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Chatting with ET: Dialogue between The Actual and The Possible

By Lynne Quarmby

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Yet, while science attempts to describe nature and to distinguish between dream and reality, it should not be forgotten that human beings probably call as much for dream as for reality.

— François Jacob, The Possible and The Actual, 1982

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Ancient Greeks knew that unicorns were exotic animals observed in India. Even by 1600 it is unclear whether translators of the King James Version of the Bible were thinking of creatures real or allegorical when they wrote “God brought them out of Egypt; he hath as it were the strength of an unicorn” (Numbers 23:22). Either way, while the translators were writing about unicorns, Giordano Bruno was burned at the stake for, among other transgressions, his belief in extraterrestrials.

In 1967, Roger Patterson filmed a female Sasquatch walking across a clearing in a northern California forest. The 16 mm footage remains the only evidence we have of this presumed intelligent and elusive ape, all other reports of sightings have proved to be hoaxes. Patterson toured Sasquatch country, from northern California to British Columbia, showing the film and telling his story. I was ten years old when my father and I sat in those folding chairs, believers.

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The other day I called my father to ask him if he still believed in Sasquatch. “No,” he said. “I think if they were real we would have more evidence by now.” That is pretty much how I feel too, but we could be wrong.

The B.C. Scientific Cryptozoology Club lists 212 “cryptid” mammals – the Sasquatch is one of 36 putative primates. Club founder Paul LeBlond is a respected scientist and a Fellow of the Royal Society of Canada – he was also one of my professors when I was an Oceanography student. Paul’s avocation is the search for scientific evidence of cryptids and when it comes to Sasquatch, he remains open to the possibility of their existence.

What of extraterrestrials? The soul-stirring wonder and awe of a clear, dark star-filled sky has fuelled the creation of a fantastic diversity of fictional extraterrestrials. Might there actually be something out there? In the race to be real, one thing ET has over Sasquatch is more room to hide.

Beyond the vastness of space and the depth of our desire for company, there are growing scientific reasons to be optimistic about finding extraterrestrial life. Ongoing work on the emergence of life on Earth indicates that life may be a common phenomenon in our universe. Last month NASA announced unexpected observations of a potential new cradle of life in our solar system. Data from the Kepler space telescope has begun to arrive and as summer progresses we are discovering that our universe is littered with planets. These are exciting times. Living generations may witness the discovery of extraterrestrial life – are we ready for that?

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Life: The Actual and The Possible

We smile knowingly at the naïve idea of human-like extraterrestrials, yet this idea might not be so naïve. How do we know what to look for? In order to search intelligently, scientifically for life in outer space, we need to establish which features of life are definitive and which are elaborations. In other words, what is essential for life?

I posed this question to friend and colleague Peter Unrau. In addition to sharing a fascination with extraterrestrial life, Peter and I share affection for a goofy comfort-loving cat named Django who once lived with me and now hangs out with Peter and his family (Django’s wilder sidekick Frida chose life on the streets). In addition to being a pushover for cats, Peter has a Ph.D. in Theoretical Physics from MIT and he currently studies the chemistry of RNA, a family of molecules that were central players during the origin of life on earth.

Peter’s answer came quickly: replication and compartmentalization are essential for life. Replication refers to the idea that living things can make copies of themselves. The oldest and simplest form of molecular replication is complementary copying of linear polymers (long chains) such as RNA. The chemical conditions on early Earth were sufficient to drive the formation of the original polymers. The resulting polymers fold into three-dimensional shapes that are entirely dependent upon the sequence of subunits..

In a rich and complex prebiotic soup, occasionally a particular RNA will have a sequence that dictates folding into a shape that can facilitate the assembly of an RNA strand complementary to the original. A second round of copying produces original sequence and replication is accomplished.

