1. ENERGY EXPLAINED v2.1

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...

2.

3. This is an improved version of the original ENERGY EXPLAINED layman's essay. Thanks for any feedback you gave, and if you have any more I'll be only to pleased to receive it.

4. Energy is the capacity to do work, and is in essence a volume of stress
*whisper* PSSST, look on relativity and you see E=MC². energy is mass*end whisper*

5. PSST: look in MASS EXPLAINED and find out why.

6. Zelos how many more times energy is NOT mass!!!!

It is equivalent to mass TIMES c squared!!

IF A = BX^2 (where X is not equal to 1)

is A = B - NO definately NOT

Now you might have read a few leaflets on Quantum do dah's but you seemed to have missed out on the basic algebra!

7. megabrain
if the formula says E=M is mass energy then?

8. equivalent yes, the same NO - think about it, the sun turns mass into energy, but the 'mass' and the 'energy' just aint the same, somehow even ol mega can see the difference between liquid hydrogen and a beam of light - you really do seem to have missed out on something, even the link I pasted of the audio of Mr A Einstein (where he says mass and energy are equivalent) you seem to have ignored.

Look a human body is equivalent to 3 or 4 buckets of water plus a bucket of trace elements but it is not the same.

EQUIVALENT DOES NOT MEAN 'THE SAME AS' !!!!!

Farsight I really don't know why you bother! - All you need do (at least for zelos) is say "Energy explained, energy = mass." - simple eh? :wink:

9. Originally Posted by Zelos
if the formula says E=M is mass energy then?
And as it doesn't, end of story, right? Megabrain is right (even though I loath his new over-active avatar).

There is, however, a neat link between equivalence and equality you might want to investigate. If you don't have books to hand, internet search on "equivalence class", or something similar. I wouldn't know, I read books, not computers.

10. Originally Posted by Guitarist
Originally Posted by Zelos
if the formula says E=M is mass energy then?
And as it doesn't, end of story, right? Megabrain is right (even though I loath his new over-active avatar).

There is, however, a neat link between equivalence and equality you might want to investigate. If you don't have books to hand, internet search on "equivalence class", or something similar. I wouldn't know, I read books, not computers.
the thing is. The REAL formula is E=M
the C² is a by product of our units

11. Guitarist, (just for you a 'quieter' avatar!).

Think about it, what zelos is saying is that e=m can be true if the units of the joule and kilogram were redefined, and, calling the speed of light 1 ... this is acceptable and would mean that e=m. I have no problem with that. It is as simple as changing the metric unit of mass Kg to the imperial one, the constant 'G' would then change by a factor of about 2.24
or so.

But as you rightly say 'equivalence' is the sticking point, 1 Kg may be equivalent to 1 Kg of feathers but only if you use the term mass. in any other way, volume, colour, texture, hardness, atomic structure etc it is different.

Zelos,

If mass and energy are identical then 1KG of sulphur is identical to 1kg of lead or butter or copper, or 1kg of anything.

12. Originally Posted by Zelos
Originally Posted by Guitarist
Originally Posted by Zelos
if the formula says E=M is mass energy then?
And as it doesn't, end of story, right? Megabrain is right (even though I loath his new over-active avatar).

There is, however, a neat link between equivalence and equality you might want to investigate. If you don't have books to hand, internet search on "equivalence class", or something similar. I wouldn't know, I read books, not computers.
the thing is. The REAL formula is E=M
the C² is a by product of our units
Erm, NO!!

The equation is E=MC2 not E=M. If ol' Albert meant E=M he would have said that. furthermore

E=MC2 isnt a real equation, all einstein was trying to say is that a large amount of energy can be converted into a small amount of mass, and reversly a small amount of mass can be converted into a large amount of energy.

I am not a mathametician so cannot work out volumes so I will be wrong in my maths (but right in the point i am about to make) ...........

1 cube metre of ice is the equivelant of 0.89 cubic metres of water. BUT...they are NOT the same.

