ENERGY EXPLAINED v2.1

[Farsight]

Energy is generally misunderstood. Our schoolroom textbooks tell us that energy is the capacity to do work, and work is the transfer of energy. The words go round in circles without getting to the heart of it, and children grow into adults with no clear concept of what energy is.

 

Let’s start by saying that energy is the property of a thing. It is not a thing in its own right. To illustrate this, I can talk about a red balloon, a red bus, or a red red ruby. All these things have the property that we call red. A thing can be red, but you cannot remove this red and hold it in your hand. You can remove the paint or the dye and hold that in the palm of your hand, but you’re still holding a thing that is red. You cannot remove the red from the dye to hold the red in the palm of your hand. Even when you imagine red, the image in your mind’s eye is a thing. You always need a thing to be red. There is no such thing as “raw red”. In similar vein there is no such thing as “raw energy”.

 

 

Another illustration is money. You can spend money like you can expend energy. But the money doesn’t disappear, just as the energy doesn’t disappear. Somebody else now has your money, just as some other thing now has your energy. Think about an old house, nestled in the countryside. It’s picturesque, worth a lot of money, and it’s built out of cob. Way back when, some guy put some energy into shifting earth and straw to make the walls of this house. He did the same with the wood, which grew out of the earth because the trees put energy into shifting water and CO2. The guy made money out of that house. They paid for the energy he put into it, through the work he did moving stuff. That’s why money and energy are similar. They get things moving, they get work done. One makes the world go round, and the other one makes the world go round too.

 

 

But money isn’t what energy is, and nor is motion. You need mass and motion before you can talk about energy. Consider a 10 kilogram cannonball, in space, travelling at 1000 metres per second. We talk about how much kinetic energy this cannonball has. We talk about KE=½mv² and we do the maths and get five million Joules. But what has the cannonball really got? Its mass seems real enough, I hefted it into my spaceship this morning before I took off. And its motion seems real enough too, because one false move and it’ll be smashing through my viewscreen taking my head off. To find out more, I take a spacewalk to place a thousand sheets of cardboard in the path of my cannonball. Each sheet of cardboard exerts a small braking force, slowing the cannonball to a halt. This takes two seconds. We know that the cannonball will punch through more cardboard in the first second than in the second second, because it’s slowing down. So we deduce that a cannonball travelling at 1000m/s has more than twice the kinetic energy of one travelling at 500m/s. We can do the arithmetic for each second, then slice the seconds up finer and finer, and we end up realising that the ½v² is the integral of all the velocities between v and 0. But what we don’t realise is that kinetic energy is a way of describing the stopping distance for a given force applied to a given mass moving at a given velocity. You can flip it around to think about force times distance to get something moving. Or you can think in terms of damage. But basically that cannonball has “got” kinetic energy like it has “got” stopping distance.

 

It’s similar with momentum. That’s a different way of looking at the mass and the motion, based on force and time instead of distance or damage. We look back to our cannonball and cardboard, and we know by definition that in the first second the same amount of time passed as in the second second. So we realise that a cannonball travelling at 1000m/s has twice the momentum of one travelling at 500m/s. But what we don’t realise is that momentum is a way of describing the stopping time for a given force applied to a given mass moving at a given velocity. A cannonball has “got” momentum like it has “got” stopping time.

 

But wait a minute. I didn’t fire the cannonball at 1000 metres a second. I dropped it off at a handy spot out near a GPS satellite, then zipped off in my spaceship in a big fat loop.

 

 

It’s me doing 1000m/s, not the cannonball. The cannonball is just sitting there in space. It hasn’t got any kinetic energy at all. I’ve got it. But I don’t feel supercharged with five million Joules of energy coursing though my veins. So where is it? Where’s the kinetic energy gone? It isn’t anywhere really, because all that cannonball has got, is its mass, and its motion. And that motion is relative to me. Kinetic energy is not a thing. It’s just a relative property.

 

So, let’s examine this property. How do you make something move? Easy. Hit it with something else that moves. And how did you make that something else move? Where did it all start? I pitch you a cannonball, you whack it with a baseball bat, and it tumbles away at one metre per second. You made that cannonball move. Now, where did the energy come from to make it move? From your muscles: “The release of ADP and inorganic phosphate causes the myosin head to turn, causing a ratchet movement. Myosin is now bound to actin in the strong binding state. This will pull the Z-bands towards each other. It also shortens the sarcomere...”

