Let’s face it: we’re all alone in this vast universe
Kepler 452b might look like an inhabitable planet, but if life existed elsewhere we’d know about it by now
Suddenly, space is getting interesting again. After decades of going boldly nowhere in low Earth orbit, Man, or rather his robotic emissaries, have made some startling discoveries in our Solar System.
Cold, distant Pluto is – who would have thought it? – turning out to be one of the most interesting planets (yes, it is a planet) in the Solar System. Before the New Horizons probe turned up earlier this month, astronomers assumed it would be a dull, grey cratered rock.
Instead, little Pluto’s surface is a rather splendid palette of reds and yellows, and it has huge ice-fields which look like they were made yesterday, by volcanic forces that simply shouldn’t be there on such a cold world. There are mountain ranges as big as the Alps and no one can explain what we see. Isaac Asimov once said that the most interesting conclusion in science is not “Eureka!” but “That’s funny…” And Pluto is funny-peculiar indeed.
Then there is the comet 67P/ Churyumov–Gerasimenko. Little Philae, the first object we have ever landed on one of these flying snowballs, came back from the dead, having been lost in space then found again. Who knows what it has discovered in the long months since last contact?
And, of course, there are the aliens. Most rocket scientists are too pofaced to admit it, but the reality is that space exploration is almost entirely predicated on the quest to discover whether or not we are alone. This week a Russian tycoon called Yuri Milner has pumped $100 million of his fortune into SETI, the search for extraterrestrial intelligence. This will buy thousands of hours of time at three powerful telescopes, which will spend years scanning nearby stars for radio and laser signals from putative civilisations.
If we find life of any kind out there – whether it be Martian microbes (we have several probes prodding the Martian surface and observing it from orbit) or a signal from superintelligent (or even mildly brainy) aliens – it will change everything. ET will force us to confront a deep truth; that humans are not the only game in town, that we live in a possibly crowded (and quite probably threatening) universe.
But here’s the thing. What if they don’t find anything? What if, 10 years, a 100 years, a 1,000 years hence, endless sky-surveys, proddings and pokings of Mars and elsewhere, turn up nothing, save rocks, gas, ice and vacuum. We had better be prepared for this because, I am beginning to believe, this seems to be the most likely result.
ET should be out there. As the physicist Enrico Fermi famously pointed out more than 60 years ago, in a universe of great antiquity and size such as ours, there ought to be many, many civilisations in space, some of which will be far in advance of our own. It is, he said, a paradox that we have not seen any evidence of this.
Fermi’s Paradox has deepened since. We now know the universe is not only older and vaster than he thought, but also that it contains billions of “earth-like” planets. This week, the most promising candidate yet, Kepler 452b, was unveiled as “Earth 2.0”.
It is a bit bigger than our world, but orbits a star similar to our Sun at a distance which would mean temperatures should be pleasantly earthlike on its surface. According to Jon Jenkins, a Nasa scientist, “It is the closest thing that we have to another place that somebody might call home.”
Logically, “out there” should be teeming with life, and life we should have seen signs of by now. Not just radio signals, but visitations (most likely by robot probes). Space is big (if we reduce our Sun to a sand grain, Alpha Centuri is another sand grain – two miles away) but even these distances can be surmounted given enough time and some serious engineering.
Given the possible age of some ET civilisations, we should see cosmic engineering writ large across the heavens. It should, in short, be
out there. After all, “they” will certainly know we are here; large telescopes of the sort we can build, on planets orbiting nearby stars, will be able to spot the telltale signs of life, methane in our atmosphere, oxygen, the glint of our oceans; even city lights.
But. Nothing. It may mean nothing, but the Universe looks empty. The “eerie silence”, as the cosmologist Paul Davies calls it, is starting to get disquieting. Of course we can never prove a negative, and I wish Yuri Milner’s quest well, but I cannot help feeling it will come to nothing.
If we decide that humans are probably alone, this will actually be a far more amazing finding than a galaxy teeming with life. And very disquieting. I am sure we could cope with the philosophical trauma of finding aliens on Kepler 452b. But the cold revelation that our small planet may be the most important thing in the entire universe, and our existence almost impossibly lonely, may be something we find very hard to face up to.