# Today I learned

Ibix
2020 Award
on the corners of cars, he said.
On an old forum I used to read someone's signature was "Use your turn signals! You people act like it's sharing information with the enemy!"

Astronuc, jack action, DaveC426913 and 1 other person
BillTre
Gold Member
2020 Award
From a fun movie I like:

Tom.G
Borg
Gold Member
I was trying to figure out where that came from and eventually ran across this one.

Stavros Kiri, OmCheeto and BillTre
BillTre
Gold Member
2020 Award
I was trying to figure out where that came from and eventually ran across this one.
It is from the movie "Shoot Em Up".

Lots of guns, lots of shooting.

Borg
fresh_42
Mentor
TIR (ecognized), that it is a very thin line that prevents us from even more people trying to prove conjectures in number theory. Wiles was able to decrease the number of FLT provers, so they seemingly all ran over to Collatz. However, there are many more unproven, and very easy to phrase conjectures. But they use ##\equiv ## and ##\mod n## instead of ##=##. So it's literally a thin line that prevents us from people who try to prove, e.g.
$$p \in \mathbb{P} \Longleftrightarrow \sum_{k=1}^{n-1}k^{n-1} \equiv -1 \mod n$$

rsk and DaveC426913
TIL our Sun switches magnetic poles every 11 years.

Finding that out is a little like being a biology enthusiast for decades and then one day discovering the existence of rodents.
Thus, the (plus, minus, plus) full-cycle polarity period is actually 22 years ...

Also the age of some trees on the Earth is actually reflected via the 11 year cycles ... (with equal number of homocentric rings/circles inside their trunk core [1 circle for every 11 years of age] ...) !

Another not commonly known intersting solar phenomenon/property is Sun's differential rotation (e.g. the period of rotation at the equator is not the same as at the poles ... [~25 vs 38 days ...]) ...

What are these rodent things?
What is a Sun? [Never heard of it! ...]

As far as being embarrassed about not knowing something, for the first sixty years of my life I thought Jupiter wasn't visible to the naked eye.
Myself I thought (was expecting, based on relative sizes) that Jupiter would seem a lot bigger than it does ...
[Kind of disappointed when first saw it (back in the 80s ...) ..., but still surprised I never wondered or looked for it earlier! ... (having noticed only the Moon as huge ... ...) - turns out I was wrong twice! ... So, don't worry!]
(After all, it turns out it's relatively pretty big though! ... [can't complain now ...])

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BillTre
Gold Member
2020 Award
TIL that there is a
radiodont Cambroraster falcatus, so named because its head carapace is similar in shape to the Millennium Falcon from Star Wars.
It lived in the Cambrian period (time of first widespread complex animal fossils).
The head carapace is like the large shell on a crab (as seen from above).

DaveC426913 and OmCheeto
Today my 72 year old brain learned just how correct my 25 year old brain was, about how pretty this picture was and still is

View attachment 174187

PS. After all these years, I still can't follow directions:(:(
A Swedish genie is a bit of a stretch, but what the heck.

My fave bit is when she spoke in Farsi. But it didn't last.

Today I learned that influenza was spread through the air.

Duh.

Ivan Seeking
Staff Emeritus
Gold Member
I am divorced and do a lot of dating. When meeting someone new, I always insist on a coffee date for a first meet. After getting catfished a number of times I learned not to commit to an expensive dinner or similar until I know if the person online is who they say they are. Most women are fine with that as it protects both of us. But I made a very rare exception to the coffee date rule when I met my current girlfriend a year ago. I had a good feeling about her and asked her out for a nice dinner on our first date.

TIL that had I insisted on a coffee date first like I normally do, she never would have gone out with me.

jack action
Gold Member
TIL about the rooftop racetrack of Fiat’s Lingotto factory:

https://www.amusingplanet.com/2015/12/the-rooftop-racetrack-of-fiats-lingotto.html said:
The manufacturing plant’s assembly line itself was unusual, and the test track was an integral part of it. Production started at the ground floor and continued sequentially up through the upper floors. As each floor passed, the cars approached their final shape until they emerged as a finished product at the rooftop where they were ready for testing.

rsk, david2, gmax137 and 5 others
Ivan Seeking
Staff Emeritus
Gold Member
TIL that people in the food tech world actually talk about the thermodynamics of a sandwich.

So just what is the R value of bread... and the heat capacity and thermal conductivity of mayo?

Reggae star Peter Tosh was able to ride a unicycle.

In Japan students are not allowed to ride automobiles to or from school.

The students clean the school. There are no janitors.

Astronuc
Staff Emeritus
In the US in 1940, coal cost $2.36 per ton, and diesel fuel was$.0436 per gallon.

From Trains, August 1, 2016, 1939’s big breakthrough: The FT

gmax137
berkeman
Mentor
In Japan students are not allowed to ride automobiles to or from school.
Yikes. What do they do when it rains?

gmax137
What do they do when it rains?
Japan has more umbrellas per capita than anywhere else I've ever been.

atyy, Astronuc and david2
Yikes. What do they do when it rains?
Use umbrellas and rain clothes.

Tokyo is full of abandoned umbrellas. Recently I passed a convenience store that had thirty of them in their trash.

There are abandoned bicycles all over the place. When people move there is often no practical way to take the bike, so they are left behind. You can buy a new one for \$140 so it isn't a big deal.

Many people don't oil their bike's chain. They get caked with rust. I feel like starting a League for Prevention of Cruelty to Bicycles.

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Today I learned that jazz trumpeter Dizzy Gillespie was of the Bahai' faith.

In related news (which I didn't learn today) Tina Turner belongs to a fringe Buddhist sect while Prince was a Jehovah's Witness.

atyy
Ivan Seeking
Staff Emeritus
Gold Member
Today I learned that jazz trumpeter Dizzy Gillespie was of the Bahai' faith.

In related news (which I didn't learn today) Tina Turner belongs to a fringe Buddhist sect while Prince was a Jehovah's Witness.
Tom Cruise and John Travolta are Scientologists

Today I learned that Chick Corea didn't write Spain. (He did co-write it.)

Yesterday I learned that John Denver didn't write Take Me Home Country Roads. (He did co-write it.)

atyy
Today I learned that nobody wrote "In America the poor think of themselves as temporarily embarrassed millionaires." It is a highly condensed and paraphrased extract from a book review by John August.

atyy
Ivan Seeking
Staff Emeritus