From “Where Is Everybody?” by Jim Al-Khalili:
“Of course, an alien planet being suitable for life is one thing, but the really big unknown is this: given the right conditions, how likely is it that life could evolve elsewhere? To answer is that we need to understand how life began on Earth. If we are indeed alone in the vastness of the cosmos, then we need to understand why we are so special. Why would the Universe be apparently so finely tuned for life to exist, yet harbour it in just one isolated corner?
One way of thinking about this is to ask yourself how come you exist? What were the chances that your parents would meet and produce you? Indeed, what were the chances of their parents meeting, and so on all the way back? We are each of us the culmination of a long and highly unlikely chain of events leading back to the origin of life itself. Break any one of the links in that chain and you would not be here to ask the question in the first place. Maybe our existence is really no more remarkable than the lottery winner contemplating his or her good fortune: had that sequence of numbers not come up, then someone else would have won and they would also reflect on the improbable odds of their win.
What life on Earth can tell us about alien existence elsewhere in the Galaxy is limited by the fact that we have a statistical sample of just one. Our own example tells us nothing about the likelihood of life elsewhere, or what it would look like if it did exist. Could there be advanced alien civilisations out there or would they only be in the form of simple, single-celled microbes? If we can’t begin to address that issue, how will we even know where to look?
Most profound of all of course is what it would mean for us if we did find them?”
From “What Are We Looking For?” by Nathalie Cabrol:
“At the crossroads of scientific disciplines, astrobiology uses advances in all fields to answer these questions: How does life begin and develop? Does life exist elsewhere in the Universe? What is life’s future on Earth and beyond?
These questions represent a puzzle of cosmic proportions, to which we are missing several key pieces. We do not have a clear definition of what life is. Could it have been seeded on Earth through panspermia (in which comets and asteroids transfer material between other bodies in the solar system on impact) and planetary exchange (the idea, for example, that there was some exchange of material between Mars and Earth at the time they were forming)? Or was it created on our planet through abiogenesis, a process by which life arises naturally from simple organic compounds and chemical processes? We also do not have a record of when – or in which environment – the transition from prebiotic chemistry to life took place. We don’t know whether life is a common universal occurrence or a fluke. But if we are to solve the puzzle, it makes sense to start with us.
The terrestrial biosphere we inhabit – even if it hasn’t provided the answers to the questions above – is a record of life’s evolution and adaptation driven by environmental and cosmic bottlenecks, extending over billions of years. Further away, we can see the solar system we belong to as a lab where, over eons, nature has created a diversity of environments surpassing in complexity anything we could develop in an experiment. Beyond the solar system, our most sophisticated instruments provide windows in space and time where we can catch a glimpse of how galaxies, stars and planets are formed. Last, but not least, the human mind can model, theorise, and generate limitless thought experiments.
With this in hand, we have started to build an understanding of what, where and how to search for life beyond our planet. By necessity, our vision is still anthropocentric: we are searching for life as we know it, and this approach is a logical one because it is always easier to start with what you know, when what we know of life is still so limited. As our knowledge broadens, hypotheses and models grow more complex, and the technology to test them becomes more sophisticated, which allows more discoveries to be made, and fundamental hypotheses and models to be refined. This is an iterative process. In that regard, the past few decades of exploration of the Earth’s most extreme environments, the solar system, and deep space have revolutionised our definition of habitability and life potential.”
From “It Came From Beyond The Silver Screen!” by Adam Rutherford:
They mostly get it wrong. Mostly. Film-makers have been infusing culture with their visions of aliens for more than a century, and almost all of them have been a lot like us. The Moon natives in the first cinematic trip into space, Georges Méliès’s La Voyage dans la Lune (1902), were Selenites, named after Selene, the Greek goddess of the Moon. They’re a bit like arthropods with bulbous heads and lobster claws, but mostly human – upright and bipedal. The next trip was when the 1919 adaptation of H. G. Wells’s The First Men in the Moon landed, which also had Selenites as the endogenous lunar men. Alas, all prints of the film are lost. In the few remaining stills from the shoot, the Selenites are also somewhat insectoid, but look disturbingly like the blue, globoid-headed, oval-bodied Igglepiggle from the bewildering otherworldly toddlers’ programme In the Night Garden. And so the tone was set for a century of aliens – humanoid, insect or insect-like humans are the mainstay of cinematic extraterrestrials. We turn to human-like forms either because of budgetary constraints or for reasons of anthropocentrism.
