Sen—There was considerable excitement this week over NASA’s announcement that the most Earth-like planet yet found has been detected by the Kepler space telescope.
In truth, the discovery of Kepler-452b was a typically over-hyped announcement. As Sen expert Kimberly Cartier explained in her blog, though there are similarities between our two worlds, such as the length of the year, the nature of the host star, and the fact it orbits in the habitable zone, we really know very little about what Kepler-452b is really like.
No one can say for sure yet even if it is rocky. And as the truly inhospitable planet Venus has shown us in our own Solar System, a world can superficially resemble Earth and yet be very different.
Nevertheless, the discovery of Kepler-452b is remarkable enough because it shows how good astronomers are getting at detecting smaller worlds around other stars. Since the first exoplanets were found around ordinary stars, 20 years ago, the vast majority of finds have been the larger, more obvious planetary candidates. Many are gas giants, but zipping around their own stars very rapidly. These so-called “hot Jupiters” are in truth nothing like anything observed in our own planetary backyard.
What is happening now is that increasingly sophisticated detection techniques are allowing smaller worlds to be detected in the data that was collected during Kepler’s four-year primary mission following launch in March 2009.
Kepler-452b may hold the crown for being the most Earth-like planet discovered so far, but you can be pretty sure that it won’t be long before other worlds are found during reprocessing of the data that have equal or better claim.
Overhyped or not, the news about Kepler-452b was widely reported by the world’s media, demonstrating an ongoing fascination by ordinary people in the prospect that we are not alone, and that there could be other intelligent life out there in space. And by chance, the announcement came in the same week that a major boost was announced in the search for extra-terrestrial life (SETI) with the award of $100 million by Russian tycoon Yuri Milner to fund the project.
The campaign, which primarily uses radio telescopes to listen for signals with a pattern that suggest they have been transmitted deliberately by sentient beings, rekindled an old argument over what to do if and when we do pick up a message from ET.
Professor Matthew Bailes, of Swinburne University, Melbourne, will be in charge of Australian efforts to detect alien signals. But when asked this week whether we should reply, he advised caution, fearing that contact with more advanced civilisations might not end well for humans!
His concern echoed that of a former Astronomer Royal in the UK, Sir Martin Ryle. When a pithy message was beamed into space in 1974 by the Arecibo telescope in Puerto Rico, towards a star cluster 25,000 light-years away, he famously warned that we were foolish to give away our presence as any aliens receiving it might be “malevolent or hungry”.
It is hard to know whether such concerns are paranoid or pragmatic. After all, when we look at humanity, dominant groups do not have a history of treating less civilised tribes well, let alone other species that show intelligence, especially if those creatures are found to taste rather good.
We might learn of ET’s presence indirectly, by detecting pollution in a nearby planet’s atmosphere, artificial structures built to harness a star’s light, or signals from spaceport radar or alien TV stations. Our own TV and radio broadcasts have travelled so far into space that star systems within a distance of 50 light-years could be enjoying early episodes of Doctor Who or Star Trek!
But that aside, how can we go about understanding any meaningful messages directly sent our way by extra-terrestrial civilisations? I asked Dr John Elliott, a researcher into the nature of communication, at Leeds Metropolitan University in the UK. He told me: “SETI has always been about listening out for evidence of alien technology such as a beacon. It was really when I came aboard that we thought, what about language? If we do pick up an alien signal, what do we do with it, how can we identify its meaning? It's all to do with the structure.
“You intuitively hear that if you listen to people speak, even if it is a language you don’t speak yourself. So that physical structure on the surface would be detectable, and then you would immediately look to see the relationship of patterns in the message to see if there is internal structure. A combination of those two elements will give you an initial and very quick tip on whether it is interesting or not.
“If a message arrives in binary structure, as a string of zeros and ones like an intergalactic e-mail, there will be a physical fingerprint of the pattern within it. I have looked at loads of languages and have ascertained that there is a universal underpinning structure to all languages that all humans and even dolphins and other animals use.
“If aliens do send us a deliberate message, then I hope they would have the foresight to include some sort of crib—a Rosetta stone—to help us break the code. Unless you have that to tell you that a particular sound or symbol means a particular thing then you are lost.
“Certainly we'd realise that it was a message but to get to its constituent parts, well it wouldn't be like the movie Mars Attacks!, you'd need an actual translation aid. We would need to be able to decipher the sounds and the syntax.
“You would hope that aliens would be intelligent enough to help us by referring to things that we might also have a concept of, such as pulsars or the laws of physics. Of course it would take a long time for us to send a reply because even the nearest star is more than four light-years away.”