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