What is understanding? What is explanation?
I finally find an answer : "structure with importance". Explanation means show your interpretation of essence of knowledge of theory with its context. It seems that a lot of clever people can do that without intention, but I have to that intentionally with intensive thoughts.
Simple facts often hard to find.
Science is communication
In USA, most of the department call researchers from other institutions and listen to their seminar. I think it is good custom. On the other hand, I recently noticed that it was the true shape of science.
Most of faculty told me that they learned important things for science not just from their advisers but from other students. All of them told me that what they learn from other students are much more valuable than ones from professors.
In order to clarify what you are thinking, talking with people is very important or much more important than people expected. Advancement of science consists of a lot of communication of scientists. It means that some ideas come from conversations and problems in papers may be clarified by discussion with others. Great sciences do not mean quality of knowledge but mean quality of communication.
Advantage of study abroad
Unfortunately, I have been meeting a lot of trouble which I did not expect. On the other hand, I feel that is the huge advantage of studying abroad. In some environment, people cannot find problems which they really need to overcome from some reason. If you changed your environment radically, you often notice the problem and have to deal with them seriously.
I try not to say that studying abroad is tough because everybody has problems respectively. In addition, the problems which people have are often common to everybody. Even if I met any difficulty in my study, I am willing to overcome it. As long as I continue to study USA, I have to continue multiple efforts.
