## Tuesday, November 13, 2007

### What was the favorite invention from your childhood?

Damien Mulley the info king for all things blogging informs us that Science Week Ireland is running a competition of blog posts. To write about various science topics. Now I am not the kind of person they want entering this. Science Week is about promoting science getting young people to think of doing it and others to be interested in doing it. Considering that I am doing a PhD in Physics it is already to late for me to be influenced but they are offering a Wii everyday this week so thought I am unlikly to win as I am going to dive straight into nerd anyway and not have some great poetic story of my youthful brush with science anyway. Here is make answer to the question.

What was the favorite invention from your childhood?

One Christmas I got a torch amongst other things but it is the torch that sticks out of my mind. I used to run around the house in the dark thinking I was in the x-files (really Famous Five but in retrospect X-files far cooler) solving mysteries and that sort of thing for hours on end. Annoyed when anyone came into the hall and turned the lights on. I always remember looking at the torch an wondering why it worked why it gave light. I used to sometimes just sit and look at it turning it on and off thinking that if I just caught it before it went too bright I might discover the reason why it worked. Alas I never did see anything but I did learn how it worked.

But it is with good reason that I did not figure it out. Because I great many people have wondered that question and not really until quantum physics was first devised did people really understand why. It is basically Black Body radiation. Black Body radiation comes mainly from a Danish Physicist by the name of Max Plank. (Some say that is Enda Kenny’s and Pat Kenny’s true surnames anyway Picture on the right). Basically this is how it works. In an Atom the electrons going around the atom have different energy states. Think of it like a ladder.

So an electron is standing on the bottom step of the ladder. Then someone heats the floor. Depending how hot the floor is he will jump up higher. (remember your Warner Brother cartoons). Basically the more the heat the more the energy the higher up the ladder he can get. Also the electron has to stand on a step he can not float in mid air between steps. These different steps which are different energy levels they are quantized. Hence we have the term Quantum Physics (which is the study of the very small because very small things are ultimately quantized they can only exist or be with in certain slots) Now the electron is scared of heights so does not like being up on a high step it is unstable. But to drop down to safety it has to lose the energy that it gained by jumping up. (If you take the real world situation of the ladder the same thing applies the person would have to lose energy to fall. In the form of causing the air to move, sound when hitting the ground etc. ) So to do this it emits a photon of light. The frequency of this light is dictated by E =hv. Where E equals energy and v is frequency of light and h is planks constant. Thus more energy higher frequency. By admitting this light the electron drops back down to the stable lower level. Here is Planks Law equation that governs it encase you are interested. Wikipedia explains it.

$I(\nu,T) =\frac{2 h\nu^{3}}{c^2}\frac{1}{ e^{\frac{h\nu}{kT}}-1}.$

This is how a light blub works. The current from the battery heats up the wire (reason why we have energy saving light blubs as most of the energy is just used as heat not light.) and the electrons go up to higher energy levels and drop down emitting photons emitting light. The light bulb was not really invented by Edison. He merely made it practical. The first incandescent light source (As normal light bulbs are) was by Humphry Davy in 1802.

It is hard to pick one favorite invention from when I was a child, indeed it is a very strange question. Much of what you had as a child you took for granted. The car is a great invention but I never thought of it was a great invention it was just a car. But that is the great thing about science. You can sit and ponder the workings of a torch. Read up on it study quantum mechanics. Work through the pages of equations that govern it. Know how it works on a quantum level and marvel at the wondrous complexity of it all and how it can be described on a piece of paper with numbers. (more numerous pieces of paper and letters) Or you can just use it and be a kid in your hallway trying to catch the smugglers under the telephone chair.