One issue is that, unless you (can) back them up yourself, digital goods can be changed. If I bought The Twits on Kindle, it literally wouldn’t be the same book that I read as a child because they decided that words like “ugly” are too much for children. Even if I bought it before they censored it - it would be “updated”.

This argument applies to almost anything that’s possible to own, though. What happens when your bike degrades to the point that it’s not usable as a bike anymore?

I agree. While Family Sharing may be an option, it really shouldn’t be necessary. Why shouldn’t “I” (whether it’s my dad playing Cities: Skylines, or actually me playing a round of Balatro on the Deck while waiting for a DotA queue to pop) be able to play two different games that I paid for at the same time without having to jump through any hoops? Before I knew about Family Sharing, I accidentally kicked my dad off Cities: Skylines far too many times simply by waking up my Deck.

Funnily enough, now Family Sharing largely isn’t necessary because I started buying a bunch of my games on GOG which means I rarely use my Steam Deck because of how difficult most GOG games are to get running.

For those who haven’t studied relativity, this thought experiment is great at showing the “Relativity of Simultaneity”.

The only way the doors can shut from the pole vaulter’s reference frame is if they close at different times. The exit door opens and shuts first, before the tip of the pole has gone beyond it (otherwise it would hit the door, obviously), and then later, only once the back end of the pole has cleared the entrance door, does it close.