Dave Holtz has operated telescopes in the Atacama Desert, searched for dark matter 10,000 feet underground in a Virginia lime rock mine, and ridden a Greyhound bus across the country. Dave is currently a data scientist at Airbnb. He also developed and taught Udacity’s Introduction to Data Science course, for which more than 44,000 students have enrolled thus far. Dave was a cosmologist prior to becoming a data scientist, and he holds a B.A. in physics from Princeton University and an M.A. in Physics and Astronomy from The Johns Hopkins University. Dave is also an avid musical theater composer and improv comedian - you can see him on the San Francisco stage as a member of Endgames Improv’s house harold team, Calhoun. For more from Dave, you can follow him on twitter @daveholtz or visit www.daveholtz.net.