 

 

It all gets a little complicated, but it’s all down to bond angles. Bonds within molecules change, and the change releases energy. Sometimes it’s a simple single change of bond angle, something like a leaf spring flattening out with a push. Sometimes there’s more than one, and the molecule resembles an elasticated deck-chair that surges from one configuration to another giving up some of the bond energy. And sometimes the molecule takes a rather different shape. A familiar shape:

 

 

They look like springs because they are springs. That’s the size of it. The energy to move your muscles is stored in tiny compressed springs. Yes, they’re electromagnetic springs rather than solid rigid springs, but that’s what all solid rigid springs are. That’s how the muscular energy is stored. It’s the same for other chemical energy, and I quote: “In the early 1980's it was pointed out that cubane's very high density and high heat of formation would make it an especially good explosive, especially if each carbon could have a nitro group attached. The resulting molecule would decompose to eight molecules of carbon dioxide, and four molecules of nitrogen, and release a lot of heat in the process. A cubane with a nitro group on each carbon is called octanitrocubane. Several factors are important in making a good explosive. The decomposition must be energetic. In cubane derivitives, the strain energy ensures a very energetic decomposition.” It’s the strain energy. There’s compressed springs in there. It’s the same with nuclear energy, only the springs are stronger. The sun gets its energy from nuclear fusion. Squeeze a couple of hydrogen atoms together and you make helium. But when you do, ping, something breaks, and things spring out between your fingers, things like photons.

 

4 1H + 2 e --> 4He + 2 neutrinos + 6 photons

 

It’s the same too for matter/antimatter annihilation. Somehow somewhere some kind of spring is letting go, and photons come bounding out at gamma-wave energies.

 

 

A photon is an interesting thing. Particle physics comes with mental baggage that says it’s a speck, a point, a particle. But we have long wave radio which reminds us that photons can be 1500m long. A photon isn’t a speck. It’s more like the slink in a slinky spring.

 

 

Only the slinky spring here is space, that vacuum void with its permittivity and permeability. A photon is a like a ripple on an electromagnetic ocean between the stars. A boat on this ocean can ride the ripple and the ripple passes on by. But tie that boat to the sea bed with a rubber rope, and you can capture the energy of the ripple, and save it in starch, or coal, or oil. You can use it to make your leaves or build your house, and whack that cannonball. It all comes down to springs. Compressed springs. The energy is in the compression. The stress. It all started at the beginning of the universe. Visualize a dark cylindrical room. You’re in the middle of it, the walls are banded and helical, you feel a tremble, and you realise with horror that the room is the biggest baddest spring you’ve ever seen. It is exerting an incredible pressure, but is bound by thick steel cables called “symmetry”. The cables are under impossible tension, and you can hear ping ping ping as individual cable wires snap. Symmetry is about to break, and you know your “prime mover” will disintegrate into a fireball of nuclear and electromagnetic springs that will go bouncing out to fill the night and make the world what it is.

 

 

The dark cylindrical room is analogy of course. Analogies are based on the things we experience with our senses, and these are not the things of the subatomic world. So analogies can be dangerous, like too much butter. But the Universe will wind down. Because the springs are not so much analogy, nor is the stress that compresses them. And that’s what your energy is. Stress is the same as pressure, which is the same as negative tension. And to quantify it we have to know that in physics stress is force per unit area, and energy is force times distance, so energy is stress times volume. So here’s the new definition:

 

Energy is the capacity to do work, and is in essence a volume of stress.

 

You know you can’t hold stress in the palm of your hand, and a volume of it doesn’t make it something you can get hold of. That’s why you can’t hold pure energy in the palm of your hand. There is no such thing as “pure energy”, just as there is no such thing as “pure pressure”. Because it’s the property of a thing, even when it’s the very last property that makes a thing the thing that it is. But you can hold energy in your hand. It’s a subtle difference, but it’s very simple. Just squeeze a fist. Use your right hand. Squeeze it tight. Now touch your left thumb to your right thumb. Feel that blood pressure. Now look at the volume of your fist. Stress is pressure, and there’s a volume of it in that fist. Your fist has energy. And if you swing that fist, it has even more.

 

As to how, it’s all to do with pushing little circles into little spirals and so making little springs. But to explain that, I’ll have to explain mass...

[Farsight]

This is an improved version of the original version, thanks for the feedback, and if you can give any more I'll be only pleased to receive it.