April 24 – Quantum Revolution Time!!

Posted on April 24, 2018

Can you imagine a world without GPS? Without smart phones? Without the internet? Without computers?

I can actually remember the world without most of these things - and although computers were invented before I was born, the computers that existed during my childhood were so few and so so so so so so different from the computers now, I'm going to say that I remember the world without ANY of these things!

But I'm glad we have all of those things now!

All of these technologies are made possible by quantum physics (aka quantum mechanics). And quantum physics got its start on this date in 1914, when the results of an experiment were presented to the German Physical Society. Because the scientists who designed the experiment were named James Franck and Gustav Hertz, the experiment is called the Franck-Hertz experiment.

What is the key idea of quantum physics that was presented in that paper? It is that atoms have only certain energy levels that are possible for electrons. 

You might already know that atoms have a central nucleus formed by protons and neutrons, plus an outer cloud of electrons. 

One possible way for atoms to exist would be for the electrons to be just anywhere, like an informal gathering around a street performer. A lot of scientists thought this might be how atoms worked.

Another possible way for atoms to exist would be for electrons to only be allowed in certain places - and not allowed in others. This would be akin to a stadium or planetarium, where there are certain individual seats and
nobody is allowed to sit in the aisles or cluster in the front or back for safety reasons. In 1913 physicist Neils Bohr proposed this model for the atoms. And the Franck-Hertz experiment proved his model correct!

Learn more about the quantum nature of atoms in Quantum Physics for Kids.

Light and other forms of electromagnetic radiation
also have a quantum nature rather than being, as
people sorta-kinda assumed, a continuous ray
of energy. Find out more about that here.

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