Emma Chapman: "If intelligent life has evolved and wants to send us a message, they'll develop a radio telescope to do that"

This article first appeared in Radio Times magazine.

When humans eventually make contact with aliens, we’ll be able talk to them about sitcoms. “There’s something called the I Love Lucy Radius,” explains author and astrophysicist Emma Chapman, referencing the long-running US comedy series of the 1950s.

Thanks to its massive popularity, “its broadcast caused significant emissions of radio waves [used in early TVs as well as radios] into space. We were very loud to the universe at that point. And the I Love Lucy Radius is how far those radio waves have travelled in the 75 years since they were broadcast – which now encapsulates a few planets beyond our solar system. If there is life on those worlds, they’ll have seen I Love Lucy.”

Chapman’s new book, Radio Universe, is full of fantastic little fact-blasts like that, but there’s something especially delicious about listening to them on Radio 4, where the work is this week’s Book of the Week, because the technology you’re utilising is the very same as that Chapman uses to listen in to the echoes of the Big Bang in her day job as a Royal Society research fellow at Nottingham University.

“When you extend the antenna on your radio – or switch on your mobile phone, which also has miniaturised antennas in it – you’ll be receiving radio waves from big stations like London’s BT Tower,” she explains, “and that’s how The Archers arrives safely to you. Radio astronomy is just using a different size or shape of antenna, and pointing them upwards to receive waves from solar flares or space weather or pulses from a spinning pulsar star or matter actually swirling and falling into a black hole.”

She’s not wrong about using a different size of antenna: if you’ve seen GoldenEye or Contact, you’ve seen Puerto Rico’s 1,000-foot Arecibo radio telescope. But just as impressive, apparently – and Chapman has worked at both – is the Square Kilometre Array Telescope currently being built in the Western Australian desert, which will consist of more than a million connected antennas when finished.

Even more mind-blowing is the revelation that radio waves are actually a kind of light. “Optical light – that’s the light humans have evolved to be able to see – is only a tiny sliver of the spectrum,” says Chapman. “In fact, most animals on Earth can also see in UV, which we can’t. But radio waves have the longest wavelength and lowest energy of the whole spectrum, so can travel really long distances.” Which is why we can use them to eavesdrop on what Chapman calls “the cosmic dawn”, and why she describes herself as a “stellar archaeologist” (it’s not, she insists, because it makes her sound like a cross between Princess Leia and Lara Croft).

But is any of this useful at all? “Absolutely! Just a few weeks ago, scientists on the International Space Station were looking at a Petri dish of bacteriophages. These are viruses that can kill bacteria, and they were found to have much stronger abilities to do that in space. Then there are the asteroids up there worth a trillion dollars each because they have all the rare metals we could need and that countries are fighting over here on Earth.

“Nasa has already sent probes, scooped up parts of asteroids and brought them back – with radio astronomy helping to map them, work out where they’re travelling and how they’re spinning, so the probes could land. We could be dragging those asteroids into Mars orbit and mining them, and we’re close to that. The physics is there, and there’s enough money down here to do it; it’s just that governments aren’t paying enough attention.”

Then there’s the small matter of black holes. “Every spiral galaxy in our universe, including our own, has what’s called a supermassive black hole at its centre – and we’re comfortable with that because it’s all the way over there. But what’s quite horrifying, when you think about it, is that there are loads of little wandering black holes just roaming around the galaxy.” Fortunately, while conventional optical telescopes can’t see black holes (“because they’re, well, black”), they can show up on radio telescopes (“because there’s so much stuff falling into them, and so much friction between those particles and gas and dust, that it emits radio waves”).

Perhaps of greater significance still is radio astronomy’s role in the search for extraterrestrial life. Which brings us back to telly. “The physics that makes radio waves so good for communications on Earth will be the same on planets around Alpha Centauri or wherever,” says Chapman, “so if intelligent life has evolved and wants to send us a message, they’ll develop a radio telescope to do that. But it’s just as likely they’ll do it by accident, through their TV broadcasts or whatever.” Maybe we’ll also be talking to them about I Love Xjgrfnujzjdtk.

• Radio Universe by Emma Chapman is available now

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