Construction around campus has been a headache. I silently swear every time I park in the lot up the hill and have to discover a new pathway down and around the construction zone. As I walked past the line of huge concrete water drainage pipes, I noticed inside each one was an o-ring.
Mathematically speaking, the big, black, rubbery ring is an unknot—meaning a closed loop without a knot in it. No two of them looked the same. Some were easier to imagine untangled than others. I documented as many as time allowed. Which is your favorite?
I don’t believe any of these are worthy of the unknot hall of fame, but they are naturally occurring unknots in real life. And I think that is cool.