From Vihart.

Is your love compatible? Do the forces of topology and mathematics smile upon your pairing? Find out with this classic mobius strip love test.

I learned this from Mike Caputo in around 2010, and as far as I know he originated this trick, or was an early popularizer of it, in his 1990 article in the Jan/Feb edition of The Oregon Mathematics Teacher (and if anyone can find this article maybe it will give more insight). I blogged about it in Feb 2011 after teaching it in a workshop when I was Mathemusician in Residence at Harvard’s Pforzheimer House (anyone here from those days? Hello!), but unfortunately all the links in that post are now dead (as is the blog itself) and my memory is fuzzy. So if you have info to share please send me a note!

But just to keep as much of the history and attribution as I can, here’s the dead links I have for Mike: http://teach.beaverton.k12.or.us/~mike_caputo/ and for the article: https://www.octm.org/TOMT.html

I’ve seen a number of great videos on this in the past ten years, but none that capture quite the spirit and framing of the original love test in the way I remember it. Or maybe this is never how it originally was and I made it all up. No idea, but I had fun making this and I hope you had fun watching it 😀

And an extra special Valentine’s Day thanks to my Patreon patrons, whose support make this possible. Thank you Ray Sidney, Pat Devlin, David Perryman, Andew Romaner, Andrea Bi Biagio, Jodi Vezzetti, Yana Chernobilsky, David Smith, Alan Boulton, Nancy Blachman, and Caleb Wright, for your extra support!

You can support this work here: https://www.patreon.com/vihart