Ghostly Dervishes

The result was a pair of ghostly dervishes, whirling side by side in opposite directions. It was as though a light bulb suddenly turned into two bulbs, one on and one off -- or a cat managed somehow to be both dead and alive.

The question is where in the progression from atoms to objects do the quantum effects leave off and where does hard-edged reality begin? How do the weird rules of the quantum realm give rise to the rock-solid, either-or certainty in what we quaintly call the real world?

The uranium atom can be simultaneously decayed and undecayed and the beryllium atom can have its electron spinning both clockwise and counterclockwise. But the cat has to be either dead or alive.

One currently popular answer is that things can remain in quantum limbo only solong as they are isolated from the rest of the universe. Once the electron brushes against something else, its two states, clockwise and counterclockwise, come unstuck and we're left with an electron that is spinning one way or the other. As for the cat, its atoms are constantly interacting with one another and with the surrounding atmosphere -- all these tiny, inanimate "observations" anchoring it in the land of either-or.

But there is still more mystery to come. Once the electron is observed, assuming one of the two possible states, where does the other one go? According to one interpretation of quantum theory, the universe splits into two universes -- one in which the electron is turning clockwise, the other counterclockwise. In each is a physicist observing a different outcome.

Absurd as that sounds, it is what the equations imply. The difficulty comes in trying to translate them into our ham-fisted language. Our brains didn't grow up down there so we can probably never really get it.

The electron, after all, isn't a particle or a wave but some barely fathomable amalgam. And it's not really clear what it means for one of these "wavicles" to spin. What then can we make of the notion that scientists pulled apart two states of a beryllium atom? Here's how they described it in the May 24 issue of Science: They "entangled" the "internal (electronic) and external (motional) states of the ion" and verified the result by detecting "the quantum mechanical interference between the localized wave packets."

No doubt it's much clearer to those who understand the table of equations published alongside.

Trying to capture the physicists' precise mathematical description of the quantum world with our crude words and mental images is like playing Chopin with a boxing glove on one hand and a catcher's mitt on the other. The scientists wince at the discordances, covering their ears as they silently sight-sing along with the written score.