These traits are not all essential, but tend to be present in most doers of great things in science. First, successful people tend to exhibit more activity, energy, than most people do. They look more places, they work harder, they think longer than less successful people. Knowledge is much like compound interest - the more you do the more you can do, and the more opportunities are open for you. Thus, among other things, it was Feynman's energy and his constantly trying new things that made one think he would succeed.
This trait must be coupled with emotional commitment. Perhaps the ablest mathematician I have watched up close seldom, if ever, seemed to care deeply about the problem he was working on. He has done a great deal of first class work, but not of the highest quality. Deep emotional commitment seems to be necessary for success. The reason is obvious. The emotional commitment keeps you thinking about the problem morning, noon, and night, and that tends to beat out mere ability.
While I was at Los Alamos after the war, I got to thinking about the famous Buffon needle problem where you calculate the probability of a needle tossed at random of crossing one of a series of equally spaced parallel lines. I asked myself if was essential that the needle be a straight line segment (if I counted multiple crossings)? No. Need they be equally spaced or is it only the average density of the lines on the plane? Is it surprising that some years later at Bell Telephone Laboratories when I was asked by some metallurgists how to measure the amount of grain boundary on some microphotographs I simply said, ``Count the crossings of a random line of fixed length on the picture?'' I was led to it by the previous, careful thought about an interesting, and I thought important, result in probability. The result is not great, but illustrates the mechanism of preparation and emotional involvement.
The above story also illustrates what I call the ``extra mile.'' I did more than the minimum, I looked deeper into the nature of the problem. This constant effort to understand more than the surface features of a situation obviously prepares you to see new and slightly different applications of your knowledge. You cannot do many problems such as the above needle problem before you stumble on an important application.
Courage is an attribute of those who do great things. Shannon is a good example. For some time he would come to work at about 10:00 a.m., play chess until about 2:00 p.m. and go home.
The important point is how he played chess. When attacked he seldom, if ever, defended his position, rather he attacked back. Such a method of playing soon produces a very interrelated board. He would then pause a bit, think, and advance his queen saying, ``I ain't ascaired of nothin'.'' It took me a while to realize that of course that is why he was able to prove the existence of good coding methods. Who but Shannon would think to average over all random codes and expect to find that the average was close to the ideal? I learned from him to say the same to myself when stuck, and on some occasions his approach enabled me to get significant results.
Without courage you are unlikely to attack important problems with any persistence, hence not likely to do important things. Courage brings selfconfidence, an essential feature for doing difficult things. However, it can border on overconfidence at times, which is more of a hindrance than a help.
There is another trait that took me many years to notice, and that is the ability to tolerate ambiguity. Most people want to believe what they learn is the truth; there are a few people who doubt every thing. If you believe too much then you are not likely to find the essentially new view that transforms a field, and if you doubt too much you will not be able to do much at all. It is a fine balance between believing what you learn and at the same time doubting thing things. Great steps forward usually involve a change of viewpoint to outside the standard ones in the field.
While you are learning things you need to think about them and examine
them from many sides. By connecting them in many ways with what you
already know
you can later retrieve them in unusual
situations. It took me a long time to realize that each time I
learned something I should put ``hooks'' on it. This is another face
of the extra effort, the studying more deeply, the going the extra
mile, that seems to be characteristic of great scientists.
The evidence is overwhelming that steps that transform a field often come from outsiders. In archeology, carbon dating came from physics. The first airplane was built by the Wright brothers who were bicycle experts.
Thus, as an expert in your field you face a difficult problem. There is apparently, an ocean of kooks with their crazy ideas. However, if there is a great step forward it probably will be made by one of them! If you listen too much to them you will not get any of your own work done, but if you ignore them then you may miss your great chance. I have no simple answer except do not dismiss the outsider too abruptly as is generally done by the insiders.
``Brains'' are nice to have, but often the top graduate students do not contribute as much as some lower rated ones. Brains come in all kinds of flavors. Experimental physicists do not think in the same way that theoreticians do. Some experimentalists think with their hands, i.e. playing with equipment lets them think more clearly. It took me few years to realize that people who did not know a lot of mathematics still could contribute. Just because they could not solve a quadratic equation immediately in their head does not mean that I should ignore them. When someone's flavor of brains does not match your may be more reason for paying attention to them.