Light is very common in daily life, whether it is artificial light or natural light has a very important role in human life.
Although it looks very ordinary, it still hurts many scientists to really study it.
Light has a very important meaning for people's lives
What is the most famous of the experiments on light? That must have been a sensational double-slit interference experiment in the physics world.
What is the purpose of this experiment? The result? What is quantum entanglement in quantum mechanics? What is the difference between Bohr and Einstein's views?
The double-slit interference experiment once shocked the entire physics community, but the later Test of Bell's Inequality made human beings even more skeptical about the authenticity of the world.
What exactly is Bell inequality detection? Why is it a verdict on the reality of the world?
Double-slit experiment
Double-slit interference experiment
The physics community has long debated the basic composition of light, with some arguing that light is made of particles and others arguing that light is made of waves.
Neither side could convince the other with their own opinions, so they decided to do an experiment together to see what light was made of, which is the origin of the double-slit interference experiment.
Although many famous scientists gathered, the experiment was not so "complicated", and the experimental props were just a light, an opaque board with two neat gaps in the middle, and a screen for display.
They are placed on a horizontal line, and scientists only need to observe the shape displayed on the screen after the light passes through the double slit to draw conclusions.
Double-slit experimental setup
If two bars appear on the screen, it means that light is composed of particles, and if interference fringes appear, it proves that light is made of waves.
As a result, the experiment did not resolve the dispute between the two sides, because the experimental process actually had two different results, and the picture recorded in the camera was different from what people saw with the naked eye.
This can't help but make scientists feel terrible, can the matter that makes up light feel that it is being observed?
Although scientists later explained this phenomenon with the conclusion that light has wave-particle duality, the experiment had a great impact on the physics community.
The result of the double-slit experiment: light has wave-particle duality
Quantum entanglement
Quantum mechanics is a very mysterious theory, and almost no one can say that they understand quantum mechanics, and even scientists who have made important contributions to quantum mechanics have always stressed that they do not understand real quantum mechanics at all.
One of the biggest reasons why people can't understand quantum mechanics is its "abnormality", and many of its theories are completely different from the concepts that people understand in their daily lives, especially the phenomenon of quantum entanglement.
Quantum entanglement means that when a pair of particles is created, once the properties of one of the particles are established, the properties of the other particle are automatically revealed.
Quantum entanglement phenomenon
For example, a pair of shoes is placed at each end of the universe, and as long as it is determined whether the shoe at one end is left or right, its properties can be immediately known even if the other shoe is far away on the other end of the universe.
The phenomenon of quantum entanglement believes that no matter how far away things are, they can be inferred by the properties of things associated with them.
The bohr and Einstein controversy
Although Einstein was the main founder of quantum mechanics, he disagreed with many theories in this system, especially the Theory of the Copenhagen School led by Bohr.
Einstein was the main founder of quantum mechanics
Einstein believed that the properties of matter are innate, that it is always present in matter itself, and that it does not appear and change with observation.
Bohr proposed, however, that particles are superimposed in motion, and that when they are observed, some aspect of the collapse occurs, and its specific properties are determined at this time.
Most people will agree with Einstein's view, after all, according to Bohr, everything in the world appears only because of human observation, and there is no such state, which is really difficult to accept.
Bohr believed that particles are a superposition in motion
The famous Schrödinger experiment with cat thought is also considered the best counter-attack on Bohr's claim.
Schrödinger proposed that if a cat was kept in a closed container containing a small amount of radium and cyanide, the radium might or may not decay, and the decaying cat would die and the cat would survive without decay.
According to Bohr's particle superposition, the radium in the container is due to the superposition of decay and non-decay, then the cat in it is also dead and alive.
This is obviously an impossible state, and to know this result you have to open the container to be sure.
Schrödinger's cat
Einstein also agreed with the phenomenon of quantum entanglement, but he believed that the connection between two entangled quanta was inherent.
Although this interconnected physical quantity is not detected, it must exist, and it is also called a hidden variable by Einstein.
Of course, Bohr did not think so, he felt that the connection between two particles was arbitrary, there was no inherent physical quantity, that is, there was no hidden variable.
Later a man named John. Stewart. Bell's men came out and spoke his mind, proposing an inequality to determine whether a hidden variable exists or not.
John. Stewart. bel
Bell's inequality determination
In fact, Bell's inequality is two probability problems, if the left side of the equation is less than or equal to the right, then prove that the hidden variable does exist, Einstein was right; if the left side is greater than the right, it means that there is no inherent relationship between the particles, Bohr's judgment is correct.
The probabilities on both sides of the equation are the statistical results obtained when two entangled particles a and b are observed from different angles.
In fact, it is not difficult to make this judgment, if you think of a particle a as a vertical upward arrow, b particle is a vertical downward arrow, imagine that they are connected by a steel bar.
Bell's inequality
Then as long as you find out whether there is really a steel bar between them, you can determine whether the hidden variable really exists.
Because if this reinforcement does exist, then no matter how the a-arrow moves, the b-arrow will move with it, and they will always point to the opposite.
If the reinforcement does not exist, then the direction of the two arrows may change.
This experiment is actually very simple, just because it is necessary to observe and record from different angles, so it needs to collect a lot of information and data to draw conclusions.
After decades of continuous observation and analysis, scientists have finally come to the conclusion that there are no hidden variables between particles, which is consistent with Bohr's judgment.
Experiments require a lot of informational data
According to this statement, then the state of matter exists only in human observation, and virtually everything is in a superposition.
Is the world and even the universe in which we live unreal?
Moreover, the idea that there is no necessary connection between things has also challenged the philosophical connection, and the real existence of the world seems to have been judged.
If things can only be determined and existed through observation, then do our family and friends, the sun and moon in the universe also exist because they are observed by people?
The world doesn't actually exist?
Although the authenticity of the world has always been doubted, it is almost idealistic in the beginning that it is this view.
Idealism holds that all the material in the world is created by human beings' own ideas, but does not exist in itself.
Of course, this view has been stifled by materialism to almost no place, after all, materialism can produce solid evidence, but idealism cannot.
Although philosophically speaking, the nature of things is innate and has long been determined, materialism is also considered to be the main backbone of understanding and transforming the world.
Marx
But these views of quantum mechanics seem to be subverting human cognition little by little, and even the theories in quantum mechanics are developing in contradiction.
Its mysterious place is also here, and the more you look at it, the more you feel that you can't understand its inner meaning.
The question of whether the world really exists has been brought back to the table by quantum mechanics, after all, according to Marxist philosophy, time is the only criterion for testing truth, so the conclusions drawn by experiments cannot be ignored.
But if there is no inherent connection between things, as the results of the experiment say, how can this not contradict philosophical views?
There is much more to physics than to explore
Although quantum mechanics has many controversies, it is indeed a major advance in the field of physics, and scientists believe that it is a weapon for people to explore the universe in the future.
Many strange things in the universe cannot be explained by classical physics theory, and it is not known what kind of situations and phenomena will be encountered in the future, and quantum mechanics, as the main theory for studying microscopic particles, has great significance for the physics community.