We lazily assume aliens will be a bit like us, because we do like thinking about ourselves. Star Trek and dozens of imitators have got away with simply gluing bits of lump onto human faces or painting them green to indicate their non-human status. The Star Wars Universe offers little but variations on humans. Budget didn’t seem to be much of a problem in James Cameron’s Avatar (2009), just a tiresome lack of imagination. ‘Let’s make them taller than us, and a bit cat-like, but sexy, and give them tails. They need to be primitive but wise. Oh, and make them blue too.’
We have a pretty good grasp of evolution these days, and our bounteous fossil record, now coupled with genetics, gives us a picture of how life evolved on Earth. There are plenty of mysteries remaining, but we know much about our nearest ancestors: the emergence of bipedalism and all the many factors by which we came to be who we are. To assume that on other worlds, evolution would deliver a species identical in physical stature is plain silly. We don’t really know why we became two-legged when almost all terrestrial animals are not, but we can hypothesise that it is an adaptation to a range of complex environmental conditions, primarily to equip a species for a life on the savanna rather than swinging in the trees, and an increased efficiency of movement. If the Earth ever got a reboot, and the story ran again from the beginning, with just a few variables altered we would not have come out like this. Even a seemingly unconnected matter like the tilt of the Earth’s axis has played a crucial role. That 23° tilt, which gives us our seasons, was caused by a rock the size of Mars colliding with the neonate Earth, and knocking off a block that would form the Moon. Imagine if the rock had missed; no tilt, no seasons, no Moon, no tides. This would have meant a different weather system, different climate changes over time, and an entirely different set of evolutionary ancestors. Imagine if that sixmile-wide asteroid hadn’t tumbled out of the Cretaceous sky into what is now the Gulf of Mexico and caused an extinction level event that wiped out the dinosaurs and so many other species, yet allowed our small mammal ancestors to thrive. Imagine that rock being half the size, and only half of the dinosaurs had been wiped out. Would we be as we are? The answer is almost certainly no. Our form is not inevitable – it’s mere cosmic happenstance.”
Winston Churchill, British prime minister and one of history’s most influential statesmen, was undoubtedly a man with weighty questions on his mind. How best to save the British Empire? he must have mused. What will the postwar world look like? he surely wondered. But the legendary leader also focused his prodigious mind on less pragmatic questions. For instance: Is there life on other planets?
In fact, in 1939, Churchill penned a lengthy essay on this very topic, which was never published. Besides displaying a strong grasp of contemporary astrophysics and a scientific mind, he came to a breathtaking conclusion: We are probably not alone in the universe. The long-lost piece of Churchilliana has just floated up to the surface again, thanks to an article written by astrophysicist Mario Livio in this week's edition of the journal Nature analyzing Churchill's work.
“With hundreds of thousands of nebulae, each containing thousands of millions of suns, the odds are enormous that there must be immense numbers which possess planets whose circumstances would not render life impossible,” Churchill concluded in his essay. He wrote these words on the eve of World War II—more than half a century before exoplanets were discovered.
Until last year, Churchill's thoughts on the problem of alien life had been all but lost to history. The reason: His 11-page typed draft was never published. Sometime in the late 1950s, Churchill revised the essay while visiting the seaside villa of publisher Emery Reves, but the text still didn't see the light of day. It appears to have languished in the Reves house until Emery's wife Wendy gave it to the U.S. National Churchill Museum during the 1980s.
Last year, the museum’s new director, Timothy Riley, unearthed the essay in the museum's archives. When astrophysicist Mario Livio happened to visit the museum, Riley "thrust [the] typewritten essay" into his hands, Livio writes in Nature. Riley was eager to hear the perspective of an astrophysicist. And Livio, for his part, was floored. “Imagine my thrill that I may be the first scientist to examine this essay,” he writes in Nature.
Churchill did his homework, Livio reports. Though he probably didn't pore over peer-reviewed scientific literature, the statesman seems to have read enough, and spoke with enough top scientists—including the physicist Frederick Lindemann, his friend and later his official scientific adviser—to have had a strong grasp of the major theories and ideas of his time. But that wasn't what left the deepest impression on Livio.
“To me the most impressive part of the essay—other than the fact that he was interested in it at all, which is pretty remarkable—is really the way that he thinks,” Livio says. “He approached the problem just as a scientist today would. To answer his question 'Are we alone in the universe?' he started by defining life. Then he said, 'OK, what does life require? What are the necessary conditions for life to exist?'”
