It’s lunchtime on Christmas Eve, but I have no Christmas-themed photos to share with you. However, I’m sure we all agree that Albert Einstein’s theory of relativity is a timeless holiday classic, and it turns out that I do have a relativity-themed picture for you. I snapped it a couple of days ago, so I got it just in the nick of time.
Eagle-eyed readers with good memories will recall that explaining relativity is one of my pastimes, but I’ve long had a pet peeve about it: namely that general relativity is routinely explained using a timeworn picture of a trampoline to describe how gravity works. I’ll spare you the long-winded reason why this annoys me (it’s here, if you’re interested), but the nutshell version is that (a) it provides a completely incorrect impression of what’s actually going on, and (b) the real explanation of what causes gravity is both easier to understand and far more interesting. However, I have come up with a timely compromise. Behold the general relativity spider web:
Check it out! It’s a trampoline-shaped spider web! The reason it’s trampoline-shaped is that the spider has erected some extra web filaments that pull the center outward, thus providing the equivalent of a non-Euclidean spacetime in which the geodesic bends toward the center.
Don’t worry about what that means. It’s bafflegab. The point is this: If you want to write about general relativity and you insist on using the trampoline metaphor, you have my permission to use this photograph anytime you like. In fact, I insist on it. I further insist that you explain the warpage of spacetime using the metaphor of a gigantic, invisible, relativistic spider. Deal?
And what the hell. Here’s another photo of the spider web. It’s taken from a slightly different angle and at a slightly different time, and for some reason this tiny change converts it from a timeless black-and-white image to a surprisingly moving color rendition that evokes the inexorable motion of the spider’s prey toward the center of the web. Fascinating, no?