It's maybe worth mentioning that, pre-quantum mechanics, this was so far from being a naïve question as to be one of the motivating concerns of early-20th-centu

It's maybe worth mentioning that, pre-quantum mechanics, this was so far from being a naïve question as to be one of the motivating concerns of early-20th-century physics. It's not the same thing as, but is closely related to, the ultraviolet catastrophe (https://en.wikipedia.org/wiki/Ultraviolet_catastrophe https://en.wikipedia.org/wiki/Ultraviolet_catastrophe).