I was reminiscing about high school physics the other day, and in particular how we were taught about energy. We were told there were different types of energy like; static kinetic, electrical, potential etc… Now it just struck me that the only difference between them is the conditions that define how they are named. What I want to know is whether the underlying “substance” of energy really differs from situation to situation.
-
-
- Well, first you need to consider the maximum conversion pote- oh damn, the sockets here are leaking again. I must have left too much stuff plugged in for too long, and then unplugged it all too fast. I guess everybody else better check theirs also. - MC
-
Is that supposed to be funny? See the quotation marks around “substance”? They are to indicate that I know energy has no substance but is the best word I could think of, not being a rocket scientist like you. Perhaps essence is better.
Don’t patronise me again old man.
This thread will probably be moved to General Questions. Also, I’m sure some of the physics gurus can offer more on this subject than I can, but here’s my 2 cents…
Energy is basically a capacity to do work. And, as you said, some energy is stored, some is kinetic, some is potential, etc. Energy can be derived from so many aspects of the universe that I don’t know if there is an underlying “substance” to it, other than a winding down of the energy released during the Big Bang which would be part and parcel with space, time, and matter.
It always busts me up when SciFi or horror movies use the term “pure energy”, as if you could put the stuff in a bucket or bottle and carry it around. “Power” is abused in much the same way. Funny stuff.
A short answer (that could probably be ripped apart a thousand ways) is that energy is a property of substances, and not a substance in itself. Substances can have temperatures, velocities, etc., but a temperature, velocity, etc., can’t really exist (meaning be measured) without a substance. Does this make sense?
[Moderator Hat ON]
I think this’ll do better in General Questions.
[Moderator Hat OFF]
The underlying “substance” of energy is matter. Anything that has mass (relativistic mass) doesn’t just contain energy, as given by E=mc^2, but it IS energy. Similarly, anytime you add energy to something, it’s mass increases.
Arjuna34
Engineer Don - that old Sci Fi chestnut always got my goat as well. There is always radiant energy, but it can’t be measured until it strikes something
*papertiger - this isn’t a guru question, it’s the first chapter of any physics book, understanding the definitions and relationships of matter, energy, force and work. Phobos gives you the starting point but for now don’t worry about relativity, that’s toward the back of the book for next semester. 
A ball on a shelf has potential energy because it could fall and produce kinetic energy. Potential energy = kinetic energy. A gallon of gasoline has potential chemical energy because of the bonds in its molecules. Combine it with a little oxygen and it is released into thermal energy. Heat some water and spin a tubine to convert to mechanical/kinetic energy. If the turbine spins a generator we start making electrons move for electric energy.
There are three types of energy in the most basic sense:
Potential
Kinetic
Internal (interactions of atoms)
All of your energy (mechanical, chemical, etc.) can be traced back to those three.
In a more basic sense there are four fundamental forces in nature:
Strong Nuclear (binds the nucleus of an atom together)
Weak Nuclear (atomic decay)
Electromagnetic (positive/negative charges on particles)
Gravity (attraction between two or more masses)
I suppose one might argue that these are the real fundamental basis (or cause) for all energy. Put a rock on a shelf and it has potential energy because here on earth gravity will pull it down. Explode an atomic bomb and you see the strong nuclear force at work. The electromagnetic force is probably what you’re most familiar with as it’s the force that keeps you from sinking through your chair and thus allows things to be built, chemicals manufactured and so on. (I’m not sure of a useful real world example of the weak nuclear force.)
So, to the OP, there may be a ‘substance’ to energy. It is commonly held among physicists that the four fundamental forces are but aspects or rather pieces of one unifying force. The search for this is called a GUT (Grand Unified Theory) where all the forces are wrapped up into one neat ball. This is the current Holy Grail of physics but there are still problems that need working out (IIRC gravity is stubbornly refusing to fit in nicely).
Unfortunately, if you want to combine all of the forces of nature into one unified ‘uber-force’ you’ll need energy densities found only fractions (teeny-tiny fractions) of a second after the Big Bang. At that moment you might see the underlying ‘substance’ of energy.