This video by Brad Plummer and Julie Karceski of SLAC (disclaimer -- they are both colleagues and friends) explains the concept of gravitational lensing -- in which a particularly large galaxy bends light in such a way that an observer can see objects behind the galaxy -- with a simple household item: the wine glass. Watch:
Phil's wine-glass-as-a-gravitational-lens analogy is great. But I think the fact that it was presented in a video made it even greater, because I don't think it would have worked in print. Imagine reading an article about gravitational lensing and coming across the sentence, "It's like holding up a lighter to the bottom of a wine glass and looking down the stem." We are all probably familiar with lighters and the physique of a wine glass, and perhaps the geekier in the crowd have enjoyed looking at distorted images of friends' faces through curved glass. But what are the chances that you have ever held up a lighter to a wine glass, or, after reading that sentence, that you would find the nearest wine glass and lighter and try it? I'm willing to bet very small.
The video does it for us, and now we not only understand gravitational lensing, but have a fancy new trick to impress our in-laws with at Thanksgiving this year.