Astrophysicist Dr Rebecca Smethurst is a research fellow at theUniversity of Oxford, working on the co-evolution of galaxies and supermassive blackholes. She is also a science communicator through her YouTube channel Dr Becky andhas recently released her book “Space: 10 Things You Should Know”. Here shetalks about her work and space exploration; its development, purpose andfuture.
Elizabeth Tatham: How did you get into space research?
Dr Rebecca Smethurst: When I was younger, I was one of those kids that was obsessedwith space, but it was only when I realised astronomy was part of physics atGCSE that I thought I could probably do this! When I finished uni I panicked alittle, having put off that “what do you want to do question” like a lot ofpeople do. In 4th year, everyone seemed to be applying for graduateschemes from big companies, but the only one relevant to me was an engineeringscheme. So, I worked for Rolls Royce for a year, but I found that engineeringand physics ask 2 different questions–one asks how and the other why. By theend of the year I really missed the academic environment of being free to askquestions, so I applied for a PhD studying galaxies and how everything in theminteracted. During my PhD I suppose you could say I fell down the black hole,hole; it fascinated me how something so tiny (compared to the size of the solarsystem) could have an effect on something as huge as a galaxy!
Elizabeth: What’s the difference between a supermassive black holeand a regular black hole?
Rebecca: They’re a lot larger. When a star runs out of fuel and collapsesunder gravity but is so massive that the atomic forces can’t overcome thecrushing inward forces of gravity, you end up with a black hole. But whereas anormal black hole is something like three times the mass of the sun, asupermassive black hole is more than 1 million to 1 billion times the mass ofthe sun and is really at the driving seat of the galaxy. It’s a bit of an astronomy’schicken and egg; the question is whether the black hole formed first, and thenthe galaxy formed around it, or whether the galaxy formed a little black holethat drew in matter until it sank to the centre of the galaxy.
Elizabeth: So the black hole is really key to galaxy function?
Rebecca: Yeah it really is. They co-evolve, we say, they grow together,and by feeding one you can starve another.
Elizabeth: Just a random question.
Rebecca: Yeah, I love random questions.
Elizabeth: What’s the difference between astronomy and astrophysics?
Rebecca: Astronomy is the observation of the sky; astrophysics is then havingthe physics knowledge to back up what you have observed. So, I would callmyself both an astronomer and an astrophysicist. Because I go to telescopes, Itake observations, then I come and analyse the data and I come up with thephysics that explains what we have seen. Someone who runs simulations, though,might only describe themselves as an astrophysicist and not an astronomer.
Elizabeth: Would you consider the work you do to be spaceexploration?
Rebecca: Space exploration to me would involve sending up a probe orsatellite. But even though we make observations using telescopes from theground instead of sending a probe, we’re still exploring the wonders of spaceeven if we’re not exploring space itself.
Elizabeth: Would you say the space race really exploded interestin space exploration?
Rebecca: Sputnik was the first satellite we put up there, but the spacerace really pushed our understanding of mathematics and the advancement oftechnology. The focus has changed though from people planting a flag to being completelyscience-focused, which is great. The mission I’m most looking forward to is theDragonfly mission to Saturn’s moon Titan. The probe being sent is going to haverotor blades instead of wheels, so will essentially be able to hop and flyaround Titan!
Elizabeth: So, where we are now, sending people into space is lessfor research purposes then?
Rebecca: People ask why we haven’t sent people to Mars yet. It has almostbecome sort of political and being the person to plant the flag. And peoplealso ask why we haven’t been back to the moon. Well we have, some 20 odd times,but just with robots and satellites, and we’ve even got 2 probes that have nowleft the solar system and are sending signals back from beyond the solarsystem. So, why haven’t we sent humans to Mars? Because we’ve done so muchother stuff. So, it’s a bit sad that when probes landed on a comet for thefirst time, it barely made front page news because it wasn’t a human thatstepped out onto the comet. But humans did do it, because guiding the process there’speople who programmed this and people who built that.
Elizabeth: Another popularised idea within space is the search forextra-terrestrial life. You had one chapter in your book titled ‘aliens doexist’- What makes you think this?
Rebecca: It’s the sheer scale and numbers in the universe. We are oneplanet around one star in a galaxy of 100 billion stars. So, even if the oddsare that 1/100bn stars are capable of forming a planet that could host life,there would still be enough galaxies for there to be one. Running the numbers,there are 100,000 possible planets in the universe that could host life. Itmakes you kind of just think, “well there has to be?”
Elizabeth: How much space exploration involves looking forextra-terrestrial life?
Rebecca: There are astrobiologists involved in the search for habitableplanets in the zone around its star that isn’t too hot or cold for water. It blowsthe mind to think about it- who knows what life could be like? I said in thebook it’s a funny thing because when people find out you’re an astrophysicist, theyask you about aliens. But to me that question isn’t really for astrophysicists.We can maybe provide the most likely region we’d think life could exist in, butwhether they exist and what they’re like, that’s more of a question forphilosophers and humanity as a whole. I don’t feel studying black holes givesme the clout to comment on it!
Elizabeth: In the future of space exploration, what do you think willbe the most prominent avenue of research?
Rebecca: Definitely dark matter and dark energy. We really don’t know what95% of the universe is. Currently we have what’s been dubbed a crisis incosmology (the study of the creation and evolution of the universe), and if wedon’t resolve this, we won’t have confidence in our best model of the universe.Essentially, when we calculate the age of the universe using cosmic microwavebackground data, we get different results to the other methods we can use. So, doesthis mean there is some new physics explaining this, or is there a systematic errorin our cosmic microwave background data?
It really shows that even with the technology we have, there’s still much more that we don’t know, and as a kid I don’t think I ever really understood that; reading books about science and space it was just like facts, facts, facts, so I thought we knew everything! But no, we really, really don’t.
Elizabeth: Would you say that’s changing now?
Rebecca: I’d hope so, and it’s what I aim to do through my sciencecommunication–to stress that we don’t know this, or I don’t know this, andthat’s okay. It’s okay to say you don’t understand something, and I think we’regetting better at communicating the humanity behind science–how we do it, andthat its okay that we don’t know it. That’s what learning is for.
Elizabeth: Now that everyone is thinking about climate change,what’s the contribution of space exploration to this issue?
Rebecca: I guess the question would be why focus on space exploration whenour planet is dying, and we are making it worse? Actually, if you look at thestats, space exploration is a tiny fraction of the carbon emissions from airtraffic, which in turn is only 5% of global CO2 emissions. And the one thingyou can’t parameterise is the idea of blue-sky research. For instance,astronomers invented the very early stages of Wi-Fi because they wanted aneasier way to transfer data between their telescopes and computers. So, youdon’t know where trying to develop new technology for space exploration will takeyou.
Elizabeth: If you could go anywhere in space, where would you go?
Rebecca: Everyone asks me this question, but I don’t really know. If youwanted to go see a galaxy or nebula, being there you’d have a really faintimage compared to the photos taken by the Hubble Space Telescope- you’d befloating in a cloud of gas and dust. So, I think I’d pick somewhere in theSolar System- I’d love to go to a moon of Saturn and have a night sky view ofSaturn and Jupiter.
