Let us recall that physicists observing the behavior of atoms noticed that an electron revolving around the nucleus can leap from one state of orbit to another. For example, from its lowest state, also called “ground state”, an electron can jump to a higher state if it receives the needed energy. It can also go back to the ground state if it gives off its surplus energy in the form of electromagnetic radiation.
This phenomenon is known as “quantum leap” since, according the particle physicists, they leave no traces in between states. As Columbia Physicist I. I. Rabbi remarked (quoted in Cynthia Sue Larson, 2013):
The atom is in one state and moves to another, and you can’t picture what is in between, so you call this a quantum jump. In quantum mechanics, you don’t ask what’s the intermediate state because there ain’t no intermediate state. It passes from one to the other in God’s mysterious way.
Basil F. Hiley and David Peat (2012), writing in memory of David Bohm, explained that in their conversations with Bohm, they all agreed with the idea that we do not know precisely what happens to subatomic particles in between leaps.
Physicists are finding it hard to explain the gap. In some mysterious ways, they could not find any footprints within. The electron simply disappears from one state of orbit and appears in the other station.
Albert Einstein and his colleagues Boris Podolsky and Nathan Rosen (known by their acronym EPR) tried to give an explanation to this by performing thought experiments. The results of the experiments, however, consistently defied the classical view of cause and effect. It even violated the special relativity theory of Einstein that no material particles can travel close to or faster than the speed of light.
In the deterministic and causal world of classical physics, the notion of quantum leap is simply ridiculous. Einstein labelled it as “spooky.” In his words: “I cannot seriously believe in [quantum theory] because … physics should represent a reality in time and space, free from spooky action at a distance.”
He was convinced, however, that there has got to be a solid theoretical foundation to explain this ghostly occurrence. But his time did not allow it. He passed away before a full-blown model he was searching for was discovered.