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Stable RNA sequences capable of replication could rapidly rule the world, but in a primordial soup the copying machine won’t get any traction. Here’s why: to produce a copy of its wonderful copying self, the RNA must first produce a complement. This “mirror image” is a different sequence and when it folds it does not have the shape required to be a copying machine. The complement drifts away and the copying machine copies whatever RNA happens along, only rarely latching onto a complement of itself and producing another copying machine. The copying machine eventually decays without ever becoming much of anything. Compartmentalization is the essential breakthrough that solves this problem and allows life to evolve.

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Every living thing known to us has a compartment: an inside and an outside. This structure solves heredity – accidental innovations that improve efficiency no longer drift away and small useful things can be retained. Today, cells are enveloped in complex biological membranes, but the earliest compartments were probably similar to soap bubbles.

When life was emerging on Earth 3.5 to 4 billion years ago, the surface of the planet was covered in ocean and speckled with landmasses actively forming from volcanic activity. Our atmosphere was carbon dioxide and nitrogen and it was warm – an average annual global temperature in the range of 15.5 to 21.1°C (the 20th Century average was 13.9°C). Under these conditions of energy flux (volcanoes) and abundant liquid water, the minerals of the earth reacted with the carbon dioxide and nitrogen of the atmosphere to form complex molecules. Among these molecules were the subunits of important polymers and primitive versions of their respective polymers. That is to say, the chemistry of early Earth produced amino acids and chains of amino acids (proto-proteins), nucleic acids and chains of nucleic acids – the primitive RNA polymers described above. Importantly for the emergence of life, this pre-biotic chemistry also produced hydrocarbon chains (long molecules made of hydrogen and carbon) such as fatty acids.

Fatty acids are long greasy chains that cluster together in clumps called micelles. When sufficiently abundant, micelles can form sheets from which water filled structures known as vesicles are made – think of blowing a bubble from a film of soap, substitute water for air and fatty acids for soap.

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Organic molecules, the building blocks of life, molecules like amino acids, nucleic acids and fatty acids, form under laboratory conditions that mimic early Earth; they have been found on meteors and, based on spectral exploration of space, they also exist in other parts of our universe. This is chemistry: deterministic, repeatable events. Given the conditions that existed on Earth about 4 billion years ago, it was inevitable that the molecules of life would form and acquire the ability to replicate and form compartments, that they would assemble into proto-cells. But was it also inevitable that life would emerge?

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What makes a proto-cell into a living cell? Most fundamentally, it would need to acquire the ability to proliferate exponentially. To achieve this, the leaky fatty acid vesicle encapsulating the proto-cell would need to acquire additional components to make it stable and allow it to develop selective permeation (keep the good stuff in, let the bad stuff out), ways to efficiently use the chemical energy stored in the organic molecules of the primordial soup (ways to digest its food), and it would need to acquire ways to divide without losing it’s precious cargo of replicating RNA and useful molecules. These may seem like daunting accomplishments, but consider that scientists have already observed the production of self-replicating RNA and the formation of proto-cells, all through chemistry in the lab. Also consider that these events had plenty of time to fall into place: conditions were ripe for at least 500,000,000 years. The inevitability of the chemistry and the large time available for proto-cells to become cells suggest that the emergence of life on Earth was almost obligatory.

Almost obligatory. The catch is that until we understand all of the events required for the emergence of life (and people like Nobel Laureate Jack Szostak are working hard on this problem) we won’t know for certain that there wasn’t a step that depended upon a highly improbable occurrence, making life on Earth a fluke.

We know that chemistry has produced the organic molecules of life elsewhere in our solar system and likely throughout the Universe. Within a decade or two we will have established the sequence of events required to form primitive cells from these molecules. When we can build a self-replicating proto-cell in the lab, we will know whether, given the right conditions, the emergence of life on Earth was inevitable. The corollary of this conclusion is that life will emerge on any planet (or moon) with conditions that match early Earth. All evidence to date suggests that microbial life is probably common in our Universe.

How might these otherworldly microbes have evolved? Was the evolution of complex cells and organisms on Earth so heavily constrained by history that it would never happen the same way twice? Surely it is true that it would never repeat precisely – a second run of the tape would not produce Lady Gaga – but the more we learn about the molecular basis of biological evolution, the more we understand that some outcomes are inherently more likely than others.

