What is energy? This is the simple, three word question that stumped me while I was tutoring physics this year. I was surprised when I realized that nobody had ever asked me this before, and even more so when I (quickly) realized that I did not have a good answer. Sure, I know the definitions of “types of energy” that I’ve memorized over the years–the ones that allow me enough of an understanding to solve some basic problems. But what is energy? Do you know? I’d love to hear your answers!
This is a problem that pervades many areas of science, not just physics. I’ve run the undergraduate gamut of physics, and very rarely have I ever heard this question asked: “OK Professor, but what is it?” And when the question was asked, the most popular response was “it doesn’t matter, as long as you know how to solve the problems.” I feel enlightened already.
Part of the problem is the nature of science itself. In many cases, we don’t know what something is. Like Richard Feynman, I’m perfectly fine living with the fact that I don’t have an explanation for what energy is. I know it’s a concept that physicists use to solve complicated problems, because it’s defined as a conserved quantity of nature. We say that everything in the Universe has some sort of energy, which manifests itself in a variety of forms: kinetic energy, which is the energy of motion; potential energy, which is the energy an object has that can allow it to do some kind of work; and internal energy, which is usually thought of as temperature and can usually be released in reactions in the form of light (remember, heat is just another form of light called infrared radiation). But I haven’t actually answered the question–a physics professor of mine literally admitted in one of our classes that potential energy doesn’t really exist, but rather it’s just a concept that physicists use to help them solve problems more easily.
But we can’t always be let off this easily. Many things in the real world do exist, and we often fail to ask the simple question. Alan Alda recently posed one of these questions in his flame challenge: “What is a flame?” The contest was for people to submit explanations for flames in a way that 11 year olds can understand (and possibly find fun as well). When I heard about this contest, I was similarly taken aback, because I realized just how hard it was to explain what a flame actually is, especially in a way that a 5th grader can understand. Apparently, as an 11 year old, little Alan Alda posed this question to his teacher, who gave a cop out answer akin to what most professors I know would give: “it’s oxidation.” How informative.
There’s two points I am trying to make here. The first is more direct, and it is that we need to spend more time asking one of the most important and simple questions: “What is it?” The reason I got interested in science as a kid was because I loved to ask that question, and to receive useful answers. I became even more excited when I realized that we don’t always know the answer, but we can spend time finding it out. The enlightenment you can get when you receive an answer (whether from a teacher, an experiment, or otherwise) can be really gratifying and exciting. The second point is an indirect spinoff of the first, which is that many teachers (of all levels) need to spend more time embracing this understanding. I find that too many focus on how to solve problems that they breeze through the concept like it doesn’t matter.
But in my opinion, it matters most of all. Before I can face the unknown problems of the Universe, I have to come to some sort of understanding of how it works. We don’t know everything, but that’s what exciting–and the things we do know need to be explained. And without the concepts, science is just plain boring. That’s why people like Bill Nye are so popular–they explain science in a way that we can all understand. And as scientists and educators, I think we all need to spend at least some time asking (and answering) the simple, tough questions. In my opinion, this is the best way to make science (especially physics) much more interesting and fun to both children and adults.
Consider this my challenge to you all. What is energy?