Can
quantum mechanics be trusted? The emergence of
quantum mechanics, like the establishment of many schools in Jianghu, seems to be silent, but in fact, it is full of melee and unification. The source of the
dispute goes back to an old question-what is the nature of light? For
hundreds of years, there have been two mainstream views on the answer to this question, resulting in two incompatible sects-the fighting process of the two sects is ups and downs, with crushing, counterattack and reversal.
Simply speaking, it can be divided into three stages.
The first stage: the micro-particle faction and the micro-particle faction have been arguing with each other for many years. At the beginning, neither of them convinced the other. It was not until a pair of bitter rivals appeared that they were temporarily divided into high and low.
They have been at loggerheads for ten thousand years: if Hooke took sides out of pure scientific speculation, then Newton took sides out of pure disgust for Hooke.
It was a close confrontation, but later Newton stood at the top of the physical arena and became the overlord of one side. The particle faction behind
him also benefited from it, and the wave faction was rubbed on the ground for a hundred years.
It is said that Newton even wrote a best-selling book after Hooke’s death to publicize his optical research.
At this time, the wave faction is leaderless, and none of them can fight, which makes them powerless to fight back. Is
that particle really unshakable?
The second stage: the wave faction counterattacks the geomantic omen turns, after more than 100 years, the wave faction appeared a British ophthalmologist, single-handedly challenges the authority.
This man was Thomas Young.
It is said that Yang Shaoxia is also a genius. He read books at the age of two, recited poems at the age of four, finished reading the Bible twice at the age of six, and was proficient in many languages at the age of fourteen.
Originally thought that a generation of literary giant was born, but who knows that Yang Shaoxia went astray, willfully chose to change his major, and began to study optics.
Then he did an experiment casually, and accidentally went down in history.
This is the famous Young’s double-slit interference experiment.
The experiment is actually very simple, just need: If Newton is right, light is really a particle, even if it goes straight through the first door.. They will also hit the second wall because they are too upright.
So in theory, it should be dark on the final screen.
But actually? What
finally appears on the screen is light and dark stripes.
This means that light is not a particle at all, but a wave! Xiao Yang’s small eyes narrowed! Isn’t this evidence for the volatility school?
Sure enough, as soon as the results of the experiment came out, the irrefutable evidence caught the particle faction off guard, and the wave faction rose.
Later, as we all know, Maxwell predicted that light was an electromagnetic wave, and Hertz proved it with experiments, which convinced the particle faction.
Does it seem that the matter of a wave alone has been set in stone and beyond doubt?
The third stage: Wave-particle system–the debate about the nature of light is not over. Thomas Young can’t imagine that after another hundred years, his name, Shaoxia Yang, is about to be lost.
In response to the fluctuation, several grandfathers stood up to express their disapproval.
This not only explained the nature of light, but also created a new theory that shocked the physics community-quantum theory. What
exactly is going on?
Let’s push the camera forward. At
that time, Hertz not only verified the electromagnetic wave, but also saw a magical phenomenon.
This phenomenon of running at the sight of light is the photoelectric effect.
In addition, to be precise, when Hertz did the experiment, he had not found electrons.
He just saw that when the metal plate was illuminated, it would be positively charged.
The phenomenon quickly grabbed the headlines, and scientists flocked to join in the fun, but it soon became clear that classical physics didn’t make sense here at all! According to the theory of classical physics, if light is a wave and high-energy light shines on atoms, electrons will run very fast! If it’s a moronic light, it doesn’t matter! Waves are characterized by continuous energy.
Light waves can stimulate electrons continuously, and energy can accumulate, so as long as they endure for a long time, electrons can accumulate enough energy to run away.
But the theory is the theory, but the experimental result is not like this! Judging from the results of the experiment, no matter how long the low-energy light shines, the electron is like a nail house, not running is not running! How can this be explained? Einstein, who
loved hot spots, was lost in thought.
Just when he was puzzled, he suddenly glanced at a handsome boy with his big eyes: Max Planck, the grandfather of quantum, a German, who could play, sing and compose music, and was an ordinary handsome man.
Originally, he could be a winner in life and go to the peak of his life by his appearance, but Pu Shuai was very self-willed and had to rely on his talent.
When he was just preparing to make his way in the world of physics, a physics teacher once advised him: Just kidding, in fact, the physicists at that time thought that the physics world was almost bald by research, and the few hairs left were dispensable.
But Planck did not believe in this evil.
Although Pu Shuai’s appearance has dropped all the way, his academic achievements are advancing triumphantly.
And the subject of his research is one of the two dark clouds-what exactly is blackbody radiation, which is too complicated to explain. Brother Hun Zi will not expand here. Those who are interested can understand it by themselves.
