[1][3][4] As Duffy was completing his doctorate, work was starting on the Australian component of the world's largest astronomical facility, the Square Kilometre Array.

His doctoral work had covered similar topics, and he was invited to join the first stage of this telescope; the Australian Square Kilometre Array Pathfinder (ASKAP).

[5][6] His supercomputer simulations have shown that in very early galaxies, the rate of star formation was not enough to consume the infalling cold gas.

[9] He has attempted to directly detect this dark matter as part of SABRE ("Sodium-iodide with Active Background REjection"), an international research consortium with teams in Italy, US and Australia.

SABRE is constructing the southern hemisphere's first dark matter detector 1 kilometre (0.62 mi) underground in a gold mine in Stawell, Victoria.

[10][11][12] He is also part of two Australian Research Council Centres of Excellence, investigating the origin of matter (ASTRO-3D) and seeing the Universe with gravitational waves (OzGrav),[13] and he was a member of the worldwide OWLS (OverWhelmingly Large Simulations) collaboration.

[21] He hosted an Evening with Neil DeGrasse Tyson at the Melbourne Convention Centre, interviewed onstage Lawrence Krauss[22] as well as Brian Greene,[23] and presented in a national tour for BBC Worldwide's The Science of Doctor Who.

[29] As part of Science Week 2017, Duffy and Katie Mack launched a virtual reality tour of the Universe, using custom-made headsets and a free app.

[30] Duffy's good looks have helped to attract media attention – MamaMia commented that "Unfortunately, I couldn’t hear what he was saying over the sound of his cheekbones.