변하는것.. 변하지 않는것.. 시간이 흘러도 변하지 않는것들... 그리고 변해가는 것들...

출처 : yudau`s cafe

 

Richard Feynman's parents were Melville Feynman and Lucille Phillips. Melville was born into a Jewish family in Minsk, Belarus, and emigrated with his parents to the United States when he was five years old. He was a business man who tried, not too successfully, many different types of business. It is clear that his talents were not in business but rather in science which was the subject that fascinated him but he never had the opportunity to make a career from it. Lucille Phillips was born in the United States into a Jewish family. Lucille's father had emigrated from Poland and her mother also came from a family of Polish immigrants. She trained as a primary school teacher but married Melville in 1917 before taking up a profession.

After their marriage Lucille and Melville Feynman moved into a Manhattan apartment and, in the following year, their first child Richard was born. Melville wanted his first child to be a son and he also wanted him to become a scientist so, overjoyed when he got the son he wanted, he did all he could to interest Richard in science throughout his childhood. Gleick writes [6]:-

Melville's gift to the family was knowledge and seriousness. Humour and storytelling came from Lucille.

Tragedy struck the family when Richard was five years old for Lucille and Melville had a second son who died when four weeks old. It meant that a sadness fell over the household which must have greatly affected the young Richard. After this, he remained an only child until his sister Joan was born when he was nine years old. The family moved several times during these years but when Richard was ten they settled in Far Rockaway.

Richard, or Ritty as his friends called him, learnt a great deal of science from Encyclopaedia Britannica and taught himself elementary mathematics before he encountered it at school. He also set up a laboratory in his room at home where he experimented with electricity. In particular he wired circuits with light bulbs, he invented a burglar alarm, and he took radios apart to repair damaged circuits. When he entered Far Rockaway High School his interests were almost entirely mathematics and science. He found little liking for arts type subjects at this time [4]:-

I always worried about being a sissy; I didn't want to be too delicate. To me, no real man ever paid any attention to poetry and such things.

At school Feynman approached mathematics in a highly unconventional way. Basically he enjoyed recreational mathematics from which he derived a large amount of pleasure. He studied a lot of mathematics in his own time including trigonometry, differential and integral calculus, and complex numbers long before he met these topics in his formal education. Realising the importance of mathematical notation, he invented his own notation for sin, cos, tan, f(x) etc. which he thought was much better than the standard notation. However, when a friend asked him to explain a piece of mathematics, he suddenly realised that notation could not be a personal matter since one needed it to communicate. He really enjoyed mathematics competitions and was a real star in his school. In his final year at Far Rockaway High School he won the New York University Math Championship.

After leaving school he applied to several universities to study there. One would have expected every university to which he applied would enthusiastically offer him a place but it was not that easy. Although his grades in mathematics and science were outstanding, he had performed much less well in other subjects. There was also the "problem" that he was a Jew, which really was a problem in the United States at this time with universities having quotas on the number of Jews they admitted. He sat an entrance examination for Columbia University and they turned him down. He never quite forgave them for charging him 15 dollars and then rejecting him. He was accepted, however, by the Massachusetts Institute of Technology.

He entered MIT in 1935 and, after four years study, obtained his B.Sc. in 1939. He went there to study mathematics but, although he found the courses easy, he became increasingly worried by the abstraction and lack of applications which characterised the course at this time. He read Eddington's Mathematical Theory of Relativity while in his first year of studies and felt that this was what he wanted from mathematics. His mathematics lecturers presented him with the view that one did mathematics for its own sake so Feynman changed courses, taking electrical engineering. Very quickly he changed again, this time moving into physics. It is interesting to think that had Feynman taken the mathematics course at Cambridge which Hoyle took around the same time, he would have found it exactly what he wanted.

The physics course that Feynman took at MIT was not the standard one. He took Introduction to Theoretical Physics, a class intended for graduate students, in his second year. There was no course on quantum mechanics, a topic that Feynman was very keen to study, so together with a fellow undergraduate, T A Welton, he began to read the available texts in the spring of 1936. Returning to their respective homes in the summer of 1936 the two exchanged a series of remarkable letters as they tried to develop a version of space-time where (quoted from one of the letters - see [6]):-

... electrical phenomena [are] a result of the metric of a space in the same way that gravitational phenomena are.

By 1937 Feynman was reading Dirac's The principles of quantum mechanics and seeing how his highly original ideas fitted into Dirac's approach. In fact Dirac became the scientist who Feynman most respected throughout his life.

