The masthead quotes Keynes on Max Plank, the father of quantum mechanics. Keynes then goes on to explain why economists might be smart enough to figure out something harder than quantum mechanics. So how hard is quantum mechanics?
Economists should know a little quantum mechanics for another reason. It’s discovery is a quintessential lesson in how science works and how scientific theories evolve. Two quotes, well know to physicists, will give some idea of what this lesson teaches.
What is a quantum?
Until Plank, light was only understood to be a wave. Maxwell had written down the equations for electromagnetic waves in 1862 and then discovered they should move at the speed of light and guessed correctly that this is because light is electromagnetic waves. If the electromagnetic field is strong, the light is bright and if it changes direction at a high frequency the light is blue instead of red. (Actually the color spectrum starting a low frequencies is: radio waves, TV waves, micro waves, infra red, red, orange, green, blue, violet, ultra violet, x-rays, and then gamma rays. So Maxwell explained quite a lot.)
Since the numbers in Maxwell’s equations could be any size (the numbers are real rather than integers), light of any color could be of any brightness. Plank discovered this is not true. There is a minimum strength for each color of light. This meant there is a smallest possible quantity of red light, and a smallest possible quantity of green light. This smallest quantity is called a quantum. to be continued …
E = hν