Eric Sembrat's Test Bonanza

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Glassy dynamics as a consequence of the equilibrium liquid to solid transition

We will review the underpinning of the micro-canonical ensemble and the more refined (and explicitly quantum) "Eigenstate Thermalization Hypothesis". We will then find and apply a simple corollary of these to analyze the evolution of a liquid upon supercooling to form a structural glass. Simple theoretical considerations lead to predictions for general properties of supercooled liquids. Amongst other things, a collapse of the viscosity of glass formers is predicted from this theory. This collapse indeed occurs over 16 decades of relaxation times for all known types of glass formers.

Georgia Tech’s Eye on the Sky Is Having a Birthday

Monday, April 3, 2017

As a doctoral candidate in astronomy at the University of Michigan in the 1980s, James Sowell regularly peered deep into the stars, trying to unlock the universe’s secrets.

Was the universe trying to send Sowell a message of its own at the same time?

A fellow graduate student was having some difficulty in class, and another student said it was because she didn’t come from a strong astronomy school. “She came from Georgia Tech,” Sowell remembers being told.

As Sowell’s lucky stars would have it, he landed on Georgia Tech’s faculty. Not only does he teach astronomy; he also established an astrophysics certificate for non-physics majors who want to enhance their educational resumes.

More important for Tech, Sowell navigated the maze of bureaucracy and fundraising that gave rise to the Georgia Tech Observatory in 2007. Sowell is its director, and the Observatory – which hosts more than 1,500 visitors each year – is celebrating its 10th anniversary on April 6.

The day has special meaning for Sowell, who says his work to get the observatory built was sparked by that not-so-stellar review of Tech’s astronomy offerings back in the 1980s.

“I’m going to make certain that is not said about my institution anymore – that Tech students are struggling because it’s not strong in astronomy,” Sowell says.

Marcus Holzinger says Sowell has delivered on that promise. An assistant professor with the School of Aerospace Engineering, Holzinger helped pay for the Observatory’s current state-of-the-art telescope.

Sowell “really is an unsung hero” in advocating for the Observatory and using it for public outreach, Holzinger says. “He did a super job putting all that together and getting the facility up and running.”

“We really do appreciate the Observatory,” says third-year physics major Darian Bender, who is also president of the Georgia Tech Astronomy Club. “It’s actually one of the best telescopes in the Southeast in terms of resolution. It’s exciting to have that on campus.”

From Tenure Track to Tracking the Sky

Sowell joined Georgia Tech Research Institute in 1989 after three years of postdoctoral research at Georgia State University. It soon became clear to him he’d taken the wrong career path.

“I got out of the tenure track realm,” he says. “I realized I was meant to be an astronomer.”

Sowell started teaching astronomy courses in 1992, and transferred full-time to the School of Physics in 1999. He knew that having a telescope and observatory on campus would boost undergraduates’ interest in astronomy and in possibly taking more astrophysics courses.

It would also be effective public outreach, something that Sowell says is in every astronomer’s blood.

“I know I’m opening the visitor’s minds,” Sowell says. “The best part of my job is hearing them squeal when they’re looking through the telescopes. Then I know they’re seeing something they haven’t seen in a while, or maybe have never seen before.”

Before that outreach could happen, Sowell had to find money to pay for a telescope and a place to house it on campus. When it comes to metro Atlanta observatories with large telescopes, Georgia Tech competes with Fernbank Museum (36-inch telescope), Agnes Scott College (30-inch), and Emory University (24-inch).

Sowell secured about $20,000 for a 16-inch Meade telescope from the Technology Fee fund.Construction of an observatory took longer. The roof of the Howey Physics Building was found to be the best location, but vibrations, heat generated by the large brick building, and the size of the rooftop enclosure had to be addressed.

In 2005, Sowell asked Northrop Grumman if it would be interested in funding observatory construction.  According to Sowell, his email was forwarded to someone else in the company with the note, “Do we do anything with Georgia Tech?”

The reply, Sowell said, was, “Where do you think half of our aerospace engineers come from? Don’t you realize I recruit there just about every month?”

Hello, $25,000! Construction began soon after and would take nearly two years. The Observatory marked its grand opening on April 26, 2007.

