In science, we learned that a color’s energy depends on its wavelength—that violet light with its short wavelength has more energy than red light with its long wavelength. But in art, we learned that red, orange, and yellow are warm and blue and violet are cool. Is that because of how the people feel about the colors, like fire is red and water is blue? — ON, Istanbul, Turkey
Both of your observations are correct: short wavelength light, such as violet, carries more energy per particle (per “photon”) than long wavelength light, such as red, and red light does appear “warmer” than blue light. But the latter observation is one of feelings and psychology, rather than of physics. It is ironic that colors we associate with cold and low thermal energies are actually associated with higher energy light particles than are colors we associate with heat and high thermal energies.