user posted image rThe good news is that polls continue to show that between one and two-thirds of the public thinks that extraterrestrial life exists. The weird news is that a similar fraction thinks that some of it is visiting Earth.Several recent television shows have soberly addressed the possibility that alien craft are violating our air space, occasionally touching down long enough to allow their crews to conduct bizarre (and, in most states, illegal) experiments on hapless citizens. While these shows tantalize viewers by suggesting that they are finally going to get to the bottom of the so-called "UFO debate", they never do. That bottom seems perennially out of reach.So what are the contentious issues here? First off, despite heated discussion by all concerned, let’s admit that interstellar travel doesn’t violate physics. It’s possible. After all, the Pioneer and Voyager probes are nearly three decades into an inadvertent interstellar journey right now. The kicker, of course, is that these craft will take 70,000 years to cover the distance to even the nearest stars (and they’re not aimed that way). With the physics we know, it’s extremely difficult to substantially, and safely, shorten that travel time. Sure, it might be theoretically possible to create wormholes or some other exotic facility for high-speed cosmic cruising; but that approach is entirely speculative.And it’s not really the point.

The problem I have with the claim that strange craft are prowling our planet is not with the transportation mode, but with the evidence. I’ll worry about how they got here once I’m convinced that they’ve really made the scene.Well, have they? How good is the evidence? In the course of a recent TV broadcast in which I participated, guest experts who have long studied UFOs argued the case for their alien nature by showing photographs of putative saucers hovering at low altitudes. Some of these objects appeared as out-of-focus lights, while others resembled hubcap-shaped Frisbees caught in mid-trajectory.

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