2008 : WHAT HAVE YOU CHANGED YOUR MIND ABOUT? WHY?

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Professor of Astronomy, Harvard University; Director, Harvard Origins of Life Initiative; Author, The Life of Super-Earths
Astrophysicist, Harvard

I change my mind all the time — keeping an open mind in science is a good thing. Most often these are rather unremarkable occasions; most often it is acceptance of something I had been unconvinced or unsure about. But then there is this one time …

October 4th, 1995 was a warm day. Florence was overrun by tourists – and a few scientists from a conference I was attending. The next day one of my older and esteemed colleagues from Geneva was going to announce a curious find – a star that seemed to have a very small companion – as small as a planet like Saturn or Jupiter. Such claims had come and gone in the decades past, but this time the data seemed very good. He was keeping the details to himself until the next day, but he told me when I asked him about the orbital period of the new planet. I was incredulous – the period was so short, it was measured in days, not years – I told my wife back in the hotel that night – just 400 days!

I was not a planetary scientist – stars were my specialty, but I knew my planetary basics – a planet like Jupiter could not possibly exist so close to its star and have a period of 400 days. Some of this I had learned as far back as last year of high school. I did not question it, instead I was questioning my colleague’s claim. He was the first to speak the next day and he began by showing the orbital period for the new planet – it was 4.2 days! The night before, I must have heard “4.2 days”, but being so incredibly foreign to my preconception, my brain had “translated” that number to a more “reasonable” 420 days, or – roughly 400. Deeply held preconceptions can be very powerful.

My Florentine experience took some time to sink in. But when it did, it was sobering and inspiring. It made me curious and motivated to find the answers to those questions that just days before I had taken for granted. And I ended up helping develop the new field of extrasolar planets research.