By now, surely you’re heard the dramatic news of the first observations of gravitational waves by the MIT-Caltech collaboration LIGO Laboratories.
While the phenomenon of gravitational waves may be new to many of us, MIT physics students have been learning about and thinking about gravitational waves and LIGO for some time. Here’s a few highlights from OCW.
If you already have some knowledge of relativity, a great entry point is 8.224 Exploring Black Holes: General Relativity & Astrophysics. This advanced undergraduate subject includes video lectures on several key topics. And for Lecture 12, the course includes PowerPoint lecture slides on “LIGO: Detecting Gravitational Waves” by Dr. Nergis Mavalvala, one of MIT’s lead contributors to the LIGO project.
One of the suggested projects for this course was right on target with the big questions (alas we don’t have any samples of the resulting projects).
Newtonian gravity assumes action at a distance, in clear violation of the principle of relativity. How does general relativity fix this? Why and how do gravitational waves stretch space and what does that mean? How are they produced and how are LIGO and other instruments preparing to detect them?
If you want more background on Einstein’s theory of relativity and its connection to gravity, 8.033 Relativity is a good starting point, especially the lecture notes beginning with Lecture 17.
Another fascinating part on this discovery is the groundbreaking sensitivity of Advanced LIGO, capable of measuring a change in its 4 kilometer mirror spacing by about 10−18 m, less than one-thousandth the charge diameter of a proton.
In Lecture 7 of 8.422 Atomic and Optical Physics II, Wolfgang Ketterle explains that “a lot of things pushing the frontier of precision measurement [are] motivated by the precision needed for gravitational wave detection.” Beginning at about 52:20 in this lecture, he describes some of the issues and solutions employed in Advanced LIGO’s precision Michelson laser interferometer.