Open Source Physics: Computational Tools for Teaching Dr. Mario Belloni
Over the past dozen years Davidson College has produced some of the most widely used interactive curricular materials for the teaching of introductory and advanced physics courses. These materials are based on Java applets called Physlets and the Open Source Physics (OSP) programs and applications. The new Open Source Physics Project has focused on the creation and dissemination of computational and educational tools for teaching. Specific examples of using modeling in intermediate classical mechanics with Easy Java Simulations (Ejs) and teaching other advanced courses (quantum mechanics and general relativity) with OSP-based programs will be shown. How the Open Source Physics Project is connected to existing Digitial Libraries like ComPADRE will also be discussed

Location: Physics Bldg., room 401

The life of a snowflake : Measuring snow from space Dr. Benjamin Johnson
UMBC Joint Center for Earth Systems (JCET) and NASA Goddard Space Flight Center

On Earth, the vast majority of precipitation originates as snow particles in the atmosphere. At middle and high latitudes, snow falling on land contributes to snowpack; a critical source of freshwater for spring and summer months. Snow on the ground also provides an atmospheric cooling mechanism due to it's high visible-light albedo. In the middle and lower latitudes, falling snow often melts, becoming rain -- feeding our streams, rivers, and lakes. The growth and melting of snow also contributes to heating / cooling of the atmosphere through phase change, influencing atmospheric motions and stability. It is critical, especially given our changing climate, to be able to accurately measure atmospheric snow on a global basis for long time periods.

One of the key challenges to measurement is understanding how the physical characteristics a snowflake influence millimeter-wavelength observations made from a satellite-based remote sensing platform. On both the microscopic and synoptic scales, the physical aspects of the initiation, growth, and dissipation of an individual snowflake are reasonably well understood. However, when considering a precipitating cloud containing a wide variety of sizes, habits, orientations, phases, of snow, the problem of characterizing the 3-D scene in analytical fashion becomes troublesome.

In this talk I will focus the physical processes which contribute to the growth and eventual destruction of an individual snowflake, and I will describe how these individual processes are treated when considering a diverse ensemble of snow particles within, for example, a precipitating cloud. I will also briefly describe how the physical properties of snow particles influence incident electromagnetic waves at centimeter and millimeter wavelengths (~1-22 mm or 13 to 220 GHz), and the ramifications for inferring information about snow based on satellite observations at these wavelengths.

Location:
Physics Bldg., room 401

No Seminar - Wednesday, March 18, 2009

Life's place in the universe Dr. Steve Freeland
UMBC Department of Biology

One, relatively new interface between biology and physics occurs within astrobiology: the quest to develop a scientific understanding of life's relationship with the physical universe (i.e. its origin(s) and likely distribution.) At present we know only one example of life, and our understanding of its origin remains patchy at best.

However, science often challenges us to extrapolate from incomplete observations of the actual into reasoned inferences of what is possible. For astrobiology, this means developing our understanding of how and why we emerged on this planet. Answers require extensive interdisciplinarity: how typical is our solar system of other star-systems in the galaxy? what properties of Earth are typical or unusual for a planet? How are these properties related to life's emergence here? What can we learn about life's boundaries by examining the biodiversity we encounter today? Once life had evolved, what aspects of our 4 billion year evolutionary history were likely or even inevitable? In this talk I will approach these questions from a biologist's perspective, showing where my own research interests lie within this bigger topic. I hope to illustrate the sorts of questions that we are learning to answer (and the assumptions we still make). I will also encourage you to help me better understand what Physics can contribute to the bigger questions.

Location: Physics Bldg., Room 401