But what we have to remember is that in order to explain this problem, Planck came to a conclusion that impacted the three views.
It is said that in the world view of classical physics, people think that energy can be infinitely divided.
But in order to explain the blackbody radiation, Planck made a bold assumption: energy can not be infinitely divided, cut to the minimum to jam! The smallest unit that can not be divided again, Planck called it energy quantum, that is, the embryonic form of quantum.
With this assumption, the problem of blackbody radiation can be perfectly explained.
But at that time, it was still the world of classical physics, and Pu Shuai’s theory was undoubtedly regarded as a devious way, and he himself did not believe it.
Even after many years, he was trying to hit himself in the face, trying to overthrow himself.
But he never thought that the thing he mentioned casually was quite good, and he was not careful to provide Xiao Ai with the idea of solving the photoelectric effect.
As we mentioned earlier, there is a problem left in the photoelectric effect: why do some light waves shoot long enough and accumulate enough energy, but they can’t shoot electrons?
Seeing Pu Shuai’s energy quantum hypothesis, Xiao Ai had a flash of inspiration: there is only one truth! Light may not be a wave, but a particle! Ha, what do you mean?
For example, if light is a wave, it will exert continuous energy on electrons, and the energy will accumulate, and the electrons will move.
But if light is a particle, the energy it produces is not continuous, but one by one! If the energy of light is not strong enough, the electrons will not go away.
As long as the energy of light is strong enough, it will make electrons run away! Einstein called this kind of light a quantum, or photon for short.
Einstein’s hypothesis perfectly explains the problem of photoelectric effect.
Soon after, Millikan, an American scientist, completed an experiment to verify the photoelectric effect, which was completely consistent with Einstein’s theory.
Einstein won the Nobel Prize in Physics in 1921.
Love sauce is also known as “back to the point” because it carries forward quantum theory.
According to Xiao Ai’s theory, light has changed from a continuous wave to a discontinuous particle, which proves that Newton is still right?
Since Young’s double-slit interference experiment proves that light does have fluctuations, and the photoelectric effect experiment also proves that light does have particles.
Einstein put forward the light quantum explanation of photoelectric effect, which made scientists at that time gradually realize that light has the dual properties of wave and particle at the same time.
This is the legendary wave-particle duality.
This is like describing a person who is both a man and a woman. What is
more frightening is that this conclusion is not a fantasy, but a precise experiment by scientists, which is effective.
Since light has wave-particle duality, a scientist has further speculated on this basis and put forward a bolder conjecture.
This man is the French nobleman de Broglie. How far is Prince
De’s brain out of line?
In his view, wave-particle duality is not the unique secret of light.
Like atoms, electrons, and even everything in the world, there is wave-particle duality! That is to say, the physical particles you think are actually fluctuating.
Such waves are called matter waves, or de Broglie waves.
Although Prince De initially made irresponsible guesses, scientists later confirmed with experiments that many microscopic particles have the properties of waves.
This also confirms de Broglie’s conjecture.
All microscopic particles have wave-particle duality! So later scientists studied the state of motion of microscopic particles.
This leads to a new theory, which is legendary-quantum mechanics. After the establishment of quantum theory, it became a hot subject for a while, and many people began to study quantum mechanics.
There is a particularly powerful school of thought called the Copenhagen School.
All right, let’s get down to business. If
quantum theory wants to study the motion state of microscopic particles, it must choose a research object.
But this time, instead of studying light, scientists have turned their attention to a new object-electrons.
In view of the movement of electrons, two great gods in the Copenhagen School have put forward two views that make people doubt life.
Let’s talk one by one. 1.the
uncertainty principle a long time ago, there was an old man named Rutherford who painted a picture of an atom.
In his view, everything in the world is common, such as the relationship between nuclei and electrons, which should be similar to the relationship between the sun and the earth.
This is Rutherford’s “atomic model of the solar system,” in which electrons revolve around the nucleus.
Later, his apprentice made some additions on the basis of this model.
This disciple was Bohr, the leader of the Copenhagen School. Yes
, the one mentioned earlier.
In Bohr’s view, everything in the world is common, such as atoms, which are actually similar to the ring road in Beijing. There are fixed orbits
outside the nucleus, and electrons will run around the nucleus in different orbits. Is
the movement of electrons really like this?
Later, scientists found that Bohr’s atomic model was not very reliable through experiments.
So a scientist came forward.
He thought that the orbit could not be seen or touched. Could it be Bohr’s imagination that it did not exist at all?
This is Heisenberg of the Copenhagen School.