The same can be said of mass and energy.

13. Erm no,

C^2 is indeed a quirk, as I said with the right weight designation then the formula becomes E=M.

E=mc^2 is only valid using metric units. Since c is a constant c^2 is also constant ie 9.0*10^16. replacing this with 'K' then gives E=Mk (perfectly valid as I have defined 'K'.

Now since the unit of mass here is the kg, converting to a unit of mass using the imperial ounce would give a value of 'K' around 2.5*10^15.

So if I define a unit of mass (call it a 'Zelos') and give it a value of 1/(9*10^16) Kilos then E=M ie the energy equivalent of 1 'Zelos' would be 1 joule. :wink:

It is unfortunate that people have always written the equation as E=MC^2 when the correct phrase is "Energy is equivalent to mass times the speed of light squared".

14. Okay, so shouldn't we be using the mathematical equivalence sign instead of the equals sign ?

15. The formula is used to asses energy conversion (say in the sun) - if you aint using it for this then it is best written as I previously did.

It would be more accurate to write ... Mc^2 + nuclear reaction = Energy.

Because it has an element of 'nuclear chemistry' in it!

I think!

16. Originally Posted by Megabrain
The formula is used to asses energy conversion (say in the sun) - if you aint using it for this then it is best written as I previously did.

It would be more accurate to write ... Mc^2 + nuclear reaction = Energy.

I think!
Are you sure its not something like MC + HAMMER = .....

17. ... Broken skull? - come on over then if that's what it takes to get it into your head.. (you asked for that!) ...

18. Originally Posted by leohopkins
Originally Posted by Zelos
Originally Posted by Guitarist
Originally Posted by Zelos
if the formula says E=M is mass energy then?
And as it doesn't, end of story, right? Megabrain is right (even though I loath his new over-active avatar).

There is, however, a neat link between equivalence and equality you might want to investigate. If you don't have books to hand, internet search on "equivalence class", or something similar. I wouldn't know, I read books, not computers.
the thing is. The REAL formula is E=M
the C² is a by product of our units
Erm, NO!!

The equation is E=MC2 not E=M. If ol' Albert meant E=M he would have said that. furthermore

E=MC2 isnt a real equation, all einstein was trying to say is that a large amount of energy can be converted into a small amount of mass, and reversly a small amount of mass can be converted into a large amount of energy.

I am not a mathametician so cannot work out volumes so I will be wrong in my maths (but right in the point i am about to make) ...........

1 cube metre of ice is the equivelant of 0.89 cubic metres of water. BUT...they are NOT the same.

The same can be said of mass and energy.
check out the planck units and what they do with the formula

and mega the planck units are as far as we know the units of the universe.

19. Originally Posted by Megabrain
C^2 is indeed a quirk, as I said with the right weight designation then the formula becomes E=M.
Weight? And where does that come in? Do you know the difference between weight and mass?

E=mc^2 is only valid using metric units.

Hmm, maybe you're teasing?

20. here is a question for you mega, how is energy stored in objects?

21. Originally Posted by Guitarist
Originally Posted by Megabrain
C^2 is indeed a quirk, as I said with the right weight designation then the formula becomes E=M.
Weight? And where does that come in? Do you know the difference between weight and mass?

E=mc^2 is only valid using metric units.

Hmm, maybe you're teasing?
I'll have a word with her about what she's been putting in my cocoa..

22. Originally Posted by Zelos
here is a question for you mega, how is energy stored in objects?
Um zelos, energy is a property of a system and not a substance found in a system - so it is not "physically" stored anywhere in any meaningful sense of the concept.

