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Common card · Science
Density wave theory, a Common card
Density wave theory or the Lin–Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain the spiral arm structure of spiral galaxies.
- Rarity
- Common
- Domain
- Science
- ATK
- 59
- DEF
- 39
- Power
- 98
- Wikipedia reads a year
- 13,000
Power 98 (ATK + DEF): stronger than 40 % of WikiCards cards.
Density wave theory quiz: 3 questions
Three questions on the Density wave theory card, the way WikiCards duels ask them. Pick an answer, the facts are just below.
Find the missing word
The Lin–Shu theory ______ the idea of long-lived quasi-stationary spiral structure.
Answer
introduces. The Lin–Shu theory introduces the idea of long-lived quasi-stationary spiral structure. From the Density wave theory article on Wikipedia.
In which decade?
Density wave theory or the Lin–Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-____s to explain the spiral arm structure of spiral galaxies.
Answer
1960s. Density wave theory or the Lin–Shu density wave theory is a theory proposed by C.C. Lin and Frank Shu in the mid-1960s to explain the spiral arm structure of spiral galaxies. From the Density wave theory article on Wikipedia.
Which of these cards hits hardest (highest ATK)?
Answer
2017 state visit by Donald Trump to China. 2017 state visit by Donald Trump to China 63 · Density wave theory 59 · Ephraim Moses Lilien 55 · SN 2025pht 52 ATK in WikiCards.
In a duel, each round asks a question like these about the opposing card, with 15 seconds to answer.
The facts on the card
The card carries these facts from its Wikipedia article.
- The Lin–Shu theory introduces the idea of long-lived quasi-stationary spiral structure.
- In this hypothesis, the spiral pattern rotates with a particular angular frequency, whereas the stars in the galactic disk orbit at varying speeds, which depend on their distance to the galaxy center.
- The presence of spiral density waves in galaxies has implications on star formation, since the gas orbiting around the galaxy may be compressed and cause shock waves periodically.
Why it is Common
Rarity in WikiCards follows a year of Wikipedia page views: the most read articles become Epic and Legendary cards. The Density wave theory article was read about 13,000 times in a year. ATK comes from the length of the article and DEF from its quality, so this card hits with 59 and blocks with 39: each hit it takes is cut by 16 %.
How to get Density wave theory
Open packs. Each pack holds five cards drawn from real Wikipedia articles, the rarest last, and the fifth card is always Rare or better. The odds are shown in the game. A free pack arrives every hour and two can wait, and the Coins you win in duels buy more packs.
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Credits
Text : Wikipedia, Density wave theory (revision), CC BY-SA 4.0. Photo : Hubble data: NASA, ESA, and A. Zezas (Harvard-Smithsonian Center for Astrophysics), GALEX , Public domain, Wikimedia Commons.
