TABLE OF CONTENTS From quantum mechanics (see page 142 if necessary), we have learned that the rules of nature only allow whole number multiples (such as 1x, 2x, etc.) of the smallest units of energy, not fractional multiples (such as 1.3x, 2.78x, etc.). A single unit of energy of electromagnetic waves such as light is called a "photon." Quantum mechanics and relativity, two powerful systems of knowledge, seem to describe separate realms of nature for the most part, only overlapping in a few places, and sometimes apparently disagreeing (or at least competing). Albert Einstein, discoverer of the rules of relativity, did not have any love for quantum mechanics, and in fact he had philosophical disagreements with some aspects of it. However, although it is not well known, Einstein actually got the Nobel Prize for discovering the "quantized photoelectric effect," which was the keystone that supported the early theories of quantum mechanics. (Surprisingly, he did not get the prize for relativity, because the judges thought his theory might be incorrect!)
The smallest unit of sound wave energy (the motions of atoms see bottom of page 212) is the phonon. In some ways the phonon, and also the electron and photon, can each behave like a wave, and in some ways each can behave like a little particle.
Just as electrons can travel long distances through a wire, photons can travel under the whole Atlantic Ocean through a glass fiber. An important modem trend is to communicate...
