Elecrons Exist?

Electrons do everything for us. All our electric gadgets run via the movement of electrons within our wires and within our tiny chips. How were they discovered?

Briefest of histories on atomic - sub atomic physics -

Democritus of ancient Greece comes up with the idea of the atom - ‘a-tom’ in greek means un-cuttable. That perhaps if you keep cutting something into smaller and smaller bits might you come to a fundamental un-cuttable bit. The smallest Lego.

Ben Franklin shows there are two distinct kinds of charge and names them + and - . Actually, he mistakenly thinks there is one kind of charge and if an object has just the right amount it is neutral and if it has too much of it, that’s a + charge and if it is deficient that’s a negative.* He shows through his experiments that rubbing a balloon on your head is not only very entertaining but that the charges were already in the balloon and the rubbing action only separated them.

Later, with the invention of the battery, electrical current could be passed through liquids and show that there are both positive and negative charge carriers. In other words, electroplating.

So, if we are to have atoms they themselves need to be neutral as normal matter is and therefore composed of both + and - charge. Bringing us to J.J. (Say Hey) Thompson. It’s 1889 and people know of a thing called cathode rays. Hook a high voltage up to plates in a mostly evacuated glass tube and you get a green glow that emanates from the negative plate. Thompson showed that it was particles of negative charge that were emanating from the plate. By trying plates made of various materials he showed that these particles were in ALL materials and therefore a fundamental part of atoms. He even measured how much charge they must have per their mass - charge to mass ratio. 

All this to note that no one has nor will they ever ‘see’ an electron. Still, we clever creatures know they exist and how much charge each one has (thanks to Milikan) what the mass of each one is and even it’s ‘spin’ (it’s ½ but don’t go there). Thompson’s experiments have been repeated in labs (high school and up) all over the world with the same results each time. Such is the evolution of our understanding of our world. Seeing is believing is a much overused term. How about reason and repeat-ability make for believing.

(btw, there is no ‘size’ of the electron. As far as we can tell it is a fundamental point with no structure inside. This, unlike the proton which is made of even more fundamental particles called quarks. Stay tuned! )

* In Ben’s defense he was applying Ocam’s Razor - The simplest explanation is usually the correct one. Or, don’t make things more complicated than necessary. In this case, things were a little more complicated.