I read a book not long ago - "The Unbearable Lightness of Life" by Milan Kundera . I remember when I was in high school, there was a reading on the Chinese language paper. It was also about the same topic. It talked about the philosophy of life. It said that it is not scary to be heavy, but it is too light to be scary.
Actually, from some aspects, this reading makes sense. When talking about lightness and weight, we use weight as a metaphor. If we are given a scale to weigh items, heavy items will be easy to measure, even if they exceed the scale; but light items will be difficult to measure. For example, the ancients did not have a large enough scale to measure the weight of an elephant, so Cao Chong thought of using a large number of stones instead. But if a substance is too light, it's difficult to measure.
The guy we are talking about today is too light to be measured. This is the neutrino .
β-decay
Speaking of neutrinos, we must start with Pauli . Pauli was an Austrian physicist. He is best known for proposing the Pauli Exclusion Principle. In addition to this, the prediction of neutrinos is also very important.
This contribution originally came from his observation of β decay . The so-called beta decay refers to the transformation of the nucleus from emitting or capturing an orbital electron, which leads to the concept of neutrino, which is the beta-decay of releasing electrons. The process of
β-decay is actually a process in which neutrons release electrons and transform into protons. We have also said that the neutron star in the universe is actually the result of electrons being pressed into protons by huge pressure and turning into neutrons, and beta-decay reverses this process.
According to this statement, the mass of a neutron should be equal to the mass of a proton plus the electron, plus the mass corresponding to the released energy - what the hell is this last thing? In fact, it is the mutual conversion of energy and mass that Einstein's mass-energy equation refers to. The release of energy means a decrease in mass.
Energy Theft Case
However, when scientists calculated it, they found that the combined mass of the three was still a little smaller than the neutron. Or expressed in terms of energy: the energy of the original atom is a little more than the sum of the energy of the new atom and β particle . Is
the wrong number? Of course not. When detecting the spectral lines of β-decay, scientists also found something puzzling in this process. Since
is not a miscalculation, is there something wrong with the energy conservation law of and ?
uses the famous saying of Song Xiaobao : What? Are you having fun? What about energy? Lost it? Let you make it? Give me a perfect explanation! The incident of
was very sensational at the time. Some scientists really began to doubt the law of energy conservation and . Some people also gave this incident a name - energy theft case .
Pauli solved the case
The case is "established", who will solve the case?
In this regard, Pauli put forward his own point of view in 1930: He believed that an unknown particle was released during the beta-decay process. Particles like are electrically neutral and have zero rest mass, but they are not photons . Another characteristic of it is that it interacts very weakly with other particles, so it is difficult to detect it with various scientific instruments.
However, when telling this story, we actually "travelled" a bit. Because at that time, scientists had not yet fully understood beta-decay, and had not even discovered neutrons. They only knew that such particles existed. So much so that when Pauli proposed this idea, he called this predicted particle a neutron.
The moment of "slap in the face" always comes so suddenly. As recently as 1932, scientists discovered real neutrons—not what Pauli had said.
is even more embarrassing, yet to come.
"Shameful" new theory
When he proposed this new particle, Pauli himself was a little shy about it.Therefore, when announcing this conjecture, Pauli himself did not attend the physics conference, but wrote a letter and asked his friends to read it out for him. As for the reason for not attending the meeting, it was because he was going to a party in Zurich and dancing all night...
If I were a physicist present, I must have run through ten thousand alpacas at that time: par your sister ty Ah, you were having a great time partaking there, I want to kick you now...
Moreover, in the letter, he also stated: This conjecture may not be credible, otherwise why hasn't it been discovered yet?
Pauli's original letter
He even said that such particles are so difficult to detect that humans may never be able to detect them.
Other scientists were also confused: You are just kidding me by talking nonsense here and finally saying that you are not sure yet?
He doesn’t believe it, but some people do. For example, the famous physicist Fermi firmly believed in this. In 1934, he pointed out the nature of β-decay. A neutron in the nucleus decays into an electron, a proton and a neutrino through weak interaction, solving the mystery of β-decay.
Pauli was slapped in the face
Until this time, people were still dubious about neutrinos. Finally, when everyone was arguing, a Chinese scientist stood up and his theory ended the dispute. He was Wang Ganchang.
Wang Ganchang is one of the greatest scientists in our country. He has had the opportunity to win the Nobel Prize many times (we will talk about it in the future). As we just mentioned, Chadwick discovered the real neutron and won the Nobel Prize , which was inspired by Wang Ganchang. While studying in Germany, Wang Ganchang had always been fascinated by neutrinos. Even after returning to China, in that turbulent era, he still couldn't forget it.
In 1941, Wang Ganchang finally thought of a way to find neutrinos-K layer electron capture . We will talk about this method in the future. In short, it was Wang Ganchang who provided the inspiration again, and foreign scientists achieved a breakthrough. American scientist Allen used this principle to successfully prove the existence of neutrinos experimentally the following year. At this point, the neutrino was finally cleared, and no one doubted its existence anymore.
However, it was not until 1956, when American physicists Kerwin, Leins, and others conducted relevant research on the nuclear reactor that the neutrino was successfully discovered for the first time, proving its existence. The search for human neutrinos has finally come to an end. After the discovery of neutrinos, Text and Reines immediately contacted Pauli to inform him of the "good" news.
In 1958, Pauli died. In his lifetime, he saw that the particle he had hypothesized but was too embarrassed to admit was confirmed to exist, and he didn't know which one was more complicated in his heart...
So, the neutrino they discovered, and Did Pauli or Fermi describe the same thing? What are the amazing characteristics of this particle? Why can it affect the entire universe? Let’s introduce it in the next issue~
