Just for added info, Polish notation has the operator first, so ‘+’ means “stand by, numbers are coming, so be ready to add them.”
And operator-first notation is incredibly common, even if most programmers don’t think of it that way. Most operators that aren’t built into a programming language are implemented using functions, and most programming languages do functions as function name first, then arguments. E.g., " add(2,2) ".
Perhaps it should have been I Notation Polish SWAP 
Hmm, or perhaps I Notation Polish SWAP −ROT
There’s a lot less absurdity than typical in this one. Most of these are quite plausible.
Hmm… Looking over the card, I think the most likely first winner would be row 4, the bar sinister, or column I.
Spurious signals from the observatory kitchen actually happened at a radio telescope. AIUI, they happened when the microwave was opened while it was running. Yes, the microwave does shut down when you do that, but it’s not quite an immediate shutdown. The magnetron takes a couple of seconds to actually stop radiating.
Lots of things have caused spurious signals at radio telescopes, and lots more would if they hadn’t anticipated them and put in measures to prevent it. In Green Bank, West Virginia, there are no local radio or broadcast TV stations, cars with spark plugs are not allowed in the facility, and the control room for the big telescope needs mesh in the windows or the scope would pick up its own control computers.
OK, but the microwave thing actually has a name:
I didn’t understand many of these, but I did understand, and appreciate, Free Space.
The optical version has been observed at least once.
At that time of the year, at that part of the world and exclusively in Principal Skinner’s kitchen window?
“Wind stress? Don’t be silly. When has wind stress ever been a problem for a suspension bridge?”
I know, I know! Teacher, pick meee!
Just replace the balloon with a space elevator and it’s easy. No more wind worries. The extra mass of the bridge just simplifies the anchoring of the space tether to the ground.
Of course, using space-elevator material for the cables would probably also extend the length limit considerably…
It occurs to me: Would this technically be a pontoon bridge?
Hmmm. That is a tough question. Truss bridges can have the truss above or below the payload deck and are still truss bridges. I suppose there’s nothing about a pontoon bridge that says the buoyancy component has to be on the underside. 
It occurred to me just now that if the central balloon is cheaper than the conventional towers near either shore, then why not have zero towers & three balloons?
At which point the max length of a suspension bridge becomes “as long as you can afford” without needing any space elevator carbon-nano-unobtanium. And no tricky and dangerous underwater construction either.
And you can pick the thing up and move it wherever you want!
Or wherever the wind takes it…
“As a side effect of the research, mice are now the only known animals other than humans to have developed a Backrooms mythology.”
“The family lore was that we’ve had it ever since it was ejected from a star-forming gas cloud, but it seems more likely that my great-grandparents probably just bought it while on vacation in the galactic thin disk.”