UFOs: The Trail is Stale

One thing that strikes me about claims of alien visitation is that so much of the evidence is musty and fusty.

Every day, I get stories and articles from people around the world who aggregate UFO news. But much of it is not news – it's olds. The folks who think there's good proof that Earth is a stomping ground for extraterrestrials are still hung up on the Roswell incident of 1947 or its British opposite number, the Rendlesham Forest event of 1980. They're still citing the testimony of aging politicians, defense establishment types, and Apollo astronauts who "know something."

The few alternatives to this vintage archive are contemporary photos and videos of vague lights in the sky, low-resolution and low-confidence material that isn't likely to sway many scientists. The good stuff seems to be the old stuff.

To better judge if this is really true, I trawled the web for listings of "the best UFO cases." I quickly collected nearly 100 events that were considered worthy, of which 60 were unique, in the sense of not being repeats (e.g., the Roswell incident appears on most of these lists).

I then plotted up the year in which each of these unique events took place, virtually all since 1940. And guess what? By far the majority occurred in the first half of the last 76 years.

The quality UFO evidence is getting long in the tooth.

So what's going on? Our technology for documenting alien spacecraft – if you assume they're real – is substantially better than even a few decades ago. An Apple iPhone's camera now boasts 8 megapixels, which I reckon is a hundred times as many as the 8 millimeter movie film we had in the 1960s. These fabulous cameras are in the hands of nearly two billion smartphone users world-wide. And yet the UFO photos are as blurry and muddy as ever. You'd think at least a few people could make snaps that aren't ambiguous or hoaxed. And I haven't mentioned the surveillance provided by the 1,100 active satellites in orbit above our heads.

Now some people deflect these puzzling facts by stating that excellent evidence for cosmic visitors really exists, but is kept under wraps by the government. This may be reassuring to some, but it's utterly goofy. Can anyone explain how beings from other worlds have managed to arrange their itineraries so that only governments are solidly aware of their presence?

Still, this idea seems to have a lot of appeal, even though it has led to a truly risible tactic by groups petitioning for "disclosure" – a maneuver that twists the burden of proof 180 degrees. These folks hope the government will make their case for them, urging the feds to come clean about what they supposedly know. "We can't prove UFOs are alien craft, but you can!" Imagine if astronomers used this scheme to verify the existence of black holes.

But hold on: Maybe there are other explanations for why the so-called good evidence for visiting aliens is as stale as Gothic croutons.

One obvious possibility is that the extraterrestrials are just plain done with us. They've abducted enough folks to satisfy their curiosity about our anatomies. The Cold War has ended, and so has their fascination with our nuclear missile silos. They've tried visiting New Mexico, but that didn't work out.

So maybe they've just declared "mission accomplished," and gone away. That would be analogous to Charles Darwin's visit to the Galapagos Islands – after he probed, bottled, and cataloged some of the natives, he weighed anchor and withdrew.

But here's another possibility drawn from a similar experience with SETI (the Search for Extraterrestrial Intelligence). In the early days of SETI, scientists would record cosmic static on computer tape or even paper. They would then look at these recordings at leisure. In the 1970s, this ex post facto observing scheme produced many "candidate signals" – hits that looked good at first, and that might have been alien transmissions. (A famous example is the "Wow" signal, found at Ohio State in 1977.) However, none of these candidates could be found a second time. Consequently, they don't qualify as solid detections. They're ambiguous, at best.

However, many of today's SETI experiments can weed out interference and other causes of false alarms immediately. And that has led to an interesting situation: When you have real-time ability to verify signals, you don't end up with a drawer-full of "interesting" cases.

In other words, as technology improved, the number of enticing candidate signals went down. In science-speak, the false alarm rate decreased. It wasn't because any aliens stopped broadcasting; it was because we stopped being fooled.

Maybe this phenomenon explains why, as our cameras have gotten better, the number of interesting UFO cases has lessened.

For SETI, the really compelling detection is still to come. One good signal detection could easily surpass the credibility of dozens of intriguing candidates from four decades ago.

The same should apply to the folks who argue that some UFOs are actually alien craft. They should come forward with a truly great piece of evidence, a trump card that would allow them to stop playing the weak hand of the past.

Seth Shostak is Senior Astronomer and Director, Center for SETI Research, and a contributor to SFGATE