It has been argued, most famously by Steven J. Gould, that if we were to “rewind the tape” of the evolution of life on Earth and play it again we would get an entirely different outcome. This argument is based on the fact that natural selection is contingent upon the chance variations offered up for selection. As the fittest of these survive, individuals carry forward emergent useful traits and all new variation is in the context of these traits.

The first of two important refutations of Gould’s argument is based on the enormous time and large number of individuals involved. This abundance of numbers and time would allow for the optimization – and therefore reproducibility – of natural selection. Optimization clearly occurred in the early phases of the evolution of life. A large number of useful molecules and molecular machines are common to all of life on Earth, indicating that we all – fungi, bacteria, humans, green algae and all the rest – arose from a single common ancestor.

Further evidence for optimization lies in the frequency with which we observe “convergent evolution” — similar solutions to a problem in the context of divergent starting material. Wings and eyes are two commonly cited examples of structures that have evolved independently several times as solutions for flight and vision. Evolution is a bric-a-brac process – bits and pieces of existing structures happen to come together in a new way and new properties emerge – if useful, they survive. In this way, humans and flies both came to have eyes. Although the structures are made of different parts, the eyes are strikingly similar in how they work.

The second reason that re-running the tape might not produce wildly different organisms from what we have today is that the extent of molecular variation available for natural selection may be much less than we once thought. Although DNA mutations and recombination (the source of variation) occurs randomly throughout the genome, the vast majority of these genetic changes do not produce altered traits. They may be lethal or cause only a trivial change. Of those that do cause significant alterations, we are discovering that cellular machines tend to be stunningly robust with respect to the shapes that they assume and the way they interact with other molecules. In other words, the process of natural selection may not have had so many options to work with as we’ve previously imagined.

Until we have more data, it remains controversial whether a replay of the tape would produce an Earth populated with entirely unrecognizable beings or whether it might look quite similar. The odds are high that somewhere out there the tape is being replayed.

Proto-cells converged upon an optimal way to convert energy flux into a contained, replicating, organic entity – the solution was the common ancestor we share with E. coli. There is no reason to expect that optimization and constrained variation ended there. While there is much we still don’t know, there is growing support for the idea that ET will be much like us: we will likely have a common biochemistry and share many features. For example, if there was light in the environment where ET evolved, it will likely have eyes, albeit ones that are built differently than ours. Among the anticipated similarities is the emergence of advanced cognition. Humans have a history of re-defining intelligence every time that we discover another animal (or computer) that can do something that we previously considered unique to us. If we step back from our biases, we can see that, like eyes and wings, advanced cognition has evolved several independent times on Earth. Consider the great apes, dolphins, octopuses, and my favorite example, crows. Not only can we expect to find life like us, we can expect it to be smart.

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Unidentified Flying Objects: Intelligent ET Pays a Visit? .

Not knowing is true knowledge. Presuming to know is a disease.

— Tao Te Ching

The first time I saw an unidentified object in the sky, I was twelve years old, standing on the beach with a friend after our figure skating class. We were looking east over the Georgia Straight, between Vancouver Island and the mainland of B.C. We both saw two large lights in the distance, not far above the horizon. The lights moved slowly and erratically for about 15 minutes and then disappeared. The second time I was 27, cycling home late at night on Point Grey, a prominent feature west of the city of Vancouver. I had stopped to look at the expansive view of the city across English Bay when I saw bright but diffuse coloured lights in the sky. The apparition hovered for a while and then disappeared.

We get excited about UFOs. Government conspiracies are commonly invoked: either there is a conspiracy to hide the fact that we are being visited or the sightings are actually of secret military planes. In fact, true to their name, UFOs are unidentified flying objects. Almost all have been subsequently identified (including hoaxes and natural phenomena) a few remain mysteries, for none is there any evidence supporting the idea that they are visitors from space.