We mentioned above that Feynman went home for his vacations. In fact he applied for summer jobs at the Bell Telephone Laboratories every summer but was always refused a position there despite the highest recommendations. Although it can never be proved, there seems no other reason that he would be turned down other than that he was Jewish.

As he approached the end of his remarkable four undergraduate years at MIT he began to think about studying for his doctorate. Since he had been so happy at MIT and also believing it to be the leading institution, he approached the head of physics, John Slater, requesting that he stay on to take a Ph.D. course. Slater told him that for his own good he had to move and he suggested Princeton.

Despite the personal recommendation that Harry Smyth at Princeton received from Slater, it was not obvious that Feynman would be accepted. He had the best grades in physics and mathematics that anyone had seen, but on the other hand he was close to the bottom in history, literature and fine arts. He had one other thing going against him - namely that he was Jewish. Smyth wrote:-

Is Feynman Jewish? We have no definite rule against Jews but have to keep their proportion in our department reasonably small because of the difficulty of placing them.

After further letters from Slater, Feynman was accepted by Princeton. His doctoral work at Princeton was supervised by John Wheeler, and after finding the first problem that Wheeler gave him rather intractable, he went back to ideas he had thought about while at MIT. The first seminar that he gave at Princeton was to an audience which included Einstein, Pauli and von Neumann. Pauli said at the end [4]:-

I do not think this theory can be right ...

In retrospect, Feynman thought that Pauli must have seen difficulties at once, for after Feynman had spent a long time working on it, he too thought that it was not satisfactory. However, he then went on to develop a new approach to quantum mechanics using the principle of least action. He replaced the wave model of electromagnetics of Maxwell with a model based on particle interactions mapped into space-time. Gleick writes [6]:-

This was Richard Feynman nearing the crest of his powers. At twenty-three ... there was no physicist on earth who could match his exuberant command over the native materials of theoretical science. It was not just a facility at mathematics (though it had become clear ... that the mathematical machinery emerging from the Wheeler-Feynman collaboration was beyond Wheeler's own ability). Feynman seemed to possess a frightening ease with the substance behind the equations, like Einstein at the same age, like the Soviet physicist Lev Landau - but few others.

He received his doctorate from Princeton in 1942 but before this time the United States had entered World War II.

Feynman worked on the atomic bomb project at Princeton University (1941-42) and then at Los Alamos (1943-45). When he was approached during his final year of research to take part in the project his first reaction had been a very definite no since he was entering the final stages of work for his thesis at the time [4]:-

... I went back to my thesis - for about three minutes. Then I began to pace the floor and think about the thing. The Germans had Hitler and the possibility of developing an atomic bomb was obvious, and the possibility that they would develop it before we did was very much of a fright.

Feynman began work on the Manhattan project at Princeton developing a theory of how to separate Uranium 235 from Uranium 238, while his thesis supervisor Wheeler went to Chicago to work with Fermi on the first nuclear reactor. Wigner, in Wheeler's absence, advised Feynman to write up his thesis and after Wheeler and Wigner examined the work he received his doctorate in June 1942.

Feynman had a difficult personal problem at this time. His girlfriend of many years, Arlene Greenbaum, had been diagnosed as having tuberculosis and his family opposed their marriage. Shortly after he was awarded his doctorate Feynman married Arlene with no family members present. Shortly after his marriage Feynman went to the newly constructed Los Alamos site to work on the atomic bomb project. His remarkable abilities soon led to him being appointed as head of the theoretical division. Arlene died in 1945 just before the first test of the bomb. Feynman would marry twice more and have two children with his third wife.

After World War II, in the autumn of 1945, Feynman was appointed as a professor of theoretical physics at Cornell University. At first he devoted himself to teaching and put his research aside. The pressure of the work at Los Alamos, together with the personal stress of watching his wife's health decline, had taken its toll. He wrote [4]:-

If you're teaching a class, you can think about the elementary things that you know very well. These things are kind of fun and delightful. It doesn't do any harm to think them over again. Is there a better way to present them? The elementary things are easy to think about; if you can't think of a new thought, no harm done; what you thought about it before is good enough for the class. If you do think of something new, you're rather pleased that you have a new way of looking at it.

He received offers of posts at other universities but felt that as a non-researcher he could not even consider them. Suddenly the desire to undertake research hit him again and he returned to the quantum theory of electrodynamics that he was working on before World War II.

In 1950 Feynman accepted a position as professor of theoretical physics at the California Institute of Technology. Since he had already planned a sabbatical leave before receiving the offer, he was able to arrange to spend the first ten months of his new appointment in Brazil. He remained at Cal tech for the rest of his career, being appointed Richard Chace Tolman Professor of Theoretical Physics there in 1959.

