Ever since Max Planck introduced the idea of the quantum to the world, physicists have argued about whether reality is more like sand or water. Planck’s famous 1900 discovery that energy is grainy — ...

Nearly a century after Danish physicist Niels Bohr offered his planet-like model of the hydrogen atom, physicists have created giant, millimeter-sized atoms that resemble it more closely than any ...

In 1913, Niels Bohr revised Rutherford's model by suggesting that the electrons orbited the nucleus in different energy levels or at specific distances from the nucleus. By doing this, he was able to ...