Citizen Science No. 16 by Jamie Zvirzdin

Energy Demystified: Potential Energy’s Untapped Value

This month, as part of our year-long series on the different kinds of real, measurable energies in our universe, we shall cover a concept that, while foundational in physics, resonates with life itself: potential energy. It may sound technical at first, but I hope to show how potential energy, and gravitational potential energy in particular, embodies the idea that even when things seem stagnant and still, there’s a world of possibility waiting to be unleashed.

Potential energy is the energy stored in an object because of its position, condition or state. It’s the energy of anticipation, the calm before the storm, the coil in the spring, the water held back by the dam, the double-A battery fresh from the factory, the caterpillar before the butterfly, that butterfly and all his friends and relatives in your stomach right before the roller coaster’s plunge. It’s the marvelous moment before a significant change that will release other forms of “actual” energy: kinetic energy, heat energy, electromagnetic energy and more.

Although Lazare Carnot first used the term force vive virtuelle (“virtual living force”) to refer to untapped kinetic energy, it was William Rankine, a Scottish physicist, who first coined the term “potential energy” in 1853. Rankine chose this term based on Aristotle’s discussion of potentiality and actuality, the capability of something to do work and the actual doing of the work when the conditions are right. His term “actual energy” was relabeled “kinetic energy,” the energy of motion, in 1867.

We’ll talk about other types of potential energy in the coming months, but let’s zero in on the easiest one: gravitational potential energy, often abbreviated as PE (or U or V, but for no good reason! Some physicists may claim they’re not good with words, but they’re obsessed with letters).

Gravitational potential energy is the energy stored in an object because of its position relative to a gravitational source. On Earth, that source is our planet’s gravitational field, which causes an object near the surface of the planet to accelerate downward—the apple falling on Newton’s head—at a rate of about 9.8 meters per second every second. I always picture a heavy round rock at the top of a steep hill: The boulder sits there, doing nothing, its latent energy waiting to be released. But give that ball a push, it starts rolling faster and faster, accelerating…and suddenly it’s a force to be reckoned with, Indiana Jones–style.

What physics has that new-age energy practitioners do not, even for a hidden, invisible, “stored” energy like gravitational potential energy, is a measurable, reliable, replicable formula: PE=mgh. Mass times gravity times height is all we need to get a first look at how much energy the rock will have if you push it down the hill. The units for potential energy are the same as for every other type of energy: Joules, as we’ve talked about in earlier articles. Energy is energy is energy, and it cannot be created nor destroyed. Such consistency and reliability, in a society that often peddles lovely magnetic bracelets and pretty magic rocks, can be comforting. Physics offers us a different kind of Joule, one that is maybe not as lovely or pretty but certainly more powerful.

Understanding this particular “virtual” energy can give us a new perspective on how the energy can be stored. It also encourages us to think about the hidden…but scientifically measurable…energy all around us. When you climb a hill or carry groceries upstairs, you’re working against gravity, increasing your gravitational potential energy. When you drop something, you convert that object’s potential energy into kinetic energy. Potential energy serves as a reminder that, even in seemingly static moments, energy is stored, waiting for the right conditions to unleash its power.

Or consider the water held back by a dam. It’s quiet and still, the opposite of popular river rapids. But that calm is deceiving. There’s tremendous energy stored in the elevated water, ready to burst forth when the dam’s gates open. As the water rushes down, it transforms its gravitational potential energy into kinetic energy, turning turbines and generating electricity in hydroelectric power plants. Such a dramatic transformation shows how energy can be harnessed from a seemingly passive state and used to power entire communities.

I think many of us are fearful of the “potential” adults often tell us we have when we’re young. The expectation that our work will yield only remarkable results causes a kind of stagnant paralysis at the top of our own personal hills. So the nudge we need to give ourselves never comes, the boulder never moves, the water never flows to the people who need it most.

This month, I encourage you to find and utilize your own reservoir of potential energy. What is holding you back? What barriers keep you transforming that potential into meaningful action? Identify those barriers and take that first step to release your energy. Like the rock rolling down a hill, once you start moving, it’s much easier to keep going.

Remember, potential energy isn’t just a term from physics; it’s a reminder of the untapped energy we possess. Find what fuels you, give yourself that push, and see how your energy transforms the world around you. Be the boulder that rolls down the hill, the spring that snaps into action, the water that powers a city. You have that energy within you—give yourself a push, and watch the world come alive.

Jamie Zvirzdin researches cosmic rays with the Telescope Array Project, teaches science writing at Johns Hopkins University and is the author of “Subatomic Writing.”