jasongg17 wrote: ↑Sun Feb 09, 2020 5:52 pm
Periplus of the Erythraean Sea wrote: ↑Sun Feb 09, 2020 5:43 pm
The tossup on "hydrogen" that referred to it as "this substance" had a clue that Rafael, Noah, and I felt was ambiguously worded, referring to the "production of the 21 centimeter line in this substance." I gave an answer of "intergalactic medium" - I assume this doesn't fit all the clues, but I thought the clue was referring to matter that can be a source of the 21 centimeter line, not the hydrogen atoms itself. It's possible that saying "element" would have made the question too easy, but I think the clue could have been made clearer.
To add another point to the hydrogen thing, even if you bracket the fuzziness of using "substance" to refer to interstellar hydrogen, the first two clues in this tossup are pretty much the two most famous, well-known things about how inter-stellar gases/HII regions (incidentally, I'm fairly certain the first clue applied to literally any dust or gas in space) work and are used by astronomers. I was completely baffled those clues came first.
2020 DI SCT wrote:
This substance produces the Fraunhofer C line at 6563 \oangstroms. In 1944 Hendrik van de Hulst predicted a radio wave feature produced when this substance undergoes a spin-flip transition, which is now known as the 21 centimeter line. The spectral classes of stars were originally arranged alphabetically based on the observed strength of (*) spectral lines in this element's Balmer ["BALL"-mur] series. The CNO ["C-N-O"] cycle and the proton-proton chain fuse—for 10 points—what element into helium?
answer: hydrogen (or H; do not accept or prompt on "H2" or "molecular hydrogen")
So first off, I did deliberately decide not to say "this element" right away because I thought that would narrow things down a bit much in DI. Given the confusion this apparently caused, I've gone ahead and changed to "this element" for future uses of the set.
I said something similar over in the DII question discussion, but to my mind phrases like "this substance produces a line at 6563 angstroms" and "this substance undergoes a spin-flip transition that generates the 21 centimeter line" clearly point to "(atomic) hydrogen" and not to "various things that contain atomic hydrogen." I guess at least some people who played the question had a different experience, and I apologize for the confusion—I didn't want to reveal "this element," but I
really didn't want to make people wonder about answers like "the IGM."
My intent with the 6563 angstrom clue was very much to draw on something that is "seared into the retinas of astronomers," to paraphrase James. To my mind, this sort of important-fact-known-to-all-astronomers clue is totally fine for a DI SCT lead-in (assuming it's not also known to all physicists/engineers/English majors/etc.). Jason, are you saying that you think 6563 angstroms is too widely known/will get too many buzzes to be an acceptable DI SCT lead-in?