Radio emission from CTA-102? Certainly. But what is CTA-102? Today we know that CTA-102 is a distant quasar. At the time, the word ‘quasar’ had not even been coined. We still don’t know very well what quasars are; and there is more than one mutually exclusive explanation for them in scientific literature. Nevertheless, no astronomers today, including those involved in that Moscow press conference, seriously contend that a quasar like CTA-102 is some extraterrestrial civilization billions of light years away with access to immense power levels. Why not? Because we have alternative explanations of the properties of quasars that are consistent with known physical laws and that do not invoke alien life. Extraterrestrials represent a hypothesis of last resort. You reach for it only if everything else fails.
In 1967, British scientists found a much nearer intense radio source turning on and off with astonishing precision, its period constant to ten or more significant figures. What was it? Their first thought was that it was a message intended for us, or maybe an interstellar navigation and timing beacon for spacecraft that ply the space between the stars. They even gave it, among themselves at Cambridge University, the wry designation LGM-1 – LGM standing for Little Green Men.
However, they were wiser than their Soviet counterparts. They did not call a press conference. It soon became clear that what they were observing was what is now called a ‘pulsar’, the first pulsar to be discovered. So, what’s a pulsar? A pulsar is the end state of a massive star, a sun shrunk to the size of a city, held up as no other stars are, not by gas pressure, not by electron degeneracy, but by nuclear forces. It is in a certain sense an atomic nucleus a mile or so across. Now that, I maintain, is a notion at least as bizarre as an interstellar navigation beacon. The answer to what a pulsar is has to be something mighty strange. It isn’t an extraterrestrial civilization. It’s something else: but a something else that opens our eyes and our minds and indicates unguessed possibilities in Nature. Anthony Hewish won the Nobel Prize in physics for the discovery of pulsars.
The original Ozma experiment (the first intentional radio search for extraterrestrial intelligence), the Harvard University/ Planetary Society META (Megachannel Extraterrestrial Assay) programme, the Ohio State University search, the SERENDIP Project of the University of California, Berkeley, and many other groups have all detected anomalous signals from space that make the observer’s heart palpitate a little. We think for a moment that we’ve picked up a genuine signal of intelligent origin from far beyond our solar system. In reality, we have not the foggiest idea what it is, because the signal does not repeat. A few minutes later, or the next day, or years later you turn the same telescope to the same spot in the sky with the same frequency, bandpass, polarization, and everything else, and you don’t hear a thing. You don’t deduce, much less announce, aliens. It may have been a statistically inevitable electronic surge, or a malfunction in the detection system, or a spacecraft (from Earth), or a military aircraft flying by and broadcasting on channels that are supposed to be reserved for radio astronomy. Maybe it’s even a garage door opener down the street or a radio station a hundred kilometres away. There are many possibilities. You must systematically check out all the alternatives, and see which ones can be eliminated. You don’t declare that aliens have been found when your only evidence is an enigmatic non-repeating signal.
And if the signal did repeat, would you then announce it to the press and the public? You would not. Maybe someone’s hoaxing you. Maybe it’s something you haven’t been smart enough to figure out that’s happening to your detection system. Maybe it’s some previously unrecognized astrophysical source. Instead, you would call scientists at other radio observatories and inform them that at this particular spot in the sky, at this frequency and bandpass and all the rest, you seem to be getting something funny. Could they please see if they can confirm? Only if several independent observers – all of them fully aware of the complexity of Nature and the fallibility of observers – get the same kind of information from the same spot in the sky do you seriously consider that you have detected a genuine signal from alien beings.
There’s a certain discipline involved. We can’t just go off shouting ‘little green men’ every time we detect something we don’t at first understand, because we’re going to look mighty silly – as the Soviet radio astronomers did with CTA-102 – when it turns out to be something else. Special cautions are necessary when the stakes are high. We are not obliged to make up our minds before the evidence is in. It’s permitted not to be sure.
I’m frequently asked, ‘Do you believe there’s extraterrestrial intelligence?’ I give the standard arguments – there are a lot of places out there, the molecules of life are everywhere, I use the word billions, and so on. Then I say it would be astonishing to me if there weren’t extraterrestrial intelligence, but of course there is as yet no compelling evidence for it.
Often, I’m asked next, ‘What do you really think?’
I say, ‘I just told you what I really think.’
‘Yes, but what’s your gut feeling?’
But I try not to think with my gut. If I’m serious about understanding the world, thinking with anything besides my brain, as tempting as that might be, is likely to get me into trouble. Really, it’s okay to reserve judgement until the evidence is in.
I would be very happy if flying saucer advocates and alien abduction proponents were right and real evidence of extraterrestrial life were here for us to examine. They do not ask us, though, to believe on faith. They ask us to believe on the strength of their evidence. Surely it is our duty to scrutinize the purported evidence at least as closely and sceptically as radio astronomers do who are searching for alien radio signals.
No anecdotal claim – no matter how sincere, no matter how deeply felt, no matter how exemplary the lives of the attesting citizens – carries much weight on so important a question. As in the older UFO cases, anecdotal accounts are subject to irreducible error. This is not a personal criticism of those who say they’ve been abducted or of those who interrogate them. It is not tantamount to contempt for purported witnesses.* It is not, or should not be, arrogant dismissal of sincere and affecting testimony. It is merely a reluctant response to human fallibility.
[* They cannot be called, simply, witnesses – because whether they witnessed anything (or, at least, anything in the outside world) is often the very point at issue.]
If any powers whatever may be ascribed to the aliens – because their technology is so advanced – then we can account for any discrepancy, inconsistency or implausibility. For instance, one academic UFOlogist suggests that both the aliens and the abduct-ees are rendered invisible during the abduction (although not to each other); that’s why more of the neighbours haven’t noticed. Such ‘explanations’ can explain anything, and therefore in fact nothing.
American police procedure concentrates on evidence and not anecdotes. As the European witch trials remind us, suspects can be intimidated during interrogation; people confess to crimes they never committed; eyewitnesses can be mistaken. This is also the linchpin of much detective fiction. But real, unfabricated evidence – powder burns, fingerprints, DNA samples, footprints, hair under the fingernails of the struggling victim – carry great weight. Criminalists employ something very close to the scientific method, and for the same reasons. So in the world of UFOs and alien abductions, it is fair to ask: where is the evidence – the real, unambiguous physical evidence, the data that would convince a jury that hasn’t already made up its mind?
Some enthusiasts argue that there are ‘thousands’ of cases of ‘disturbed’ soil where UFOs supposedly landed, and why isn’t that good enough? It isn’t good enough because there are ways of disturbing the soil other than by aliens in UFOs – humans with shovels is a possibility that springs readily to mind. One UFOlogist rebukes me for ignoring ‘4,400 physical trace cases from 65 countries’. But not one of these cases, so far as I know, has been analysed with results published in a peer-reviewed journal in physics or chemistry, metallurgy or soil science, showing that the ‘traces’ could not have been generated by people. It’s a modest enough scam compared, say, with the crop circles of Wiltshire.
Likewise, not only can photographs easily be faked, but huge numbers of alleged photographs of UFOs have without a doubt been faked. Some enthusiasts go out night after night into a field looking for bright lights in the sky. When they see one, they flash their flashlights. Sometimes, they say, there’s an answering flash. Well, maybe. But low-altitude aircraft make lights in the sky, and pilots are able, if so inclined, to blink their lights back. None of this constitutes anything approaching serious evidence.