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Brian Cox asks: are we alone in the universe?

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Professor Brian Cox believes it’s a question that could be answered within a decade

The most wonderful thing about science is that, by asking questions that sound almost childlike, you’re sometimes led to very profound discoveries. Take Einstein and the theory of general relativity – he didn’t set out to discover how the universe began, he was interested in why, if you drop a bowling ball and a feather in a vacuum they hit the ground at the same time. This led him to rebuild the theory of gravity, which eventually became a theory about the structure, history and future of the universe. Shortly afterward, Edwin Hubble discovered the universe was expanding, providing an experimental confirmation of a theoretical prediction.

So the idea now is that the universe began 13.8 billion years ago with the Big Bang, but we didn’t discover that by asking “How did the universe begin?”

Science is curiosity driven. It needs to be. If I tweet about New Horizons to say it’s remarkable what they’ve discovered on Pluto, some people will reply saying we should focus on the problems here on Earth. But you can’t – it’s not possible to target scientific research efficiently to deal with immediate problems, because you never know what piece of knowledge you might need.

New Horizons

The New Horizons spacecraft exploring Pluto

Destination Pluto

The story of the New Horizons spacecraft is a beautiful example of exploration for the sake of exploration. We didn’t know exactly what we were trying to find, we just sent a spacecraft to somewhere that we’ve previously only seen as a dot on a telescope. It could have been a barren rock, but it wasn’t. It turns out it will revolutionise our understanding of how the solar system formed. And there are huge unanswered questions, the primary one being: how is it geologically active? It’s a terrifically difficult question to answer. It’s so small, but somehow it’s managed to retain an internal heat source, powerful enough to drive activity so long after it was formed. It wasn’t expected at all. And we don’t know why.

This leads us to reassess questions such as how did the Earth form? Why is there a solar system? What is the universe? And the one we’ve asked since the dawn of civilisation: why am I here? These aren’t trivial questions. Another one: are we alone in the universe?

It’s a profound question, and one that might well be answered in the next decade. One of the things we’re doing is launching ExoMars, a series of missions to Mars to discover whether microbial life existed there, or even still exists beneath the surface. And I wouldn’t be surprised if we found it. I wouldn’t be surprised if we found it on Jupiter’s moon Europa. I wouldn’t be surprised if we found it in the ocean that may well exist below the surface of Pluto. Imagine that.

If it turns out there are easily accessible microbes on Mars, or even the remains of them, it could revolutionise biology. We’d be able to compare it with life on Earth and determine which properties of living things are accidents, and which are inevitably governed by the laws of nature. Are there some properties of living organisms that have to be the same everywhere in the universe?

But if you ask the same questions about complex, multi-cellular life and intelligence, I think you could make the argument that would be very rare indeed. In fact, I think you could make the argument, quite persuasively, that we’re the only civilisation currently in the Milky Way galaxy. If I had to put money on it, that’s what I’d bet. But we’re just starting, for the first time, to look systematically, which is incredibly exciting. And we’re doing it by searching for radio waves and probing the atmospheres of planets to see how light passes through them. We also have a new telescope array that’s capable of picking up an aircraft landing radar within 50 light years. So if anyone within that distance has a runway, we’ll see it. We’re getting pretty good.

The Milky Way

Our Milky Way galaxy

Intelligent life

Simply, there are two possibilities that exist: we’re alone, or we’re not. You can’t prove a negative, but you can get a handle on how rare civilisations may be if you do serious, coordinated, properly funded searches. And at last we’re doing that. But I don’t think they’ll be there. 

If you ask astronomers, they’d say we’re discovering so many planets, and it looks like most stars have planetary systems, and a lot of those have Earth-like planets. The current number being bandied around is 20 billion in the Milky Way. So if you’re an astronomer you’d say there must be a civilisation on one of those.

But then if you hang around with biologists they’d say the history of life on Earth tells you the emergence of complex, multi-cellular organisms is unlikely. It took a hell of a long time on this planet. For more than three billion years of life existing on Earth, there was nothing you’d call complicated. Everything was single-celled, and they weren’t building cities because they didn’t have arms. Or brains. Then something happened: one single celled organism got inside another one, survived, and that’s the theory of the origin of all complex life on Earth. And it only happened once. We got really lucky.

That’s why biologists are more pessimistic than astronomers about the existence of civilisations. Not the existence of life – because life popped up on Earth pretty much as soon as it could – but complex, intelligent life. Simple life is just the chemistry of an active planet. And that’s why Pluto proved so interesting – could all these bodies in the frozen wastes of the solar system actually be active?

New Horizons didn’t set out to answer that question; it was untargeted exploration. But it could be revolutionary. There’s a famous quote from Ernest Rutherford who discovered nuclear physics. He said anyone who thinks it will be used as an energy source is “talking moonshine”. That was in the Twenties, but by the Forties we had nuclear reactors doing just that. So while new research can be difficult, very expensive and you may not initially see where the reward’s going to come, it can help make discoveries that change the world.

(Images: NASA/Rex)

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