Experts in the News

Somebody give David Hu's graduate and undergraduate students medals for bravery -- and maybe some hazmat suits. Hu, an associate professor in the School of Biological Sciences and an adjunct associate professor in the School of Physics, is a 2015 Ig Nobel Prize winner for his "urination duration" research, and he and his intrepid fluid dynamics team have also gotten hands-on (yuck) with frog saliva. Now he has studied the physics of poop among mammals, venturing to Zoo Atlanta to follow elephants around and figure out things like speed, duration, size, mucosity, etc. Hu, also an associate professor in the George W. Woodruff School of Mechanical Engineering, makes the connection between his research and a better understanding of gastrointestinal health. The research also helped his team design state-of-the-art undergarments for astronauts. Hu's study was published April 25 in the journal (wait for it)....Soft Matter. 

To explore the mathematical possibilities of alternative geometries, mathematicians imagine such ‘non-Euclidean’ spaces, where parallel lines can intersect or veer apart. Now, with the help of relatively affordable VR devices, researchers are making curved spaces — a counter-intuitive concept with implications for Einstein’s theory underlying gravity and also for seismology — more accessible. They may even uncover new mathematics in the process. “You can think about it, but you don’t get a very visceral sense of this until you actually experience it,” says Elisabetta Matsumoto, a physicist at the Georgia Institute of Technology in Atlanta.

It’s no secret that supermassive black holes are heartless beasts: These objects of immense gravity that let nothing, not even light escape, have fascinated astronomers since the early 20th century. While it’s believed that so-called supermassive black holes lurk at the center of most galaxies, including our own, there’s still much we don’t know about how they formed, or why, except to remind us of our own mortality. But new research from an international team of scientists might have some answers to at least one of the critical questions -- namely, how supermassive black holes, which range in size from millions to billions of solar masses, apparently formed very quickly in the early universe. Using computer simulations, the researchers found that these giants can grow incredibly fast if they can suck the life (read: radiation) out of a nearby galaxy, disabling their host galaxy’s ability to create stars...The researchers found that the neighboring galaxy supplying the radiation had to be a certain size and distance away from the black hole’s host galaxy -- though these cosmic energy sources could be smaller and closer galaxies than other studies estimated. “The nearby galaxy can’t be too close, or too far away, and like the Goldilocks principle, too hot or too cold,” study co-author John Wise, an associate astrophysics professor at Georgia Tech, said. Wise is an associate professor in the School of Physics. 

New research clarifies how toroidal droplets—which initially take the shape of a donut—evolve into spherical droplets by collapsing into themselves or breaking up into smaller droplets. Work with droplets has implications for the life sciences, and could improve industrial processes....“Surface tension drives the evolution of the droplets,” says Alexandros Fragkopoulos, a PhD candidate at Georgia Institute of Technology. “Fluids tend to minimize their surface area for a given volume because that minimizes the energy required to have an interface between different fluids. Spherical shapes minimize that energy, and as a result, toroidal droplets want to evolve to become spherical. We’re studying how that transition occurs."...The impetus for the experimental work was inconsistencies between theoretical predictions and computer simulation of toroidal droplet transitions. What the researchers found tends to back up the simulation results. “However, the earlier theoretical work was essential in guiding the theory efforts and in illustrating what the problem was in order to correctly describe the experimental results,” says Alberto Fernandez-Nieves, in whose lab the research took place. Alexandros Fragkopoulos is a graduate teaching assistant in the School of Physics, where Alberto Fernandez-Nieves is an associate professor. 

You never know when a frog playing an electronic game will lead to an experiment on the physics of saliva....Alexis C. Noel, a Ph.D. student in mechanical engineering at Georgia Tech, and her supervisor, David L. Hu, were watching a viral YouTube video in which a frog is attacking the screen of a smartphone running an ant-smashing game. It appears to be winning. They started wondering how — in reality — frog tongues stick to insects so quickly when they shoot out to grab them, and decided it was a phenomenon worth studying. David Hu is an associate professor of mechanical engineering and of biology, as well as an adjunct associate professor of physics, at Georgia Tech.