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Is there anybody out there?

(170105) -- BEIJING, Jan. 5, 2017 (Xinhua) -- Photo taken on Sept. 24, 2016 shows the 500-meter Aperture Spherical Telescope (FAST) in Pingtang County, southwest China's Guizhou Province. The FAST, world's largest radio telescope, measuring 500 meters in diameter, was completed and put into use. (Xinhua/Liu Xu) (zkr) (Photo by Xinhua/Sipa USA)

The world’s largest radio telescope, the Five hundred-metre Aperture Spherical Telescope in Guizhou province, southwest China

In a forest in Puerto Rico, a mountain range in China’s Guizhou province and the genteel heart of rural Cheshire, some of mankind’s most advanced technology is engaged in an unlikely project with a tiny chance of success. Vast radio telescopes trained on the far reaches of space are channelling terabytes of data each minute to a global network of scientists and enthusiastic amateurs for analysis. Their hope: to uncover signals which could not have been produced naturally and which therefore suggest the existence of intelligent life outside Earth.

So far, it’s not going well. Despite almost 60 years of combing the skies, we’ve not heard a single verifiable peep from ET.

But then it’s incredibly unlikely that we would have done. For the Search for ExtraTerrestrial Intelligence (SETI) to succeed, life forms need to have evolved on other worlds to the level at which they can construct broadcast equipment. They need to have decided that constantly spraying signals out into the cosmos in the general direction of our planet is a worthwhile use of their time and resources. The signals need to be sent in a format which can be picked up by what aliens may well regard as our laughably basic technology. And the message they contain needs to be identifiable to us as such, even though the creatures who made it might have about as much in common with us as a dugong does with a MacBook.

“If SETI succeeds, it’s probably the most important discovery ever made”

Even if an unequivocal alien signal were to be received, it would be hard to know what to do with it. In the time its broadcast took to cross the unimaginable expanses of space, the alien civilisation might have blown itself up or climate-changed itself out of existence. In the period before our response arrived, we humans might have done the same.

But these slim odds haven’t stopped an eclectic band of academics from throwing themselves into SETI. Astronomers, data analysts, biologists, philosophers, mathematicians and computer programmers have all contributed to the hunt, often without funding. Anthropologists have pondered the impact on human civilisation of discovering we are not alone; linguists have wrestled with the protocols of responding to first contact; physicists have struggled with the “zoo hypothesis”, the idea that alien civilisations are abundant but have designated Earth as an uncontactable nature reserve so that humans can evolve in peace.

So why would some of the world’s best minds throw themselves into this quixotic and quite possibly epically futile quest? “Because the payoff is so enormous,” says the UK’s astronomer general, Professor Martin Rees, 76.
“I mean, if you succeed, then it’s probably about the most important discovery ever made – so I think many people are prepared to take that gamble.”

Rees has little time for those who say that after more than a half century of fruitless SETI monitoring, we ought to give up the hunt. “The amount of data we’ve got is a tiny fraction of what we might get, and we’re sampling just a tiny corner of the galaxy,” he says. “It’s rather like looking at one bucketful of water, and saying we’ve learned what’s in the ocean.”

“Microbes or mathematicians”

There have been some encouraging developments in recent years.

When former SETI Institute director Dr Jill Tarter, 74, began her career, there were just nine planets in the known universe, one of which, Pluto, would later be demoted to the status of dwarf planet. The first confirmed detection of an “exoplanet” – a planet outside our solar system – did not take place until 1992.

Since then our knowledge of exoplanets has grown exponentially, thanks in large part to Nasa’s Kepler space observatory, which identified thousands of them during its nine years in operation. Launched in 2009, it was put to sleep on 6th July 2018, shortly before its mission ended and it was consigned to cosmic oblivion.

Some of the exoplanets uncovered by Kepler sit in the “habitable zone”, just close enough to their stars for water not to freeze and just far enough for it not to boil away into the void. Such observations have led scientists to claim by extrapolation that there may be billions of habitable Earth-like planets in our galaxy. As these are identified, SETI’s radio telescopes can be trained more accurately on potential breeding grounds for life.

