You are made of stars
Literally. A few minutes after the Big Bang, the universe was cool enough for the first elements to spontaneously form, deuterium and helium. That was all that existed for hundreds of millions of years, until the first stars formed, creating
The thing is, even millions of degrees at the pressure of a stellar core is insufficient to fuse that helium into anything heavier. Those reactions need to happen in red giant or larger stars, which probably required the first stars to first die out after burning for billions of years, and gradually created carbon, oxygen, silicon, and so on. Just imagine how weird planetary systems must have been during those first few billion years: every planet a gas giant or small ball of gas.
But that isn’t even the most amazing part. Even in the center of the largest supergiant stars, there isn’t enough temperature and pressure to fuse any element heavier than iron. With an atomic number of 26, that includes all of the cobalt, nickel, copper, and zinc in the universe. Those are all created in the fractions of a second where supernovas collapse in on themselves. They are then blasted around the universe with the force of a, uh, supernova.
You, of course, would not be able to function without all of the zinc (32 ppm), copper (1 ppm), selenium (0.19 ppm), and iodine (0.16 ppm) inside of you. You probably could not have existed just if the universe were only 5 billion years old. In a very real way, you are made of exploded stars.
neon
The element neon was discovered and named in 1898, when the periodic table looked like this. You may notice the lighter elements are nearly all accounted for, except for the noble gases, which remained elusive due to not interacting with anything. That year, Sir William Ramsay and Morris Travers used a novel apparatus to isolate and remove all gases individually from a sample of air, identifying three previously unkown trace (neon is 18 ppm of air) nonreactive elements. Neon was named after Greek νέος (néos), meaning “new”. The other two elements were named krypton (hidden) and xenon (foreign).
A naturally-occurring element, the vast majority of all neon in existence originates from oxygen-helium fusion in main sequence stars. While experimenting with his discovery, Ramsay noticed that neon gave off a brilliant, unforgettable red glow when electric current was passed through it. Commercial exploitation of this valuable property was initially discouraged by neon’s scarcity and cost. Once neon started being extracted from air in useful amounts in 1902, the first neon lights were created in 1923 (prototyped 1910) by replacing the nitrogen in Moore Tubes with neon. People would stop and stare at the unmissable lights even in daylight, describing them as “liquid fire”.
The neon sign’s heyday was the 1930s through 1950s, with a retro revival in the 1980s. They could be used as a visible shorthand for the growth of the modern advertising industry. Today, most light fixtures we call “neon signs” are actually LEDs. The adjective also stuck for the “neon colors” we associate with those signs (actually produced by phosphor coatings that fluoresce under UV light, which neon lights emit), commonly used to refer to highlighters. Sixteen Crayola crayon colors were rebranded as neon colors in 1993.
paywall
The virtual palisade paywall is first used to describe a membership-restricted sports website in 2004. The Wall Street Journal’s site had been paywalled since 1996, but this was such a rare practice that we didn’t need a word for it until much later. The Great Paywalling did not in fact begin until the early 2010s, when it became clear the previously dominant ad-supported model could not sustainably fund good journalism. For example, the NYT’s paywall went up in March 2011.
Paywall is obviously a compound of the common words pay- and -wall, but the choice of -wall in particular is influenced by the parallel firewall. Referring to computer security systems since 1971 and popularized in the 1983 hacker movie WarGames (“the only winning move is not to play”), a firewall referred to any system that separated unauthorized users from other critical systems. It settled on its current more specific meaning of a passive deterrence that blocks automated intrusions in the 1990s.
Firewall’s computer security meaning arose from a metaphor for its physical meaning, a fire-resistant barrier preventing the spread of fires by separating burnable things from each other. Uncontained, wildly spreading fires used to be a major problem for cities; firewalls, first attested in 1851, were one of many tools developed and deployed to combat this. The more general meaning of a protective barrier of any sort is from 1907.
checkmate
The interjection checkmate originates from the Persian phrase شاهمات (šāh māt), meaning “checkmate”, literally translated as “the king is amazed”. شاه, pronounced “shah”, is recognizably the Persian word for king. As the phrase was adopted in Arabic some time before 1000, it was reinterpreted as شَاه مَاتَ (šāh māta), literally “the king is dead”. Over the next few centuries, the customary chess winning interjection traveled with the game into Old French as eschec mat, arriving in Middle English as chekmat before 1350.
“Checkmate, atheists”, meanwhile, originates from a satirical YouTube video from the previous culture war, created by Edward Current in 2007. That specific phrasing wasn’t widespread until satirical Facebook and Tumblr pages devoted to it were created in 2011.
weekend
The periodic time period weekend is first found in 1793 as a North England regionalism. It did not enter general English usage until 1878. This delay is probably because instead of “weekend”, you could just as well say “Sunday” or “Sabbath”. Six-day work weeks were the norm for most of history, including the 1800s. Which day was the day of rest differed by religion, typically Sunday for Christian countries, Saturday for Jewish communities, and Friday for Muslim countries.
According to UK records, the average worker worked 70 hours a week in 1800. This number only began to decrease in the 1870s as workers gained bargaining and political power through collective organizing and increased skill requirements. One UK movement in this period advocated for giving workers Saturday off after 2pm in exchange for the pledge to be refreshed and sober on Monday morning. Over the next 30 years, half-day Saturdays went from unthinkable to radical to sensible to policy, enabling the newly radical eight-hour day movement to begin agitating in the 1910s. They advocated for “8 hours for labour, 8 hours for rest, 8 hours for recreation” and a fully five-day workweek, which was first instituted by a single US cotton mill in 1908.
Spain became the first country to enshrine the 40-hour workweek into law in 1919. The US did not follow suit until 1940, although Ford was shutting down its factories all day Saturday and Sunday by 1926. The enactment of the 1938 Fair Labor Standards Act, which also established the first federal minimum wage of 25 cents per hour, was celebrated on Labor Day for decades. Futurists writing in the 1920s and 1930s extrapolated this historical trend of increased worker power and leisure to fifteen-hour workweeks by the year 2000. Clearly this has not come to be, but average hours worked per year in the UK has at least decreased roughly linearly from 2,257 in 1925 to 1,670 in 2017.