Theoretical physics may be difficult and complicated, "but it does have sex appeal." So says quantum physicist Jim Al-Khalili. "It's easy to find an audience for popular science or for a TV documentary about the Big Bang or about black holes," he recently told me. Al-Khalili's work in the field has led to the fascinating new book Aliens: The World's Leading Scientists on the Search for Extraterrestrial Life, which explores what he believes is the likely possibility of alien life.
The Iraqi-born, UK-based Al-Khalili's intro opens with an anecdote: The Nobel Prize–winning physicist Enrico Fermi is jokingly discussing flying saucers with some colleagues at the Los Alamos National Laboratory when he poses a simple question: "Where is everybody?" His point, Al-Khalili writes, is that the universe is so massive and contains so many planets, that it makes little sense for Earth to be the only place where life blossomed, unless our planet is "astonishingly and unjustifiably special."
Aliens, out this week from Picador, proceeds in the way that one imagines that Fermi's conversation at Los Alamos might have: serious scientists, in occasionally cheeky dialogue with one another, acknowledging that the question they're pursuing—Is anybody out there?—has long been pursued by kookier personalities, conspiracy theorists obsessed with Area 51, and alien abductions. Instead, Al-Khalili's book offers research-driven essays by prominent astronomers, astrophysicists, geneticists, and neuroscientists, and their pieces offer a wide range of ways to think about the question of extraterrestrial life. Several astrobiologists consider what life requires and which planets and moons might have the right mix: neuroscientist Anil Seth considers the "alien" intelligence of the octopus here on Earth; cosmologist Martin Rees speculates on the possibility of humans merging with machine intelligence and setting out to explore the universe as a new cyborg species.
But for the most part, these experts are weighing in on one fundamental question: Is life special, a unique and almost impossible trick that happened here on Earth? Or is it easy, almost inevitable, a spark that just arises where the conditions are right? It's an age-old question, that, as Al-Khalili explains, we may finally have the technology to answer.
VICE: What drew you to the questions that the book addresses? Are you someone who has had a lifelong interest in the idea of aliens?
Jim Al-Khalili: It's not so much aliens, but more to do with the question of what is special about life. Probably all scientists find that topic fascinating. There are certain questions in science that we don't have answers to, which we say, those are the big questions: What was there before the universe, before the Big Bang? How did life begin on Earth? How did chemistry turn into biology? What is the nature of consciousness? These are the questions that transcend disciplines. If you get a chemist, a physicist, a biologist, a computer scientist—all of them are going to be fascinated by this.
When I was young, I suppose I was interested in aliens like anyone else. I'm a sci-fi fan. But, for me, the question was really what is so special about life—how did it start on Earth and whether it is unique to Earth.
The book is serious, but the interest in extraterrestrial life has a reputation for being pretty quirky.
Someone once told me that half the internet is devoted to conspiracy theories to do with alien abductions and UFOs. Half is probably too much, but there's so much out there, from X-Files to science fiction in movies, that it is surprising to think that scientists would treat the question of extraterrestrial life seriously at all. And that's what made this so refreshing. The book is highlighting the fact that there are lots of questions that are of interest to scientists that you can actually treat seriously. If you really want to know the possibility of whether there are little green men out there, here are the serious scientific takes on it, from all angles. So, it's meant to be of interest to the wider lay audience but dealt with in a grown-up way.
You mention that there has been a shift within the scientific community toward taking this seriously and away from the era of imagining little green men. Do you have thoughts on when and how that changed?
This shift has come about because of advances in astronomy and space exploration in the last decade or two. We have started to send probes to Mars, to the moons of the gas giants Saturn and Jupiter, and we are seriously starting to be able to study the places where there potentially could be life in our solar system. And at the same time, in the past decade, we have discovered planets around stars outside our solar system, exoplanets. Astronomy has been advancing so quickly that what was unthinkable a decade ago is now reality. We can now not only pinpoint which stars have planets going around them, but we can look at those planets and even tell whether they have an atmosphere. Just from the light passing through the atmosphere from the star that they are going around, we can study that light and that can tell us the chemical composition of the atmosphere—and that can tell us what elements, what molecules, what compounds are in that atmosphere, and would they be there naturally or would there have to be life present to have made them. So, these advances in astronomy and space exploration suddenly mean that we can actually address this question. It's got to the point now where I'm quite optimistic that in my lifetime, it's likely that we will discover life elsewhere.
