Boxes.
Can’t live with them, can’t bring home twenty bottles of Scotch without them.
(As Alex’s dad will tell you.)
If you’re a quantum cat, they’re indispensable.
Schrödinger, Alex’s awesome quantum cat, only attains his mysterious universe-hopping abilities via the medium of a box.
You thought Schrödinger’s Cat was about cats being alive or dead?
Uh-uh. Those cats are inter-dimensional travelers.
But what happens when your beloved box goes missing, or inexplicably moves across the room?
Schrödinger has had this happen to him, and it makes him mad.

“Miaow,” he told us, which roughly translated means, “I hate those wandering boxes.”
“One moment I’m inside, curled up and happy, just back from a trip to another universe. Then I wander off for a bit of light mousing. If I’m really lucky I get to annoy Horace the pigeon while I’m at it.”
“And then what do you know, when I get back, my box has gone.”
Schrödinger thinks his box has been stolen by inter-dimensional quantum kittens.

Or it could be that it’s recycling day.
Who knows? Alex knows better than to tell him the truth.