Quantum physics in simple words
Quantum physics in simple words. Quantum physics: the most difficult thing in simple language
“If you ask if his position is constant, you have to say no, if you ask if it changes over time, you should say no. If they ask if he is motionless, you must say “no”, if they ask if he is moving, you must say “no.” The laws of quantum mechanics are very difficult to grasp, like mystical revelations, and these words of Robert Oppenheimer about the behavior of the electron could well have been said by Lao Tzu two and a half thousand years before the advent of modern physics.
Introduction
Introduction. The fundamental difficulty of understanding quantum theory
It is difficult to imagine what our civilization would look like without classical physics and mathematics. The concepts of an absolute “objective reality existing independently of our consciousness”, of three-dimensional Euclidean space and uniformly flowing time are so deeply rooted in our consciousness that we do not notice them. And most importantly, we refuse to notice that they are applicable only in some routine situations and for the explanation of the structure of the Universe are simply incorrect.
Although something similar was already expressed centuries ago by Eastern philosophers and mystics, Einstein was the first to speak about it in Western science. It was a revolution that our consciousness did not accept. With condescension, we repeat: “everything is relative”, “time and space are one,” always keeping in mind that this is an assumption, a scientific abstraction that has little to do with our habitual stable reality. In fact, just our ideas are weakly correlated with reality – amazing and incredible.
The language of mathematics is strict, but has little to do with our direct perception.
After the general outline of the structure of the atom was discovered and its “planetary” model was proposed, scientists were faced with many paradoxes, for the explanation of which a whole branch of physics appeared – quantum mechanics. It developed rapidly and advanced far in explaining the universe. But these explanations are so difficult to understand that until now very few people can grasp them at least in general terms.
Indeed, most of the advances in quantum mechanics are accompanied by such a complex mathematical apparatus that it simply cannot be translated into any of the human languages. Mathematics, like music, is an extremely abstract subject, and scientists are still struggling to adequately express meaning, for example, the folding of functions or multidimensional Fourier series. The language of mathematics is strict, but has little to do with our direct perception.
Moreover, Einstein showed mathematically that our concepts of time and space are illusory. In reality, space and time are inseparable and form a single four-dimensional continuum. It is hardly possible to imagine it, because we are used to dealing with only three dimensions.
With our 3D mind, it is hardly possible to imagine a 4D spacetime continuum
Planetary theory. Wave or particle
Until the late 19th century, atoms were considered indivisible “elements.” The discovery of radiation allowed Rutherford to penetrate under the “shell” of the atom and formulate a planetary theory of its structure: the bulk of the atom is concentrated in the nucleus. The positive charge of the nucleus is compensated for by negatively charged electrons, whose dimensions are so small that their mass can be neglected. Electrons revolve around the nucleus in orbits, like the rotation of planets around the Sun. The theory is very beautiful, but a number of contradictions arise.
First, why don’t negatively charged electrons “fall” onto the positive nucleus? Secondly, in nature, atoms collide millions of times per second, which does not harm them in the least – how can one explain the amazing strength of the entire system? In the words of one of the “fathers” of quantum mechanics, Heisenberg, “no planetary system that obeys the laws of Newtonian mechanics will never return to its original state after a collision with another similar system.” In addition, the size of the nucleus, in which almost all the mass is collected, is extremely small in comparison with the whole atom.
We can say that an atom is a void in which electrons rotate at a breakneck speed. In this case, such an “empty” atom appears as a very solid particle. The explanation for this phenomenon goes beyond the classical understanding. In fact, at the subatomic level, the speed of a particle increases the more the space in which it moves is limited. So the closer the electron is attracted to the nucleus, the faster it moves and the more it is repelled from it. The speed of movement is so high that the atom “looks solid” “from the side”, as the blades of a rotating fan look like a disk.
Data that do not fit well with the classical approach appeared long before Einstein. For the first time, such a “duel” took place between Newton and Huygens, who tried to explain the properties of light. Newton argued that this is a stream of particles, Huygens considered light to be a wave. It is impossible to reconcile their positions within the framework of classical physics. Indeed, for her, a wave is a transmitted excitation of particles of a medium, a concept that is applicable only for a variety of objects.
None of the free particles can move along a wavy path. But an electron moves in a deep vacuum, and its movements are described by the laws of wave motion. What gets excited here if there is no environment? Quantum physics offers a Solomon solution: light is both a particle and a wave.
Probabilistic electron clouds. Nuclear structure and nuclear particles
Gradually it became more and more clear: the rotation of electrons in orbits around the nucleus of an atom is completely different from the rotation of planets around a star. With their wave nature, electrons are described in terms of probability. We cannot say about an electron that it is located at such and such a point in space, we can only describe approximately in what areas it can be located and with what probability.
Around the nucleus, electrons form “clouds” of such probabilities, from the simplest spherical to very bizarre shapes similar to photographs of ghosts.
For an electron, we can only roughly describe in what areas it can be located, and with what probability
For an electron, we can only roughly describe in what areas it can be located, and with what probability
But anyone who wants to finally understand the structure of the atom must turn to its basis, to the structure of the nucleus. The large elementary particles that make it up – positively charged protons and neutral neutrons – also have a quantum nature, which means that they move the faster the smaller the volume they are enclosed.
Since the size of the nucleus is extremely small even in comparison with the atom, these elementary particles are carried around at quite decent speeds, close to the speed of light. For a final explanation of their structure and behavior, we need to “cross” the quantum theory with the theory of relativity. Unfortunately, such a theory has not yet been created and we will have to restrict ourselves to a few generally accepted models.
The theory of relativity has shown (and experiments have proven) that mass is only one of the forms of energy. Energy is a dynamic quantity associated with processes or work. Therefore, an elementary particle should be perceived as a probabilistic dynamic function, as interactions associated with the continuous transformation of energy.
This gives an unexpected answer to the question of how elementary elementary particles are, whether it is possible to divide them into “even simpler” blocks. If we disperse two particles in an accelerator, and then collide, we get not two, but three particles, and they are exactly the same. The third will simply arise from the energy of their collision – thus, they will both separate and not separate at the same time!
If we disperse two particles in an accelerator, and then collide, we get not two, but three particles, and they are absolutely identical – the third will arise from the energy of their collision
If we disperse two particles in an accelerator, and then collide, we get not two, but three particles, and they are absolutely identical – the third will arise from the energy of their collision
A participant instead of an observe
In a world where the concepts of empty space, isolated matter lose their meaning, a particle is described only through its interactions. In order to say something about it, we will have to “pull” it out of the initial interactions and, having prepared it, subject it to another interaction – measurement. So what do we measure in the end? And how legitimate are our measurements in general, if our intervention changes the interactions in which the particle participates – and therefore changes it itself?
In modern physics of elementary particles, more and more questions are raised by the figure of the observer scientist. It would be more correct to call him a “participant”
In modern physics of elementary particles, more and more questions are raised by the figure of the observer scientist. It would be more correct to call him a “participant”
In modern physics of elementary particles, more and more complaints are caused … by the very figure of the scientist-observer. It would be more correct to call him a “participant.”
The observer-participant is necessary not only for measuring the properties of a subatomic particle, but also in order to determine these very properties, because they can only be talked about in the context of interaction with the observer. As soon as he chooses the method in which he will carry out measurements, and depending on this, the possible properties of the particle are realized. It is worth changing the observing system, and the properties of the observed object will also change.
This important point reveals the deep unity of all things and phenomena. The particles themselves, continuously passing one into another and into other forms of energy, do not have constant or precise characteristics – these characteristics depend on the way in which we decided to see them. If you need to measure one property of a particle, the other will certainly change. Such a limitation is not associated with imperfection of devices or other completely correctable things.
This is a characteristic of reality. Try to accurately measure the position of a particle, and you won’t be able to tell anything about the direction and speed of its movement – simply because it will not have them. Describe exactly the movement of the particle – you won’t find it in space. Thus, modern physics presents us with problems of a completely metaphysical nature.
It is worth changing the observing system, and the properties of the observed object will also change.
It is worth changing the observing system, and the properties of the observed object will also change.
The principle of uncertainty.
The principle of uncertainty.. Place or momentum, energy or time
We have already said that a conversation about subatomic particles cannot be conducted in the exact terms we are used to; in the quantum world, we are left with only probability.
This, of course, is not the probability that one speaks of when betting on horse racing, but a fundamental property of elementary particles.
They do not really exist, but rather – they can exist.
They don’t just have characteristics, but rather – they can have them. Scientifically speaking, a particle is a dynamic probabilistic scheme, and all its properties are in constant mobile equilibrium, balancing, like Yin and Yang on the ancient Chinese symbol taiji.
No wonder the Nobel laureate Niels Bohr, elevated to the rank of nobility, chose this sign and motto for his coat of arms: “Opposites complement each other.” Mathematically, a probability distribution is an uneven waveform. The greater the amplitude of the wave at a certain place, the higher the probability of a particle in it.
Moreover, its length is not constant – the distances between adjacent crests are not the same, and the higher the wave amplitude, the stronger the difference between them. While the amplitude corresponds to the position of the particle in space, the wavelength is related to the momentum of the particle, that is, to the direction and speed of its movement.
The larger the amplitude (the more accurately you can localize the particle in space), the more uncertain the wavelength becomes (the less you can say about the particle momentum). If we can pinpoint the position of a particle with extreme precision, it will have no definite momentum at all.
The faster the process, the more uncertain the amount of energy involved in it, and vice versa.
This fundamental property is mathematically derived from the properties of the wave and is called the uncertainty principle. The principle also applies to other characteristics of elementary particles. Another such interconnected pair is the energy and time of the course of quantum processes.
The faster the process goes, the more uncertain is the amount of energy involved in it, and vice versa – it is possible to accurately characterize energy only for a process of sufficient duration.
So, we understood: nothing definite can be said about a particle. It moves there, or not there, or rather, neither here nor there. Its characteristics are such or such, or rather – not so, and not that. It is here, but it may be there, or it may not be anywhere. So does it even exist?