A Man of Science and Engineering in Troubled Times Wandering in the Late Qing Dynasty

Chapter 255

If there is any physical experiment in human history that is the most "scary", the double-slit interference experiment is the second, and I am afraid that no one dares to admit that it is the first.

All kinds of parallel universe explanations have come together.

Even weirder is the determinism of consciousness.

Even metaphysical explanations come out as demons.

In fact, they don't understand the essence of quantum mechanics, and only guessed after reading a few press releases.

As for the interference experiment that Li Yu wants to do, since it is a photon, it is somewhat easier to understand and accept. After all, a photon has no mass, and it is a boson in a professional way.

Later, humans also used particles with mass, that is, material particles, called fermions in technical terms, to conduct double-slit interference experiments.

The first double-slit interference experiment was successfully done using electrons.

In modern times, in 2012, single-electron double-slit interference was done.This is incredible!The so-called "horror" refers to it!
Many people who don't understand are directly led to the rhythm.

Because the photon has been accepted for quite some time anyway as a wave that can interfere.

But electrons are fundamental particles that have mass and make up matter. How could it be possible for it to complete wave interference with itself?
I can't even think of it!
Especially when the scientific community also explained it with parallel universes, it exploded directly on the spot.

Many people who don't know the truth and are "overestimated" (that is, they don't understand quantum mechanics) have started to engage in the various determinism of consciousness and metaphysical theology just mentioned, which is ridiculous.

Even all kinds of idealist theories have come, but those who really understand in the scientific community dismiss them.

Most of the time, Li Yu didn't bother to talk to these people, but would scare them with some theoretically more "scary" things.

Everyone must know about Yang’s double-slit interference. This experiment can be done by high school students, so they can talk about the double-slit interference of electrons.

This thing is extremely difficult to explain, because in quantum mechanics, particles do have wave-particle duality.

To explain the electron interference experiment, you need to know a lot of basic knowledge of quantum mechanics.

So Li Yu thought of a famous animal in quantum mechanics: Schrödinger's cat.

In fact, most people don't understand the true meaning of "Schrödinger's cat", let alone Schrödinger's really powerful wave function.

But it doesn't matter, because Li Yu didn't say that this cat is neither dead nor alive.

Because the wave function is very interesting, because according to the wave-particle duality, human beings also have wave-particle duality, that is, human beings also have the nature of waves.

So Li Yu told these smart people: According to the theory of quantum mechanics, you also have the property of waves, and matter waves are a kind of probability waves, which are the probability of matter appearing in a certain position in space.

Your wave function is dispersed in the whole space, so the probability that you may appear anywhere in the next second is the probability of appearing on Mars. Theoretically, pay attention, it is theoretical, and it is not zero.

Hearing this, the gangsters went crazy.

Needless to say, the rest of Li Yu drove these people crazy.

Let me tell you secretly here, in fact, according to de Broglie's formula, the wavelength is equal to Planck's constant divided by the momentum, and the calculated value of this wavelength can be said to be negligibly small.

According to the probability explanation of the Schrödinger equation, even if you have existed since the Big Bang, until now, the probability of you teleporting to Mars is so small that you will not appear once.

So don't worry!
Back to the double-slit interference of single electrons, this experiment has indeed touched the heart of quantum mechanics.

Many people misunderstand this experiment, and then think about which gap an electron passes through. In fact, it is wrong to think so.

The reason everyone thinks this way is because electronics are drawn as small balls in textbooks.

But in fact, what is the structure of the electron, or whether there is a lower limit to the size, until the time when Li Yu traveled, the physics community still did not know.

——Although the electron is the first elementary particle discovered by human beings, little is known about it.

In the core view of quantum mechanics, the properties of microscopic particles have no meaning when you measure them.

And it is not just a small ball, its spatial distribution is a probability distribution.

Therefore, it is impossible for you to know the actual position of the electron. If you know it, it means that you have measured it; and once you have measured it, you must have used some kind of equipment, no matter how weak it is, which must have disturbed it; and Once disturbed, electrons will only show particle properties, and naturally cannot see the nature of waves.

Although a bit convoluted, this is the core content of quantum mechanics.

It involves a lot of advanced theories such as wave function collapse, uncertainty principle and so on.

As long as you know about it, it will be mentioned later.

In a word, it is impossible for you to know the specific position of the electron, and it is impossible to know how it passes through the double slit.

That's right, I don't know!

So it's not right to discuss which slit to pass through.

When Planck heard Li Yu mention the "single photon experiment", he realized the problem, and he continued to say to Li Yu: "You know, according to speculation, please pay attention to my wording, it is just speculation, if there is such a thing as photon If there is a kind of thing, then it will only be two bright spots behind the two slits, how can there be interference patterns!"

Li Yu said: "The professor is right, so the premise of my experiment itself is that light has particle properties."

Planck frowned a little, put down the knife and fork in his hand, thought carefully for a while and said, "Are you so sure?"

Li Yu said seriously, "Yes!"

Planck's brows stretched: "Well, if this is the case, Mr. Newton will be pleased to know in heaven."

After all, Li Yu came to Europe again after traveling so hard, so he should make some big moves.

This experiment can make Einstein move faster. After all, the explanation of the photoelectric effect really establishes the particle nature of light.

That is to say, Li Yu is somewhat "advanced".

Li Yu’s previous words were very rigorous, with the prefix “single photon” followed by “double slit interference experiment”, which can be understood as assuming the particle nature of light in advance, and then proceeding from this to prove its wave nature.

Although it sounds a bit convoluted, isn't this exactly the wave-particle duality?

It seems to have turned around and returned to the original point, but the process itself is extraordinary.

Moreover, Li Yu's "photon" theory obviously fits Planck's quantum theory.

Although the single-photon double-slit interference experiment is not a very extraordinary and important experiment, and it does not seem to reach the Nobel Prize level, it is very inspiring, especially in the embryonic stage of quantum mechanics.

Li Yu's choice of this less "scary" experiment is considered "gentle" to the physics community.

(End of this chapter)