06-28-2011, 08:03 PM
I'm rereading Brian Greene's "The Fabric of the Universe". I like it because he explains the physics of space, energy/matter and time pretty well without getting into too much math (which, in quantum mechanics and relativity theories, is way, way over my head). One of the things that I'm really curious about is how the planck constants that he mentions, e.g., planck length and planck time, are "derived" (if that's the right term). I've tried to do internet searches, but usually all I get are sites that explain how planck constants are used - which I kind of understand - not how they are derived. How did Planck come up with the constant(s)? Is it some kind of ratio? If so, a ratio of what to what?