For millions of years – as long as humans have existed and gazed upwards –  people will have questioned are we alone in the Universe? Yet, it is only in the past 60 years or so, with rapid technological advances, that it has become possible to make serious attempts to answer that age-old question.

Listen to interview with Myles Dungan on The History Show, RTE Radio 1 (broadcast 2/04/17)

Ancient

The ancient Greeks, the foundation stone upon which much of our western way of life today has been built, were the first, in the west at least, to consider the possibility that the Universe was infinite and that it contained an infinite number of civilisations.

The arrival in the 16th century of the Copernican model of our Solar System, where the Earth revolved around the Sun, impacted on our thoughts of ET life too.

This radical science, which place the Sun at the centre of the Solar System, not the Earth, implied that our planet was not perhaps as important as we had thought.

If Earth was just one planet of several orbiting the Sun, and not at the centre of everything, then why could there not be life, like us, on other similar planets?

This, of course, caused complications for some established religions, as if there was life, like us, on other planets, then had Jesus come down to save them too?

There things stood, with lots of questions, but no ability to answer them, for several centuries until the second half of the twentieth century.

Principles

In the 1950s, at the height of Cold War paranoia, the number of reported sightings of UFOs increased dramatically across the United States.

In 1959, two young scientists at Cornell University decided to try and take a serious scientific look at how mankind might try to tune in to alien communications.

The paper appeared in Nature, one of the world’s top scientific journals, and it was called ‘Searching for Interstellar Communications’.

This paper changed everything because it established the scientific principles by which scientists might try to find, and listen in to alien communications, if they existed.

The authors, Guiseppe Cocconi and Philip Morrison were both physicists based at Cornell University in upstate New York. They said that the possibility of extra-terrestrial ‘intelligent’ life couldn’t be determined, or ruled in or out. However, given that mankind evolved it was likely that other intelligent creatures evolved too, on planets near a Sun. Some of these civilisations might, the authors said, be more advanced than our own and may want to contact us and other intelligent beings that resided on planets – like them – close to a warm Star.

The two physicists considered how intelligent extra-terrestrials might make contact with us, and decided that electromagnetic waves, which travel at the speed of light and are not easily knocked off course, would be the most logical way to transmit a message.

Furthermore, they decided that the most likely frequency the aliens would broadcast on would be 1,420 megahertz as that is the ‘emission frequency’ of hydrogen, the most abundant element in the Universe. This is the frequency of the radio wave emissions given off when an atom in an element, in this case hydrogen, is given off as the element moves from a high energy atomic configuration into a lower energy configuration.

The aliens, the logic went, would chose this frequency because they knew other intelligent beings would also understand its importance and tune in accordingly.

SETI

The paper inspired a now-famous astronomer called Frank Drake to perform the first scientific experiment to search for extra-terrestrial intelligence. That was 1960.

Drake, is still alive, aged 86, and an active astronomer, and considered the Father of SETI the Search for Extra-terrestrial life, and the SETI Institute in the USA.

Drake pointed a radio telescope at two ‘nearby’ stars called Tau Ceti and Epsilon Eridani to see whether there was anything being broadcast from planets orbiting these Sun-like bodies in the hydrogen emission frequency from that location. There wasn’t.

Today, the SETI Institute, based in Northern California, has access to a $30 million array of telescopes, funded by Paul Allen, the co-founder of Microsoft. It has a permanent staff of scientists, and is supported by donations and computer power by SETI enthusiasts all over the world. It is not reliant on US taxpayers’ support.

Drake, apart from founding SETI, is also famous for producing something called the Drake equation along with Carl Sagan, to predict how many civilisations there might be in the Universe, based on known parameters.

In 1961, when the Drake equations was first produced, it predicted there was from 1,000 to one billion such civilisations, and the range was down to the fact that the parameters were nebulous.

The Drake equation has become more accurate over the years, based on better knowledge of parameters such as how often Sun-like Stars form, and how many of these stars have planets. But we still don’t know how precisely life begins, even on Earth, or what fraction of life will evolve to become intelligent.

Criticism

The implications of the Cocconi and Morrison article took time to be absorbed by the mainstream scientific community, but eventually, in 1971, NASA got on board by setting up Project Cyclops at NASA. This was the first formalised, publicly-funded research project into searching for ET life.

The funding wasn’t enough for scientists at Cyclops to do a great deal, but even at its low level of funding, it soon came under political attack.

In 1978, Senator William Proxmire bestowed one of his infamous ‘golden fleece’ awards on the SETI programme, deriding it as a waste of taxpayers’ money.

In 1981, a Proxmire amendment killed off SETI funding for the following year with Proxmire saying that it was a silly search for aliens unlikely to produce results.

In 1993, NASA got back into SETI work, this time with the High Resolution Microwave Survey Targeted Search programme. But, again, this project too came under political attack and lost is operational funding just one year after it began.

It wasn’t just politicians who were critical of SETI work, scientists were critical too, who supported the view outlined by the late nuclear physicist Enrico Fermi.

Fermi, who had died in 1954, did not accept the view (held by many at SETI) that the Universe was teeming with life, based on its size, and number of planets near Stars.

Fermi said that if the SETI people were to be believed, and the Universe was teeming The Earth was 4.5 billion years old, Fermi had said, and there was no evidence of extra-terrestrial life visiting here in all that time.

He had asked the question if there is so much life out there, ‘where is everybody’. It was a simple, yet, devastating riposte to the Drake equation.

Fermi had come up with his idea in 1950, but many scientists still point to it.

Evidence

Yet, Fermi was not alive when two things happened, both in the mid-1970s, which are the best pieces of evidence for the existence of extra-terrestrial life.

The first story concerns an experiment that took place when the Viking landers landed on Mars in 1976. Some readers will remember the amazing colour pictures of the surface of Mars shown on TV at the time.

Viking 1 and Viking 2 were NASA space probes sent to Mars for the sole purpose of determining whether life existed on the planet.

One of three experiments on board worked was set up to see if the soil contained microbes. If it did, the life forms in the Martian soil would ingest and metabolise the nutrients and release either radioactive carbon dioxide or methane gas which could be measured by a radiation detector on the space probe.

The minute the nutrients were mixed with the soil sample there was a huge reaction with something like 10,000 counts of radioactive molecules being produced. This was a huge spike because the radiation background on Mars was 50 or 60 counts.

The experiment was, thus, positive for life, but NASA did not announce it had found life because the other two experiments on board which were negative for life.

The other piece of ‘evidence’ that is put forward concerns what is called the ‘Wow signal’, which was received by the Big Ear Telescope on 15th August 1977. The telescope was scanning for signals coming in from potential ET intelligent beings.

This was a strong narrowband signal which appeared to come from the constellation Sagittarius, and was in the 1,420 MHz frequency band. It was precisely the sort of signal that the SETI researchers were looking for as being of ET origin.

Jerry Ehman, a volunteer astronomer working with SETI spotted this massive, powerful, narrow band Wo signal on the paper readouts he was going through while sitting at his kitchen table a few days later.

Ehman was stunned by the signal and was so taken back by it that he wrote the comment ‘Wow’ in the paper margins, hence the name Wow signal.

The signal lasted 72 seconds, then the Earth rotated, the signal dropped out of view of the telescope, and when the same region of sky came into view again, it was gone.

The signal helped inspire the film Contact (1997) starring Jodie Foster.

Jerry Ehman went through every conceivable possible earthbound source for the signal, such as nearby military and civilian communications, but nothing could explain it. It remains the strongest candidate ever detected for an alien radio transmission.

Recent

The biggest thing to happen in recent years was the announcement in 2015 of $100 million privately funded search for ET life over 10 years, or about 10 million per year. This is big even compared to the annual funding for SETI of about 2 million dollars per annum. The Breakthrough Listen and Breakthrough Message initiatives are supported by the Russian internet investor and physicist Yuri Milner and supporter by big names like Stephen Hawking, Martin Rees and Frank Drake.

This will survey the one million stars in the Milky Way closest to Earth, as well as the 100 closest galaxies for signs of intelligent life beyond Earth, in the form of artificial radio or optical transmissions that cannot be explained by natural phenomenon.

The advance of technology and our ability to scan more areas of our vast galaxy and Universe mean that people like Seth Shostak, an astronomer at SETI believes that we will have discovered ET life, intelligent or not, inside the next 20 years.

Get ready to meet ET!