Sen—There has been a ripple of excitement this week over radio signals from space that some hopeful folk are suggesting might be an attempt by aliens to make contact.
A New Scientist article highlighted the mysterious broadcasts from deep space, though Sen has written about the phenomenon, known as fast radio bursts (FRB), before.
They are extremely short-lived and have left radio astronomers baffled as to their origin. But what has alerted the ET hunters is the recent suggestion that there is a pattern to their behaviour.
Astronomers use a technique called a dispersion measure to relate the time the burst arrives in its range of frequencies to the distance that the burst has travelled. And the New Scientist article reports a data anaysis that concluded the ten bursts so far detected all have dispersion measures that are a multiple of the number 187.5.
I should say straight away that leading experts in astronomy are claiming that the pattern is not really there. But in any case, it is a huge jump to go from saying you don’t understand something to assuming an alien cause. And with the sources apparently spread so widely across the Universe, it seems unlikely that they are physically linked.
So perhaps any apparent pattern is coincidence or the signals are actually produced by an object closer to home, such as a satellite, or other instrument, that has fooled the astronomers.
It wouldn’t be the first time that we have been tricked into thinking a radio signal was extra-terrestrial contact. Today we are well aware of pulsars, those extremely dense neutron stars that flash at us at incredibly precise intervals, like cosmic lighthouses, as they spin.
But when the first was discovered, way back in 1967, it was dubbed LGM-1, standing for Little Green Men, because it was thought it might be a beacon transmitting an alien message!
Before that, in 1963, another radio source labelled CTA-102 was hailed as evidence of ET by Soviet scientists, but later identified as a quasar, the active nucleus of a faraway galaxy.
In 1977, a brief signal in the narrowband part of the spectrum, and coming from the direction of Sagittarius, was detected by the Big Ear radio telescope in Ohio. It’s cause is a mystery still, but it has been dubbed the Wow! Signal, after observer Jerry Ehman scribbled Wow! on the computer printout that caught it.
As well as these accidental recordings, there have been dedicated searches for evidence of intelligent alien life since Giuseppe Cocconi and Philip Morrison, two scientists at Cornell University in the US, first proposed that astronomers tune in to nearby stars to listen for signals in 1959.
The earliest search was Project Ozma in 1960, when radio astronomer Frank Drake, pointed the Green Bank telescope in West Virginia at nearby Sun-like stars Tau Ceti and Epsilon Eridani. Then in 1984, the SETI Institute was established in California, standing for Search for Extraterrestrial Intelligence.
An early example of citizen science came when a screensaver was devised that would hunt for aliens when your home computer was at rest. Run by the University of California at Berkeley since 1999, the project, called Seti@home, has enlisted volunteers to help analyse radio signals from space.
The project, now in its second incarnation, works by harnessing the power of thousands of desktop computers around the world, to mimic a supecomputer and examine chunks of data collected by the Arecibo telescope in Puerto Rico.
In the past, a number of observatories took time out to joint the quest to find ET. For ecample, the iconic Lovell Dish, at Jodrell Bank, near Manchester in the UK, took part in the Project Phoenix program led by the SETI Institute from 1998 to 2003.
Working alongside Arecibo, it would check out around 1,000 relatively nearby stars for any strange signals. Using the two widely-separated telescopes allowed the alien-hunters to rule out any “messages” that were due to local interference, such as a microwave oven or mobile phone.
For most observatories, dedicating time to search for aliens is impossible to justify in today’s more austere times, when telescope time is expensive and in demand for pure astronomical research. So another way to satisfy our natural demand to know if we are alone in the Universe is to monitor the sky while carrying out other scientific observations.
In effect the ET search will piggyback on top of the routine work of the observatory. This is what Jodrell Bank is currently gearing up to do as part of a linked array of radio telescopes across the UK called e-MERLIN.
It would, of course, be a profound discovery to find that there is intelligent life elsewhere in the Universe. But many astronomers and philosophers are pessimistic about finding such a thing due to what is know as the Fermi Paradox. It asks a simple question: If the aliens exist, then where are they?
There are plenty of stars in our Galaxy that are billions of years older than our Sun. That would have allowed any civilisations orbiting them to advance to a far more advanced technological state than we humans have reached, and that would presumably include interstellar travel.
So with still no real evidence of visits by any alien space voyagers, despite the wishful thinking of flying saucer enthusiasts, perhaps we should just face up to the fact that the Milky Way is not teeming with intelligent life. We may really be unique after all.