New York Times, Thursday, February 27, 2020

ANDREW: This puzzle is a personal favorite (not just because it has my name at 24-Across). This was my first foray into Thursday puzzles, so I figured I'd mess with some crossword rule, and the two-letter rule seemed like a fun challenge. I quickly turned to John for help with the idea, and together we got the M-E-O-W letters to work without too much glue and awkward cluing. John gets all the credit for the apropos CROSS THE BORDER and I NEED SOME SPACE bonuses.

JOHN: I'm glad I got to work with Andrew on this one, our fourth Times collaboration. It was an inspired idea that was great fun to help shape into its final form. Andrew and I will also be collaborating on the fourth edition of Boswords, the crossword tournament we co-direct in Boston that is open to solvers of all levels. This year's version will be on Sunday, July 26 and you can find more information about Boswords here.

SCHRÖDINGER'S CAT was just in another recent crossword. Perhaps it's both there and here today! That darn cat.

Will Shortz once told me that solvers like to fill in boxes, the more definitively, the better. There's something so satisfying about completing that last square and calling it a victory. So I immediately paused when I saw the note about 16 possible solutions. Talk about indefinite!

However, I enjoyed Andrew and John's concept. There have been a lot of Schrödingers in the NYT by now, and this one isn't quite like any I've seen.

And how meta, that TWO is played upon in the lower right corner! So appropriate for having TWO solutions down there.

It wouldn't have occurred to me that there were multiple solutions if it hadn't been for the note, though. For example, in that lower right, I put in TEEN and WOWS without another thought. Even after realizing that there needed to be an alternate solution, I struggled to come up with OWS as "reactions to shocks." A stretch.

Also a stretch: I NEED / SOME SPACE. It's not nearly as good at explaining the concept as CROSS THE BORDER.

All in all, a solid construction, impressive considering how difficult it is to work around Schrödinger squares. The solve left something to be desired, though, since it's already hard to know what to put inside a Schrödinger box, and having a combination of rebus / single letters makes it that much more confusing.

I wonder if putting a circle between the two squares — giving a place for solvers to write in the back-and-forth letter — would have made for a more satisfying (if not as Schrödinger-esque) solve.

ADDED NOTE: It wasn't until Andrew and John sent their thoughts that I noticed which four letters were swapping back and forth: M E O W. What a nice touch!