What is a quantum leap?

Quantum leaps

Have you noticed that nothing seems to be a mere “improvement” these days? Now, every change seems to be a “quantum leap”. The implication, of course, is that a quantum leap is hugely significant.

Not so.

Quite the reverse, in fact: a quantum leap is the smallest change possible. Here’s why.

Early last century, physicists worked out that the atom is like a (very) small solar system, with tiny planet-like electrons orbiting a sun-like nucleus. A little later, along came Planck, Heisenberg (of Uncertainty Principle fame), and Einstein. Thanks to these three in particular, we now “know” (and there’s a word to explore in a future column!) that, rather than those electrons whizzing around in clearly defined orbits, they are vague and evasive little creatures. Along with this knowledge came the realisation that each electron can only exist in a certain number of energy states. Try to pump some energy into an atom (perhaps by exposing it to light), and you’ll find that the excitation level of an electron goes up by a fixed amount. Allow the atom to return to its unexcited state, and it will give off a tiny “packet”, or quantum, of energy. In effect, a quantum is a particle of energy, and it can’t be divided or made any smaller. A quantum leap is the change in excitation level of an electron when it absorbs or emits a quantum.

Here’s an analogy. Before 1c and 2c coins were taken out of circulation (and before the GST played Heisenberg with our financial certainties), we were accustomed to paying whatever price appeared on a ticket. Even now, if we are paying by electronic means, the single cent is an available unit of currency. It’s also the smallest; nothing goes up by 0.8 cents. (The unit price of something like petrol might change by fractions of a cent, but try taking a hacksaw to a one-cent coin and see whether your local service station will accept it…)

No doubt you can see where I’m heading. In financial terms, the single cent is a the equivalent of a quantum. Next time you hear a politician (or any other kind of sales-person) talk about “a quantum leap”, reflect that perhaps the change they are getting excited about is only a matter of a 1c coin. You never know: you might be closer to the truth than you expect.