Fermi hit the rabbit with her car | I read

Text/Zhou Jie (Senior Media Person)

Fermi drove to work And hit / The rabbit ran / Thanks to a bunch of good colleagues / Invited him to dinner and suppressed the shock Well / He said / They are building atomic bombs / They are all in the wilderness / They are running everywhere / They are all scientists / They have all crashed with rabbits / So, ask: Can you calculate the number of rabbits from the frequency of collisions?

Singing here, I have to tell the background of the story. During World War II, Fermi was responsible for the design and construction of the U.S. atomic bomb nuclear fission reactor, which was confidential, the design room and the manufacturing plant had to be placed in a very remote place, and there had to be a considerable distance between the two places, so Fermi had to drive back and forth from the design room to the manufacturing plant, passing through a large wasteland, and from time to time there were hares on the road to sing children's songs: I am not afraid of the car coming, I have a fight with the car.

The group led by Fermi naturally gathered the elite of scientists from all over the world, circled in a small range, in addition to the atomic bomb can not do anything else, can not contact with the outside world, lack of entertainment, a long time, it is a little boring, so everyone uses the time to eat nonsense, and afraid of thinking rusty, around the world to find some fun to do some ideological gymnastics. Fermi said that the car accident, everyone had this experience, so Fermi wrote a question for everyone:

Based on the speed of the vehicle and the number of rabbits that hit, the number of rabbits per square kilometer is estimated based on probability and reasonable assumptions.

This topic contains physics, mathematics, probability, inference, estimation and other elements, very challenging, is idle head closed door closed scientists come to the spirit, one by one brain holes, not only have to answer, but also intensified, ask more similar questions, such as:

How many piano tuners are there in Chicago? How much turf does a soccer field have to be laid?

These strange problems are summarized and called "Fermi problems", reflecting the curiosity and thinking games of scientists in their spare time.

Scientific research has a grand motive for the benefit of mankind and the help of the country, but in the final analysis, it is still a personal interest and hobby, and I can't help but be curious about what I don't know, and I can't help but give an explanation to what I don't know, which is the driving force of scientific research. Curiosity, to answer, it becomes a kind of thinking game, good scientists must not be able to play, can not help but have fun, everywhere brain games ox knife small test, bring themselves great pleasure, but also let everyone deeply infected people.

The infection also included Fermi's wife, who, although a layman, could not help but record one thing in her memoirs:

Fermi and his wife hiked in the countryside, suddenly stopped, bent down, and brought the narrow pointed nose close to an ant nest, muttering to themselves, "How many brain cells are working to build this nest?" In terms of brain mass units, do ants do more or less work in their brains than human brains? "Then take the slide rule out of your pocket." Let's see... In a cubic centimeter of neurons..." After a moment's effort, he looked up at his wife with a look of devotion, "I have figured out the answer." What about you? ”

The place where the ellipsis is estimated to be a large amount of principle data that the wife cannot understand and cannot remember, but this matter is enough to shock her for a lifetime, the brain circuit of the scientist thinking about the problem is really different from ordinary people, and the vision of the scientist who finds the problem is really different from ordinary people. Fermi's wife's memoir is called "Atoms in My House," and "atom" contains at least one layer of meaning, as Bohr puts it, "Whoever says he understands atoms must be talking nonsense." "A wife wants to understand a scientist husband just as a scientist wants to understand atoms.

The "Fermi problem" is probably only equivalent to the scientist's idleness in making the mind take a vacation in the midst of complexity and dullness, but it is this leisure that makes the strangeness of scientists in the eyes of ordinary people become the funny style of scientists, and even the direction of the wind - a casual sentence, subverting human cognition.

Or Fermi. Once, when scientists relaxed and chatted, they talked about extraterrestrial life, and the conversation was warm and wonderful. The next day Fermi had lunch, looking confused, and suddenly asked, "Where are we all?" This caused the people around him to laugh, and Teller recalled, "This question is a ridiculous question, no head and no brain, but everyone immediately fell into contemplation." The question was later extended to the "Fermi paradox": if alien civilizations did exist, some of them should have existed long enough, extremely intelligent, highly developed, and should already have the ability to travel in space. Earth and human civilization have existed for so long that they should meet their ships. But that didn't happen. Why? It has sparked a series of thoughts such as whether there is intelligent life on other planets, where they are, why we can't detect any of their signals, and so on. The "Fermi paradox" has been a hot topic of debate in the astronomical community since the 1960s in the search for alien civilizations. Especially in science fiction movies, the "Fermi paradox" is always on the lips, showing that although we do not understand science, we still know how difficult it is. It's the same as dragging "Schrödinger's cat" in his arms.

I often think that the reason why Fermi is known as the last master to combine experiments and theories is that he is profound in his theory, but he never lets go of any practical problems, no matter the size of the problem, no matter the physics and mathematics it contains, deep or shallow, as long as it is interesting, you can make yourself sharp in the exercise of thinking, happy, you can't help but put it forward, to solve. This also makes Fermi a rare scientist in the history of modern science who is both humane and serious and lively, and he lets us see the "whimsy of uncle science" instead of "weird".

Reading List:

The Autobiography of John Wheeler: Witnesses to The History and Future of Physics by Wheeler/Fowler translated by Chengzhi Cai, Shantou University Press

Atoms in My Home: My Life with Enrico Fermi by Laura Fermi translated by He Zhaowu/He Vinci, Shanghai People's Publishing House

"Heaven and Earth Have Great Beauty: The Great Equations of Modern Science" by Graham Famiro, editor-in-chief Tu Hong, Wu Jun, translated by Shanghai Science and Technology Education Publishing House

The Artist of Performing Science: A Biography of Sagan by Davidson by Yongning, Translated by Shanghai Science and Technology Education Publishing House

【Editor: Ye Jun】