There is a great deal in our world that is unexplained, including a few UFOs. When we lack the tools or information to distinguish between the actual and the possible, the event remains unexplained. There is no convincing reason that intelligent aliens would want to visit us and there is no evidence that they have done so. It is unlikely that we’ve had visitors from space, but that doesn’t mean that there isn’t intelligent life out there.

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The Search for Signs of Life in our Solar System

By searching seriously for microbial life close to home, we’ll get a sense of how common it might be in the Universe. Finding evidence that life emerged more than once would provide impetus for the even more challenging undertaking of finding intelligent life in the further reaches of space.

Where do we look and how will we recognize the signatures of life? All of the complex reactions and interactions described above, the formation of polymers that can make copies of themselves, the encapsulation of these self-replicating molecules, the growth and proliferation of these cells – it all requires liquid water and a flux of energy. Liquid water and energy are the reasons that the search for life in our solar system has focused on Mars and the moons of Jupiter and Saturn. These barren-looking places may not appear welcoming to life, but discoveries such as small worms living in ground water more than 3 Km below the surface of the Earth remind us that our lush surface is not the only way to grow.

After intriguing observations made during its first pass in 2004, NASA extended the mission of its Cassini spacecraft in order to obtain series of close fly-bys of Enceladus, one of Saturn’s moons. In May 2011, NASA announced that Enceladus has shot to the top of the list of places to find life within our Solar System.

Cassini captured images of plumes in the southern pole region of Enceladus, where it also recorded surprisingly warm temperatures. The warm temperatures are thought to be a consequence of friction caused by an orbital wobble and the tidal pulls of Saturn and its other moons. Through fissures in the moon’s surface, an underground ocean is spewing salt water and organic molecules, generously sending plumes of its sea into space for us to sample. Unfortunately, because this spectacular opportunity was unanticipated, undreamed, Cassini is not equipped to detect complex molecules indicative of life. We need to go back.

What signs of life will we look for on Enceladus or on Mars? The signature of life will be written in its molecules: Life deviates significantly from the molecular palette formed by abiotic chemistry. The combination of molecules that comprise life on Earth define our specific signature, not a general signature of life. ET will have it’s own unique signature, a distinct amalgam of molecules, deviating in its own way from the palette offered by abiotic chemistry.

One example derives from the fact that almost all organic molecules have an asymmetry and occur in two mirror-image or chiral forms that cannot be superimposed, like a right and left hand. Life is sensitive to this chirality. Everything that happens in life depends upon the interactions of molecules and the interactions of molecules are supremely sensitive to shape. A dramatic example of the importance of chirality is a small molecule that smells like spearmint in its right-handed form and like caraway when it is left-handed.

Chirality is important to the molecular machines that make life a success. The complex molecules and assemblies of molecules that efficiently process chemical energy, provide selective permeation across the membrane, and help the cell divide without losing its contents only recognize one chiral form of a molecule in the same way that your right glove fits only your right hand. Chirality is also important when molecules assemble into higher order structures. On Earth, the amino acids that link together to form cellular proteins are left-handed and our sugars are right-handed.

While life requires molecules of a uniform chirality, we don’t know of any reason that right- or left-handed molecules are superior. The particular chiral biases that we observe on Earth most likely arose as a result of chance events that occurred when life was emerging. A molecular signature of extraterrestrial life may have left- or right-handed amino acids, but it will be strongly biased to one or the other and therefore distinct from amino acids produced by abiotic chemistry.

Life also builds many complex molecules that do not exist in the abiotic world. While we might get lucky and find some variation of these, they are much less stable than the smaller molecules. This would require excellent preservation of samples – like the wooly mammoths found frozen in ice on Earth – or a direct sampling of life. Our odds of finding signs of life are higher when we look for signatures that would survive long after life has passed by.

To build the structures that make life work, cells require a steady flux of energy. As they process energy and use it to organize the structures that keep them alive, cells digest molecules. In so doing, they create waste products – the smoke of the fire of life. Although this “smoke” is comprised of small molecules that are not in themselves signatures of life, they may bear the signs of having been produced by life. Life on Earth has a strong bias for one of the two stable isotopes of carbon. We prefer carbon-12 over the heavier carbon-13, possibly because of its chemistry, possibly because of chance. It isn’t clear that ET will share this bias of ours, but we will look for enrichment of carbon-12 when we sample the plumes of Enceladus.

