Flash forward to 2017 and Mr Ross, 26, has combined his two passions to be the centre focus of his PhD at the Australian National University.

"I was always reading about space and stuff as a kid and science was always my favourite subject at school," Mr Ross said.

"I must confess - I had a lot of Lego."

Mr Ross was runner up in Wednesday night's ANU "three minute thesis" competition, while cancer research student, Erin Andrew was crowned the winner from the 12 ANU PhD students who delivered a short, sharp and snappy presentation on their complex research.

Students explained their research and why it is important in just three minutes with only the help of a single PowerPoint slide.

"The rules of Lego are quite simple - there are only so many ways you can put bricks together but even with that you can build amazing things," he said.

"What my thesis is about is we use laser beams to control the interaction betweens atoms which is kind of like changing the rules that Lego plays by - maybe you wanted to change the number of bricks you could stick to another brick for example.

"So you investigate the possibilities you could explore with a new role."

Mr Ross's research looks at how atoms work together to produce collective behaviour.

"I'm working on a device to allow us to investigate how many individuals can cooperate to produce different emergent behaviours."

For Ms Andrew, 24, her PhD was sparked by a personal experience of cancer.

"When I was 16, I was diagnosed with Hodgkin's lymphoma and had to go through chemotherapy," Ms Andrew said.

"I walked into the hospital as a 16-year-old girl who had a lump on her neck and would walk out feeling horrible."

Ms Andrew said she was in and out of hospital because of the side effects of the chemotherapy and said she wanted to help improve the way other patients received treatment.

"I grew to have this passion that cancer treatment shouldn't be the way it is.

"The side effects are almost as bad as the cancer - and so I grew to love learning and getting an understanding of how the body worked and thought there must be an easier way."

Ms Andrew is looking into how dead bacteria can be used to stimulate a response that can remove cancer.

"For the last few years we've been treating naturally occurring tumours in dogs and horses," she said.

"My thesis is trying to understand exactly how it works, what immune cells it's using to create the attack against the cancer, how it's doing it, so then I can try and force this reaction of the immune cells in every patient."

The technique is being used in a clinical trial in cancer patients at the Canberra Hospital, in a study that looks at complete freund's adjuvant in patients with refractory and relapsed solid tumours.

Ms Andrew also won the people's choice award. She will now enter an Asia-Pacific final.

The 2017 finalists: