Understanding path integralsDamn you Feynman

It starts tomorrow at 8:00 – the exam for my Quantum Field Theory course.


Quantum Field Theory has been a very absorbing course, but also a trying experience. It is probably the course I have worked with the most, ever. The bulk of the work have been hand in exercises on topics like SU(2) gauge invariance, cross sections for various scattering interactions, etc. And at some point an obser­vation from a fellow student cued this interaction with our professor.

– Problem two of the homework assignment is horrible.

– Life in general is horrible.

Tomorrow is the grand finale! No one knows really what to expect since the course has a new exam model this year. And when a single one of our previous calculations can require a couple of days of work to conclude, none of that can possibly be on a five hour exam. All we really know is that the exam will have "problems that are orthogonal to what we have done so far".

One of those orthogonal topics is path integrals. So how do one get a fundamental grasp of this involved mathematical method in a few days available before an exam? I attempted a learning technique from Feynman: explain it to someone else. So I wrote some notes about the introductory details of path integrals. Perhaps it is needless to say I didn't get very far in the limited time. But the notes could surely be useful anyway. Are you at all curious about path integrals? Download below.

Understanding QFT Path Integrals