British biologist Jack Haldane once famously opined that "the universe is not only stranger than we imagine, it's stranger than we can imagine."
Impressively poetic, and suitably modest. But I don't agree, because whenever anyone notices something new about the cosmos, they have no difficulty imagining something exceptionally strange, namely alien handiwork.
The latest example is an odd phenomenon that's descriptively called a "fast radio burst." FRBs are the latest celestial discovery to capture the attention of both astrophysicists and the media -- and be labeled by some as the work of crafty extraterrestrials.
No one had either heard of or imagined FRBs until one was discovered by astronomer Duncan Lorimer in 2007, using data from a radio telescope in Australia. It was a brief "flash" of radio energy -- about 20 times speedier than an eye blink -- coming from a mostly blank area in the southern sky. Since the flash was seen only once, many astronomers were inclined to write it off, figuring it might be some sort of instrument glitch. If you see Bigfoot only once, you can pretty much dismiss the experience. (In fact, you can always dismiss it.)
Well, it now seems the FRB was as real as the nose on your countenance. Another 10 have been found. Indeed, an extrapolation of these discoveries suggests that if our radio telescopes were able to observe all the sky, all the time, they'd be picking up thousands of bursts a day.
So the big question is: What's making these radio pings? What are they? The biggest clue comes from the fact that the bursts "whistle," which is to say they decrease in frequency during the flash, somewhat like quickly letting out the slide on a trombone. And that's a phenomenon that astronomers understand. Any brief radio signal will drop in frequency because of scattering by hot gas between the stars (and even between galaxies). And logically enough, the more gas the radio wave passes through, the slower the slide down the dial.
That's all a bit of nerdy astrophysics, but it means that by looking at how quickly the FRBs whistle, you can get a rough idea of how distant the signal sources are. The slower the whistle, the farther the source. Most astronomers have reckoned that the FRBs are very far away, maybe billions of light-years. That, of course, would mean that they must be generated by exceptionally powerful events; otherwise the signals would have faded to near-nothingness before reaching us.
But now there's something new -- and disturbing. A trio of astronomers claims that, looking at the speeds of the whistles, they find a pattern. The speeds are all integer multiples of one number.
That's like measuring the weights of all the kids in your Latin class and finding that every weight is an exact multiple of 20 pounds, with nothing in between -- 100 pounds, 120 pounds 140 pounds, etc. That would be more than a little disturbing.
Mind you, this could happen by chance if there were only a few kids taking Latin. But even though there are merely 11 known FRBs, the astronomers claim that the odds against the pattern being a statistical accident are thousands to one.
So what's going on? The answer is... we don't know. It's possible that there's some astrophysical reason for this series of "magic numbers," such as the effect of colliding stars or tangling black holes. Cosmic exotica.
Then again, maybe they're caused by something that doesn't require Stephen Hawking's brain to understand. Maybe this is all part of a cosmic signaling scheme organized by aliens, a galaxy-wide effort to bring young societies into a club of advanced beings. And they have organized the whistle settings on their transmitters to, for example, identify the senders.
That's sure appealing, but don't get too excited (not about this, anyway). History's not on the side of an explanation dependent on alien artifice. In 1967, when the first regularly pulsing radio source was discovered by British astronomers, they referred to them as "little green men" (LGMs). Well, it turned out that the sources were neither little nor green nor men. They were pulsars -- spinning dead stars.
In 1965, when Russian astronomers found that a distant radio source known as CTA 102 was rapidly varying in signal strength, they suggested that it might be under the control of aliens bent on an intergalactic shout-out. We later learned that CTA 102 is a quasar. And quasars get louder and softer for perfectly natural reasons.
It's always tempting to invoke dramatic explanations for novel phenomena -- after all, that makes them both more interesting and more important. But history suggests that caution is a good idea, and more likely to be justified in the end. In the case of the FRBs, one possible explanation -- still not ruled out -- is positively prosaic: They could be some type of man-made interference that only seems to be coming from deep space.
When we see lights in the sky, discover odd debris in the New Mexico desert, or discern patterns in British wheat, some among us will quickly assume that aliens are to blame. But perhaps we shouldn't rush to judgement.