# Interesting Physics Riddle I Devised

DifferentialGalois
A theoretical astrophysicist was absentmindedly working through papers on Mossbauer spectroscopy, eventually coming to the Pound Rebka experiment, a remarkable test of GR. (Gamma rays were sent from the top of a building to a receiver, so as to measure the gravitational blueshift in such an experiment). Deeply immerse in a physics textbook, it takes the professor a while to realize that outside his cottage, a delivery truck is parked.

"Vodka dlya prodazhi. Zdravstvuyte! Prodazha odnogo funta za butylku!"
"Vodka for sale. Hello! Selling one pound per bottle!"
The words come from a mathematician specialising in combinatorial geometry, albeit struggling to gain a working salary from it and thus, working in food delivery services.

The physicist takes a sip of his quark soup, and places his head outside the window. When he notices that the combinatorial geometer is selling bottles of vodka, he quoth, "I expect that the quantity is some Catalan number. I regret to inform you that I've quite enough of combinatorics for a lifetime."

The combinatorial geometer beams briefly, but not for too long as the resident of the abode becomes exasperated.

The astrophysicist professor emits a gamma ray, causing the delivery truck man combinatorial geometer to dash away at tachyonic velocity. "That lad ought to be five years old."

1. Why does the geometer beam briefly at the mention of the Catalan number? What relevance does the Catalan number have?
2. Within propinquity of the end, the professor states that the geometer's mental age is five. Propose a reason as to why this is the case.

Gold Member
Among Catalan numbers C3 = 5 is unique as being both Odd and Prime.

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Gold Member
Why does the geometer measure a bottle of vodka by weight (one pound) instead of by liquid volume (liter or quart)? Pretty sure you are not referring to Pounds Sterling as cost per bottle.

"Beam" in English has many different meanings but you ambiguously use "beam":
• smile (verb)
• transmit electromagnetic radiation and/or particles (verb)
• the transmitted object -- radiation a/o particles; e.g., gamma ray beam (noun)
The astrophysicist is only reading papers not conducting gamma ray experiments. I presume her "beam" is also a smile and the vodka seller's departure speed simile?

[Edit: I caught the reference to Robert Pound and the use of Iron lattices used in that experiment and latices formed by Catalan numbers; but that experiment verified Relativity.]

Robert Pound has no relation to "funta" in Russian that I can detect; nor pound-as-weight to geometry. I distantly remember a joke about the Doppler effect and a street vendor...

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DifferentialGalois
Interesting interpretation, with some aspects mentioned in your answer quite different to my original no
tion. Hint: Consider alphabetical shift.

Gold Member
Interesting interpretation, with some aspects mentioned in your answer quite different to my original no
tion. Hint: Consider alphabetical shift.
I see it now, I think; quite clever. One of the times I encountered Catalan numbers at work was while matching sub-strings in character arrays and also for parentheses checks.

I have an anecdote about 'rune shifts' in artificial languages but do not want to divert your thread. Thanks, though. I have been contemplating Perfect numbers all morning in relation to Mersenne numbers thanks to researching your Catalans. Also combinatoric geometry is a fascinating idea.

Gold Member
Since you have an entire thread I wrote a riddle/joke:

What language should we use to program Catalan numbers?
LISP
If you have to explain a joke, then it is not funny. Since this joke is not very funny, I better explain, right?
Catalan also refers to the language spoken in Catalonia where people often speak with a lisp.