In the meantime, research into extremophiles – organisms that survive in environments on Earth which had been thought incapable of sustaining life – has expanded our understanding of the range of planets that might be home to ETs.

“With exoplanets proving to be so plentiful, and extremophiles showing us the amazing ability of life to survive in environments that seemed unthinkable when I was a student, we now understand that there’s potentially so much more habitable real estate out there than we could have imagined,” says Tarter. “It’s so exciting to be living in a period when we may find out whether any of it is inhabited, either by microbes or mathematicians.”

New investment is also opening up the possibility of smarter searches. In 2015 Israeli-Russian billionaire Yuri Milner announced the launch of Breakthrough Listen. This project would plough $100 million into SETI over ten years, opening up thousands of hours of radio telescope observation time for scientists.

On Monday 10th September 2018 Breakthrough Listen, on whose advisory committee both Rees and Tarter sit, announced the successful use of a new machine-learning algorithm. The AI-driven tool, claimed the project’s lead investigator Dr Andrew Siemion, has learnt to spot signals missed by standard SETI algorithms.

The Breakthrough project’s scientists set the AI analyst loose on some data supplied by the Green Bank radio telescope in Virginia, from a galaxy three billion light years away. The data had already been scrutinised using the usual mathematical analysis techniques, which had uncovered 21 “fast radio bursts” (FRBs).

Breakthrough’s new system uncovered an additional 72 bursts in the data, a 340 percent increase in registered activity. “Up until now, we’ve always asked the machines to find particular patterns in the data,” says Tarter. “But now the machines will hopefully be smart enough to just tell us whether there’s anything there at all that isn’t noise [and] that isn’t natural.”

FRBs, which were discovered ten years ago, are radio bursts which last for just a few milliseconds. They pulse with huge intensity: SETI Institute astronomer Seth Shostak has described them as emitting “enough energy to run humanity (at its present, prodigious burn rate) for ten trillion years” in less than a heartbeat. This enigmatic phenomenon could be natural in origin – but no definitive explanation has been found for it so far.

Jill Tarter and Larry Webster monitor computer screens at the radio observatory in Arecibo, Puerto Rico, in October 1992

“Duncan Forgan, crank-mail archivist”

The recent developments and investment in SETI have been a welcome turn of events for a discipline that was overlooked and underfunded for years.

SETI has long been the unloved stepchild of astronomy proper, seen by many scientists as beneath their dignity. “When I published my first SETI paper, my supervisor got called up by somebody fairly senior who told him, ‘You should tell your students to stop working on this,’” says Dr Duncan Forgan of the Centre for Exoplanet Science at the University of St Andrews. “There was a definite feeling that this is not what a good astronomer should be doing.”

“We really had such a terrible time, early on, with the public and indeed even the funders being confused about SETI being the same thing as UFOs,” says Tarter. “We had to spend a long time establishing the legitimacy of this as a science.” SETI, in short, had a big image problem. It wasn’t helped by the media, which has had a tendency to overhype any announcements about research, leading to inevitable heartbreak when hordes of little green men fail to materialise on cue.

“In some ways we’ve been dealing with fake news much longer than the mainstream,” says Forgan. “You’d be trying to do rigorous science, to hold a very important question up to the highest of academic standards, then you’d see this utter poppycock [about SETI] in the news. Stuff would go into the media that was distorted, or people would get the wrong end of the stick.”

SETI, says Forgan, has been “plagued by false alarms”, in part thanks to its tendency to attract conspiracy theorists. “The subject has always had this problem with people reading things into [research] that’s clearly not true,” he says. “When I began studying SETI I started getting the weirdest stuff through the letterbox. People with their own theories of the universe, people who think the pyramids were built by aliens, and that they have proof. People who were convinced they could spot aliens using dowsing rods. All this absolute gubbins. My unofficial job title in the office was ‘Duncan Forgan, crank-mail archivist.’”

