2008 : WHAT HAVE YOU CHANGED YOUR MIND ABOUT? WHY?

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Theoretical Physicist, Caltech; Author, The Particle at the End of the Universe and From Eternity to Here: The Quest for the Ultimate Theory of Time
Being a Heretic is Hard Work

Growing up as a young proto-scientist, I was always strongly anti-establishmentarian, looking forward to overthrowing the System as our generation's new Galileo.  Now I spend a substantial fraction of my time explaining and defending the status quo to outsiders.  It's very depressing.

As an undergraduate astronomy I was involved in a novel and exciting test of Einstein's general relativity — measuring the precession of orbits, just like Mercury in the Solar System, but using massive eclipsing binary stars.  What made it truly exciting was that the data disagreed with the theory!  (Which they still do, by the way.)  How thrilling is it to have the chance to overthrow Einstein himself?  Of course there are more mundane explanations — the stars are tilted, or there is an invisible companion star perturbing their orbits, and these hypotheses were duly considered.  But I wasn't very patient with such boring possibilities — it was obvious to me that we had dealt a crushing blow to a cornerstone of modern physics, and the Establishment was just too hidebound to admit it.

Now I know better.  Physicists who are experts in the field tend to be skeptical of experimental claims that contradict general relativity, not because they are hopelessly encumbered by tradition, but because Einstein's theory has passed a startlingly diverse array of experimental tests.  Indeed, it turns out to be almost impossible to change general relativity in a way that would be important for those binary stars, but which would not have already shown up in the Solar System.  Experiments and theories don't exist in isolation — they form a tightly connected web, in which changes to any one piece tend to reverberate through various others.

So now I find myself cast as a defender of scientific orthodoxy — from classics like relativity and natural selection, to modern wrinkles like dark matter and dark energy.  In science, no orthodoxy is sacred, or above question — there should always be a healthy exploration of alternatives, and I have always enjoyed inventing new theories of gravity or cosmology, keeping in mind the variety of evidence in favor of the standard picture.  But there is also an unhealthy brand of skepticism, proceeding from ignorance rather than expertise, which insists that any consensus must flow from a reluctance to face up to the truth, rather than an appreciation of the evidence.  It's that kind of skepticism that keeps showing up in my email.  Unsolicited.

Heresy is more romantic than orthodoxy.  Nobody roots for Goliath, as Wilt Chamberlain was fond of saying.  But in science, ideas tend to grow into orthodoxy for good reasons.  They fit the data better than the alternatives.  Many casual heretics can't be bothered with all the detailed theoretical arguments and experimental tests that support the models they hope to overthrow — they have a feeling about how the universe should work, and are convinced that history will eventually vindicate them, just as it did Galileo.

What they fail to appreciate is that, scientifically speaking, Galileo overthrew the system from within.  He understood the reigning orthodoxy of his time better than anyone, so he was better able to see beyond it.  Our present theories are not complete, and nobody believes they are the final word on how Nature works.  But finding the precise way to make progress, to pinpoint the subtle shift of perspective that will illuminate a new way of looking at the world, will require an intimate familiarity with our current ideas, and a respectful appreciation of the evidence supporting them. 

Being a heretic can be fun; but being a successful heretic is mostly hard work.