A quarter of all known stars in the universe are thought to host a ‘perfect planet’ — one the same size and temperature as Earth. There are approximately a ‘zetta’ of them … that’s a trillion billions — a one with 21 zeroes after it.
So it is presumptuous for us to assume we are the only intelligent beings in this vast cosmos. In fact, to imagine we humans are alone in space is not merely arrogant, it is scientific nonsense.
On October 19, 2017, a telescope in Maui, Hawaii’s second-largest island, glimpsed the first known interstellar visitor.
Without question, this object came from a distant solar system.
Was this a natural phenomenon, or one engineered by an intelligent life-form? The simplest explanation is the latter: that it was created by an intelligent civilisation not of this Earth.
Earth cannot possibly be the only planet that supports life. Even in our own galaxy, the Milky Way, about a quarter of the 200 billion stars are orbited by planets with the right conditions for liquid water and, thus, the chemistry of life as we know it.
Given so many worlds — 50 billion in our own galaxy — it is very likely that intelligent organisms have evolved elsewhere.
But there has been no positive proof, which is why the object spotted from Hawaii’s observatory — 1I/2017 U1 (‘I’ for interstellar; 2017 for the year it was seen) or, as it came more popularly to be known, ‘Oumuamua (pronounced ‘oh moo-ah moo-ah’, meaning ‘scout’ or ‘messenger from afar, arriving first’) — is so significant.
Given so many worlds — 50 billion in our own galaxy — it is very likely that intelligent organisms have evolved elsewhere. Harvard professor Avi Loeb explores the idea in his new book [Stock image]
Among Hawaii’s state-of-the-art telescopes are those that make up the Panoramic Survey Telescope and Rapid Response System [Pan-STARRS].
Canadian astronomer Robert Weryk was the first at the observatory to spot the object in the Pan-STARRS data, as a point of light speeding across the sky.
Immediately, scientists wanted to know more about its appearance. We did not have a crisp photograph and, in the 11 days during which it was visible, we could not obtain one. But we could tell two important facts: it was not a sphere, and it was rotating — tumbling through space, in fact.
When an object spins, the amount of sunlight it reflects will vary, unless it is perfectly round like a ball. The more irregular its shape, the greater the variation. And ‘Oumuamua varied immensely as it rotated about once every eight hours, increasing and decreasing in brightness by a factor of ten. That is, it was ten times brighter at midnight (for example) than it had been four hours earlier.
At its brightest, it seemed to be a round pancake. At its dimmest, it took the shape of an elongated cigar, about 100 yards long — that’s roughly the length of a football pitch.
Theories to explain this bubbled up straight away.
Perhaps its strange features were caused by exposure to cosmic radiation over hundreds of thousands of years. Or perhaps it had been violently expelled from a planet and stretched by gravity.
But neither of these explanations took into account ‘Oumuamua’s strangest anomaly. As it sped away from the Sun, its path deviated from what might be expected under the Sun’s gravitational force. It went off at a tangent, an odd angle. There was no obvious reason for this.
It couldn’t be a comet. It had no tail (the trail of gas, called outgassing, and debris, disintegration, a comet leaves). To explain this, some scientists suggested it might be an icicle of frozen hydrogen, whose tail was invisible.
‘Oumuamu came speeding into the Solar System, which sparked the idea that it could be a comet. However, it does not have a cometary trail to explain its excessive push
But in a detailed paper, my Korean collaborator Thiem Hoang and I were able to dismiss that too: a hydrogen iceberg travelling through interstellar space would evaporate long before it reached our solar system. As the lightest element in the universe, hydrogen easily boils off an icy surface.
In any case, the idea that a comet could propel itself by the evaporation of hydrogen ice, emitted only from its tail, was nonsense — about as likely as the natural erosion of a boulder creating a fully functioning space shuttle.
However, something was powering ‘Oumuamua.
And if it wasn’t outgassing or disintegration, the only logical explanation was solar energy. This object was propelled by sunlight bouncing off its surface, like wind off a sail.
