Science on Tap will explore the mystery of our universe: Dark matter

October 27, 2014  


Rafael Lang

Rafael Lang 
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WEST LAFAYETTE, Ind. - Rafael Lang, a Purdue professor of physics and astronomy, will take listeners on a tour of the universe from the Big Bang to colliding galaxy clusters and discuss detectors of dark matter during the next Science on Tap.

The talk, titled "Dark Matter: Darker than Stout," is at 6 p.m. Thursday (Oct. 30) in the upstairs of Lafayette Brewing Company, 622 Main St., Lafayette. The informal lecture, which is free and open to those 21 and older, is sponsored by the Purdue Department of Earth, Atmospheric and Planetary Sciences; the Department of Physics; the College of Science; and Discovery Park.

As our galaxy rotates at incredibly fast speeds, gravitational pull is what holds it together. According to Lang, such a pull would not be possible without dark matter.

"When we calculate the gravity of every mass we know, it is nowhere near enough force to keep the galaxy together," said Lang, who was featured in a July episode of "Through the Wormhole with Morgan Freeman" shedding light on dark matter for millions of viewers. "Dark matter is what makes up the difference."

Lang is part of an international team of scientists attempting to build a detector to identify the dark matter that Earth plows through as it moves in space. The international team's projects, called the XENON100 and XENON1T, get their names from the noble gas xenon, which acts as the "net" in the detectors.

The detectors are equipped with electronics that can detect individual electrons and photons; this high degree of sensitivity is necessary to detect the weak signals expected from dark matter, Lang said.

The current detector, XENON100, is buried in the Gran Sasso National Laboratory in central Italy. Nearly a mile of rock separates the detector from radiation and ensures that no background noises can interrupt a potential signal from dark matter interaction. In just over a year of operation, XENON100 has not yet detected any particles that could be dark matter, but a bigger detector is currently being built and will be commissioned next year, Lang said.

"Our current net isn't big enough and no dark matter has shown up in it, but it has helped us narrow our search. While we don't yet know what dark matter is, we do know what dark matter isn't," Lang said. "The new detector will be 100 times more sensitive. We are optimistic that we will capture dark matter by 2020 if our ideas about it are correct."

Lang completed his dissertation in 2008 at the Max Planck Institute for Physics in Munich, Germany, using scintillating crystals at millikelvin temperatures to search for dark matter.

The "Through the Wormhole with Morgan Freeman" episode was titled "Is There a Shadow Universe?" and explored dark matter theories and research. Part of the Science Channel episode was filmed at Wildcat Creek in Lafayette, Indiana. Lang used the creek to illustrate some of his descriptions of dark matter.

"It was a unique experience and an honor to be on such an inspiring and well-respected show that draws viewers into the biggest scientific questions of our time," Lang said. "It is important to share scientific theories and research beyond the classroom because science impacts all of us. Plus, aren't we all a little curious about the nature of our universe?"

Science on Tap, led by graduate students David Welkie, Anju Karki and Nelda Vazquez, provides Purdue faculty and collaborating researchers the opportunity to share research activities in an informal setting with presentations that are designed to appeal to a more general audience. Attendance at the monthly event has averaged 80 during the program's first four years.

Writers: Anna Schultz, 812-447-5229, schult70@purdue.edu

Phillip Fiorini, 765-496-3133, pfiorini@purdue.edu 

Sources: Rafael Lang, 765-494-3048, lang10@purdue.edu,

David Welkie, 765-494-0455, dwelkie@purdue.edu

Nelda Vazquez, nvazque@purdue.edu

Anju Karki, 765-494-0455, akarki@purdue.edu

Videos: The Quest for Dark Matter: https://www.youtube.com/watch?v=i1-LMGdfrDY 

The Hunt for Dark Matter – Dr. Rafael Lang: https://www.youtube.com/watch?v=wco8kAQT5SI

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