Physicists seem to love their confusing language. Why do they associate Bell’s theorem with “local realism”? I get “local,” that maps to Lorentz invariance. But what does “realism” even mean? That’s a philosophical term, not a physical one, and I’ve seen at least 4 different ways it has been defined in the literature. Some papers use the philosophical meaning, belief in an observer-independent reality, some associate it with the outcome of experiments being predictable/predetermined, some associate it with particles having definite values at all times, and others argue that realism has to be broken up into different “kinds” of realism like “strong” realism and “weak” realism with different meanings.

I saw a physicist recently who made a video complaining about how frustrated they are that everyone associates the term “dark matter” with matter that doesn’t interact with the electromagnetic field (hence “dark”), when in reality dark matter just refers to a list of observations which particle theories are currently the leading explanation for but technically the term doesn’t imply a particular class of theories and thus is not a claim that the observations are explained by matter that is “dark.” They were like genuinely upset and had an hour long video about people keep misunderstanding the term “dark matter” is just a list of observation, but like, why call it dark matter then if that’s not what it is? They just inventing confusing terms then getting frustrated people are confused about them.