Question: what does Quantum mean? :)

Joseph Finlayson answered on 14 Jun 2011:

The word quantum comes from the Latin quantus, for how much.

However, in physics it refers to the smallest amount of energy that can exist. To analogise, when we do chemistry or physics, we know that if we take a drop of water and keep dividing it in half, eventually we might get to something that can no longer be divided. This might be the molecule H2O. However, we can actually divide this further into 2 Hydrogen atoms, and one Oxygen atom. More recently (in the last hundred years) we’ve realised that we can further subdivide it into electrons, neutrons and protons – and experiments similar to Large Hadron Collider ( http://www.youtube.com/watch?v=j50ZssEojtM ) have shown that these can be further subdivided into quarks (they have silly names like ‘up’, ‘down’ and ‘strange’). However, theory holds that there is a stopping place, where you can no longer divide the particle.

Early on in the 20th century physicists found that energy (like light energy for example) works similarly. You take the energy, and you can’t keep cutting forever. There will eventually be a ‘packet’ or ‘parcel’ of energy that cannot be subdivided. This ‘packet’ is the quantum, the packets plural are called quanta. These packets exhibit very odd characteristics. They act sometimes like a wave and sometimes like a particle, depending on how they are being measured. They can appear and disappear out of thin air – and other odd things.

Hope that helps,

Joe