Churchill identified liquid water, for example, as a primary requirement. While he acknowledged the possibility that forms of life could exist dependent on some other liquid, he concluded that “nothing in our present knowledge entitles us to make such an assumption.”
"This is exactly what we still do today: Try to find life by following the water,” Livio says. “But next, Churchill asked 'What does it take for liquid water to be there?' And so he identified this thing that today we call the habitable zone.”
By breaking down the challenge into its component parts, Churchill ended up delving into the factors necessary to create what is now known as the “Goldilocks zone” around a star: that elusive region in which a life-sustaining planet could theoretically exist. In our own solar system, he concluded, only Mars and Venus could possibly harbor life outside of Earth. The other planets don't have the right temperatures, Churchill noted, while the Moon and asteroids lack sufficient gravity to trap gasses and sustain atmospheres.
Turning his gaze beyond our own solar system raised even more possibilities for life, at least in Churchill's mind. “The sun is merely one star in our galaxy, which contains several thousand millions of others,” he wrote. Planetary formation would be rather rare around those stars, he admitted, drawing on a then-popular theory of noted physicist and astronomer James Jeans. But what if that theory turned out to be incorrect? (In fact, it has now been disproven.)
“That's what I find really fascinating,” Livio notes. “The healthy skepticism that he displayed is remarkable.”
Churchill suggested that different planetary formation theories may mean that many such planets may exist which “will be the right size to keep on their surface water and possibly an atmosphere of some sort.” Of that group, some may also be “at the proper distance from their parent sun to maintain a suitable temperature.”
The statesman even expected that some day, “possibly even in the not very distant future,” visitors might see for themselves whether there is life on the moon, or even Mars.
But what was Winston Churchill doing penning a lengthy essay on the probability of alien life in the first place? After all, it was the eve of a war that would decide the fate of the free world, and Churchill was about to become Prime Minister of the United Kingdom.
Such an undertaking was actually quite typical for Churchill, notes Andrew Nahum, Keeper Emeritus at the Science Museum, London, because it reflects both his scientific curiosity and his recurring need to write for money. It was skill with the pen that often supported Churchill and his family's lavish lifestyle (recall that he won the 1953 Nobel Prize for Literature, with a monetary award of 175,293 Swedish Kroner worth about $275,000 today).
“One recent biography is entitled No More Champagne: Churchill And His Money,” Nahum says. “That was a phrase he put into a note to his wife about austerity measures. But he didn't know much about austerity. He liked luxury so he wrote like crazy, both books and articles that his agent circulated widely.”
That’s not to say that Churchill was simply slinging copy about aliens for a paycheck. “He was profoundly interested in the sciences and he read very widely,” notes Nahum, who curated the 2015 Science Museum exhibition “Churchill's Scientists.” Nahum relates the tale of how as Chancellor of the Exchequer, Churchill was once sent a book on quantum physics, and later admitted that it had occupied him for the better part of a day that should have been spent balancing the British budget.
He not only read scientific content voraciously, but wrote on the topic as well. In a 1924 issue of Nash's Pall Mall Magazine, Churchill anticipated the power of atomic weapons. “Might not a bomb no bigger than an orange be found to possess secret power to destroy a whole block of buildings nay, to blast a township at a stroke?” he warned. In 1932, he anticipated the rise of test-tube meat in the magazine Popular Mechanics: “Fifty years hence, we shall escape the absurdity of growing a whole chicken in order to eat the breast or the wing, by growing these parts separately in a suitable medium,” he wrote.
In 1939 he authored three essays, tackling not just extraterrestrial life but the evolution of life on Earth and the popular biology of the human body. Two were published during 1942 by the Sunday Dispatch, Nahum discovered when reading Churchill's papers at the University of Cambridge. It remains a mystery why his thoughts on alien life went unpublished.
In the rediscovered essay, Churchill admits that, because of the great distances between us and other planet-harboring stars, we may never know if his hunch that life is scattered among the vastness of the cosmos is correct. Yet even without proof, Churchill seems to have convinced himself that such a possibility was likely—perhaps by swapping his scientific mind for one more finely attuned to the human condition during the troubled 20th century.
“I, for one, am not so immensely impressed by the success we are making of our civilization here that I am prepared to think we are the only spot in this immense universe which contains living, thinking creatures,” he wrote, “or that we are the highest type of mental and physical development which has ever appeared in the vast compass of space and time.”
Seventy-five years after Churchill's bold speculations, there's still no proof that life exists on other worlds. But, as was often the case, his analysis of our own still seems prescient.
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