"Between themselves, a national laboratory scientist need not worry too much about money matters, while a university professor has the task of procuring funding to cover all expenses for the research and training of his or her PhD students, which is why he or she is called the boss. And once that is in hand, he or she enjoys broad latitude in deciding whatever research is to be carried out in the team."

Greater freedom always comes with greater responsibility, in the fulfillment of which personal characteristics such as charm are often as important as academic credentials.

The Princeton professor Yan, whose achievements at a relatively young age and easy grace have made her a household name in China, says that on top of academic freedom, professorship guarantees identity, without which none of her fame would have existed.

"You are your own boss, and your sense of accomplishment is fueled by your insatiable need for truth and your persistent drive to meet that need. In addition, your name in published papers entitles you to your work. With industry, you work as the member of a team and generally assume less responsibility. You may also make big contributions but are unlikely to be remembered for that."

Fei Long, who has resorted to the graph cited at the start of this article as an illustration of his own mental journey, calls the entire experience humbling.

"The more you learn, the more you are confronted with your own limitation. However, to clearly see one's potential is one thing, and to come to terms with it is another. For anyone who had made a personal commitment to expand the scope of human knowledge, to drastically adjust one's self-expectation and to re-prioritize within two or three years is emotionally demanding, even painful. For some, it could have repercussions for many years to come.

"But all this hasn't stopped the Purdue years from being my fondest memories. The impact of the education I received there is enduring, seeping into every aspect of my life. Both the problem-solving method and the self-knowledge I gained during those years have allowed me to engage more meaningfully and productively with a career and the life that has followed.

"The pains I endured were growing pains, something I have learned to embrace and feel thankful for."

And if you listen to Zhang of MIT, prolonged inner struggle is an inbuilt part of the eternal quest for knowledge.

"With science, one can only be proven totally wrong or partially right. A person without a strong, unwavering heart cannot engage for long with cutting-edge science," he says.

While pushing consistently into the unknown requires monumental drive, to think five or 10 years ahead one also needs to sustain mighty loneliness.

"You need to get to know yourself before picking a direction," Yan says. "Industry or academia: you've got to be true to yourself and feel comfortable in your own skin. When you've made the right decision, you just know it."

Sun sees learning as a lifelong endeavor that is likely to be affected by the major educational and career choices one makes, but will not be terminated by any of them.

"The discovery of one's genuine academic interest requires a long, tortuous search, during which one may falter and even get sidetracked. For those who are into serious academic study, anything short of real passion simply would not do."

Kong Wenzheng contributed to the story.