Chapter II, Section A. Energy is what it’s all what is it?

If you ask a college freshman science class to define energy, you’ll be hard pressed to get a straight answer. To their credit, you’ll usually start to get a correct list of the possible forms of energy–heat, light, kinetic, potential, etc–and perhaps a statement of the famous first law of thermodynamics: that energy is neither created nor destroyed, it just changes form. In addition to that list, or perhaps mixed into it, you’ll get a list of its resources...the economic connection: oil, gas, coal, nuclear, hydro, solar, wind etc. But the definition of energy itself will usually elude them. They will get close, confusing the definition of force for that of energy. The struggle of that freshman class is not surprising. Open any college physics textbook and you’ll see hundreds of equations describing the many forms of energy. You’ll have to search to find a sentence defining what energy is.

And yet, acknowledged or unacknowledged, our economics, our very lives, depend on energy. So, what is it? That sentence defining energy in the physics textbook usually includes a statement that energy is the ability to perform work, and is followed by a precise definition, complete with equations, of the physical definition of work. One then learns that work is a form of energy. This suggests the definition of energy is incomplete; it seems to violate the syntactic rule not to use the word in its own definition. The concept of energy is more of an abstraction than that of force. It’s an amount of something, rather than an action of some kind such as a force focused in a specific direction. The impression is left that energy is a circularly reasoned, self-defined entity. What is this “something” measured as a quantity? Why focus on the “work” form of energy in its definition? From the physics perspective, the work form of energy is the connection between energy and force: energy is the ability to create a force working through a distance, overcoming resistance. Physicists are interested in the forces that can manifest from different forms of energy, but simpler yet, work makes things go. “It’s the economy, stupid.” It’s the work we want.

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