TIL: Today I Learned

[Birdjaguar]

It's obsolete in the US now, but in the past every year you renewed your registration, they gave you a small sticker that went on the plate which showed it was an up to date registration.

We still have stickers in NM.

 

[Takhisis]

Since the Sun will be dead by that time (and Earth long before then), I doubt there will be anyone around to worry about it.

Which is why we worry now.

 

[aimeeandbeatles]

Since the Sun will be dead by that time (and Earth long before then), I doubt there will be anyone around to worry about it.

The things some people will do to get out of work.

 

[Takhisis]

The things some people will do to get out of work.

This lends a new dimension to the old ‘compiling!’ joke from xkcd.

 

[aimeeandbeatles]

Today I learned that the VLC traffic cone has a Satan hat.

 

[Birdjaguar]

Is that a Satan hat because it flops to the right?

 

[Kaitzilla]

TIL an explanation for the math term e that I really liked.

https://betterexplained.com/articles/an-intuitive-guide-to-exponential-functions-e/

e is NOT Just a Number
Describing e as “a constant approximately 2.71828…” is like calling pi “an irrational number, approximately equal to 3.1415…”. Sure, it’s true, but you completely missed the point.

Pi is the ratio between circumference and diameter shared by all circles. It is a fundamental ratio inherent in all circles and therefore impacts any calculation of circumference, area, volume, and surface area for circles, spheres, cylinders, and so on. Pi is important and shows all circles are related, not to mention the trigonometric functions derived from circles (sin, cos, tan).

e is the base rate of growth shared by all continually growing processes. e lets you take a simple growth rate (where all change happens at the end of the year) and find the impact of compound, continuous growth, where every nanosecond (or faster) you are growing just a little bit.

e shows up whenever systems grow exponentially and continuously: population, radioactive decay, interest calculations, and more. Even jagged systems that don’t grow smoothly can be approximated by e.

Just like every number can be considered a scaled version of 1 (the base unit), every circle can be considered a scaled version of the unit circle (radius 1), and every rate of growth can be considered a scaled version of e (unit growth, perfectly compounded).

So e is not an obscure, seemingly random number. e represents the idea that all continually growing systems are scaled versions of a common rate.
​

I knew why pi was important, but never really understood e before.

There is another article for the natural logarithm (ln) here.
The Rule of 72 should really be 69.3 for the best accuracy.
https://betterexplained.com/articles/demystifying-the-natural-logarithm-ln/

 

[Kaitzilla]

TIL of a juicy forum talking about failed dissertation defenses.
https://www.chronicle.com/forums/index.php?topic=40982.0

Apparently, if you fail your dissertation defense twice it is game over and you have to withdraw from the doctoral degree program?
And yet Carter Page got his on a 3rd try.
https://www.theguardian.com/world/2017/dec/22/trump-carter-page-phd-thesis-trump



Also, Friednich Leibniz has over 100,000 mathematical descendants.
He was an advisor to people who were advisors who taught yet more people who became many more advisors etc. etc. down through about 4 centuries.
In the wiki, just keep on clicking "Doctoral Student" and you will be amazed at all the people in the 1600's, 1700's, 1800's, and 1900's that can trace their "Doctoral Advisor" all the way back to Friednich.
https://en.wikipedia.org/wiki/Friedrich_Leibniz#cite_note-10

 

[aimeeandbeatles]

Is that a Satan hat because it flops to the right?

No, I just kan't spel write.

 

[Valka D'Ur]

Is that a Satan hat because it flops to the right?

Look at all our Satanic smileys. Shame on us.

 

[Birdjaguar]

today I learned that I can get the most recent post in lots of threads by spamming writing topical posts in the forums when no one is around.

 

[The_J]

TIL of a juicy forum talking about failed dissertation defenses.
https://www.chronicle.com/forums/index.php?topic=40982.0

Apparently, if you fail your dissertation defense twice it is game over and you have to withdraw from the doctoral degree program?
And yet Carter Page got his on a 3rd try.
https://www.theguardian.com/world/2017/dec/22/trump-carter-page-phd-thesis-trump

These things depend on country, and partially also on the university. Including what constitutes a failure.
In the Netherlands you cannot really fail at the PhD defense, since the defense itself is a ceremony, and not really a test. If you were so bad to fail, you would not even get on stage.
How many people do not defend and do not get a doctor... that's a different matter.

 

[Bamspeedy]

We still have stickers in NM.

And WI.

Sure, if the cop runs your plates they will find out if your car is up to date or not. Car missing the sticker, or a color of the sticker that is expired they can see it from a quick glance and gives them a reason to pull you over and check your registration more thoroughly.
Dated a girl who would steal the stickers off other cars to put on hers. Eventually, she would get caught of course when her plates were checked on the computer.

 

[aimeeandbeatles]

Today I learned that Greenland is actually really tiny. This website lets you drag countries around the map to compare their actual sizes.

 

[Cutlass]

TIL of the ‘Tsunami of Molasses’ of 1919' in Boston.

By Erin McCann

• Nov. 26, 2016

“A dull muffled roar gave but an instant’s warning before the top of the tank was blown into the air,” The New York Times wrote in 1919. “Two million gallons of molasses rushed over the streets and converted into a sticky mass the wreckage of several small buildings which had been smashed by the force of the explosion.”

“Wagons, carts, and motor trucks were overturned. A number of horses were killed. The street was strewn with debris intermixed with molasses and all traffic was stopped.”

It was January. The place was Boston. And when 2.3 million gallons of molasses burst from a gigantic holding tank in the city’s North End, 21 people were killed and about 150 more were left injured. The wave of syrup — some reports said it was up to 40 feet tall — rushed through the waterfront, destroying buildings, overturning vehicles and pushing a firehouse off its foundation.

