Why is it impossible to predict exactly where an electron is at a given moment?

1 Answer
Jul 29, 2014

O.K., welcome to quantum mechanics! Glad you stopped by.

Electrons are not very very tiny versions of BBs. Electrons are something for which there is no macroscopic equivalent. They sit on the border between a particle and a photon, but are neither.

The Heisenberg Uncertainty Principle says that you can know the position or the energy of an electron at any given moment, but not both. The more precisely you know the position of an electron the less you will know about its energy. The more precisely you know the energy of an electron, the less you will know about its position. Anything you do to measure either of these properties will have to interact with the electron, and as soon as you do that, you have changed the very property you were trying to measure.

These results are completely at odds with what we observe in the macroscopic world. Great minds have had a hard time with this concept. Einstein famously once said (approximate quote): "God does not play dice with the Universe." in rejecting quantum mechanics. He did not understand that just because things were expressed as probabilities does not mean they are not real, or that the probability will not happen.

Quantum mechanics is just weird!

Cheers!