Humanity desperately needs the invention of a door that humans can open and pass through *without* enabling cats to zoom by in or out at the same time. This is likely to involve 4th or higher dimensional physics.
Huh? I mean a simple ladder going to a hatch in the ceiling (instead of a staircase and a door). You don't need to use your arms for anything other than balance on typical ladder.
@robryk That's a plot point in The Postman Always Rings Twice Spoiler Cat climbs ladder and is electrocuted when wife and boyfriend try to kill husband
@robryk A bit inconvenient for routine use, me thinks.