Perimeter welcomes cosmologist Neal Dalal to faculty

New Faculty member Neal Dalal wants to make the most of the influx of cosmological data in order to understand physics on every scale.

From probing neutrino masses and determining the “clumpiness” of dark matter to bridging the communication gap between research specialists, cosmologist and new Perimeter Faculty member Neal Dalal has his eye on more than just the sky.
Dalal is part of the recently launched Centre for the Universe, an interdisciplinary research cluster designed to tackle the toughest questions in cosmology. 
He will join the Centre’s steering committee alongside Perimeter researchers Asimina Arvanitaki, Avery Broderick, Luis Lehner, and Kendrick Smith. The Centre, which is headed by Perimeter Institute Director Neil Turok, includes Stephen Hawking and 2015 Nobel Laureate Art McDonald as its scientific patrons.
“Neal has a genius for spotting new ways to learn about basic physics from astronomical observations,” said Turok. “His forthcoming observations of galaxies using gravitational lensing should tell us whether the dark matter in galaxy halos is clumpy (as the simplest theories imply) or smooth: very cool! We are thrilled Neal has joined us and look forward to many exciting ideas and results.”
Dalal hopes to strengthen Perimeter’s connections to several major experimental efforts currently underway, including large-scale surveys of galaxies that will be used to study dark energy and map the geometry of space. “In astrophysics and cosmology, the vast majority of the progress that we’ve made has been driven by new observational results,” Dalal said.  
After completing his PhD at the University of California at San Diego, Dalal took up postdoctoral positions at the Institute for Advanced Study in Princeton and the Canadian Institute for Theoretical Astrophysics in Toronto, and then joined the faculty at the University of Illinois at Urbana-Champaign in 2011. 
His research focuses on using new cosmological observations and surveys to probe fundamental physics on many scales, including the very small. Last year, Dalal and collaborators showed that cosmic structures called voids – vast regions in space where galaxies tend not to cluster – are affected by the flux of neutrinos (tiny, neutral, weakly interacting subatomic particles) in space. By constraining the properties of the cosmic voids (understanding, for example, how they cluster), we can measure certain properties of the neutrinos, such as their masses. 
In his new role at the Centre for the Universe, Dalal will not only tangle with cosmic questions; he also hopes to tackle the very human challenge of bridging the communication gap that can exist between specialists. 
“It can be hard to communicate, because people use different words for the same things. Oftentimes progress is made just by being able to translate one area to another, and vice versa,” he explained. “In the past, I’ve worked pretty closely both with theorists and also with experimentalists, so hopefully we can bring some of that here.” 
Ultimately, he said, there is a lot that can be learned in the coming years, particularly with the advent of gravitational wave physics adding even more data to the mix. For instance, gravitational waves provide very accurate distance measurements to the events that create them. These distance measurements can be compared to the brightness of the sources: a discrepancy can indicate that some kind of mass between the source and us is distorting space. This is known as “gravitational lensing.”
While surveys examining the shapes and brightnesses of galaxies (the distortions of which are known as “shear”) are already routine, incorporating gravitational waves could help hone the technique to an even finer grain. Because gravitational wave sources tend to be much smaller than galaxies, gravitational waves could even provide a means to refine measurements of dark matter “clumpiness” on small scales.
The notion is just one of many ideas that Dalal is mulling over in his quest to get the most out of the tidal wave of new measurements. Perimeter’s research environment, he said, provides an ideal place to brainstorm.
“Normally, finding blocks of time just to think is nearly impossible. Here, it’s been great that there are no distractions pulling me away from sitting and thinking about things,” he said.
“It’s also great because people’s doors are open. Everyone is happy just to have you walk in to bounce some idea off the wall.”
– Stephanie Keating



About Perimeter Institute

Perimeter Institute is the world’s largest research hub devoted to theoretical physics. The independent Institute was founded in 1999 to foster breakthroughs in the fundamental understanding of our universe, from the smallest particles to the entire cosmos. Research at Perimeter is motivated by the understanding that fundamental science advances human knowledge and catalyzes innovation, and that today’s theoretical physics is tomorrow’s technology. Located in the Region of Waterloo, the not-for-profit Institute is a unique public-private endeavour, including the Governments of Ontario and Canada, that enables cutting-edge research, trains the next generation of scientific pioneers, and shares the power of physics through award-winning educational outreach and public engagement.

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“Neal has a genius for spotting new ways to learn about basic physics from astronomical observations.”


– Neil Turok, Perimeter Institute Director