A Better Telescope for Research and Outreach

Marcus Holzinger had just arrived at the School of Aerospace Engineering in 2012 when he met Sowell to inquire about installing a bigger, better telescope in the Observatory. Holzinger needed it for his research into observations of Earth-orbiting space debris. “Not a whole lot of universities or nonmilitary places have systems capable of tracking these things,” he says.

The  16-inch Meade was great for wowing crowds with closeups of Moon’s craters, Saturn’s rings, and various other bright objects, but “it just wasn’t going to cut the mustard for tracking various space objects,” Holzinger says. “So I was faced with this wonderful situation where there was already an observatory facility; Jim is easy to work with, and we came quickly to an agreement.”

In 2014, a 20-inch Officina Stellare replaced the 16-inch Meade as the Observatory’s main telescope. A donated 12-inch Meade scope is also on the roof, used for spillover crowds.

“When it comes to the telescope, we went from a Toyota to a Jaguar,” Sowell says. “And then there’s the mount. There we went from a Volkswagen to a Rolls-Royce.”

That mount allows the Stellare to easily track objects 200 kilometers above Earth, whizzing by at seven kilometers per second. The telescope’s impact on Holzinger’s research contracts includes a 2017 U.S. Air Force Office of Scientific Research Young Investigators Award.

“It really differentiates the work we do from other institutions because we’re no longer validating algorithms that we’re coming up with in simulations,” Holzinger says. “We’re taking actual observations of actual objects. We were one of the first nonmilitary academic institutions that built something specifically for tracking low-Earth-orbiting objects.”

With Holzinger as partner, the Observatory is truly a Tech team effort, not just of two schools, but of two colleges. Holzinger’s students, meanwhile, are highly sought after by the Air Force and private sector. “The students can barely graduate without two or three offers,” he says.

The Aloha Telescope and Planning for a Planetarium

When the weather is clear, the Observatory averages about 40 visitors each night, Sowell says. The Observatory is open on Public Nights, held on Thursday evenings on most months of the year; on Monday evenings every other week for astronomy students; on alternate Mondays for the Georgia Tech Astronomy Club; and for private visits such as Scouting groups, school classes, and special events.

“I want to grow the outreach,” Sowell says, and the Aloha Telescope will soon help achieve that goal. Thanks to a joint effort with the Air Force, an 11-inch Celestron on the island of Maui will allow Georgia public school classes to learn more about astronomy by letting teachers remotely control the telescope. Students will see images via a video feed.

“The issue with astronomy is that kids in the classroom can’t see celestial objects during the day,” Sowell says. “A sense of discovery is what I want to give young children.”

Another unfinished business item for Sowell is a Georgia Tech planetarium. He tried to get one built three years ago, but couldn’t find a building that would support a 30-foot dome for the facility. So the dimensions may be scaled back, but Sowell wants to keep pushing the idea.

“Planetariums are a very immersive experience” that could provide several uses for other schools on campus, Sowell says. “You can have fish swimming around you or DNA coils coming to life. You can have film festivals. It can be a wonderful learning environment, not just for astronomy. It would be a tremendous asset.”

A Day to Celebrate 

On April 6, the Georgia Tech Observatory will commemorate the facility’s 10th anniversary with a day of special events. All events are free:

  • A portable, 20-foot-diameter planetarium will be installed in Clough Undergraduate Learning Commons. From 9:30 a.m. to noon and 1-5 p.m., planetarium design expert Philip Groce will provide tours of the known universe and preview the Great American Solar Eclipse on Aug. 21.
  • WSB-TV Chief Meteorologist Glenn Burns will give a public lecture on “How Star Trek Changed Everything,” referring to landmark sci-fi TV series and how it inspired stargazers to think about the possibilities of life and other planets outside our solar system.
  • Weather permitting, Sowell will roll back the roof on the observatory for a Public Night at 8-11 p.m. at the Howey Physics Building.
 
Media Contact: 

Renay San Miguel
Communications Officer/Science Writer
College of Sciences
404-894-5209

 

Summary: 

On Georgia Tech Observatory's 10th anniversary, we take a look back at its history and what it has offered students, researchers, and citizens of Atlanta.

Intro: 

On Georgia Tech Observatory's 10th anniversary, we take a look back at its history and what it has offered students, researchers, and citizens of Atlanta.

