aimed the Green Bank radio telescope at the nearby stars Tau Ceti and Epsilon Eridani and listened for signals. Although he heard nothing, this kicked off over half a century’s search for signs of Extra Terrestrial Intelligences.
Last Thursday, the UK SETI Research Network had a symposium at Manchester University to discuss the latest attempts to hear the whispers of intelligences from elsewhere. As I mentioned in a previous post, I’ve been interested in the search since I was a boy, and it was a real honour to be able to attend the meeting, although I was a little nervous because I was also due to give a talk.
The first lecture was by Professor Mike Garrett, the Director of Astronomy & Astrophysics at Jodrell Bank radio telescope, entitled ‘All Sky Radio SETI.’ He began by asking whether SETI was sensible, concluding yes, in terms of the physics of receiving transmissions and also the basic technology.
It was less clear whether there were any signals to detect. He found it a little disturbing that current astronomical data seems to show no apparent sign of ET civilizations at all. This problem has been termed ‘The Great Silence.’
In addition, a telescope would need to be pointing in the right direction to pick up a transmission at all. This was one of the reasons that finding any aliens might be tricky.
Garrett suggested that since intelligent life took a long time to arise on this planet, it might be very rare and easy to miss, partly due to the limitations of current instruments.
These technical limitations can be seen in the case of a natural phenomenon called Fast Radio Bursts (FRBs). FRBs happen all the time, all over the sky, but most get missed because current radio telescopes can only look at a small percentage of the sky at once.
This implies that field of view is important for a SETI signal, and Garrett suggested that multi-beam receivers were needed to widen the view. Multi-Beam Receivers were first suggested by Arthur C Clarke in his novel Imperial Earth. They consist of ‘thousands of little wires,’ and would be suitable instruments for scanning the whole sky.
Next, Duncan Forgan looked at the possibility of using exoplanet transits to find and initiate communications with aliens. This talk brought up another significant problem in SETI: the fact that we have potentially the entire universe to search.
Space, as Douglas Adams once noted, is big. There are between 100 and 400 billion stars in the Milky Way galaxy alone, and about 200 billion galaxies in the universe (and possibly ten times more). Since the scale of the search makes finding a needle in a haystack seem simple, some have been thinking about ways of narrowing that search.
Forgan suggested one method by using what’s known as exoplanet transits. Exoplanets – planets around other stars – can be detected when they pass in front of the face of their parent star. When this happens, there’s a small dip in the light output of the star. The problem is that only a fraction of planets are suitably aligned so that they will pass in front of their star from the point of view of the Earth.
As well as planet detection, this method will soon allow researchers to glean spectrographic data on the composition of planetary atmospheres. If life-signs can be found, this should narrow the search for possible homes of ET civilizations. For example, if we discovered a planet with an oxygen rich atmosphere, then it might be a good place to look.
Transits might also allow different ETs to communicate with one another. If one ET fired a powerful laser in the direction of an observer that they knew was looking for a transiting planet, then the observer would be able to detect the laser light in the spectrographic data that they were picking up from the ETs’ star.
This means that transits could be used for ‘handshakes’ between ET civilizations, and civilizations communicating in this way might create a galaxy spanning network, in time.
The third speaker was Arik Kershenbaum, an expert in animal communications. He was concerned with the difference between communication and language, suggesting that humans are only Earthly species who possess language. One of the problems is actually defining language, which has in the past been seen in terms of semantics, or meaning.
This definition is not useful if you don’t understand a language, and more technical approaches have been suggested, although none are without problems. But as Lawrence Doyle suggested, this issue is important, because ‘how can we expect to talk to aliens if we can’t even talk to dolphins?’
After lunch, Jamie Drew of the Breakthrough Initiatives gave an outline of their mission. Breakthrough Listen is funded by Internet billionaire Yuri Milner, Stephen Hawking and Mark Zuckerberg. Over the next decade, Breakthrough Listen is supplying a large amount of funding for SETI ventures, helping the search to enter the mainstream in a way that has not been possible before.
Drew suggested that private investments might be important in determining ‘the shape of space to come.’ He pointed out the long history in the US of private philanthropists putting money into space exploration. James Lick’s funding of an observatory in 1876 is a good example, but the rocket pioneer Robert Goddard was also helped by private investors in the 1920s. Today, a number of Silicon Valley entrepreneurs are dedicated to putting significant money behind various space ventures.
Drew also suggested that Breakthrough Listen would bring a ‘Silicon Valley ideology’ into SETI. This would include developing the tools to search for signals in the vast datasets that are already being accumulated from radio telescopes. He suggested that a priority would be developing analytical software for this purpose.
Breakthrough Listen will use a number of telescopes, including the Green Bank Telescope, Parkes, the APF at Lick and the new giant Chinese FAST telescope.
My talk on consciousness and SETI was next. My claim was that cognitive science – the science of thinking – had a lot to contribute to SETI. This was because consciousness needs to be seen in terms of the larger picture of cosmic evolution, and as part of evolution of intelligence. It included the serious problem of Zombie Aliens.
Claudio Maccone’s technical talk followed mine, on his mathematical models for how life and civilization arises in the universe. I found this interesting, but I must admit that I struggled with the maths a little bit.
I ended the day feeling relieved that my talk had gone well, but also encouraged by the number of novel approaches that are being suggested to help the search for intelligence elsewhere. The involvement of Breakthrough Listen, in particular, is already giving the field the boost that it probably needs to solve such a difficult, but provocative problem. More next time.