A further expectation is that the molecules of life anywhere will be built from combinations of the same elements as life on earth: CHNOPS (carbon, hydrogen, nitrogen, oxygen, phosphorous, and sulphur). There was a big hoopla last December when scientists reported that bacteria from the sediments of Mono Lake (in California) could substitute Arsenic for Phosphorus in DNA and other key molecules of life. If true, this would have greatly expanded our perception of the possibilities for life. As it turns out, the experiments were not carefully controlled and within days of publication the scientific community rejected the conclusions. For now, the possibility of life based on any other chemistry is entirely speculative and remains beyond the reach of science.

We can also look for fossils in chunks of rock delivered to Earth by meteors or by sampling missions to the surface of Mars. The fossilized remains of extraterrestrial microbes could provide evidence of life, but such fossils are difficult to verify. One problem is that non-organic processes can produce structures that look like fossils. Another problem is the possibility of contamination by Earthly microbes, an especially important issue when examining meteors that have been on Earth for years, as was the case for the ET fossils reported this year by NASA scientist, Richard Hoover.

Hoover discovered structures that looked like fossils of microbial life inside meteorites that fell to Earth years ago (the Ivuna in 1938 and the Orgueil in 1864). Based on the composition of the meteors, they derived from water-bearing asteroids or comets. Hoover published the work in The Journal of Cosmology (not a top science journal like Nature or Science) and the exclusive scoop was granted to Fox News. Predictably, news of the announcement spread like wildfire. Within hours of publication, the scientific community rejected the conclusions on the basis of the likelihood of Earthly contamination. This is not to say that the structures are not fossils of microbial ET, simply that there is no solid scientific evidence that they are not fossils of the Earthly microbes that they are purported to resemble.

In response to the outpouring of vitriol from scientists over the publication of this paper, the journal issued an official statement:

Richard Hoover’s paper was received in November. It was subjected to repeated reviews and underwent one significant revision. Hoover’s paper is further evidence that life is pervasive in this galaxy and exists on astral bodies other than Earth. The alternative view is life exists only on Earth, and originated on Earth, as described in the Jewish and Christian Bible and which is the official position at NASA. We believe the choice is simple: Religion vs Science. The Journal of Cosmology is devoted to promoting science.

Oh, my. To be clear, the alternative view held by NASA and most scientists has nothing whatsoever to do with religion. The alternative view is that to move forward, science must be conducted with rigor.

While journalists are buying into big claims by weak science, the real story is slower and deeper and ultimately more exciting. It will be another decade before we taste the plumes of Enceladus. In the meantime, we will continue to refine our ideas about the molecular signatures of life and how to look for them. We will also expand our vision beyond microbes and beyond our neighborhood.

An Astronomical Unit (AU) is defined as the average distance from the Sun to Earth. Mars, at a distance of 1.5 AU is relatively close to home (as my son likes to say of those cold winter days in Montreal, “there are spots on Mars that are warmer than this”). In contrast, Enceladus is in a much colder neighborhood, orbiting Saturn at an average distance from the Sun of 9.6 AU. Yet even here, where sunset would look like the setting of a bright star, we find sufficient warmth for life (likely derived from gravitational friction, as I said earlier). Not so long ago we would have considered this an unlikely cradle of life. Let’s go farther out.

Consider for a moment the tremendous number of planets and moons that might keep company with the 200-400 billion stars that comprise our Milky Way, a galaxy so big that it takes light 100,000 years to cross it. It is difficult to get one’s mind around it, but when looking at the Milky Way, the entire solar system is one dot.

Now consider an image of our nearby Universe where the entire Milky Way is a single dot. Do you think that there might be intelligent life out there? The question seems rather small.