In an attempt to bring clarity and balance to a complex and much-misunderstood topic, in 2000 Iván Almár and Jill Tarter introduced the Rio scale, which ranks space signals on a scale of importance from zero (‘none’) to ten (‘extraordinary’). A Rio score is created by multiplying two numbers: the first is a measurement of the scientific interest of the signal. The second is an estimate of the probability of that signal being real. “The idea was to try to quantify things and calibrate the conversation,” says Forgan. “In the same way that, if you were to read a story about an earthquake and it gave a reading on the Richter scale, you’d get an intuitive sense of whether it’s a bad earthquake or not.”

On 24th July 2018, Forgan published a paper introducing Rio 2.0, an updated, refined version of the scale, created in collaboration with Almár and Tarter. “When Rio was created, the principal source of news was TV,” he says. “Whereas now we have online news and social media. They have completely rewritten the way we do things in terms of communicating to the public about science.” The new scale has been released as an online calculator, so members of the public can check exactly how scores are reached: no signal discovered to date has registered a score above one. “Transparency and helping to inoculate the public against bad stories were our driving motivation to get this to work,” says Forgan.

This sober reassessment of a scale designed to diminish misleading press hyperbole didn’t produce the desired effect in all quarters, however. In the UK’s Express newspaper the story of the launch of Rio 2.0 was published under the following headline: “Alien life BOMBSHELL: SETI institute makes MAJOR announcement on hunt for alien life”.

“The end of Martian hunting season”

SETI didn’t just have problems with its image – money was just as big an issue.

In 1971, Nasa funded a study, Project Cyclops, which recommended the creation of a radio telescope array with 1,500 dishes. It also made the case for SETI as “a legitimate scientific undertaking [which] should be included as part of a comprehensive and balanced space programme” and tried to manage expectations about its outcome. “The search will almost certainly take years,” it claimed, “perhaps decades and possibly centuries.”

“The closest thing to a candidate for an alien signal was found in data from a telescope
affectionately known as ‘Big Ear’”

The mega-battery of dishes envisioned in Cyclops was never built – its $10 billion cost ($62 billion in today’s money) was seen as prohibitively expensive – but a smaller series of listening projects was funded by Nasa. Then, in 1993, disaster struck for SETI. US senator Richard Bryan, a Democrat, led a successful campaign in Congress to choke off funding to Nasa’s SETI programme, declaring “the end of Martian hunting season at the taxpayer’s expense”.

Part of the issue was that SETI ventures had nothing to show by way of big discoveries, so in the atmosphere of fiscal prudence following the early ’90s recession in the US it was hard to justify their funding.

The closest thing to a candidate for an alien signal had been found 15 years earlier in data from a radio telescope at Ohio State University, affectionately known as “Big Ear”. Big Ear used to be run for a few days at a time, until its one-megabyte hard drive was full: it would then shut down while the data were printed out.

Looking through one of the stacks of printouts on 15th August 1977, volunteer Jerry Ehman spotted an abnormal flash of radio energy from the Sagittarius constellation. The signal, which was 30 times higher than the background noise level, lasted for 72 seconds, the longest amount of time that Big Ear could focus on any given point. So impressed was Ehman that he circled the spike in the data with a red Biro and wrote ‘Wow!’ next to it. By the time Big Ear was back up and running again, the abnormal pulse – which later became known as the ‘Wow signal’ – had gone. Multiple subsequent attempts to replicate the finding over the next 40 years have failed.

With Nasa out of the picture after 1993, SETI scientists went on the hunt for private backing to continue their intergalactic eavesdropping. The SETI Institute raised the money to create the Allen Telescope Array, a set of 42 radio telescopes in California’s Cascade Mountains, funded by donors including Paul Allen, the co-founder of Microsoft. Meanwhile, the Berkeley SETI Research Center launched SETI@home, a programme which allowed people around the world to lend some of their home computers’ processing power to analyse data from Green Bank and Puerto Rico’s Arecibo telescope.