Alumni: 

A "Gut Reaction" to Georgia Tech Biology Research

Monday, April 3, 2017

The story of warring bacterial armies started as a Georgia Tech research published in February. Now it's a nationally distributed podcast produced by the National Science Foundation (NSF), and you can thank the researchers' unique mix of biology and math for inspiring NSF to tell the story widely in this format.

"The Discovery Files" recently highlighted the work of Brian Hammer, Will Ratcliff, Samuel Brown, and Peter Yunker in a 90-second radio feature titled "A Gut Reaction." The podcast is based on a paper published on Feb. 6, 2017, in the journal Nature Communications. 

The researchers used math and physics equations to find patterns and consistency in how two competing armies of cholera bacteria attack each other. The work could someday help scientists develop targeted therapies using engineered microbes that could kill infectious, harmful bacteria while sparing helpful ones.

NSF, which helped fund the research, creates a weekly audio report on the latest scientific research. "The Discovery Files" airs on radio stations throughout the U.S. 

You can listen to "A Gut Reaction" here.

Hammer and Brown are associate professors in the School of Biological Sciences. Ratcliff and Yunker are assistant professors, respectively, in the School of Biological Sciences and the School of Physics. 

Media Contact: 

Renay San Miguel
Communications Officer/Science Writer
College of Sciences
404-894-5209

 

Summary: 

The National Science Foundation's "Discovery Files" radio feature has highlighted the work of Brian Hammer, Will Ratcliff, Samuel Brown, and Peter Yunker in a 90-second audio feature titled "A Gut Reaction." The feature was based on a paper published on Feb. 6, 2017 in the journal Nature Communications. 

Intro: 

The National Science Foundation's "Discovery Files" radio feature has highlighted the work of Brian Hammer, Will Ratcliff, Samuel Brown, and Peter Yunker in a 90-second audio feature titled "A Gut Reaction." The feature was based on a paper published on Feb. 6, 2017 in the journal Nature Communications. 

Alumni: 

Warped Reality: Virtual Trip to Hyperbolic Space

Thursday, March 30, 2017

Hold tight for a psychedelic trip to hyperbolic space, where the floor drops out from beneath your feet.

Math just met “warp drive” in a virtual reality headset to transport anyone who dons the visor to a reality twisted by hyperbolic geometry. The program was co-created by Sabetta Matsumoto, a physicist and applied mathematician at the Georgia Institute of Technology as a visual aid to researchers exploring geometries that deviate from the everyday norm.

Splashed in color, the virtual space’s graphics can seduce even the most math-phobic mind to roam, crawl or slither about. But mathematicians and physicists can make great use of it.

Read the story here.

Media Contact: 

Research News
Georgia Institute of Technology
177 North Avenue
Atlanta, Georgia  30332-0181  USA

Media Relations Contact: Ben Brumfield (404-660-1408)

Writer: Ben Brumfield

Summary: 

Mindbending geometry comes to life in a virtual reality program splashed in color. Hyperbolic geometry helped in the development of the Theory of Relativity, but it usually eludes perceptual grasp. Georgia Tech applied mathematician and physicist Sabetta Matsumoto has helped change this, giving anyone a view of hyperbolically twisted space.

Intro: 

Mindbending geometry comes to life in a virtual reality program splashed in color. Hyperbolic geometry helped in the development of the Theory of Relativity, but it usually eludes perceptual grasp. Georgia Tech applied mathematician and physicist Sabetta Matsumoto has helped change this, giving anyone a view of hyperbolically twisted space.

Alumni: 

Dunn Institute Chair To Support Two Professorships

Thursday, March 23, 2017

EDITOR'S NOTE: This story was first published in the Winter 2017 issue of Philanthropy Quarterly.

Back when Douglas Dunn was a Georgia Tech student (PHYS 1964, MS IM 1965), he worked in the physics department, breaking labs down and setting them back up again every weekend. That experience, he recalls, made the depart­ment as much a part of him as he was of it. So when the Dunn Family Foundation designated a gift for an Institute Chair at Georgia Tech, it was with one request — that the first term-of-years recipients would be in the School of Physics. Thereafter, the Office of the Provost will periodically re-deploy the Dunn Institute Chair across other academic disciplines.

For this appointment, Paul Goldbart, dean and Betsy Middleton and John Clark Suther­land Chair in the College of Sciences, proposed an idea: Split the endowment between two physics faculty members.

Dunn said that was fine with him. “With gifts, you want the recipients to use the money wisely and well,” he said.

