In May 1914, Alexander Graham Bell delivered a commencement address to some high school students in Washington, DC. The 67-year-old inventor of the telephone gave a peculiar speech--a crotchety ode to observation, measurement, and gumshoe curiosity. He spent much of his time proposing areas of investigation for his teenage audience to take up. "Did you ever try to measure a smell?" he asked. "What is an odor? Is it an emanation of material particles in the air, or is it a form of vibration like sound?" he asked. "If it is an emanation, you might be able to weigh it; and if it is a vibration, you should be able to reflect it from a mirror," he went on. "If you are ambitious to found a new science, measure a smell."
More than a century later, no one has yet been able to measure a smell, and there is even still some debate as to whether smell is a vibration or a chemical interaction between particles. (The vibration theory is far more controversial, but no one understands olfaction well enough to dismiss it entirely.)
I had no idea about the "vibration" theory. In either case, it seems like the ratio in a biological nose aren't 1:1 receptor to type of recognizable smell (like a piano that can only play 88 notes) but more like chords (where a piano can play thousands of chords)
I used to be bad when I was a kid but ever since then I have gone straight, as I can prove by my record -- 33 arrests and no convictions.