reality is an unhardened jelly. It is not the world itself, but its potentiality. And we, by our involvement in it, by an act of observation and reflection, make this jelly harden. So our life is an integral part of the process of creating reality. It is determined by our attention."

In the Einstein Universe, objects have exact values ​​for all possible physical parameters. Most physicists would now say that Einstein was wrong. The properties of a subatomic particle appear only when they are forced to do so by measurements... In those cases when they are not observed... the parameters of a microsystem are in an indefinite, "foggy" state and are characterized solely by the probability with which this or that potential possibility can be realized. — Brian Greene, The Fabric of Space Why

quantum logic

Quantum Logic To the question of whether the electron remains unchanged, we are forced to answer: "No." If we are asked whether the position of an electron changes with time, we should say, "No." If we are asked the question whether the electron remains at rest, we answer: "No." To the question of whether the electron is in motion, we say: "No." — J. Robert Oppenheimer, inventor of the atomic bomb

The quantum logic of John von Neumann revealed the main part of the measurement problem: only the decision of the observer leads to the measurement. This decision limits the degrees of freedom of a quantum system (for example, the wave function of an electron) and thus affects the result (reality).