Star Wars character who wears Mandalorian underwear I mean armor / THU 5-11-23 / Onetime extravaganzas that included diving displays and water ballets / Measurement whose name derives from the Latin for elbow / Expression of relativity depicted five times in this puzzle / 2020 Taylor Swift song with the lyrics "You'll poke that bear 'til her claws come out" / Selene's Roman counterpart / Title lyric after ours is a love in a Jimmy Dorsey hit

Theme answers:

• SWIMCAP / HEADER (2D: Bit of latex pool attire / 20A: Certain soccer shot)
• ARMCANDY / AQUACADES (!?!!?!) (12D: Celeb's red-carpet companion, perhaps / 18A: Onetime extravaganzas that included diving displays and water ballets)
• E EQUALS MC SQUARED / EINSTEINIAN (7D: Expression of relativity depicted five times in this puzzle / 36A: Like some concepts in theoretical physics)
• DREAMCAR / BENCHMARK (39D: Vehicle you'd buy if money were no object / 56A: Standardized point of reference)
• SIMCITY / SULLEN (45D: Video game whose working title was Micropolis / 54A: Ill-tempered)

Word of the Day: E EQUALS MC SQUARED  —

The famous equation E = mc^2, derived by Einstein, means that energy is equal to mass times the speed of light squared. Equivalently, it also means that any amount of mass is equal to energy divided by the speed of light squared. This little equation is central to the theory of special relativity, and also explains how nuclear fusion and fission can generate energy. // In a famous paper written in 1905, Albert Einstein discovered an equality between mass and energy. He found that the conservation of mass (a famous and important law in physics) is the same as the conservation of energy, and vice versa. These insights were a part of his development of the theory of special relativity, which describes the relativity of motion, particularly at near light speed. (livescience.com)

The central (literally central!) idea here is ingenious, but unlike with matter converted to energy, there's no real ... pop. I got the E/MC "square" thing very early and ... that was pretty much that. That's the joke. That's the gag. Just gotta find more squares like that. Now, the one thing this puzzle does have that's pretty impressive is architectural—that is, the equation itself is a perfect grid-spanning 15 letters long *if* you smush the MC into one box, *and* when you smush the "MC" into one box, that box sits dead center. So the revealer dramatically spans the grid and is itself a theme answer, with the thematically appropriate EINSTEINIAN providing the "E" cross, boom, right in the middle. So, structurally, that is very interesting. Gives the puzzle a certain ELEGANCE. But it didn't make the puzzle any more fun to solve. In fact, the revealer was, for me, at that point, completely redundant. I got SWIMCAP/HEADER with very little problem, so I knew exactly what was going on. "Why would "MC" be smushed into one square when the cross is just ... Oh, it's an E = MC SQUARED theme. Cute." So the revealer revealed nothing—just made the puzzle a lot easier. 

Finding the other "MC" squares was kind of fun, a little adventure, but there wasn't really any challenge there except for the absolutely painful challenge of trying to work my way to whatever the hell AQUACADES are (18A: Onetime extravaganzas that included diving displays and water ballets). Just ... gruesome. ICE CAPADES, I've heard of. AQUACADES??? Yuck. When you have to reach back into ye olden ("onetime") terminology to pull off your theme, it kinda harshes the vibe. ARM CANDY is great, but oof, AQUACADES. I don't really get why the puzzle made the "MC" squares all symmetrical. I know this might seem elegant, but usually you get much better results in the *fill* (you know, the bulk of the puzzle) if you give yourself leeway with the rebus squares. I feel like AQUACADES is a symmetry casualty. BENCHMARK works perfectly, a very inconspicuous answer, but if you insist on that "MC" square being in *exactly* the same (rotationally symmetrical) position in the corresponding themer, well, you end up with AQUACADES, I guess. Anyway, theme idea is ingenious, theme execution is OK, with only the "MC" hunt providing any real interest. I admire the architecture of this one, but it wasn't terribly fun to solve. 

Only two thorny parts for me today. "MAD WOMAN" peaked at 47 on the US charts. If you are a Fan (and millions are) then that was a gimme for you, but my fandom is just casual and definitely lowercase-"f," so that song got by me (as far as her most recent songs go, my knowledge drops off quick after "Anti-Hero") (11D: 2020 Taylor Swift song with the lyrics "You'll poke that bear 'til her claws come out"). That made the NE a little more challenging than it might be (and it was already mucky from the AQUACADES nonsense). CMDR gunked it up a bit more, as did CRASS, with its ridiculously overdramatic clue (31D: Swearing up a storm, say)—if you're swearing up a *storm*, seems like you left mere CRASSness behind. Anyway, slowish there, slowish again around KAI (??) / PEDI, both because KAI means nothing to me and I had PEDI as PERM. Is KAI supposed to be a weird bonus themer? KAI Bird is the author of an Oppenheimer bio ... and Oppenheimer is the "father of the atom bomb" ... and E=mc2 is the "equation that gave birth to the atom bomb" ... and the movie OPPENHEIMER (which is *based* on the KAI Bird bio) is coming out this summer ... wait a minute, is this puzzle sponsored content? *Waaaaaaait* a minute, did Christopher Nolan write this puzzle? Am I in a Christopher Nolan movie right now? How would I know? How deep does this theme go?

The fill on this one is largely nondescript. We get Orion again, weirdly (HUNTER) (46D: Orion, for one) and, probably more weirdly, me get REMAP again—both things we've already seen this week. I had SEC before SEG (47A: Div.), and that's among the most interesting non-thematic things that happened to me. Hope this one AROUSED you somewhat more than it did me—though, again, I respect the concept, and nod admiringly at the central crossing. The wordplay involved in the basic rebus idea (i.e. putting E and MC into one "square"), and the arrangement of the revealer, with its own rebus square sitting dead center, both elevate this above your run-of-the-mill rebus. See you tomorrow.

Signed, Rex Parker, King of CrossWorld

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