Gas in a harmonic trap

Gas in a harmonic trap is a way to contain gas. It's like a box with walls that are bent inwards like the sides of a bowl. All the walls are made of the same material and they all curve the same way. The gas particles bump into the walls, but because the walls are curved, the particles are always pushed back to the center. That keeps them inside the box. Even though they can move around, they never get to the edges and stay inside the box. It's like a playground with a see-saw and a roundabout - the gas particles can move around but only within the safe boundaries of the trap.