A Few Photons Can Stop 2 Tons Of Steel

Driving along in my car, I arrive at an intersection. Above the intersection, there is a traffic light. A few photons of light of a wavelength we refer to as "red" are focused onto a few cells in the back of my eye. These cells happen to be somewhat special and they respond by chemically messaging a few nearby cells. Now, there are a few billion of these special cells, and they're all hooked up in different structures. So, when the photons hit those special cells, all hell breaks loose in this system. There are signals going this way and that way. The raw input is abstracted, given symbolic meaning, STOP! Signals get sent down my spine, down to the muscles in my leg. These signals trigger chemical reactions in the fibers of my muscles, causing them to tighten and relax an appropriate sequence to cause my foot to lift off the gas and press the break pedal. This, through a series of mechanisms has the effect of converting the forward momentum of my vehicle into heat energy in my breaks, or in simpler terms, 2 tons of steal has just stopped abruptly… All because a few photons happened to hit a few cells.......and I won't even go into how the energy in those photons from the traffic light actually originated 95 million miles away, in the sun, when a few hydrogen atoms bumped into each other!