A PhD degree in Physics represents a new contribution to the body of scientific knowledge; but, it is more than that. The power of new physics is not in the generation of new information, though that is one important side effect. It is the new or deeper understanding of the nature of how how things work that are its treasures. It is not a process in which a student goes through steps 1, 2, 3, 4, 5, and then is done, but a journey of exploration that often can come up empty handed. Putting in lots of time and effort is not enough. There needs to be a tangible result that adds to the corpus of Physics.
The dissertation documents the contribution a PhD student has made to science. The process of writing up ones work and results inevitably uncovers errors, weakness in logic, and oversights that need to be addressed. As such, the period of writing prior to submitting the dissertation to the examining committee is filled with stress. One never knows if the errors that are uncovered will be fatal to the thesis. Many students are unaware of the magnitude of the demands. In the end, it has to be right (internally self consistent and in accord with the rest of Physics) and the dissertation committee needs to be convinced that the work is significant enough to be worthy of a PhD.
I write this as Shiva is finishing up his dissertation and getting ready to defend. The work is excellent and I believe that it will be a major contribution to the body of Physics. We have proposed a novel model based on experimental observations that pass the test of simplicity - with only three parameters all of the data is explained over a huge range of conditions; and, it suggests new physics, namely, that a polymer mediates the interaction between molecules in a way that coerces them into healing after they are damaged by powerful laser pulses. This phenomena is new and its explanation is bound to be controversial; and it may end up being wrong...
In the process of writing his dissertation, Shiva had to make major changes to the analysis of the data, needed to take additional data, and had to take into account complications that had slipped by our attention. Each time he thought he was done, there always seemed to be one more thing to check, one more experiment to do or one more calculation to correct. I can imagine the ups and downs associated with the relief of being done followed by the anxiety over a potential error that could mean the downfall of the dissertation.
As I write this post, I believe that his dissertation is finally done, and I am comfortable with the scrutiny that is to come from the committee. There are certainly loose ends that will be addressed, but those can be completed prior to the oral or as minor revisions after the defense.
I have advised dozens of graduate students over the years. Many have vocalized the childhood question asked of parents during a long road trip, "are we there yet?" Others think about their progress quietly while some may assume that they will get a degree as a result of making an effort. In the end, only students who persevere after what appears to be endless failure and hardships will make it through to the end. The process includes hard work, independence, cleverness, deep thinking, and extreme grit. As a result, the future employer of a PhD physicist is not getting just an expert. If that is what they think, the employers miss the best part. They are getting an individual who is fearless in the face of new challenges that require a nonexistent expertise.
Expertise is stagnation. Dealing with the unknown is wrought with fear, insecurity, and doubt; but, there is an air of exhilaration from the possibility of successes. The PhD student builds problem-solving skills and the ability to think beyond his or her knowledge base and to thrive in a world of uncertainty. It is character not just expertise that the PhD represents.
The beauty of nature is that she is consistent and filled with rich and wondrous phenomena. On the downside, she holds the highest standards and is intolerant of contradiction. I am glad to have a job that allows me to be continually confused, insecure and humbled. Every new piece of knowledge or expertise gained drives me into a new unknown realm. I am simultaneously frustrated and ecstatic, perhaps a required blend of opposites that lead to fulfillment and happiness.
Having acquired a taste for this life, I wish the same for my students. As Shiva is finishing up, I look to the next generation of students coming up through the ranks in the hopes that they too will succeed.