The idea is centuries old. It was first proposed in 1610, when Shakespeare was alive, by the astronomer Johannes Kepler. And I have long been fascinated by this concept.
Working with a brilliant Russian-born entrepreneur from Silicon Valley, Yuri Milner (named by his parents in honour of the Soviet cosmonaut Yuri Gagarin), and with the help of my students and postgraduate researchers, I set to work developing the idea.
In a paper published in 2018, we calculated that a 100-gigawatt laser beam hitting a sail about the size of a human being could send it through space at almost unimaginable speeds — accelerating so fast from the edge of Earth’s atmosphere that, by the time it was five times farther away than the Moon, it would be travelling at about one fifth the speed of light, or around 38,000 miles per second. At that rate, it would be going fast enough to reach the nearest star within our lifetimes.
‘Oumuamua was discovered in October 2017 by a telescope in Hawaii millions of miles away
Everything we proposed was within existing technological bounds. Difficult? Yes. Expensive? Somewhat — the cost would be similar to that of the biggest science projects, such as the Large Hadron Collider at CERN, though cheaper than the Apollo programme.
Once built, a launch system could be used to send thousands of such craft into space. We called them ‘StarChips’.
And if humans could imagine this light-driven spacecraft, no doubt other technological civilisations might do the same. They could be launching sails into space right now . . . or have done so millions of years ago.
If just a minute fraction of those 50 billion potentially habitable planets hosted intelligent life during the history of the Milky Way, then there might be plenty of their relics remaining.
If we could visit these planets, maybe we would see abandoned mega-structures or find merely the faintest atmospheric or geological traces.
But even more intriguing is the possibility that we will find, flying through our solar system, relics with no detectable function: space junk.
Some scientists have accused me of being fanciful. But there is nothing outlandish about the idea. Evidence of it mounts up every day, on beaches around the world.
Take a walk along any seashore and you will find two sorts of things washed up. One is natural, such as driftwood, seaweed and seashells. The other is man-made, particularly plastic pollution.
Harvard Professor Avi Loeb (pictured) says science is too conservative, too concerned with reputations and funding, and not enough with exploration and adventurous thinking when it comes to questions of extraterrestrial life forms
There is a growing amount of plastic waste because we dump about eight million tons of it into the oceans every year.
Either ‘Oumuamua is a natural phenomenon, a sort of interstellar driftwood, or it is manufactured, like plastic.
Now consider how many aspects of the object were unnatural: its shape, its invisible power source, its regular rate of rotation, the smoothness of its propulsion, its sheer speed and that it appeared from another star system.
For this to be a series of accidents and coincidences is a mathematical impossibility.
Now add one further, vital observation: as ‘Oumuamua receded from the Sun, its deviation from a gravitational trajectory diminished. In other words, although it was still travelling at extraordinary speed, its power source appeared to be fading.
That is exactly what you would expect to happen, if its power source was the Sun.
But there is another possibility, one that points even more strongly to the idea that ‘Oumuamua was a piece of constructed technology.
Ask yourself this: what if this object did not cross the void to our solar system? What if it happened the other way around: ‘Oumuamua was sitting still in space and our solar system slammed into it?
Because the universe is expanding and our galaxy is spinning, stars do not remain at a fixed distance from each other. The Sun is hurtling through space, taking Earth and all its planets with it.
It is not beyond the realms of imagination that a highly advanced extraterrestrial civilisation could place a network of buoys in space, tethered in place, a little like the fleets of satellites that humans have fired into orbit around Earth over the past 64 years.
These could act as a communications grid, or an alert system, or lighthouses, or navigation devices, or stop signs — there is a wealth of possible explanations.
The point is that all of these must be the technology of an intelligent organism.
Even if ‘Oumuamua has been defunct for millennia, it once served a purpose, just like a plastic bottle washed up on a beach also once served a purpose.
So what happened to the civilisation that designed and built this technology?
