Dr Julian Onions Attempts to Answer Complex Questions About The Universe in His Role as an Astrophysicist

First things first, your name is wonderful. Dr. Onions, are there many layers to what you do, and has it ever made you cry?
I think the start of my PhD was the nearest I came to crying! I was so much in the deep end, and I wasn’t sure if I would ever come out. Fortunately, I did in the end.

Judging from my first question, you can probably tell that I’m not someone that understands astrophysics. What is it exactly?
Astrophysics is basically the study of everything outside of the Earth. It’s split up into lots of subdivisions, but the term “astrophysics” covers everything: how stars work, how galaxies form, how the universe behaves. Specifically, I work on simulations, so rather than studying the Universe through telescopes, I load big models of it into a computer and, if we’ve got all of the equations right, we are able to press “go” and see the Universe in front of us. If everything goes right, it should look similar to the real Universe. We can use this system to make predictions, because we are able to spin the Universe around and know what it will look like from all angles, which allows us to see where a lot of invisible stuff is.

What invisible stuff?
Well a lot of this is driven by something called dark matter, which we can’t actually see or detect – other than its effect on gravity. But in the simulations, we can just throw dark matter in and see where it is and what effect it has. Dark matter wasn’t known about until the late eighties, and about two decades ago we discovered dark energy, which we know even less about. Dark matter we can do reasonable simulations with and, even though we don’t know exactly what it is, we’ve got a fairly good handle on how it behaves, whereas dark energy is something that we’re quite at sea about. There are lots of theories about it, but nothing concrete at this stage. Dark matter and dark energy make up 95% of the Universe, which means for the last two hundred years, we’ve only been studying 5% of the Universe.

What is actually at the edge of the Universe?
Nobody knows. The trouble with the Universe is that we’re limited by the speed of light; so how far light has travelled is as far as we can see. The Universe began 13.8 billion years ago, and we can pretty much see the edge of that - about 400,000 years after the Big Bang - but we’re almost sure that’s not the real edge. It’s a bit like standing in the middle of Nottingham; you can see everything around you, but you can’t see Leicester because it’s over the horizon.

To what extent is the human brain actually equipped to handle this level of information?
Not really at all I don’t think. Every time I try and think of the distances and times involved, I have to go and lie down, but after a while you get more used to it. We deal in something called gigayears, which is a billion years, and I often have to stop and think, “that’s a few billion years I’ve casually been tossing around.” Sometimes the numbers are just nonsensical.

Do you think there is something innate in humankind that drives us to try and understand the Universe?
I think it’s really just curiosity. It’s always been there; we all just want to know why things work. The more you look at things, the more you realise you don’t quite understand it all, and you want to answer that next question. We didn’t know that dark energy existed twenty years ago, and now we really want to know what it is. It’s not going to give us flying cars or hovering skateboards, but it might - who knows. It’s changing at a rate that we will need to know what it does in millions of years time, if we haven’t wiped ourselves out by then.

How much has the popularity of people like Brian Cox helped push the study of the Universe into the wider public sphere?
We definitely saw a significant bump in undergraduate applications with Physics when Brian Cox and people like him become popular; we mythically call it the Brian Cox effect across universities. It can only be a positive thing; it increases diversity. Physics used to be really bad; when I first started, out of a class of 150 students, only three were females. Now it’s about ten or fifteen percent, and going up each year, which is really good.

Have you got a favourite planet?
Saturn! It’s just amazing. The first time I saw it through a telescope it looked exactly like it does in a book, and you just think ‘Wow, that’s crazy’. Every planet has something special about it.
 
Is there any validity in astrology?
No. None whatsoever.

Obviously Space Jam is number one, but what is the second best film ever made about space?
That’s difficult. I’ve got a real sweet spot for 2001: A Space Odyssey, I’ve seen that a number of times, probably more than I should have. I really like Contact too – Carl Sagan really made sure that most of his ideas were scientifically valid. But usually I can keep my suspension of disbelief in check. Although saying that, Gravity has some moments. For astronomers, the worst part of that film is the breaking of the Hubble Telescope. I couldn’t care less about Sandra Bullock, but seeing that get wrecked was absolutely heartbreaking.