The Ghost of Caloric: Energy's Metaphor

Scientists actually thought heat was an invisible liquid called caloric for the longest time.

They believed this fluid flowed from hot objects to cold ones, physically pushing

particles apart to melt ice or boil water. It worked perfectly until they realized

the force used to lift weights was the same thing changing temperatures. So they swapped

caloric for energy. But here is the twist. We still treat energy exactly like that

old ghost fluid. We talk about it flowing, being stored, and moving between

systems like it’s physical stuff. We killed the theory but kept the metaphor because it just

works.