WHEN Sydney physicist Brendan McMonigal got down on one knee to propose to his partner of seven years, Christie Nelan, he pulled out a physics paper, not a ring.
His paper, Two Body Interactions: A Longitudinal Study, pictured right, is laden with science geek speak and tracks the couple's relationship, including a graph (''happiness over time'') and the all important question.
Fellow physics major Ms Nelan - who said yes - published a link to a digital copy of the proposal on social news site Reddit this week and it went viral, viewed over 1.7 million times with tens of thousands of Facebook shares and dozens of news articles.
''I guess we won the internet,'' said Ms Nelan.
While the proposal actually happened on March 23 last year (their seventh anniversary), she decided to publish it online this week, before their wedding (March 23 this year).
Ms Nelan said the pair, both 26, had no idea it would be so popular. ''The reaction has been overwhelmingly positive. Lots of comments telling us to go make smart babies, to 'enjoy your entanglement', and lots of congratulations.''
Mr McMonigal lured Ms Nelan to the spot where they had met at the University of Sydney, where they both studied advanced maths and physics, saying he needed to show her a paper he was having trouble understanding but had left it at the university.
''I subtly got down on one knee to get the paper from my bag and hand it to her, then stood up to wait for her reaction,'' he said.
''She hadn't noticed what was happening at all, but as a typical physics grad, she read the abstract and then skipped straight to the conclusion and quickly cottoned on.''
Ms Nelan said she had a feeling a proposal was brewing but was still ''blown away''.
''We had been in a date 'war' for a while, as I thought our anniversary was the 23rd May, when we actually started dating, but he thinks it is the 23rd March, when we first met,'' she said.
''So I knew he would propose on the 23rd March, so he could win the date war.''
Mr McMonigal is now doing his PhD while Ms Nelan works as a science communicator in the Questacon Science Squad.
The story With this physics paper I thee ... graph of true love turns into proposal first appeared on The Sydney Morning Herald.