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The Search for Extraterrestrial Intelligence (SETI)

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In 1959, the journal Nature published a theoretical paper wherein physicists Giuseppe Cocconi and Philip Morrison cogently argued that given the vastness of our Universe we probably have intelligent company. At about the same time, astronomer Frank Drake began using the Greenbank radio telescope to listen for signals from extraterrestrial intelligence. One way or another, we’ve been listening ever since.

In the early days of the search for extraterrestrial intelligence (SETI) Drake presented an equation to calculate the number of civilizations in our galaxy with whom we might communicate as a function of several parameters: the rate of star formation, the fraction of those stars with planets, the average number of planets/star that can potentially support life, the fraction of those possible cradles of life where life actually emerges, the fraction of centres of life that develop intelligent life, the fraction of civilizations that develop a technology that releases detectable signs into space, and finally, the length of time for which such civilizations release detectable signals into space. The Drake equation may be the most nebulous equation in science, yet it has provided a valuable framework for exciting research.

Based on the amount of noise that we were making in the 1960’s (such as TV and radio broadcasts) we have been listening for similar signals from civilized ET. But our noisy period was fleetingly brief. Advancing technologies, such as cable and cell phones, are making us much quieter. The move to digital TV, for example, allows for much weaker signals and does not contain strong narrow-band signals. Digital signals more closely resemble the background noise of the universe and are more difficult to detect. Satellites beam their signals down to Earth, releasing very little out into space. Perhaps the accidental noise of another civilization is not, after all the best way to search. Current thinking is that we should be listening in the microwave region of the spectrum, where the universe is its quietest – surely this is where a smart ET would broadcast an intentional signal. In a 2011 paper, Frank Drake writes: “Perhaps our best, and very optimistic, hope is that altruism is common in civilizations, and technologically advanced civilizations sense a duty to transmit powerful information-rich signals to less advanced civilizations.” While we continue to listen for intentional signals from ET, we also ponder other ways to detect alien civilizations that might not be reaching out to us. For example, Drake predicts that within fifty years we will have developed telescopes capable of detecting the light of cities on distant planets.

Over the past fifty years telescope technology has improved in leaps and bounds – sensitivities have improved by 1000-fold and we can now listen to millions of channels simultaneously. No longer do we need to carefully rationalize ET’s bandwidth selection. And while our ability to listen for signals from space has been improving, stunning new discoveries are giving us a much better idea of where to listen.

The primary purpose of the Kepler space telescope is to discover planets that orbit stars other than our Sun. The so-called exoplanets are small and dark and difficult to see next to the brightness of the star they orbit. Previous NASA missions detected exoplanets by observing their subtle gravitational effects on the stars they orbit. The gravitational pull between a planet and a star is always reciprocal, but in the case of small planets like Earth the effect on the star is not detectable; only large planets in relatively tight orbits can be detected by this method. Big planets in tight orbits cause their star to move in a small ellipse that follows the orbit of the planet – from Earth it looks like the star is wobbling.

Kepler detects exoplanets using what is called the transit method. The space telescope keeps an unblinking watch on the brightness of a star. A dip in this brightness suggests that a planet may have passed between the star and Kepler, if so, then the dimming will re-occur with a periodicity dependent upon the size of the orbit. It takes three transits to establish the periodicity of the dimming. By virtue of its outstanding optics and ability to watch a specific star for an extended period of time Kepler is able to detect small planets in longer-period orbits than earlier telescopes.

A central goal of the Kepler mission is to discover Earth-like planets in orbits just the right distance from their suns to allow for liquid water (the so-called Goldilocks or “habitable” zone). Given that Earth’s orbit around the Sun takes a year, detection of planets with Earth-size orbits takes about three years. Kepler was launched on March 7, 2009. We are on the threshold of exciting times.

Kepler has been monitoring the brightness of approximately 130,000 stars for almost two and a half years. One of the joyous things about a NASA mission is that data quickly becomes available in ways the public can appreciate. For example, an animation of the data for Extrasolar planet Kepler 4b can be found here (don’t forget to come back).