This endowment is one of three major gifts to Georgia Tech from the Dunn Family Foun­dation, which was established upon the death of Dunn’s father, an educator. “Our family has always believed in education as a source of strength for our society,” Dunn said. “This is our way of supporting faculty as they engage in their research, teaching, student, and commu­nity service agendas.”

Goldbart says this gift could not have come at a better time for the two recipients. “A natural but thorny challenge is what we sometimes call ‘the bootstrap problem,’” he said. “How to achieve lift-off with the most innovative and adventurous projects when the path forward isn’t yet clear and it’s too early to secure extramural support. The Dunn family’s generosity overcomes precisely this challenge, empowering our professors to tackle high-risk, high-reward questions. That is exactly what we want them to do.”

The current recipients of Dunn Family Institute Professorships are physicists Deirdre Shoemaker, director of the Center for Relativis­tic Astrophysics, and Daniel Goldman, a leader of the Physics of Living Systems Network.

 “Shoemaker’s theoretical work on the astrophysics of black holes and gravitational waves, and Goldman’s experiments on animal locomotion and its implications for robotics, are splendid examples of adventurous projects that are producing high-impact results,” Gold­bart said. “We are very proud to have them as our colleagues, and we are deeply grateful to the Dunn family for their tremendous support.”

Photo Captions

Dunn Family Associate Professor Deirdre Shoemaker discusses the astrophysical implications of the LIGO discovery confirming the existence of gravitational waves with Ph.D. candidate Karan Jani and Postdoctoral Research Fellow James Clark.

Dan Goldman, Dunn Family Associate Professor in the Georgia Tech School of Physics, is shown with the “MuddyBot” robot, which uses the locomotion principles of the mudskipper to move through a trackway filled with granular materials.

To inquire about making a gift to the School of Physics, contact Art G. Wasserman, director of development for the College of Sciences, at 404.894.3529 or arthur.wasserman@cos.gatech.edu.

Media Contact: 

A. Maureen Rouhi, Ph.D.
Director of Communications 
College of Sciences

Summary: 

The donor for Dunn Family Institute Chair at Georgia Tech requested that the inaugural award be in the School of Physics. College of Sciences Dean Paul Goldbart had an idea: Split the endowment between two physics faculty members.

Intro: 

The donor for Dunn Family Institute Chair at Georgia Tech requested that the inaugural award be in the School of Physics. College of Sciences Dean Paul Goldbart had an idea: Split the endowment between two physics faculty members.

Alumni: 

Computer Simulations of Polymers and Soft Matter: A Path to Design New Materials

During the last decade our understanding of polymers and soft matter has tremendously benefited from synergistic approach combining computer simulations, theory and experiments. In this talk, I will describe several examples where this approach was instrumental.

Scientists forecast the behavior of turbulent fluid flow using recognizable recurring patterns.

Friday, March 17, 2017

Recent progress by physicists Michael Schatz and Roman Grigoriev, professors in Georgia Tech’s School of Physics, along with graduate researchers Balachandra Suri and Jeffrey Tithof could one day help sharpen weather forecasts and extend their range by making better use of weather and climate data.

Turbulence can curve as a puff of air, swirl past a river bend or churn as a hurricane, and though its curlicues may appear random, turbulence lays down signature patterns that the physicists are investigating. They have developed a simple mathematical model that has helped them show how turbulent flows will evolve.

And, in a novel experiment, they verified their predictions physically in a two-dimensional turbulent flow produced in a lab.

The research results are published online in the journal Physical Review Letters  and featured online in the Georgia Tech Research Horizons magazine.  (http://www.rh.gatech.edu/features/predicting-turbulence).

 

Intro: 

Recent progress by physicists Michael Schatz and Roman Grigoriev, professors in Georgia Tech’s School of Physics, along with graduate researchers Balachandra Suri and Jeffrey Tithof could one day help sharpen weather forecasts and extend their range by making better use of weather and climate data.

Alumni: 

On bacterial growth and form

Cells typically maintain characteristic shapes, but the mechanisms of self-organization for robust morphological maintenance remain unclear in most systems. Precise regulation of rod-like shape in Escherichia coli cells requires the MreB actin-like cytoskeleton, but the mechanism by which MreB maintains rod-like shape is unknown. We have used time-lapse and 3D imaging coupled with computational analysis to map the growth, geometry, and cytoskeletal organization of single bacterial cells at subcellular resolution.

