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?
Great post, Dan. I agree with your general message wholeheartedly: that in the end, it should be these questions of fundamental understanding that we’re most interested in.
But I think you might be looking for an answer to what energy is too soon. If you could really give an answer to what energy is that could be considered a ‘good enough’ explanation, would there be much of anything left in physics to discover? When I was trying to answer the question, I kept thinking that energy must be the most elementary building block of all ‘stuff’;’ not just matter, but all things in the universe, all particles, including light, other bosons, etc. (and in certain forms it composes the particulate ‘stuff,’ while in others it forms the means by which particulate matter can move spatially and through the arrow of time, or something to that effect). My feeling is that humanity just simply hasn’t come to a point that it actually understands the very basics of everything (surprise!), and that it should be obvious to everyone that there are still many challenging holes in our knowledge of all the ‘stuff’ that keeps us from fully understanding it. I think that energy has become that mental construct which we place at the very base of all physicality, but we don’t actually know what it is anymore than what we’ve defined it as in our equations.
But then again, I’m a biologist, so what do I know?
Thanks Dallas! Indeed I would agree with you–I don’t actually expect anyone to be able to truly answer the posed question. But as I said in the post (and as you would agree), that doesn’t mean we shouldn’t pose and think about the question. It’s my hope that by posing this question, I can get others to think more deeply about this, and maybe through their attempted answering of the question, as you have thoughtfully shown in your response, come to some sort of better understanding of (or at least excitement for the wonders of) how we look at things. And I’m always looking for eloquent ways to explain this to a student who poses the question to me. ;)
I appreciate this post a lot Dan. As emerging scientists we are truly at the crosswords of being inquisitive students but also critical/discerning investigators. This is the time to really develop our own sense of what those big questions are really asking. After all, we are the upcoming generation of experts who will be relied on to answer (or at least discuss) those questions. I never want to forget the questions that brought me the most anticipation and what answers I was most disappointed to hear.
Dallas brings up a good point here. Searching for the right kind of question is the more fruitful endeavor of science right now. This doesn’t mean that the big “what is it” question should be dismissed. It should neither be dismissed nor answered simply (the simple answer degrades the depth of the question). It should spark discussion. I don’t think that physics can answer a question like that – it’s really more up to our imagination. But encouraging that kind of question is the right kind of motivator to do science, to equip oneself with the tools and the language to better imagine the most abstract, open-ended concepts.
Science is our tool for explaining behavior and testing it through predictions. To many of us, the fun part is imagining what it all means.
Great post – interesting to consider the meaning of a flame, energy, and other illusive terms (I myself have no idea how to define many of them). As an aspiring evolutionary biologist (and lover of experimental social psychology), I am generally more interested in the “why,” and “how,” than the “what,” questions, but we need answers to all framed questions to develop a full understanding of our beautiful planet. This isn’t a profound statement, I know, but it is what came to mind after reading your new entry.