@mcc Btw., I just rewatched the SpaceTime video (first saw it years ago) and found it quite well made — which was definitely in part due to having seen it and similar lectures about the topic before. So I've already developed a certain tolerance to this weirdness, but still I still had to occasionally pause the video at a few points to mentally catch up. That's how I discovered that other video: YT suggested it as related and I watched it in those breaks.

@mcc I don't see how this analogy could be helpful here; I also didn't get the impression that O'Dowd was trying to imply anything like that.

To me this is a completely ordinary rotation, it's just that some objects (spin n + .5 where n is integer) behave like that under rotation — this seems familiar when you've used quaternions for 3D graphics or similar.

Watching this could help: https://www.youtube.com/watch?v=pKKy2mmsziI

@mcc Suppose you're helping someone learn square roots and they're currently learning for their first test for which they need them.

If you told them to take the square root of -1 as a practice example, you'd *want* them to say “this is BULLSHIT!”, right? I think this is a normal an necessary step towards understanding 😄