Energy is really weird when you stop and think about it – what is it? Matter we can all cope with, it’s solid and real. We can see the big lumps even if the things that make it are too tiny to see. We can generally cope with the paradox that 99.9% of everything even inside you is empty space, a factoid kids adore, because it makes no practical difference to our lives. But what is energy?
Energy is the mover and shaker. It does things or lets us do them. It takes the lumps of matter and changes them around so that things happen. And it comes in several flavours.
- Movement – electrons to people to planets.
- Heat – Movement too! Heat is a measure of how fast the microscopic matter is zipping around, a bit like if you run fast you get hotter but much smaller. Heat is sort of the end of all energy – it is the most common waste energy and everything is decaying slowly into heat.
- Sound – Yep, movement. This time it’s movement of things like drums or voiceboxes that push air molecules that push other molecules all the way to your eardrums, that then push liquid that pushes nerve cells.
- Electrical – Movem… well, sort of. It’s easy to understand and completely wrong to think of electricity going through wires as if the electrons are cars driving along roads. It’s more like a party with a couple of awkward guests. What happens in a battery is there is a chemical reaction at one end that produces an extra electron. There are only so many spots for electrons around any given atom so one gets kicked out. It’s attracted to the next atom, but there are too many electrons so one gets kicked out. Which one gets kicked out at each atom is up to chance, it isn’t the same poor forlorn little electron searching the whole party wire for a group atom to join. Power stations are even more fun because they use magnets to make currents! But you don’t need to know any of that technical stuff to know that electricity is pretty darn important to our lives.
- Chemical– Well since I’ve mentioned batteries and we got down to the level of atoms, I suppose I’ll have to include chemical energy as a type of movement too, but this is starting to get silly. It’s all based on chemical reactions, where atoms swap electrons or join up in new and interesting ways. Mainly we care about batteries and food.
- Nuclear – This one is actually more of a magical disappearing act. I suppose if you want to be really technical you can call it movement, but then you explain it. This is the one Einstein was talking about with E=mc2, Energy is the mass that’s destroyed times the speed of light squared, which is a very, very big number. So even when we are talking about the tiny, tiny nucleus of an atom (hence nuclear), it turns into a very, very large amount of energy. This is bombs, power stations and the sun.
- Potential – This one always feels a little bit like cheating, like it’s just there to make the numbers add up right. It’s stored energy, the stuff you know is going to go off any second now. Like the moments before the rubber band pings or Coyote runs off the cliff.
- Light – Let’s not even talk about photons. Or let’s, because this is where it get’s strange(r). Sometimes light acts as if it’s a wave, and sometimes it acts as if there is a physical particle carrying it, the photon. If photons exist, and sometimes they don’t, we don’t know what they are made of or how they actually carry said light because they don’t have mass (at least I don’t know, possibly particle physicists do). But when they hit the back of your eye they make signals your brain interprets so you don’t run into things, so it’s useful even if I can’t explain it. And then there’s the electromagnetic spectrum including fun things like microwaves and radio waves which are actually light. I think I prefer movement 😉
And just because it’s really cool, here’s a demonstration of sound as movement. A bag of rice on a board over a speaker, it’s definitely worth watching.
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