During this time, the technology available to SETI scientists also improved rapidly. The number of channels that could be monitored at a time went from thousands to billions, automated re-observation of results was introduced and signal-spotting computer algorithms replaced red-Biro-toting volunteers.

And then came the boost from the Breakthrough initiative with its unprecedented investment. Its founders explicitly recognised the uphill struggle faced by SETI scientists over the years. “For the last half-century, small groups of scientists have listened valiantly for signs of life in the vast silence,” they wrote in one of their mission statements. “But for government, academia and industry, cosmic questions are astronomically far down the list of priorities. And that lengthens the odds of finding answers. It is hard enough to comb the universe from the edge of the Milky Way; harder still from the edge of the public consciousness.”

“You’re all Earthlings”

On 26th September 2018 a workshop at the Lunar and Planetary Institute in Houston sent a ripple of excitement through the SETI community.

The workshop was hosted by Nasa, and was convened to discuss “technosignatures”’, defined by the agency as “signs or signals, which if observed, would allow us to infer the existence of technological life elsewhere in the universe”. This includes radio signals, but also laser emissions and planetary atmospheres filled with artificial pollutants such as CFCs, which might suggest the presence of aliens with fridges.

“There’s a feeling of optimism, that we’re going somewhere, that we can bring SETI into the mainstream”

Technosignatures might also include signs of “massive structures”. That could be a “Dyson sphere”, in which a star is surrounded with photovoltaic cells by alien engineers to capture its energy. It could even be a “Clarke exobelt”, a thick ring of geosynchronous satellites around a planet, which could in theory be distinguished from a natural ring of ice and dust particles.

The workshop in Houston was designed to assess “the current state of the field, the most promising avenues of research in technosignatures and where investments could be made to advance the science”. So is Nasa getting back into the SETI game under a new name after a 25-year absence?

“We really do hope so,” says Tarter. “There’s some wording in the appropriations bill for Nasa from the House of Representatives that suggests that there should be specific funding for looking for technosignatures… I’m just delighted because for a number of years, SETI was a four letter word at [Nasa] headquarters.”

Forgan believes that SETI is finally gaining momentum. “There has been a sea change,” he says. “There’s a feeling of optimism, that we’re going somewhere, and that as long as we keep this funding up, keep the interest up, the legitimacy up, we can bring SETI into the mainstream.” The mission to track down alien life, he believes, is a question of common sense. “The universe contains at least one technological civilisation. If you find one example of a rare object, the first thing you do is you try and find more. If we’d stopped at the first pulsar, then we would know nothing about neutron stars or how they rotate. If we stopped at the first detection of a black hole, where would we be? Why is it so different when we’re looking for people?”

It might not be people that are found, however, but a new form of inorganic intelligence that doesn’t need an Earth-like planet or water to survive. “The most likely source of an artificial signal may not be a civilisation like ours, but some sort of electronic machine, which could be the creation of some long-dead civilisation,” says Rees. “Electronic entities don’t want gravity, they don’t want an atmosphere, so they could be anywhere.”

For Rees, the phase of intelligent biological organisms equipped with technology may just be a short blip before the inevitable creation of superior, immortal electronic beings. These would be able to adapt and develop far faster than puny organic life with its glacial evolutionary processes. On Earth, says Rees, humans may see SETI taken out of their hands within the next couple of centuries by inorganic intelligence which isn’t limited by telescope time or the vagaries of Nasa budgets.

For the brief period during which we are still the dominant beings on our planet, though, could SETI help bring humanity together? “There are so many challenges that we currently face – climate change, water and food security, poverty, war… and we need to find a way to work together to solve them globally,” says Tarter. “One of the things that SETI does is hold up a mirror to everybody on the planet, and says, ‘See? Compared to anybody else out there you guys are all the same, you’re all Earthlings.’ I think this trivialising of the differences between us is something we absolutely have to do for our future.”

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