You push, and the door pushes back with a logic older than any hinge. What you are actually doing, when you lean into that heavy pane of glass, is fighting inertia: the door's rotational mass wants to keep doing whatever it was doing, which was nothing, and your palm delivers a torque that overcomes it.
The wonderful part is how little you need. Because the mass sits far from the central axis, the whole assembly has a large moment of inertia, so it turns slowly and grandly, like something that has decided to take its time.
And it barely stops. Notice the door still drifting after you have stepped away, coasting on the energy your hand left in it. That motion doesn't vanish; it bleeds into warmth. The nylon brushes at the edges, sweeping against the frame, drag your kinetic energy down into the faint jostling of molecules, into heat too small to feel.
You paid a few joules to get inside. Those joules are now scattered irretrievably into the lobby air, one more tiny installment on the debt the universe never lets anyone repay.
The glass itself is a slow liquid pretending to be a solid, its atoms locked in a jammed, disordered sprawl because it cooled too fast to ever properly crystallize. And the silicon in it was forged in a dying star, blown across the galaxy, gathered into a rock, melted by people, and stood upright so a commuter could shoulder through it without looking up.
You spun a fragment of an exploded sun on a bearing, warmed a room by a millionth of a degree, and were briefly, gently trapped in a quadrant of turning starlight.
Then you went to get coffee.