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Physicist Claudia de Rham: ‘Gravity connects everything, from a person to a planet’

Physicist Claudia de Rham: ‘Gravity connects everything, from a person to a planet’

Prof Claudia de Rham is a theoretical physicist at Imperial College London, developing and testing “new models and paradigms” at the intersection of gravity, cosmology and particle physics. She has just published her first book, The Beauty of Falling: A Life in Pursuit of Gravity, charting her lifelong attempt to understand the “true nature” of the force around her, which has seen her train as an astronaut, diver and pilot.

In your book, you say you have been “chasing gravity my entire life”. What does that mean?
It’s something we all have in ourselves, this playful relationship with gravity. But to some extent, it has taken on a meaning of its own for me in terms of really trying to go to outer space, to challenge gravity in a slightly different way. And when that hasn’t worked out, then to do that from a more scientific point of view, in terms of understanding the underlying framework behind the models we have for gravity; coming up with new models, and finding ways to see if we can experiment with those.

What is it about gravity that you find so compelling?
Gravity is so universal. And I think this is very fundamental, it’s a phenomenon that affects everything, everyone, all the time, everywhere. It does absolutely everything: it connects everything and everyone. We all experience it in the same way, whether we are a person or a planet, a black hole or a balloon, a hammer, a feather, a piece of cheese, or a pumpkin seed. It’s something which is within us without us being able to defeat it. The feeling of weightlessness, the feeling of freefall is what gravity is. It is a complete freedom in itself.

You’ve trained as a diver and a pilot to better understand the fundamental forces around us, and got to the final selection stage of astronaut training for the European Space Agency. How did that journey begin?
It started from wanting to chase gravity, in some sense. For me that meant trying to go into outer space and experience gravity inside a different environment, and experiencing this feeling of weightlessness on a deeper level. So once I was able to formulate that in my head as a child, that really became a long-term goal. For such a long period of my life, every single thing I would do was focused on the idea that I wanted to become an astronaut, I wanted to participate in astronaut selection and put myself in the best position for that.

What did astronaut training entail?
We were subjected to a battery of tests, most of which were designed to assess our team-based abilities in stressful situations. This included a pretend rescue expedition through the “jungle” – we were asked to plan the risky mission knowing resources were limited, night was coming, and, if we weren’t careful, some of us may not make it back. Another saw us paired up as pretend air traffic controllers in an overcrowded airport, tasked with landing several planes running short of fuel. The twist was that each of us only had access to half of the information, so we had to engage in precise communication and collaboration with our partner to complete the mission. Out of nearly 10,000 applicants to apply, 99.5% had been rejected by the last stage. Only 42 got to this second training stage.

Your hopes were cut short by the discovery of latent tuberculosis during the final selection round, which you describe as “a little souvenir I must have unknowingly brought back with me from my time in Madagascar” from your childhood. Do you wonder what life might have been like had you not fallen ill?
I see the candidates going out to space… it’s, of course, a dream. But at the same time, I don’t regret the path my life has taken since then. I think it opened up other opportunities.

How much more is there to learn about gravity that we don’t already know?
The beauty with gravity as we know it now is that there is much more to learn about it. We now know that Einstein’s theory of general relativity stops being a consistent and accurate description of what happens in some situations, like very close to the centre of black holes, or the big bang. His theory would seem to suggest that we could measure some physical quantities, like the curvature of spacetime, that would seem to become infinite (we call this singularity), but measuring an infinite value would simply not make sense. In order to understand what takes over when his theory is no longer valid, we may want to ask ourselves questions like “what happens at the very centre of a black hole?” or “what happened at the time of the big bang?” – but if the notions of space and time no longer make sense, then the questions themselves may not make sense either. We don’t even have the language to phrase the questions we have, less still answer them.

What can gravity tell us about the future?
What we know at the moment is that the expansion of the universe is accelerating, which sort of was a surprise 25 years ago. What we need to understand is what is causing this accelerated expansion, and whether the laws of gravity that we’re using to describe that are valid. We need to understand this better to [understand] what will happen in the future. Will this accelerated expansion continue for ever? Will it become even more accelerated? Will it stop? We don’t know, because we don’t even know precisely what the origin of this phenomenon is. So the fate of our universe, and the fate of space and time in some sense, will depend on what the driver of this accelerated expansion of the universe is.

Is it frustrating to have so many questions, and so few answers?
It’s exciting. It’s little steps. If what you’re trying to do is see if there’s going to be an application of your discoveries for tomorrow, then this is not the field for you. But you do learn: you gain a much deeper appreciation of nature all around you, and it’s these everyday small steps that really lead to the biggest steps in the longer term. Every single small understanding is a breakthrough in itself, because it will allow us to go deeper. In science, even a negative result is a result in itself.

  • The Beauty of Falling: A Life in Pursuit of Gravity by Claudia de Rham is published by Princeton University Press (£20). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply

Source: theguardian.com