This year we've been keeping track of some of the surprising things that we have learned. For December, we're compiling a list of some of the things we've learned this year.

Here are the "Today I Learned", or TILs, from September 2021.

September 2, 2021:

• TIL One inch of rainfall equals 4.7 gallons of water per square yard

• TIL about hobby tunneling - people who dig tunnels for a hobby. https://en.wikipedia.org/wiki/Hobby_tunneling

The American engineer and supercomputer architect Seymour Cray is known to have been a hobby tunneller. Cray built an 8 by 4 feet (2.4 by 1.2 m) cedar-floored tunnel under his house, explaining that the digging helped him to think about computer designs. "While I'm digging in the tunnel, the elves will often come to me with solutions to my problem," he said.

September 5, 2021:

• TIL the human eye can see more shades of green than any other color. I don't quite understand why, but it is deeply tied up with rod cells vs cone cells, the different densities of those types of cells, and which frequencies of light they capture. Also relates to why red-green colorblindness is the most common type, and why green screen backgrounds produce the best edge detection for the human eye. And probably evolved so that long-ago humans could better detect and evade predators stalking around in the brush.

September 6, 2021:

• TIL Fargo, North Dakota is right across the ND-MN border from Cass County, MN, where my maternal grandfather grew up.

September 15, 2021:

• TIL: legs for days https://www.theguardian.com/australia-news/2021/sep/15/rainbow-colours-and-legs-for-days-australian-fly-species-named-after-drag-star-rupaul

September 16, 2021:

• TIL TIL: All GISers know about null island (located at 0, 0), but today I learned about Soulbuoy, which is actually located at 0, 0 and is part of a 17-piece buoy network, all named after music genres.

September 20, 2021:

• TIL one in every three Americans experiencing homelessness lives in California. https://www.huduser.gov/portal/sites/default/files/pdf/2020-AHAR-Part-1.pdf

September 24, 2021:

• TIL the ham sandwich theorem https://en.wikipedia.org/wiki/Ham_sandwich_theorem

September 29, 2021:

• TIRLFTTT (today I re-learned for the third time) about apscheduler, this is kind of embarrassing, I also forgot its name so I spent 15 minutes trying to find it. https://apscheduler.readthedocs.io/en/3.x/userguide.html

This year we've been keeping track of some of the surprising things that we have learned. For December, we're compiling a list of some of the things we've learned this year.

Here are the "Today I Learned", or TILs, from August 2021.

August 4, 2021:

• TIL the Boise, Idaho real estate market is booming. :expressionless: (Link)

August 6, 2021:

• TIL the Licklider Transmission Protocol is used for point-to-point networks in deep space. (Link)

August 9, 2021:

• TIL Bill Hwang lost $20 billion over the course of 10 days in March 2021. Roughly $1.5M per second. I did not know money could travel at that velocity. (Link)

August 10, 2021:

• TIL you can open a wine bottle with a shoe. (Link)

August 11, 2021:

• TIL about the Dambusters, a Royal Air Force squadron specializing in precision bombing. (Link)

August 16, 2021:

• TIL about Isambard Kingdom Brunel, an English civil engineer considered one of the most ingenious and prolific figures in engineering history. (Link)

This year we've been keeping track of some of the surprising things that we have learned. For December, we're compiling a list of some of the things we've learned this year.

Here are the "Today I Learned", or TILs, from July 2021.

July 2, 2021:

• TIL Ted Kaczynski, the Unabomber, who went to Harvard to study mathematics when he was 16, was recruited in his sophomore year to participate in a "purposely brutalizing psychological experiment" where students would share their deepest-held beliefs, views, and goals, which were then used to belittle and verbally abuse the students. The study was a part of the CIA's MK-Ultra program studying methods of mind control. (Link)

July 8, 2021:

• TIL Nunavut is a territory of Canada that was formed in 1999 and provided to the Inuit people for independent governance. (Link)

July 9, 2021:

• TIL people 55 and older own 72% of the wealth in the US; they make up 28.5% of the population. (Source: USA FACTS, via PBS News Hour)

• TIL that throughout most of the 2010s, the population of millennials was soaring, but number of households headed by people under 35 was declining. But since 2016, household formation rates among millennials have been rising, with the pandemic having only a short term negative impact on that trend. (Source: Harvard report, "The State of the Nation's Housing")

July 10, 2021:

• TIL how modifying the number of suits and number of cards per suit in a deck of cards can affect the relative probability of the most rare outcomes (straight, flush, and full house).
  • For example, for regular deck of cards, 13 cards per suit, 4 suits, the ranking is straights lose to flushes lose to full houses.
  • But if you use a modified deck with 13 cards per suit and 8 suits (clubs/spades/diamonds/hearts/tridents/roses/hatchets/doves), straights are easier, as are full houses, so the ranking becomes straights lose to full houses lose to flushes.
  • Related: https://charlesreid1.com/wiki/Cards

July 11, 2021:

• TIL about apscheduler (advanced Python scheduler), which allows you to run Python code at specified dates, intervals, or schedules. (Link)

July 15, 2021:

• TIL that giant brushes make cows very happy. (Link)

July 16, 2021:

• TIL about the gamer motivation model. There is a survey by the inventors to see what kind of a gamer you are. I am a bounty hunter. (Link)

July 17, 2021:

• TIL that China was formerly referred to as the Celestial Empire. It was common in 19th century US, Canada, and Australia. The name originates from how the Chinese characters for "China" are translated (basically, celestial/heavenly dynasty)

July 18, 2021:

• TIL you can calculate the perimeter of a Möbius strip, all you have to do is integrate a complex parametric curve from 0 to 4π (also fun fact, it can't be done analytically). (Link)

July 30, 2021:

• TIL: Monrovia, the capital of Liberia, is named after US President James Monroe. (It's the second capital city named after a US president, the other being Washington DC.) It was called that because in 1816 a group of emancipated slaves arrived there under the American Colonization Society, with support from the US government. They named the city after James Monroe because of his support of the colony as a place for emancipated slaves to go, if they preferred that to life as an emancipated slave in the US.

July 31, 2021:

• TIL there's a branch of mathematics called braid theory, that is a kind of intersection of topology and linear algebra, and has some really interesting applications (and visualizations). (Link)