Rule Of Seven / Real Life

• In the sinking of the Titanic, lifeboat 7 was the first to depart the ship.
• Seven continents on Earth.
• Seven seas.
• Seven wonders of the world.
• Seven days in a week. Which is, in turn, caused by the presence of seven celestial objects regularly visible from Earth — the sun, moon and five planets.
• Seven colors of the rainbow. This is actually a contrivance of Sir Isaac Newton, a well-known scientist and not-well-known mystic. Observing the spectrum of sunlight produced by his prism, he convinced himself that the area between blue and purple was a separate color, indigo, because seven colors would fit his numerology better. The joke of this is, he missed a real seventh color: cyan, between green and blue. In Russian language, cyan IS addressed as the true seventh color.
• As a homage to this trope, the highest jackpots on a slot machine is often assigned to three 7s.
• 21 (7×3) in blackjack.
• Seven is the most likely roll of a pair of standard six-sided dice. In craps, you can win by rolling a seven (or eleven) first, and lose by getting seven on any subsequent roll. The fact that seven is the most likely sum for the outcome of rolling two dice (with a probability of 1/6) is likely the origin of the whole "seven is a lucky number" superstition.
• In chemistry, the pH scale is neutral at 7. And it's not arbitrary at all, since H+ molarity in water is approximately 10^(-7), and pH is a logarithmic scale (though the mole's value, from which molarity comes, is indeed a fixed one).
• By analogy to the Pleiades, "The Seven Sisters" is used to refer to:
  • The seven historic women's colleges of the United States (Barnard, Bryn Mawr, Mount Holyoke, Radcliffe, Smith, Vassar, and Wellesley).
  • The seven largest oil companies in the world from 1940 to 1973. More specifically, they were part of the Consortium for Iran oil cartel. Before they were sidelined by OPEC, the seven were responsible for a rather large amount of unpleasantness in the Middle East. They are (current names): BP, Gulf Oil, Chevron, Royal Dutch Shell, Esso, Exxon-Mobil, and So Cal.
  • The original seven Hollywood film companies: 20th Century Fox, Columbia Pictures, Metro-Goldwyn-Mayer, Paramount, RKO Pictures, Universal, and Warner Bros.
  • The seven main denominations of the American Protestant church: Episcopalian, Lutheran, Methodist, Presbyterian, Congregationalist, Baptist, and Reformed.
  • The common English nickname for the seven Stalinist skyscrapers built in Moscow in late '40s to early '50s: Hotel Ukraine, Hotel Leningradskaya, Ministry of Foreign Affairs main building, Red Gates administrative building, Kotelnicheskaya Embankment building, Kudrinskaya Square building and the Moscow State University main building. Built on a massive scale in a combination of American Art Deco and Russian Baroque styles, they were to represent the power of the country emerging victorious from the ruin of WWII. Ironically, two more were planned, but never built, as Stalin died and Khruschev wasn't a follower of his notions of grandeur. Note that the name isn't used in Russia itself, where these are called simply (Stalin's) Highrises.
• Almost all mammals have seven cervical vertebrae.
• A lot of cities are claimed to have been built on "Seven Hills." Rome is the most famous and would be the trope namer if this were a trope itself, but the other wiki has a whole list of them.
• A (seven-spotted) ladybug has seven spots.
• Seven is the atomic number of nitrogen, which makes up the majority of Earth's atmosphere.
• In physics and metrology, there are seven SI base units: Meter (length), kilogram (mass), second (time), kelvin (temperature), mole (amount of substance), ampere (electric current), and candela (luminous intensity).
• Television channels with the number seven love this.
• Microsoft Windows 7, the first to use the numbering scheme in its marketing since way back with Windows 3.1. Windows 7 lived up to its number when it became one of the most popular Windows releases right up there with XP. Many who were dissatisfied with Windows 8's polarising UI held on to Windows 7, and continued to do so even after Windows 10 was released and Microsoft discontinued support for 7 (though paying enterprise customers stil get security updates for 7).
• The reason Ian Fleming gave James Bond the number 007 is because of Real Life Elizabethan spy John Dee, who would sign his letter to Queen Elizabeth I as "007" - the 00 indicating the letter was for her eyes only, and "7" being the luckiest number.
• In the event of a catastrophe that shuts it down, fourteen people from around the world have been entrusted with seven keycards to restart the internet.
• In the working world, this is often combined with the Rule of Two as it's an unspoken rule that, if you quit, you should give at least two weeks (14 days, 7*2) notice before leaving.
• In the navy, mainly before World War 2 are the Big Seven Battleships which survive the scrapping after the Washington Treaty happened. They were Nelson and Rodney in the Royal Navy. Colorado, Maryland and West Virginia in the United States Navy and lastly are Nagato and Mutsu in the Imperial Japanese Navy.
• The Curse of Tippecanoe, according to legend, managed to claim the lives of seven Presidents (William Henry Harrison, Abraham Lincoln, James Abram Garfield, William McKinley, Warren Gamaliel Harding, Franklin Delano Roosevelt, and John Fitzgerald Kennedy, in that order) between 1841 and 1963 before going dormant in the '80s.
• Seven Earth-like (at least in terms of size and mass) planets are known to orbit the faint, nearby, star TRAPPIST-1.
• In dating, the rule of 7 is used as a scale for a socially acceptable relationship. The rule of thumb is that you must half your own age (divide it by 2) and then add 7 to it. Whatever the result, you can't date anyone lower than the answer. The formula does have its flaws; if it's a .5 answer (i.e. 19.5 or 21.5) then you're better off rounding it up to the nearest whole number to avoid confusion or trouble, the relationship can still be seen as creepy with or without the rule of 7, and different countries have different ages of consent.

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