Physics and Astronomy

Extended departmental description for PHYS 123

April 4 Craig Heinke “Observing Neutron Stars with X-ray Telescopes to Constrain the Behavior of Matter at the Highest Densities”

Neutron stars are the dense remnants of massive stars that have gone supernova (and somehow avoided collapsing down into a black hole). Their central density and pressure are higher than can be probed on the Earth. This makes studies of neutron stars an excellent probe of the behavior of matter at high densities. I will discuss two methods by which X-ray observations can constrain the interior structure and composition of neutron stars; constraints on the sizes of neutron stars from measuring the surface temperature, and constraints on the nature of neutron star cores by observing cooling neutron stars.

Craig Heinke (class of 1997) is a Reseach Associate at the University of Virginia.

April 11 Cliff Frohlich “Deep Earthquakes and the Secrets of Seismology”

About a quarter of all earthquakes originate at depths more than 60 km (40 miles) beneath the Earth’s surface, and some at depths as great as 700 km (440 miles). Since their discovery in 1927, these 'deep' earthquakes have been an enigma because pressures and temperatures are too great at these depths for ordinary brittle fracture to occur. Deep earthquakes pose a serious hazard in a few parts of the world, including Romania, parts of South America, and (possibly) in the northwestern United States. Dr. Frohlich’s talk will address what is known and unknown today about the mechanical origin of deep earthquakes and explain why they have been used disproportionately in studies of the Earth’s interior structure. Frohlich will use familiar items to illustrate Earth structure and explain many principles of earthquake mechanics. Seismology as presented by Frohlich will involve, baseballs, coffee pots, champagne bottles, diamonds, air hockey, and ultrasound. In every profession there are 'secrets', that is, basic information that is known to all who practice the profession but somehow unknown or misunderstood by the public. For example, most people are unaware that seismologists most often focus on understanding earth structure rather than investigating the properties of earthquakes themselves. All who attend Frohlich’s lecture, young and old, will learn a great deal about basic earthquake seismology, including much that all seismologists know but seldom tell.

Cliff Frohlich is the Associate Director of the University of Texas at Austin Institute for Geophysics.

April 18 Sue Coopersmith “Classical and Quantum Computers”

The computers that form the backbone of the information revolution use a computational paradigm that is based on the laws of classical physics. The fundamental laws of nature are quantum-mechanical, and exploiting the laws of quantum physics may lead to remarkable increases in computational power. This talk will discuss why quantum computers may be more powerful than classical ones as well as current research efforts to build quantum computers.

Sue Coopersmith is a professor and chair of the department of physics at the University of Wisconsin.

April 25 Mike Lach “A Career In K-12 Science Education”

Michael Lach graduated from Carleton College in 1990 with a physics degree. Since then, he's been a high school science teacher in several different districts, a Capitol Hill policy wonk, and a large district administrator. In this talk, he'll describe the paths he took, reflect on his Carleton preparation, and outline some of the various career opportunities in education for graduates.

Michael Lach (class of 1990) is the Officer of High School Teaching and Learning at Chicago Public Schools.

May 2 Becky Anthony “Silicon Nanocyrstals”

Tiny nanocrystals of silicon photoluminesce when excited by UV light. Since silicon is non-toxic and abundant, these nanoparticles have many possible uses, particularly in biological applications such as tumor targeting. Becky will discuss her research into methods to maintain the photoluminescence efficiency of these nanoparticles when they are exposed to air and water environments.

Becky Anthony (class of 2003) is a graduate student at the University of MN.

SPECIAL OPTIONAL (BUT FUN!) EXTRA TALK:

May 9 Claire Pettersen “Ice-Fishing for Neutrinos (and other tales from the South Pole)”

The IceCube Neutrino Detector is a neutrino telescope currently under construction at the South Pole. Like its predecessor, the Antarctic Muon And Neutrino Detector Array (AMANDA), IceCube is being constructed in deep Antarctic ice by deploying thousands of spherical optical sensors (photomultiplier tubes, or PMTs) at depths between 1,450 and 2,450 meters. The sensors are deployed on "strings" of sixty modules each, into holes in the ice melted using a hot water drill. The main goal of the experiment is to detect neutrinos in the high-energy range, spanning from 1011eV to about 1021 eV. Not only is IceCube an exciting high-energy astrophysics experiment, it is also one of the largest and most challenging engineering projects of recent years.

Claire Pettersen (class of 2000) is an engineer at the University of Wisconsin - IceCube