Feynman's main contribution was to quantum mechanics, following on from the work of his doctoral thesis. He introduced diagrams (now called Feynman diagrams) that are graphic analogues of the mathematical expressions needed to describe the behaviour of systems of interacting particles. He was awarded the Nobel Prize in 1965, jointly with Schwinger and Tomonoga:-

... for fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles.

Other work on particle spin and the theory of 'partons' which led to the current theory of quarks were fundamental in pushing forward an understanding of particle physics.

In early 1979 Feyman's health had deteriorated and he had surgery for stomach cancer. This was very successful and his doctors believed that he would not suffer a recurrence. After his recovery he enjoyed the limelight as a famous public figure, a role which was enhanced when the book [4] became a surprise best seller. His final major task was as a member of a committee set up to investigate the cause of the explosion on the space shuttle Challenger on Tuesday 28 January 1986. The fascinating story of the science and politics of this investigation is told in Feyman's own words in [5]. It was a very difficult time for Feyman since throughout the investigation his health was deteriorating. Near the end of 1987 cancer was found again in his abdomen. After his death, Chandler wrote on 17 February 1988 in [17]:-

Feynman, who died at the University of California at Los Angeles Medical Center after an eight-year battle with abdominal cancer, was a popular and energetic lecturer who, despite his illness, continued to teach at the California Institute of Technology until two weeks ago.

Feynman's books include many outstanding ones which evolved out of lecture courses. For example Quantum Electrodynamics (1961) and The Theory of Fundamental Processes (1961), The Feynman Lectures on Physics (1963-65) (3 volumes), The Character of Physical Law (1965) and QED: The Strange Theory of Light and Matter (1985).

In [6] Gleick described Feynman's approach to science:-

So many of his witnesses observed the utter freedom of his flights of thought, yet when Feynman talked about his own methods not freedom but constraint ... For Feynman the essence of scientific imagination was a powerful and almost painful rule. What scientists create must match reality. It must match what is already known. Scientific creativity, he said, is imagination in a straitjacket ... The rules of harmonic progression made for Mozart a cage as unyielding as the sonnet did for Shakespeare. As unyielding and as liberating - for later critics found the creator's genius in the counterpoint of structure and freedom, rigour and inventiveness.

Feynman received many honours for his work. He was elected to the American Physical Society, the American Association for the Advancement of Science, the National Academy of Science, and the Royal Society of London. Among the awards he received were the Albert Einstein Award (1954), the Einstein Award, and the Lawrence Award (1962).

As to Feynman's character, he was described in [17] as follows:-

He was widely known for his insatiable curiosity, gentle wit, brilliant mind and playful temperament.

Gleick [6] describes him as:-

... mystifyingly brilliant at calculating, strangely ignorant of the literature, passionate.

Article by: J J O'Connor and E F Robertson

 

이영완 기자
2004년 2월 4일 puset@donga.com

어려운 문제를 붙잡고 끙끙대고 있을 때 미국이나 영국에서는 ‘sleep on it’이란 말을 한다. 말 그대로 한숨 자고 나서 생각해보란 뜻. 수험생들에게는 호사스럽기 그지없는 말로 들릴지 모르지만 최근 과학자들의 연구에 따르면 잠을 자는 것이 실제로 문제 해결에 도움을 준다. 독일 뤼베크대 신경내분비학과의 얀 본 박사 연구팀은 간단한 수학 퍼즐을 통해 잠을 자는 것이 문제 해결에 어떤 도움을 주는지를 알아냈다.

잠을 푹 자고 나면 골머리를 앓던 문제가 술술 풀리는 경우가 많다. 이는 잠을 자는 동안 기억이 정리되고 영구화되는 과정에서 문제해결에 대한 새로운 통찰력이 만들어지기 때문에 밝혀졌다.
실험 결과 문제풀이를 여러 번 한 다음 8시간 동안 수면을 취한 그룹이 깨어 있었던 그룹에 비해 다음 문제풀이에서 두 배 정도 우수한 능력을 보였다. 이 연구는 ‘네이처’ 1월 22일자에 소개됐다.

