Bugs and Osmosis
Why more fly in than out.
Bugs fly into my car window faster than they fly out. In fact, over time, a tent or car or other small room with a hole in it, will accumulate a greater concentration of bugs inside than out. It is a kind of osmotic pressure: The vast number of insects traversing a course that intersects with YOUR car window is FAR greater when you're drawing from a pool of millions of bugs in the meadow, compared to the pool of a few dozen bugs inside your car. Osmotic pressure. Osmosis. The tendency for a molecule, particularly an aqueous solution, to equalize across a membrane. Gets the water to the top of a Sequoia tree, makes your thoughts cross synaptic clefts, and other miscellanous wonders.
If only all of life's forces were as simple as osmotic pressure.