Radiation from Nearby Galaxies

Wednesday, March 15, 2017

The appearance of supermassive black holes at the dawn of the universe has puzzled astronomers since their discovery more than a decade ago. A supermassive black hole is thought to form over billions of years, but more than two dozen of these behemoths have been sighted within 800 million years of the Big Bang 13.8 billion years ago.   

In a new study in the journal Nature Astronomy, a team of researchers from Dublin City University, Georgia Tech, Columbia University and the University of Helsinki add evidence to one theory of how these ancient black holes, about a billion times heavier than our sun, may have formed and quickly put on weight.

In computer simulations, the researchers show that a black hole can rapidly grow at the center of its host galaxy if a nearby galaxy emits enough radiation to switch off its capacity to form stars. Thus disabled, the host galaxy grows until its eventual collapse, forming a black hole that feeds on the remaining gas, and later, dust, dying stars, and possibly other black holes, to become super gigantic.        

“The collapse of the galaxy and the formation of a million-solar-mass black hole takes 100,000 years — a blip in cosmic time,” says study co-author Zoltan Haiman, an astronomy professor at Columbia University. “A few hundred million years later, it has grown into a billion-solar-mass supermassive black hole. This is much faster than we expected.”

In the early universe, stars and galaxies formed as molecular hydrogen cooled and deflated a primordial plasma of hydrogen and helium. This environment would have limited black holes from growing very big as molecular hydrogen turned gas into stars far enough away to escape the black holes’ gravitational pull. Astronomers have come up with several ways that supermassive black holes might have overcome this barrier. 

In a 2008 study, Haiman and his colleagues hypothesized that radiation from a massive neighboring galaxy could split molecular hydrogen into atomic hydrogen and cause the nascent black hole and its host galaxy to collapse rather than spawn new clusters of stars.

A later study led by Eli Visbal, then a postdoctoral researcher at Columbia, calculated that the nearby galaxy would have to be at least 100 million times more massive than our sun to emit enough radiation to stop star formation. Though relatively rare, enough galaxies of this size exist in the early universe to explain the supermassive black holes observed so far.

The current study, led by John Regan, a postdoctoral researcher at Ireland’s Dublin City University, modeled the process using software developed by Columbia’s Greg Bryan. This study includes the effects of gravity, fluid dynamics, chemistry and radiation.

After several days of crunching the numbers on a supercomputer, the researchers found that the neighboring galaxy could be smaller and closer than previously estimated. “The nearby galaxy can’t be too close, or too far away, and like the Goldilocks principle, too hot or too cold,” said study coauthor John Wise, the Dunn Family Associate Professor in Georgia Tech’s College of Physics.

Though massive black holes are found at the center of most galaxies in the mature universe, including our own Milky Way, they are far less common in the infant universe. The earliest supermassive black holes were first sighted in 2001 through a telescope at New Mexico’s Apache Point Observatory as part of the Sloan Digital Sky Survey.

The researchers hope to test their theory when NASA’s James Webb Space Telescope, the successor to Hubble, goes online next year and beams back images from the early universe.

Other models of how supermassive black holes evolved, including one in which black holes grow by merging with millions of smaller black holes and stars, await further testing. “Understanding how supermassive black holes form tells us how galaxies, including our own, form and evolve, and ultimately, tells us more about the universe in which we live,” said Regan, of Dublin City University.

The study is titled “Rapid formation of massive black holes in close proximity to embryonic protogalaxies.” The other authors are Eli Visbal, now a postdoctoral researcher at the Simons Foundation Flatiron Institute; Peter Johansson, an astrophysics professor at the University of Helsinki; and Greg Bryan, an astronomy professor at Columbia and the Flatiron Institute.

Written by Kim Martineau, Columbia University

Intro: 

Modeling supports one view of massive black hole creation in early universe

Alumni: 

Chiral active metamaterials

Active liquids are composed of self-driven microbots that endow the liquid with a unique set of mechanical characteristics. We design metamaterials using polar active liquids, i.e., liquids that flow spontaneously and without the need of external forcing. Specifically, we create chiral steady-state flow using periodically shaped microchannels. This induced flow gives rise to topologically protected density waves, which are robust against both disorder and backscattering.

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