Friday, April 08, 2005

Einstein and Quantum Mechanics

One Hundred Years of Uncertainty: Brian Greene, a professor of physics and mathematics at Columbia writes, "...about a hundred years ago, Albert Einstein began writing a paper that secured his place in the pantheon of humankind's greatest thinkers. With his discovery of special relativity, Einstein upended the familiar, thousands-year-old conception of space and time. To be sure, even a century later, not everyone has fully embraced Einstein's discovery. Nevertheless, say 'Einstein' and most everyone thinks 'relativity.'

What is less widely appreciated, however, is that physicists call 1905 Einstein's 'miracle year' not because of the discovery of relativity alone, but because in that year Einstein achieved the unimaginable, writing four papers that each resulted in deep and formative changes to our understanding of the universe.

Yet, it is the remaining 1905 paper, written in March, whose legacy is arguably the most profound. In this work, Einstein went against the grain of conventional wisdom and argued that light, at its most elementary level, is not a wave, as everyone had thought, but actually a stream of tiny packets or bundles of energy that have since come to be known as photons.

This might sound like a largely technical advance, updating one description of light to another. But through subsequent research that amplified and extended Einstein's argument scientists revealed a mathematically precise and thoroughly startling picture of reality called quantum mechanics.

Quantum mechanics does not merely challenge the previous laws of physics. Quantum mechanics challenges this centuries-old framework of physics itself. According to quantum mechanics, physics cannot make definite predictions. Instead, even if you give me the most precise description possible of how things are now, we learn from quantum mechanics that the most physics can do is predict the probability that things will turn out one way, or another, or another way still.

Although we have yet to fully lay bare quantum mechanics' grand lesson for the underlying nature of the universe, I like to think even Einstein would be impressed that in the 50 years since his death our facility with quantum mechanics has matured from a mathematical understanding of the subatomic realm to precision control. Today's technological wizardry (computers, M.R.I.'s, smart bombs) exists only because research in applied quantum physics has resulted in techniques for manipulating the motion of electrons - probabilities and all - through mazes of ultramicroscopic circuitry. Advances hovering on the horizon, like nanoscience and quantum computers, offer the promise of even more spectacular transformations.

So the next time you use your cellphone or laptop, pause for a moment. Recognize that even these commonplace devices rely on our greatest, yet most puzzling, scientific achievement and - as things now stand - tap into humankind's most supreme assault on the idea that reality is what we think it is."

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