Changes

Quantum mechanics consists of the breakthrough in physics in the 1920s in understanding how particles behave inside atoms.  Classical mechanics, as initially discovered by [[Isaac Newton]], cannot explain atomic behaviour.

Quantum mechanics consists of the breakthrough in physics in the 1920s in understanding how particles behave inside atoms.  Classical mechanics, as initially discovered by [[Isaac Newton]], cannot explain atomic behavior.

Classical mechanics would predict that an electron orbits a proton just as planets orbit the sun.  Classical electromagnetism would predict that the orbiting electron would emit a time-varying electrical field just as a radio station does.  But the electron would lose energy as it emits this radiation, and would orbit closer and closer to the proton, until it collapses into the proton!  Such a model cannot be correct.

Classical mechanics would predict that an electron orbits a proton just as planets orbit the sun.  Classical electromagnetism would predict that the orbiting electron would emit a time-varying electrical field just as a radio station does.  But the electron would lose energy as it emits this radiation, and would orbit closer and closer to the proton, until it collapses into the proton!  Such a model cannot be correct.