A tsunami is unnoticeable in the open ocean－a long, low wave whose power becomes clear only when it reaches shore and breaks. ＿＿（36）＿＿ Spotting the wave while it's still crossing the ocean is tricky, which explains why so few of us are aware of the one that's approaching. ＿＿（37）＿＿ As it does, it will make the computer revolution look like small change. It will affect everything from the batteries we use to the pants we wear to the way we treat cancer. The main thing to know about nanotechnology is that it's small. Really small. Nano, a prefix that means "dwarf" in Greek, is shorthand for nanometer, one-billionth of a meter. ＿＿（38）＿＿ This comma, for instance, spans about half a million nanometers. To put it another way, a nanometer is the amount a man's beard grows in the time it takes him to lift a razor to his face. ＿＿（39）＿＿ Tear a piece of aluminum foil into tiny strips, and it will still behave like aluminum－even after the strips have become so small that you need a microscope to see them. But keep chopping them smaller, and at some point－20 to 30 nanometers, in this case－ the pieces can explode. ＿＿（40）＿＿ With them, scientists can engineer a cornucopia of exotic new materials, such as plastic that conducts electricity and coatings that prevent iron from rusting.