Ten years ago, I wouldn't have thought that. Now, all these things are coming together. One of the contributors in the book, [professor of evolutionary biochemistry] Nick Lane, talks about the building blocks of life. What do you need? Is there anything magical? You get molecules getting more and more complicated, and then eventually you get something that can make copies of itself, and that's the first precursor of life. Well, until recently we thought there was a missing step—"and then some magic happens"—and then you get biology from chemistry! But there seems to be no magical steps necessary. I now reckon that the consensus among most scientists is that it would be quite surprising if we don't find life elsewhere, probably within our lifetime. It might not be interesting life—it won't be men in flying saucers—it will be some form of microbial life. But, hey, for scientists that will be enough.
"Astronomy has been advancing so quickly that what was unthinkable a decade ago is now reality. It's got to the point now where I'm quite optimistic that in my lifetime, it's likely that we will discover life elsewhere."
So on the big question in the book, which is something like "is life on Earth special and unique or is it common?"—and there are great arguments posed for each side—where do you fall on that spectrum personally?
There's a wide spectrum of opinion among informed scientists. So the fact that I sit somewhere in the middle is because I've been influenced by both sides. My kind of naïve view is that we only know of life happening somewhere: on Earth. We are beginning to see that the conditions on Earth are not unique. Forgive the metaphor, but a lot of stars have to have aligned for that—we have to be the right distance from the sun, we have to have an atmosphere, we have to have a moon that gives us tides, we have to have a big planet like Jupiter that is sucking up the debris so it doesn't bombard us. But there are so many other star systems; there are so many other exoplanets, just in our galaxy alone, that there must be millions, billions of other Earths that have the conditions necessary for life. So in that sense we know we are not unique.
But that doesn't mean that we know how life got started, just because those conditions exist. We know that life began on Earth very soon after Earth cooled down enough for life to possibly exist, almost 4 billion years ago. Now, over 4 billion years ago, the Earth was just a ball of fire. It wasn't conducive to anything. So, as soon as the conditions were right for life, life got started. But it didn't develop into complex life until much, much later. So I'm of the view that life as a simple single cellular form may well be not that difficult. It may be almost ubiquitous in the universe. But multicellular life, life that could then evolve into complex organisms, some of which could develop consciousness and intelligence and civilizations—that actually may be the harder step. How hard it is, we don't know yet.
I wonder if you can talk a little bit about the role of human radio, TV, and satellite communication and how that factors into the search for alien life. Why do people assume that aliens would also use this same kind of signaling?
We're starting with the assumption with the idea that the laws of physics and the forces of nature are the same throughout the universe. We know of four of these forces. Two of them are active inside of atoms, the nuclear forces. And the only other ones are gravity and the electromagnetic force. Gravity is limited technologically, but the electromagnetic force is versatile: Light is the electromagnetic force, and radio waves are the electromagnetic force. So it's a means of sending information from one place to the other. So we're assuming that whatever form life takes elsewhere, even if its not carbon based—it could be something really beyond our imagination—we still think they will make use of electromagnetic forces. It is a potentially universal way of communicating.
So if we are announcing our existence to the rest of the universe, then it may be that life elsewhere that is doing the same thing. Which is why the whole SETI program is about listening out into the universe to hear some electromagnetic signal that we don't think could have just happened naturally. Of course, we've only been announcing our existence to the world for about 100 years or so, when we first developed radio. So our electromagnetic signals have only extended out to a radius of 100 light years. And actually there aren't that many star systems within 100 light years. The universe is vast—there's billions of stars in our own galaxy—but there are only a handful within that range. Of course, an alien civilization may have been announcing their existence to the universe millions of years ago, for all we know, so those signals, if we do receive those signals, they may have traveled across vast distances—it won't mean that we can then say, "Hi, we're here," and then make contact with them. But just the knowledge that there is life out there somewhere would be profound.
Rachel Riederer is co-editor-in-chief of Guernica. Follow her on Twitter.
Aliens: The World's Leading Scientists on the Search for Extraterrestrial Life is available in bookstores and online from Picador.