Upfront
Gerry Gilmore
by Marilyn Head
Marilyn Head talks to New Zealand-born astronomer Gerry Gilmore about life, the universe and everything.
“Do you know the longest period a work of art has been hung upside down in a public gallery?” demands Gerry Gilmore, professor of experimental philosophy at Cambridge University. “Forty-three days! It was a work by Matisse shown at the Museum of Modern Art in New York in 1963 – 273,000 people, including every major art critic, saw that exhibition, yet no one noticed. Why not?”
Hard question. Tantalising answer. That’s pretty typical for the Kiwi astronomer who is one of the most cited authors in astrophysics and space sciences.
When he was seven, Gilmore told his brother that he was going to work on hard problems – not ones that were too hard, because then he wouldn’t be able to solve them, but ones that were just hard enough to be interesting. Now he says he’s having enormous fun working on such “not-too-hard” problems as, “What is wrong with the universe today?”
Is there something wrong with the universe? “Absolutely – for a start, we don’t know what 99 percent of it is! And there’s something wrong even with the bit we think we know about, because the theories that explain how things work on the grand scale are inconsistent with the theories that explain how things work on the small scale – there’s something missing between General Relativity and Quantum Mechanics. We’ve got ideas, but it’s very difficult to test theories at this level, because you need to measure very small effects on very distant objects. But that’s something we’ll be able to do with Gaia!”
Gaia is the European Space Agency’s prime astrophysical mission, a satellite with two space telescopes armed with cameras that will scan the entire sky every few months, literally mapping the universe. Gaia got the go-ahead last year when Gilmore presented the scientific justification for the mission to all the heads of state at UNESCO headquarters in the “big shootout” to see what got funded. He is still jubilant about getting the half billion euros needed. “Gaia is about 10,000 times better than anything else we’ve had. It will revolutionise astronomy!”
In the youthful even mischievous face and disconcertingly clear eyes before me it is easy to recognise the precocious Christchurch teenager who worked through a list of prohibited experiments, silvercoating pennies to flog off as 20c coins, and inadvertently blowing up the lab. Mercurial, articulate and opinionated in the best sense of the word, he assures me that he is where he is simply because he was too lazy not to accept the chances that came his way. “I’ve just drifted into things because they were offered to me and they seemed like fun – if they weren’t, I’d stop doing them!”
Having “drifted” into astronomy and in 1978 received the first New Zealand doctorate in that subject, Gilmore then moved to Edinburgh to continue his work on quasars, the highly red-shifted, extraordinarily energetic “quasi-stellar objects” that are the most distant objects observable. “The trouble with quasars is that they’re rare and I needed to find a way to get rid of all the stars and galaxies that were in the way. I thought I would build a little model [a theoretical computer model] to help me predict their numbers. But the best one I could build didn’t agree with what I could see in the sky.”
So he constructed a new one. The standard Milky Way model comprised a thin disk of bright young stars surrounded by a sparsely populated halo of old stars. Gilmore’s model incorporated an intermediate population of stars in a “thick disk”. It was a significant discovery and enough to establish the reputation of any astronomer. But the timing couldn’t have been worse: it was seen as a threat to the most prestigious astronomical project of the century: the Hubble space telescope (HST).
Almost immediately he found himself pitted against America’s most eminent astronomers and scientists, led by John Bahcall, from the Institute for Advanced Study in Princeton. “I had no idea that these models were critical to the HST, because they predicted how many stars there were that the HST could use as ‘guiders’. Just when it was politically essential that there was no question that the Milky Way model that John had just built was right, here was this prat from New Zealand telling everyone he’d got it all wrong!”
In the vicious debate that ensued (Bahcall even wrote to Gilmore’s boss, suggesting he be sacked), Gilmore was vindicated. “I survived only because I was so completely ignorant of how powerful these people were that I had no qualms about telling them they were wrong.”
It was a victory he was to hammer home in two more bouts with the embattled Bahcall.
“John never believed I wasn’t out to get him, because the next thing I did proved him wrong again. I was following up his brilliant analysis of data which suggested that dark matter [the matter we know exists, but haven’t detected] was close. I honestly expected to be just measuring its distribution, but he’d used old data. I developed a new technique and came up with the opposite answer – there is no dark matter nearby. That was the nail in the coffin of our relationship!”
And the third time?
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