Sixth lecture advanced quantum mechanics
was given in exceptional circumstances of fair weather. I could not recall this occasion for the last lecture before the semester break for all years of my service. Believe me or not, I managed to say more than I was going to. We have started with e.m. field as collection of classical oscillators, a debt from the weeks past. I gave the material in more or less reverse order: first explained the result of the activity, them the activity. Unexpectedly, this appeared to be rather convenient, and I moved reasonably fast. I wonder if the students liked it, yet they did not protest. So accelerated, we have accomplished our main task: field quantization – just before the semester break.
I expected the classical oscillators to be the most boring part of the lecture. Unfortunatelty, I was wrong. The most boring part appeared to be the last one where I talked about zero-point energy, uncertainty relations and vacuum fluctuations. I do not know why. Usually it’s rather interesting, since it goes over "fancy" subject the students have heard about but would like to hear more. Usually the audience is more interested so I also talk in more detail. Perhaps it was unwise to hurry up with this, I could have postponed the discussion till the second half of the semester. However, it’s done, and frankly I am happy to get over with.
There was an interesting discussion afterwards. The idea of a student was that the uniform mass background arising from the zero-point energy should lead to a uniform gravitational potential. So no gravitational field would have been felt. We had to write down an equation to figure out that it can not be true: the gravitational potential from a uniform mass distribution can not be uniform. Yet perhaps such reasoning is a step towards true solution of the problem?
