Every now and then, I think about people who are no longer here and ask myself what they left with me. A lesson. A phrase. A moment I still can’t fully explain.
Mr. McNally left me a question.
He was teaching us about entropy in his AP Chemistry class and asked why the air in a bicycle tire doesn’t simply settle to the bottom.
Air has weight. Gravity acts on it. So why doesn’t all the air sink to the lowest part of the tire like a pile of sand? Why does it keep pressing outward against the walls?
It’s a simple image, which is probably why I still remember it almost fifty years later.
The air inside the tire is made up of tiny particles moving rapidly in every direction. They collide with each other, and with the inside wall of the tire. Those collisions create pressure.
Gravity is present but its pull is weak compared to the thermal energy of all those molecules.
The air fills the space it’s given. It presses outward. It resists settling.
That old chemistry question came back to me recently as a life question.
What keeps us from settling? From succumbing to the gravitational pull in all of us.
Staying where life feels familiar. Waiting for more certainty. Keeping the pattern because changing it will cost us something.
Waiting sounds reasonable. It borrows the language of patience, prudence, and practicality. And at times, those are the right virtues. Wisdom often tells us to slow down.
But inertia can dress itself up as wisdom. Fear can call itself realism. Comfort can pretend to be peace.
That’s when we begin settling to the bottom of our lives.
The air doesn’t fulfill its purpose by collecting in the lowest place. It fills the available space. It presses against the walls. It creates pressure because motion is still happening inside.
Human life has its own version of that energy.
Purpose. Discipline. Faith.
These keep us from sinking into the lowest-energy version of ourselves.
The tire reminds us that pressure comes from movement. A life with purpose has an outward push to it. It presses against fear, complacency, and inertia. It expands into the space it has been given.
We don’t have to be reckless or maintain constant motion. But we need enough internal purpose to overcome the quiet pull of our internal gravity.
I’m grateful Mr. McNally asked that question all those years ago. At the time, it was a chemistry lesson about entropy, motion, and pressure.
Decades later, it’s still teaching me.
The tire doesn’t fight gravity. It just has something inside it that never stops moving.
I think that’s all any of us can ask of ourselves.
Photo by Leon Seierlein on Unsplash
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