Why the layman should care about the "Pioneer Anomaly"

So I've been spending the past week or so in "holiday" mode, by which I mean sitting on the couch and taking frequent naps. It's been good, but something tells me it's time to get up. The only problem is that I've found a long layoff makes the return to blogging fairly difficult. So you'll forgive me if I take it slow, and restart by dealing with a fairly esoteric topic: what exactly is the deal with gravity?

We thought we had this one licked--apples, event horizons, the inverse-square law and all that. But it turns out that gravity may be a far more subtle beast than we'd given it credit for. For it appears that, despite everything that we "know" about gravity, our deep-space probes are slowing down.

It's nothing serious: it's just that the Pioneer 10 and Pioneer 11 probes, launched in the early 1970s and now flying off into interstellar space, are about 250,000 miles closer to the Earth than they should be, and nobody knows why. Many scientists seem eager to believe it's because of some property of the probes themselves (e.g., an unanticipated micro-leakage of gas), which is of course a natural first thing to consider. Scientists are eagerly poring over the available data (Pioneer 10 stopped broadcasting in 2000, Pioneer 11 several years earlier) for evidence that our gravitational model is not in error. For if it is...

But this is the way of science. I don't think the public appreciates it, and I think the scientific community is remarkably bad at explaining it. All we have to go on is what we can observe, or measure, or estimate. "Theories" represent scientists' attempts to make models that account, as accurately as possible, for the complexity of creation. Models come and go, even some of those that are compellingly close (the Ptolemaic model of the universe was quite well refined and worked great for most things, it's just that the Copernican one was better); and (and I have to say this) there is a certain hubris in any scientist ever saying "this is the way it is."

It's a process of creative destruction, as the economist Schumpeter might have said. You may come up with a new theoretical model for some phenomenon, but it's often not enough merely to set two theories next to one another and let people choose--you put the two in the academic arena and see which one comes out alive. That's why we're not still having a debate about phlogiston vs. oxygen. I suspect it is this fact that has so many scientists frothing at the mouth (admit it, it's true) about the Intelligent Design debate. It's not an opponent they can slay in the same way as "scientific creationism."

The ID community is attempting to destroy a scientific theory by advocating a non-scientific theory. "No fair!" cries the scientific community, and quite rightly. But there is an exchange I long to hear, though I am despairing of it:

ID-ologue: "Evolution is just a theory!"
Evolutionist: "You're right, but so is your view."

Apologies for the rant. Tomorrow I promise more tasty meat about the follies of the left or something unflattering about the French.

Tags: Pioneer Anomaly, Gravity, Physics, Intelligent Design, Evolution, Phlogiston