My name is Geoffrey Challen, although I’m frequently hailed as /gw√§/, the pronunciation of my (former; see explanation) initials. I’m a sixth-year Computer Science Ph.D. candidate in the School of Engineering and Applied Science (SEAS) at Harvard University, where I am advised by Matt Welsh. I received my undergraduate degree in Physics, also from Harvard.

Affiliation Change Update

I have accepted a tenure-track offer in the Computer Science and Engineering Department of the University at Buffalo, State University of New York. I will defer for a year and begin my appointment in August, 2011. I am extremely excited about continuing my work at UB and doing interesting research with strong colleagues.

Name Change Update

On a cold, clear January 17th, 2009, in Kennebunkport, Maine, my wife Suzanna Chapman and I were married. 1 As a nod to the intertwining of fates that marriage brings, we decided to unite our names as well, and Chapman and Werner-Allen joined to become Challen, the name that both she and I now legally carry. Challen is not an entirely new name, so it does carry some history, but isn’t particularly common as far as we know.

My full legal name is now Geoffrey (First) Werner (Middle) Challen (Last).

To maintain continuity with my previous publication history I will, for the time being, publish with my full name as Geoffrey Werner Challen. Our HotOS’09 Peloton paper was the first to bear that moniker. However, it should be noted (and some, like the organizers of NSDI’09 have been confused), that Werner is my middle name, not part of a de-hyphenated, un-joined dual last name. After years suffering at the bottom of the alphabet I am planning on enjoying the promotion!


As a computer scientist I investigate ways to use networks of small, cheap, resource-limited computers to improve our understanding of the world around us. Over the last century improvements in scientific instrumentation advanced our understanding of the world on small scales. Now, furthering scientific understanding requires marshaling technology to provide larger views, allowing scientists to observe entire systems with planetary-scale high-resolution sensing. Some have termed this new instrument the macroscope. Sensor networks, my primary interest, are an important part of this effort, which will eventually require connecting many different types of devices, as well as collaboration between computer and domain scientists.

My project has involved instrumenting active volcanos using sensor networks. Using small, light, cheap devices allows us to quickly achieve a scale and resolution difficult to achieve with more traditional volcano monitoring instrumentation. However, the resource-limited nature of our nodes makes providing high-quality output suitable for scientific analysis challenging, particularly given the high data rates and complex signal processing required by this application. To date we have fielded three sensor networks on active Ecuadorean volcanos, each yielding valuable insights and furthering our scientific goals. Further information can be found on my publications page.


I maintain an active role in undergraduate life at Harvard in two primary ways. Six times over the last seven years (‘03,’04,’05,’06,’07,’09), or every time it has been taught, I have served as a teaching fellow for CS161: Operating Systems. Widely held to be a challenging and rewarding course, it perennially receives excellent course ratings.

Additionally, I serve as a resident tutor at Eliot House, one of the twelve major undergraduate residence halls at Harvard. While aspects of the role are similar to what might be termed “Resident Advisors” at other schools, we like to think that Harvard tutors play a more central and vital role than simply supervising parties. We live in the house and are available to dispense academic, career and personal advice to students, while also participating and encouraging the vibrant communities that center around house life at Harvard. It’s a great pleasure and responsibility and something I enjoy immensely.

Contact Information

For email you have a few options. There’s (new) last name + BUFFALO dot EDU. Or you can try first name DOT last name at GMail. Don’t like sharing stuff with the new evil empire? Sorry. I don’t mind much, and everything ends up there anyway.

Suzanna and I are back in Eliot K-21, a beautiful couple suite with river views and multiple pieces of territory for our dog Chuchu to watch over. My office is in Maxwell-Dworkin, room 238. My mailing addresses are as follows:

Home: 553 Eliot Mail Center
Work: 33 Oxford St
Home/Work: Cambridge, MA 02138

  1. 1. Mandatory slideshow link here. The photographers were great, actually, and the photos turned out wonderfully. []