We know that some stars exist because we can see them with our own eyes. In this lecture Walter Lewin provides illuminating evidence of stars we cannot see. He describes the birth of stars, in the arms of a nebula, to their explosive or implosive ends. There are super hot white dwarves, detectible only by measuring the shift in color as light leaves them. As some massive stars age, they collapse into incredibly dense neutron stars—1000 times smaller than white dwarves—that release more x-rays than light. One teaspoon of neutron star matter would weight 500 million tons. Lewin champions Jocelyn Bell, who discovered evidence for these stars in 1967 but was overlooked for the Nobel Prize. When Bell’s radio telescope picked up mysterious signals pulsing every 1.3 seconds, her lab described the phenomenon as “little green men,” at first unsure if these might be signs of intelligent alien life. In his ringing finale, Lewin pulls out a tuning fork to demonstrate the Doppler Effect, where the pitch of a sound changes as it moves. Astronomers measured an analogous Doppler shift in star light to prove the existence of black holes. ABOUT THE SPEAKER: Walter H. G. Lewin is well-known at MIT for his lectures on both Newtonian mechanics and electricity and magnetism. Videos of his lectures can be viewed on the web via the Open CourseWare and Pivot links below. Lewin received his Ph.D. in Nuclear Physics in 1965 at the Technical University of Delft, The Netherlands, and has been a member of the MIT Physics faculty since 1966. During his MIT career, Lewin's investigations in astrophysics have included satellite and high-altitude balloon X-ray observations, world-wide coordinated observations of optical and X-ray bursts, and international collaborations observing X-ray sources. In addition, Lewin has collaborated over the years with various artists on sky art events. From 1998 to 2000, Lewin worked with MIT's Center for Advanced Educational Services on creating the Physics Interactive Video Tutor project -- video help sessions for freshman physics students. Walter Lewin's home page Walter Lewin's Course 8.02 on OCW Lewin 8.03 at OCW NOTES ON THE VIDEO (Time Index): Video length is 1:13:25. This video was made at Northwestern University. There are times when the color is a little off, and also a few times where the image is a little out of focus. Q&A begins at 1:10:32 The information on this page was accurate as of the day the video was added to MIT World. This video was added to MIT World on 2003-10-31.