flashlights
one argument against human made global warming is that the effect of humans is so small it gets lost in the much larger but random natural weather effects. hrm. consider flashlights. there are electrons in the wires that are free to move around. and they do. they zip around bumping into things. then they take off in a different direction. now, push the button and the light lights up. closing the circuit creates an electric field in the wire. this field gives the electrons a drift velocity towards the plus end of the battery. it's pretty tiny compared to the thermal brownian motion velocity. if you apply the above argument you'd predict that the light won't light and we'd all live in darkness. try it. see the light?