Julian Onions


Favourite Thing: Find out new things, solve problems.




Degrees in physics and biology, an M.Phil in computer science, hopefully doctorate in astronomy

Work History:

Nottingham university and for software companies

Current Job:


Me and my work

I build universes in some of the biggest computers on the planet.

I work as an astronomer, trying to find out more about the universe. It can be very slow work sometimes, but we have nearly 14 billion years of history to unravel. So ask me anything about astronomy, physics or science in general

I start with what we think the universe was like in the early days and then apply the laws of physics, and let it run in a very big computer, then look at what we’ve got and see if its like what we see.

We have to match up galaxies, stars, super nova, black holes and all sorts of other objects, and compare it to information we get from the big telescopes like the VLT and Hubble space telescope.


My Typical Day

Find out why my program failed, or if my some miracle it worked – start plotting graphs of its findings.

Usually I’m running computer programs, or finding out why they are not running.

With super computers you can’t just run a program, as it will typically use anywhere from a few hundred to a few thousand processors. So you prepare your program to run, and then submit it to be scheduled. At some later time, when there are enough processors free, it will run your job in between other peoples. It will usually run for a day and then stop and save itself. At this point you can check how it’s going, and if its working out, send it back to run a bit further.

The longest simulations can run for several months.

Once it is finished, you have to analyse the results. This usually means plotting graphs of things to see if they look like you expect. There is far too much data produced to look at the numbers individually.

Then we sometimes make pretty pictures of the data, to show it happening, or movies of it.

What I'd do with the money

I visit a lot of astronomy societies and clubs and scout and guides, so would use it to help with that.

Some things really help show others what is happening out in space. No one forgets their first view of Saturn through a telescope.

So a small portable telescope is very useful to show principles and some of the sights. A green laser pointer is the best thing for showing people around the night sky.

Of course a lot of the year outreach at night is not possible, so having the option of a solar telescope is also useful.

My Interview

How would you describe yourself in 3 words?

nerdy sciencey jokey

Who is your favourite singer or band?

Too many to list, and they change

What's your favourite food?

Almost anything, but I do like a good cheesecake

What is the most fun thing you've done?

Flown a plane

What did you want to be after you left school?

Be a pilot or a scientist

Were you ever in trouble at school?

Usually only for late or incomplete homework

What was your favourite subject at school?


What's the best thing you've done as a scientist?

Publish my first paper

What or who inspired you to become a scientist?

No one particularly, I always loved the subject. I have a few heroes like Feynman, Hubble etc.

If you weren't a scientist, what would you be?

A computer programmer (I’m one of those too)

If you had 3 wishes for yourself what would they be? - be honest!

more time in a day!

Tell us a joke.

sodium sodium sodium sodium sodium sodium sodium sodium – BATMAN

Other stuff

Work photos:

This is one of the large computers I run my programs on.

It’s in Switzerland, I’ve never seen the computer itself, I log into it over the internet and give it work to do. It’s currently the 6th fastest computer in the world!

Here is a video of one of the simulations I did, running from almost the beginning of the big bang to now.