Book
The Character of Physical Law
by Richard P. Feynman · 1965 · 1 reading card
1 card
The Character of Physical Law · 1965
Quantum physics is strange, not magic: if you swap ‘quantum’ for ‘magic’ and the meaning does not change, it is not physics.
Feynman's line, ‘nobody understands quantum mechanics’, is often quoted to justify anything at all. He meant something else: the rules of the theory work with astonishing precision, but they are hard to square with our everyday intuition. ‘Strange’ does not mean ‘anything goes’. Quantum theory makes very precise predictions, and many ‘quantum’ claims in advertising and self-help books flatly contradict them. Three common abuses. First: ‘the observer creates reality’ or ‘your thoughts change matter’. You saw in the double-slit lessons that ‘observing’ means the which-path information ends up somewhere — in a detector, in a wisp of air, in an instrument with no consciousness. Second: entanglement as telepathy or an ‘energetic link’ between people. You saw in lesson 16 that no message passes through entanglement. Third: ‘quantum healing’, ‘quantum’ water, bracelets or supplements. Delicate effects such as superposition vanish extremely fast in a large, warm, wet object like the human body. There is serious quantum biology, studying for example photosynthesis or how birds navigate, but it works at the scale of molecules and publishes measurements; it does not sell products. A short checklist. Does the claim name a measurable quantity, with units? Does it cite a published experiment, with numbers? Is it trying to sell you something? Does it use ‘frequency’, ‘vibration’ or ‘energy’ without saying how much? If you replace ‘quantum’ with ‘magic’, does the meaning change at all? If nothing changes, you are looking at a buzzword, not physics. What is genuinely open is something else: what is real behind the rules. The Copenhagen interpretation says the theory only gives the odds of results. The many-worlds interpretation says every result happens, in different branches. Pilot-wave theory says particles always have a position, guided by a wave. The relational interpretation says properties exist only relative to other systems. All of them predict the same results for every experiment done so far; physicists do not argue about what works, but about what it means.
“There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. [...] On the other hand, I think I can safely say that nobody understands quantum mechanics.”