He proposed matrix mechanics and established himself as the “father of quantum mechanics.”.
So in the eyes of Dad Hai, how do electrons move?
In other words, at that time, some scientists observed the position and velocity of electrons through experiments.
Based on these data, Heisenberg summarized a set of theories.
He felt that the electronic thing was very coquettish, to what extent?
It’s like a ninja of social phobia.
Electrons do not run around the nucleus honestly according to the orbit, but are extremely self-excited, jumping randomly outside the nucleus.
You can’t figure out its routine at all.
What’s even more amazing is that when we want to know its exact location so that we can observe it, it suddenly stops and its face is covered.
So we can never know the position and momentum of an electron at the same time when it is not observed.. This is the uncertainty principle.
Although it is difficult to understand, scientists have proved that the uncertainty principle is reliable through experiments.
One of the most famous is the electronic double-slit interference experiment designed with reference to Young’s double-slit interference experiment.
We shoot electrons at a baffle with two slits.
Because the electron is wavy, it will diffract and eventually appear as bright and dark stripes on the screen.
But once we want to observe how electrons pass through these two holes, the experimental results have changed! It doesn’t travel like a wave, it travels like a particle. There are only two bright lines on the
screen.
Isn’t it amazing! At the same time, the wave-particle duality of microscopic particles is further verified by the double-slit interference experiment of electrons.
That is to say, the state of microscopic particles has both fluctuation and particle nature.
Since the movement of electrons is so magical, is it really so arbitrary?
2. Probability explains that at the same time as Heisenberg, another scientist came to a similar conclusion from another angle.
He was Schrodinger, one of the founders of quantum mechanics.
This person’s gender is male, and his hobby is female. He is the only scum man in the physics world. He is given the nickname: scum Xue. If there are too many scum, he will not be allowed to broadcast. The theory proposed
by Zha Zha Xue is called wave function, and we will not expand on it.
Why not expand it?
Because even he himself was so confused that he could not say why.
Fortunately, another big bull of the Copenhagen School, Born, stood up for him.
Born explained the wave function in this way: In fact, the position of the electron is a mass of probability, which is random and not human.
However, although we can not determine its position, the probability of electrons appearing in each position can be calculated.
This is the probabilistic interpretation proposed by Born.
To sum up, the uncertainty principle and probability interpretation together constitute the core of quantum mechanics-the main content of Copenhagen School interpretation.
Although this explanation perfectly solves many problems, everyone’s three views are really crushed.
So there are doubts, and many people say that it’s nonsense to say that the motion of microscopic particles is random! As a result, the supporters and opponents borrowed several times to build the League and fought several times.
Let’s look at the key points several times.
First, the first appearance of the Fifth Solvay Conference was the Copenhagen School led by Bohr.
The other side, led by Einstein, questioned the research of the Copenhagen School, and we called them the radical school.
There is also a group of onlookers, all of whom are big names.
All right, here we go.
The two sides had a heated discussion on whether the motion of microscopic particles is random or not.
Anyway, there is no result after talking for a long time, and no one can convince anyone.
Put in a word. After
a quarrel, there was no conclusion. They felt that they were idle anyway, and it was rare to get together, so they sat together in rows and took a group photo.
Yes, this is the famous picture.
Later, the God of love and the God of glass quarreled several times, but there was still no result.
Of course, not only did the elder brothers take the lead in pinching hard, but also the younger brothers were not idle.
As Einstein’s younger brother, Schrodinger also stood up and criticized the Copenhagen School.
He came up with a crazy thought experiment-Schrodinger’s cat to explain briefly.
But once they decay, they trigger the hammer, break the poison bottle, release the poison gas, and poison the cat to death.
So Schrodinger believes that, according to the Copenhagen School, if the atom is in a superposition state, the cat should also be in a superposition state of both dead and alive.
To earthlings, a cat is both dead and alive, which is impossible to understand.
So Schrodinger thinks that the Copenhagen School is ridiculous and is talking nonsense. Later,
of course, people found that the experiment was not rigorous and there were many problems, so they could not refer to it.
Having talked so much, in fact, the debate about quantum mechanics has not ended until today.
But according to some later experiments, the theory of the Copenhagen School is more tenable at present. Compared
with the theory of relativity, the development of quantum mechanics has brought about tremendous changes in human civilization in the past 100 years.
For example, chip, nuclear magnetic resonance, superconductivity, laser and other technologies are developed on the basis of quantum mechanics.
However, science is also a double-edged sword. Using quantum mechanics, human beings have also created some strange things, such as: OK, the story of quantum mechanics is here, and the main part of our history of science is here.
Finally, we use a picture to summarize the development structure of the whole history of science.
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