A Survivor’s Guide to Quantum Physics

As a pointer, and a service to other amateur physicists, I thought it would be useful to sum up the main pitfalls and discoveries I stumbled upon while working my way through Feynman’s Lectures. I call it a Survivor’s Guide to Quantum Physics because – at times – it did feel like going through a jungle, or wading through deep water, or climbing a mountain for which there is no map. Indeed, while there is a tendency to present quantum physics as a coherent set of principles and theory, it is not. At best, it is a toolbox with some novel mathematical techniques, approaches and models. At worst, it tries to present itself as an alternative to classical physics, which it is not. Quantum physics is, in essence, a combination of Maxwell’s equations and the Planck-Einstein relation. That is it. Nothing more. Nothing less. In the QED sector, at least. The one and only quantum is Planck’s quantum of (physical) action, and its physical dimension – a force times a distance times a period (cycle time) – is, unfortunately, not always well understood by those who are supposed to understand it – which is why there is a lot of nonsense around. In short, we hope this short paper might help you to avoid the mistakes I made, and that is to waste time on things you should not waste time on: stuff that is not useful, or plain wrong even. And then I will also try to highlight the little shortcuts or visualizations that may help you to get a much more intuitive grasp of things.