UC Berkeley Astrophysicist Dan Werthimer has been studying the first set of Kepler data released by NASA on February 2, 2011. He estimates that based on what Kepler is finding so far, there may be 50 billion planets in the Milky Way (50,000,000,000 planets in our one dot on the nearby Universe map). On May 8 the Green Bank Telescope in West Virginia began listening to stars systems with 86 of Kepler’s first Earth-like planets. Previous SETI (search for extraterrestrial intelligence) projects have listened to stars with properties similar to our Sun, but being able to focus on stars known to host Earth-like planets increases the excitement significantly. Incidentally, data analysis for this project will use the SETI@home distributed computing project run by Werthimer. The project uses the home computers of over three million volunteers to help analyze the phenomenally large amount of data acquired in these experiments. You can sign up for SETI@home and participate in the search for extraterrestrial intelligence by having packets of SETI data analyzed on your computer every time you step away for a cup of coffee.

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Cosmic Curiosity

Science is almost certain that life emerged more than once in the Universe and there is a reasonable chance that we will find its signature somewhere beyond Earth within the next twenty years. Whether we will also find extraterrestrial intelligence is an open question. We are curious about different manifestations of life, but microbes from space do not capture our imaginations in the same way as intelligent beings with whom we might communicate.

“Intelligence” is as difficult to define as “life.” So far we are looking for the only signs that we could hear and recognize: patterns buried in the noise of electromagnetic waves. In the future we may be able to scan for city lights although I wonder if, like our noisy broadcast period this too might be a short-lived sign of civilization – will an energy crunch help us learn to tame light pollution?

Meanwhile, we wonder what might be out there. While some fear malevolence or malignancy, others hope for benevolence and wisdom. Such fears and hopes are likely to be irrelevant. As uncomfortable as it might be, we are not that significant. Perhaps we are simply hoping for company, just to know that we are not alone in this unthinkably enormous Universe. Perhaps. Yet always, “…it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring” (Carl Sagan).

Ultimately, we are driven by curiosity. Whatever we find or don’t find, it is the looking that is important. The most interesting, exciting and ultimately valuable discoveries are those that catch us by surprise. Mysteries multiply. Today we wonder about the worlds of sub-atomic physics and strangeness in the universe, we try to understand consciousness and why there is something instead of nothing. Finding signatures of life, possibly intelligent life, would mark yet another in a long series of profound scientific discoveries that have revealed a richer, weirder world than the most creative among us can dream.

This essay is dedicated to Jacob Sheehy and his inspiring enthusiasm for space exploration.

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Notes

I am grateful to Roger Patterson’s widow for allowing the Sasquatch video to proliferate on the Internet. It is my understanding that the original film has been lost and the footage survives only in bootleg form.

For the movies included in the segment “Life: The Actual and The Possible” I thank Janet Iwasa and Jack Szostak for generously sharing via license to the Creative Commons.

All of the space photos and animations used in this essay are from NASA and reside in the public domain. NASA was key source of information in the preparation of this essay. NASA’s press release on the Cassini discoveries can be found here and more about the Kepler mission is here.

Another important source was a special issue of the Philosophical Transactions of the Royal Society A (Mathematical, Physical and Engineering Sciences) February 13, 2011 on the topic of finding extraterrestrial life.

Omitted from this essay was a discussion of the probes we’ve sent out as scouts, the Pioneer 10 with its Plaque and Voyagers 1 & 2 carrying the Golden Record. These probes are important for the valuable data about space that they continue to send home, but they are not a serious component of our scientific search for contact with an Other. For perspective, the Voyager probes will take 40,000 years to reach their target stars and even then will only come within 1.5 light years, i.e. these four cubic metre craft will come as close to a planet in an Earth-like orbit as the distance between Pluto and Earth. As ambassadors of our civilization, they are a lovely idea more akin to art than science.

I thank Peter Unrau and Jacob Sheehy for fun discussions that taught me a great deal about the search for ET. Douglas Glover generously provided a thorough and thoughtful editorial review of an earlier draft.

I would be grateful to hear of any errors you find in this essay. Thanks for reading.

— Lynne Quarmby