For nearly 100 years, no one really knew why the spill was so deadly.

But at a meeting of the American Physical Society this month, a team of scientists and students presented what may be an important piece of the century-old puzzle. They concluded that when a shipment of molasses newly arrived from the Caribbean met the cold winter air of Massachusetts, the conditions were ripe for a calamity to descend upon the city.

By studying the effects of cold weather on molasses, the researchers determined that the disaster was more fatal in the winter than it would have been during a warmer season. The syrup moved quickly enough to cover several blocks within seconds and thickened into a harder goo as it cooled, slowing down the wave but also hindering rescue efforts.

“It’s a ridiculous thing to imagine, a tsunami of molasses drowning the North End of Boston, but then you look at the pictures,” said Shmuel M. Rubinstein, a Harvard professor whose students investigated the disaster.

When the molasses arrived in Boston’s harbor, it was heated by just a few degrees. The warmer temperature made it less viscous and therefore easier to transport to a storage tank near the waterfront.

When the tank burst two days later, the molasses was still probably about four or five degrees Celsius warmer than the surrounding air, said Nicole Sharp, an aerospace engineer and science communications expert who advised the Harvard students. (She runs the website FYFD, through which she explains the principles of fluid dynamics to people outside academia.)

The students performed experiments in a walk-in refrigerator to model how corn syrup, standing in for the molasses, would behave in cold temperatures. With that data in hand, they applied the results to a full-scale flood, projecting it over a map of the North End. Their results, Ms. Sharp said, generally matched the accounts from the time.

“The historical record says that the initial wave of molasses moved at 35 miles per hour,” Ms. Sharp said, “which sounds outrageously fast.”

“At the time people thought there must have been an explosion in the tank, initially, to cause the molasses to move that fast,” she added. But after the team ran the experiments, she said, it discovered that the molasses could, indeed, move at that speed.

“It’s an interesting result,” Ms. Sharp said, “and it’s something that wasn’t possible back then. Nobody had worked out those actual equations until decades after the accident.”

If the tank had burst in warmer weather, it would have “flowed farther, but also thinner,” Mr. Rubinstein said.

In the winter, however, after the initial burst — which lasted between 30 seconds and a few minutes, Ms. Sharp said — the cooler temperature of the outside air raised the viscosity of the molasses, essentially trapping people who had not been able to escape the wave.

About half the people who were killed “died basically because they were stuck,” Mr. Rubinstein said.

A firefighter who survived the initial wave managed to stay alive for nearly two hours while he waited to be rescued, they said, but he drowned.

“Men and women, their feet trapped by the sticky mass, slipped and fell and were suffocated,” The Boston Globe wrote in 1968. “The stronger tried to save others, and many of them died for their heroism.”

The exact cause of the tank’s failure has never been known. Last year, a team of engineers using modern methods to analyze the century-old disaster blamed poorly designed steel tanks.

Ronald Mayville, a structural engineer who worked on that study, told The Boston Globe that the tank’s walls were at least 50 percent too thin and were made of a type of steel that was too brittle.

The project at Harvard grew out of Mr. Rubinstein’s Introduction to Fluid Dynamics class, which asks students to create a final project. “Choose an interesting project and make an appealing video,” he said.

Mr. Rubinstein and Ms. Sharp said they would like to eventually build an entire course around the disaster. Students could apply what they learn in other classes to understanding not just why the molasses behaved the way it did, but also what other forces shaped the events of that day in 1919.

The Boston molasses disaster, Mr. Rubinstein said, is “a beautiful story for teaching.”

https://www.nytimes.com/2016/11/26/science/boston-molasses-flood-science.html

 

[aimeeandbeatles]

Today I learned that there was a prototype version of Pokemon Gold and Silver that had a lot of neat Pokemon that were omitted from the final version, as well as some weird early designs for other ones.

 

[Ajidica]

Less a "Today I Learned" and more a "Today I Remembered", but we only learned about the whole Stormy Daniels kerfuffle back in January 2018.
https://thehill.com/homenews/administration/386209-timeline-trump-cohen-stormy-daniels-and-130000

 

[Phrossack]

Less a "Today I Learned" and more a "Today I Remembered", but we only learned about the whole Stormy Daniels kerfuffle back in January 2018.
https://thehill.com/homenews/administration/386209-timeline-trump-cohen-stormy-daniels-and-130000

Only? That's three years of this now!

 

[ryanmusante]

Today I learned that it is best to keep global makeflags at -O2 or better.
https://github.com/Tk-Glitch/PKGBUILDS/issues/61

CFLAGS="-march=native -pipe -O2 -fstack-protector-strong"
CXXFLAGS="${CFLAGS}"
LDFLAGS="-Wl,-O2,--sort-common,--as-needed,-z,relro,-z,now"

 

[Kaitzilla]

TIL that the 'ok' hand sign is now considered a symbol for white power and will get you terminated at your job.
https://www.splcenter.org/hatewatch/2018/09/18/ok-sign-white-power-symbol-or-just-right-wing-troll

• Coast Guard removed http://www.newser.com/story/264659/coast-guard-guy-fires-for-this-hand-gesture.html
• Police Officers suspended https://thehill.com/blogs/blog-brie...ce-officers-suspended-for-making-hand-gesture
• Fired https://www.zerohedge.com/news/2019...white-power-hand-symbol-and-topless-putin-pic
• Attacked on social media https://www.vox.com/2018/9/5/178219...avanaugh-confirmation-hearing-zina-bash-*****

I guess I'll stop saying "I'm Okay" before that gets me fired too.
Might flash the sign when explaining what it means.


Really annoyed because I've been using 'OK' for decades!
Thumbs up is just lazy and even someone dying can give one of those.