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No. 2434:
Physics or Metaphysics

by Andrew Boyd

Today, physics or metaphysics? The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

rockIt's hard to imagine we could ever confuse physics with metaphysics. Physicists want to understand how a rock falls to the ground. Metaphysicians want to know what it means to be a rock.

Yet, physics and metaphysics routinely bump into one another. We need look no further than Sir Isaac Newton and The Principia.

the Principia

The Principia is arguably the greatest scientific work ever written. Among its many jewels is a universal theory of gravity. Thanks to Newton, we understand that rocks falling to the ground and planets going around the sun can be explained by the same, simple, mathematical principle. He proposed a theory, then showed that it fit observed data. The Principia is a true work of physics.

But it was criticized on metaphysical grounds. Gravity requires action at a distance. When I raise my coffee cup, I must first reach down and pick it up. I can't simply will it to my lips. But gravity does just that; it imparts force without physical contact.

Newton wisely stayed away from trying to explain exactly what gravity is. But many scholars saw action at a distance as nothing less than witchcraft. Over time the issue abated. But not before Newton dealt with a barrage of attacks.

Action at a distance was only one metaphysical problem. In The Principia, Newton mechanizes the universe. It becomes a machine described by mathematical laws. So where did that leave God?

Newton was a devout man who wrote extensively on religion during his life. His work in physics never changed his beliefs. "Gravity explains the motions of the planets," he wrote, "but it cannot explain who set the planets in motion." Newton went further. He couldn't believe that God simply wound up the universe like a clock and then let it go. It left no room for things like divine intervention. And that's something Newton couldn't bring himself to accept. "God governs all things," he wrote, "and knows all that is or can be done." Newton the physicist saw the universe as a divine machine; and God the divine mechanic, ever-ready to provide a needed tune-up.

solar system

Physics and metaphysics live in different houses, but they'll always be neighbors peering at each over the back fence. Today's metaphysicians are found in philosophy departments. Physicists are housed in colleges of natural science — surrounded by mathematics; grounded in the scientific method. They make tiny particles collide at incredible speeds in an effort to understand the very beginning of the universe. They puzzle over the mind boggling mysteries presented by quantum theory. They imagine new physical dimensions tightly wound up in things called strings. Physicists may not be metaphysicians, but you can be certain they dream metaphysical dreams. 

I'm Andy Boyd at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Isaac Newton. From the Wikipedia web site: Accessed November 18, 2008.

Newton's Philosophy. From the web site of the Stanford Encyclopedia of Philosophy: Accessed November 18, 2008. 

H. Hellman. Great Feuds in Science. New York: Wiley and Sons, 1998.

All pictures are from Wikipedia Commons.