This debate is a whole metaphysics nightmare and its easy to start chasing your own tail here. Let me be pedantic about a few definitions:

Relativistic mass is a horrid old school term for the "inertial mass" that an inertial observer would measure for a moving particle. As the particle moves faster and faster the inertial mass increases with out bound which puts a speed limit on how fast a particle can go, which happens to be the speed of light. Now this is related to energy, as the energy of the particle goes up its relativistic mass also increases, but it is not invariant (so two different observers can't agree on the relativistic mass, each measures their own) but it is additive (so the relativistic mass of two particles relative to one observer is just the sum of the relativistic masses of each one separately). The physics world would be a whole lot happier if the general public would expunge this idea from its mind, as it leads to a whole host of silly concepts (especially when combined with that other favourite of mass mad science, black holes)

Rest mass (or just plain mass) is the mass of any particle in its rest frame (or for a system where its center of mass is at rest or equivalently when its total energy is at a minimum) and this is the measure of "stuff" that makes up the particle in question. Rest mass doesn't change, and it is the thing people are referring two when they talk about the mass of a particle. It is invariant (so everyone measures the same rest mass) but is NOT additive in general (which makes it messy when dealing with systems of particles) as you cant find in general a reference frame in which every part of your system is at rest relative to you. In general, the m that appears in an equation in physics is this beast, for example the m in the equation E<sup>2</sup> = m<sup>2</sup>c<sup>4</sup> + pc<sup>2</sup> is the rest mass of a particle (and this equation serves to define the rest mass of a system of particles btw)

Now here is the crux of the matter - relativistic mass and energy are intertwined, in fact relativistic mass is a measure of the energy of a system. But this link does not carry over to the invariant mass (or to be pedantic just plain mass) of a single particle. It's not all peaches and cream though as it does kind of carry over for a system of particles, as the energy content increases or decreases the mass of the system changes as given by E=mc<sup>2</sup>!

The philosophical implications of that fact force you to deal with the ideas of substance and properties and metaphysics which gives me a headache.

23. river_rat, if you look up the energy is stored in objects. as mass

24. Energy is in essence stress, quantified by volume. In empty space with nothing to hold it in place, a stress travels, like a ripple in a rubber sheet. We can call it a photon. It has momentum, and energy. But it’s all relative. The photon is moving, so you feel its momentum when it hits you. If however you apply a little relativity and imagine it's you moving, you'd feel its inertia when you hit it.

If you use "pair production" to convert a photon into an electron (and a also positron but forget that for now), what's you're basically doing is wrapping it round in a circle. You're "nailing down" the energy into one location. Then the momentum becomes inertia, and the relativistic mass becomes rest mass. Some of you might scoff and say "nobody understands mass", but I assure you it's really simple once you do understand it. See MASS EXPLAINED for details.

25. Originally Posted by Zelos
river_rat, if you look up the energy is stored in objects. as mass
It does in general? Then why doesn't the mass of a single point particle increase as i pump more kinetic energy into it?

26. river rat: Imagine a "particle" that is made out of a "something" that is tracing a circle. In simple terms, this circle is your rest mass. Now push this circle along. The path now being traced is a spiral. That's your relativistic mass. Within it there's still that circular component which is "invariant".

27. It does in general? Then why doesn't the mass of a single point particle increase as i pump more kinetic energy into it?
it does, all particles that is pumped with kinetic energy increase in mass

28. Must be why the barrel gets larger as the projectile accelerates then?

29. Originally Posted by Zelos
It does in general? Then why doesn't the mass of a single point particle increase as i pump more kinetic energy into it?
it does, all particles that is pumped with kinetic energy increase in mass
I think you are missing the point here Zelos - a point particle's mass is invariant, almost by definition. The relativistic mass of a point particle is not mass in any real sense, it has no gravitational effect for example. Think of it this way, compared to some far off observers we have a velocity close to the speed of light - do you feel more massive because of that fact?

30. It depends on how you define mass. If you define it to be the ratio between the force applied and the acceleration you got, mass increases with velocity and even it depends on which direction you push it.

31. Originally Posted by temur
It depends on how you define mass. If you define it to be the ratio between the force applied and the acceleration you got, mass increases with velocity and even it depends on which direction you push it.
Which is a good reason why mass is not defined that way - personally i am allergic to having to treat mass as a vector quantity

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