"Let's find them, then. And also get you some cargo pants."

"Unless you happened to see a ghostly department store anywhere..."

"Can't say I have."

She starts searching the floor - under things - weird implausible places -

But finds no tools.

She glances on the desk first pass, then - 

"There's a hole in the calendar."

A deep one, a circle punched right over the '17' day, swallowing it. Lily steps closer, and... It goes all the way into the wall.

"Want me to stand over here in case something jumps out at you?"

"Sounds good."

Now - what's in the hole?

- Her pocket knife. No screwdriver. But, in the back... A crumpled up piece of paper.

"Well, found my knife."

She retrieves that and the paper, unfolding it carefully.

It's incredibly small, a thin strip with a single line written in pen - in the same handwriting she saw while snooping.

L. Do not cross own history. Back bad, forward worse. Events lock. t = ψ - J

"...I think it's from that woman. Josephine." (Her name had been on some papers.)

"Don't cross our own history - if we go forward, events lock. And an equation, but - I don't get it."

"Can I see?"

She nods and hands it over.

"So... Math symbols get reused a lot, and what each means can be context dependent, but..."

"Pretty sure given the context we have - that t is for time, and the Greek letter would be a wave function. That's not, like, really an equation though, so I think she's just saying that class of equations applies? Or 'time is a wave' type thing."

"...I do not know physics."

She smiles a little. "Sorry. Have you ever heard of Schrödinger's cat?"

"Uh, in a poorly explained high school physics class. Something about how if you haven't seen something for yourself, and it could have two different states, then until you observe it both are true. So the cat's both alive and dead."

"...Kind of. Anyways, that was a thought experiment making fun of a rival interpretation of quantum mechanics, it's not directly related. But Schrödinger's equation was the first thing that popped into my head looking at that - though that isn't, like, actually that equation, it just has the same symbols."

"...It's quantum mechanics, pretty much."

"Well, that's literally all Greek to me. I'll just hand any time machines to you, how about?"

"I'll brush up on my practical engineering, then."

Snort.

"Anyways - I get the feeling my screwdriver isn't here, or - it isn't here and now."

"Yeah. Sorry."

"Thanks."

"It was - a weird dream screwdriver, I didn't have it before I passed out. So maybe it's just... Stopped being real."

That idea makes her weirdly sad.

"...You know, equations or not, I'm increasingly sure this isn't running on physics."

"You're just now thinking that?"

"I did say increasingly."