In the popular TV series, “Numbers”, the crime solving mathematician protagonist, Charlie Eppes, says this in one episode: “You’ve observed the robbers. They know it. That will change their actions.” He’s making a loose reference to the Heisenberg Uncertainty Principle in that statement. OK, so just what is the Heisenberg Uncertainty Principle? Well, to answer the question we must first address quantum mechanics. It’s the branch of physics that deals with those extremely small particles. You know, electrons, protons, neutrons, and other subatomic particles. They don’t just behave like tiny marbles in the sand. They live in a world of probability and uncertainty. It’s a counterintuitive land where particles can be in one place at one instance and a entirely different location in the next instance. In this “Bizzaro World” of science the Heisenberg Principle states that the better you know the position of a particle, the less you know it's momentum and vice versa. So, it's not that observing a particle changes it, but more of an uncertainty of your measurement based on the strange probabilistic nature of the particle itself.
The other term that we hear a lot of is “quantum leap”. An advertisement in a popular science magazine touted a bedwarmer by stating its, “a quantum leap forward from electric blankets.” And, I’m sure most of us have watched a popular sci-fi TV program entitled “Quantum Leap” in which the hero is doomed to “leap” into the bodies of various characters during different eras from week to week. We almost intuitively know that the term implies some fantastic change. In fact, the “Oxford Dictionary of American Usage and Style” defines quantum leap as “a sudden extensive change (usually an improvement) in the rate of progress”.
So, what’s the real story? The simple model of an atom can help explain this. In the model the nucleus, consisting of protons and neutrons, is surrounded by electrons orbiting like planets around a sun. The electrons can move from one orbit to another instantaneously. Each orbit is at a discrete level or quantum state and when the electron moves it leaps from one quantum state to another. Think of arising in the morning, showering, dressing, getting your coffee then suddenly finding yourself at your desk at work twenty miles away. But, each of those quantum states is a very small change. Counter to the popular definition then, a quantum leap is sudden but pretty small.
The irony in all of this is that the metaphors, touting dramatic ideas, actually find their origins in rather pedestrian although complex concepts. I’m certain I won’t change anyone’s usage of these terms. They are too well imbedded in the popular culture. But, it’s always nice to know the origins of those science terms when we use them in non-science writing.
Well, there you have it. My rant is ended. It wasn’t too painful, I hope.