In Extraterrestrial: The First Sign of Intelligent Life Beyond Earth, Loeb argues that ‘Oumuamua could hold the key to confirming there is life on other planets
That echoes the famous question of the brilliant physicist Enrico Fermi, one of the fathers of the atom bomb, who died in 1954.
Over a lunch with colleagues, Fermi pointed out a paradox. Given the vastness of the universe (and at that time, no one realised how many billions of habitable planets existed), the probability of alien life seemed overwhelming. But we had seen no evidence of it. ‘Where is everybody?’ Fermi asked.
His own career might partly answer that question: Fermi’s theories enabled engineers to build bombs that could wipe out all life on Earth.
In other words, humans achieved the dubious distinction, in the 20th century, of being smart enough to obliterate their own civilisation.
In cosmic terms, that problem might be far from unique. The point when a civilisation reaches our stage of technological advancement — the window where it can signal its existence to the rest of the universe and begin to send craft to other stars — is also the moment when its technical maturity becomes sufficient for its own destruction, whether through climate change or nuclear, biological and chemical wars.
The civilisation that built and launched ‘Oumuamua might have ceased to exist long before human history began. That makes it all the more important that we learn everything we can from it.
Fermi’s question has often been used by scientists as a convenient excuse to avoid thinking about the biggest issue in cosmology, the probability of extraterrestrial life. Among astronomers, SETI (the Search for Extraterrestrial Intelligence) has long faced hostility. I find that bizarre. Mainstream theoretical physicists now widely accept the study of extra-spatial dimensions: we are all familiar with the 3D of height, width and depth, plus the fourth dimension of time, but ‘string theory’ now posits the existence of ten, 11 or even 26 dimensions.
This is despite the absence of any physical, laboratory evidence for the extra, invisible dimensions. The theories rely on maths — just like my arguments for the extraterrestrial origin of ‘Oumuamua.
In the same way, many of the most brilliant minds in science accept the hypothesis of the multiverse — an infinite number of universes existing simultaneously.
But it is far rarer to find astronomers and astrophysicists who openly encourage theories of extraterrestrial life. Science is too conservative, too concerned with reputations and funding, and not enough with exploration and adventurous thinking.
Too many scientists are like the priests 400 years ago who put Galileo on trial for heresy for his contention that the Earth goes around the Sun, rather than the orthodox notion of our planet as the centre of the universe.
The clerics refused even to look through Galileo’s telescope. In the same way, many leading scientists shut their eyes rather than consider the evidence for alien civilisations.
But imagine our planet the day after we get irrefutable confirmation of life elsewhere in the universe — if, for instance, a photograph revealed close-up details of another object like ‘Oumuamua.
Finding that evidence would, I believe, change every branch of science — not just astronomy but psychology, philosophy, religion, education. Every child would be taught differently because humanity would see itself differently.
All over the world, people would have a much greater sense that we are all part of a unified team and would stop worrying and warring over issues such as geographical borders and separate economies.
And if we made contact, the changes would be greater still. As the science fiction writer Arthur C. Clarke said, any sufficiently advanced alien technology would appear almost magical to us, perhaps even godlike.
But we should remember that the extraterrestrials might be equally awed to discover us.
They, too, would very likely have stared out into the abyss of space for countless generations. They, too, would understand that the galaxy teems with planets capable of supporting life, yet life elsewhere in the universe seems exceptionally rare.
Quite possibly, they would worry about their reception from our species, and their information about life on Earth might be hopelessly out of date — humans have only been around for a couple of hundred thousand years, after all.
Science has to shed its blinkers and open itself up to the new, the controversial, the unexpected. There are more habitable planets in our galaxy than there are grains of sand on any beach.
I believe the galaxy is rich with undiscovered life. And that is where I find the most cause for hope.
- Adapted from Extraterrestrial, by Avi Loeb, published by John Murray at £20. © 2021 Avi Loeb. To order a copy for £17.60, go to mailshop.co.uk/books or call 020 3308 9193. Free UK delivery on orders over £15. Promotional price valid until February 29, 2021.