The world seems to be putting itself together piece by piece on this damp gray morning along the coast of Maine. First the spruce and white pine trees that cover High Island materialize from the fog, then the rocky headland, and finally the sea, as if the mere act of watching has drawn them all into existence. And that may indeed be the case. While this misty genesis unfolds, the island's most eminent residentdiscusses notions that still perplex him after seven decades in physics, including his gut feeling that the very universe may be constantly emerging from a haze of possibility, that we inhabit a cosmos made real in part by our own observations.
John Wheeler, scientist and dreamer, colleague of Albert Einstein and Niels Bohr, mentor to many of today's leading physicists, and the man who chose the name "black hole" to describe the unimaginably dense, light-trapping objects now thought to be common throughout the universe, turned 90 last July. He is one of the last of the towering figures of 20th-century physics, a member of the generation that plumbed the mysteries of quantum mechanics and limned the utmost reaches of space and time. After a lifetime of fundamental contributions in fields ranging from atomic physics to cosmology, Wheeler has concerned himself in his later years with what he calls "ideas for ideas."
"I had a heart attack on January 9, 2001," he says, "I said, 'That's a signal. I only have a limited amount of time left, so I'll concentrate on one question: How come existence?'"
Why does the universe exist? Wheeler believes the quest for an answer to that question inevitably entails wrestling with the implications of one of the strangest aspects of modern physics: According to the rules of quantum mechanics, our observations influence the universe at the most fundamental levels. The boundary between an objective "world out there" and our own subjective consciousness that seemed so clearly defined in physics before the eerie discoveries of the 20th century blurs in quantum mechanics. When physicists look at the basic constituents of reality— atoms and their innards, or the particles of light called photons— what they see depends on how they have set up their experiment. A physicist's observations determine whether an atom, say, behaves like a fluid wave or a hard particle, or which path it follows in traveling from one point to another. From the quantum perspective the universe is an extremely interactive place. Wheeler takes the quantum view and runs with it.
As Wheeler voices his thoughts, he laces his fingers behind his large head, leans back onto a sofa, and gazes at the ceiling or perhaps far beyond it. He sits with his back to a wide window. Outside, the fog is beginning to lift on what promises to be a hot summer day. On an end table near the sofa rests a large oval rock, with one half polished black so that its surface resembles the Chinese yin-yang symbol. "That rock is about 200 million yearsold," says Wheeler. "One revolution of our galaxy."