과학의 역사를 살펴보면 꿈을 꾸다가 문제를 해결한 경우가 종종 있다. 원소 주기율표를 만든 러시아의 드미트리 멘델레예프는 꿈속에서 원소들이 공중에서 떨어지면서 자기 자리를 잡아가는 것을 보았다고 한다. 또 프리드리히 케쿨레는 뱀들이 서로 꼬리를 물고 있는 꿈을 꾸고 벤젠의 고리모양 분자구조를 생각해냈다고 한다. 이들처럼 본 박사의 실험에서 잠을 잔 사람들은 문제 해결에 대한 ‘통찰력’을 얻은 셈.

실험에 동원된 수학 퍼즐은 세 가지 숫자(1, 4, 9)를 무작위로 배열해 8자리 수를 만들었다(예 11449494). 여기에 두 가지 규칙을 적용시켜 새로운 7자리 배열을 만들게 했다. 인접한 두 수가 같으면 다음 배열에선 그 수를 쓰고, 다르면 세 가지 숫자 중 나머지 수를 쓰는 식이다. 즉 1과 1은 1이 되고, 1과 4는 9가 되는 식이다. 퍼즐은 7자리 수로 이뤄진 새로운 배열에서 마지막 숫자를 알아내는 것이다.

흥미로운 점은 일일이 계산하지 않고도 답을 알아낼 수 있는 숨겨진 지름길이 있다는 사실. 실험 결과 잠을 잔 그룹에서는 60%가 지름길을 알아냈지만 나머지 그룹에서 알아낸 사람은 22%에 불과했다.

일반적으로 잠을 자는 동안 기억들이 정돈되는 과정이 일어난다고 한다. 낮에 본 사람이나 사건, 대화에 대한 기억들은 일단 대뇌의 해마융기에 저장됐다가 신피질로 옮겨가 영구기억이 된다. 연구팀은 “잠을 자는 동안 퍼즐 풀이에 대한 기억들이 정돈되면서 숨겨진 해법을 찾게 된 것”이라고 설명했다.

잠이 문제 해결을 도와준다는 사실은 다른 연구에서도 확인됐다. 미국 시카고대 심리학과의 대니얼 마고리아시 교수 연구팀은 알아듣기 힘든 외국어를 공부한 뒤 잠을 자고 온 그룹이 깨어 있었던 그룹보다 새로운 단어를 훨씬 쉽게 이해한다는 실험 결과를 지난해 ‘네이처’ 10월 9일자에 발표한 바 있다.

그런데 잠을 잤는데 케쿨레나 멘델레예프처럼 꿈을 꾸지 않았다면 모든 게 허사일까. 최근 연구에 따르면 일단 푹 잤다면 안심해도 좋다.

꿈을 꿀 때는 눈동자가 빨리 움직이는 렘(REM)수면 상태에 들어가게 되는데 전체 수면의 20∼25%가 이런 상태다. 과학자들의 꿈속 연구는 기억을 영구화시키는 유전자가 이 렘수면 상태에서 작용하기 때문으로 설명되기도 했다. 이에 비해 꿈을 꾸지 않고 깊은 잠을 잘 때는 뇌파가 느린 서파수면 상태에 이르며, 수면시간의 대부분을 차지한다.

그런데 최근 연구는 렘수면보다 서파수면이 기억을 정돈하고 새로운 통찰력을 얻는 데 더 중요하다는 점을 보여주고 있다.

미국 듀크대 시다르타 리베이로 박사는 쥐에게 처음 보는 물체를 보여주고 잠을 자는 동안 뇌가 어떻게 활동하는지를 살펴보았다. 그 결과 뇌의 해마융기와 신피질 모두에서 특이한 뇌파가 감지됐다. 즉 새로운 기억들을 정돈해서 영구화시키는 작용이 활발히 일어난 것. 뇌 활동이 렘수면보다 서파수면에서 더 강했다는 사실도 새롭게 밝혀졌다.

리베이로 박사는 ‘퍼블릭 라이브러리 오브 사이언스(PLOS)’ 1월 19일자에서 “서파수면의 긴 시간 동안 뇌는 개별 기억을 다시 떠올려 증폭하는 역할을 하며 짧은 렘수면에서는 이 기억들을 공고히 하는 유전자를 순간적으로 작동시킬 뿐”이라고 설명했다. 꿈꾸는 시간보다 깊은 잠을 잘 때가 뇌의 기억 기능이 활성화되는 데 더 중요한 셈이다.

공부에 지친 학생들에게 ‘한숨 자라’는 과학적 충고를 해보는 것은 어떨까.

생각해보면 나도 이런 경험이 있을듯 하다...
앞으론 어려운 문제를 풀때 계속 끙끙대지 말고 한숨 잔 다음에 생각해 보자고~~ㅎㅎ