Today I Learned

[fresh_42]

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.
$$
p \in \mathbb{P} \Longleftrightarrow \sum_{k=1}^{n-1}k^{n-1} \equiv -1 \mod n
$$

 

[Stavros Kiri]

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 ...])

 

[BillTre]

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).

 

[kyphysics]

https://abcnews.go.com/Business/wireStory/officials-health-care-rationing-spread-idaho-79895419
Idaho is rationing care amid COVID. Tough decisions.

 

[Hornbein]

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.

 

[Hornbein]

Today I learned that influenza was spread through the air.

Duh.

 

[Ivan Seeking]

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]

TIL about the rooftop racetrack of Fiat’s Lingotto factory:

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.

 

[Ivan Seeking]

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?

 

[Hornbein]

Reggae star Peter Tosh was able to ride a unicycle.

 

[Hornbein]

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

The students clean the school. There are no janitors.

 

[Astronuc]

In the US in 1940, coal cost $2.36 per ton, and diesel fuel was $.0436 per gallon.
https://www.trains.com/wp-content/uploads/2020/10/trnm1114.pdf

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

Seventy-five years ago (in 2016) on Nov. 25, 1939, Electro-Motive Corp.’s FT demonstrator diesel locomotive No. 103 left its birthplace at the company’s La Grange, Ill., plant. Nobody, not even its builders, knew what the new creation could do. True, the 17-year-old Electro-Motive had been a pioneer in diesel propulsion for railroad use, having built a successful line of self-propelled passenger cars (doodlebugs), diesel switchers, and diesel passenger locomotives. But the new FT would make the company’s fortunes soar. No. 103 became the prototype for, in the words of Trains Editor David P. Morgan, the world’s first standardized, mass-produced line of diesel freight locomotives with “no equal in railroading.” The tour was more experiment than demonstration. The builder’s tone was, “We’d like you to help us find out just what we’ve got here.” They learned that the locomotive not only could pull record tonnage in record time while using half the fuel of a steam locomotive but it also needed minimal maintenance and had excellent reliability in all kinds of weather. It was equally adept at hauling passengers as it was freight. By the time the FT returned to La Grange in October 1940, 83,764 miles later, the diesel locomotive revolution had begun its meteoric rise. Sixteen of the railroads that hosted the FTs ordered them as soon as possible after the tour. Many roads on the trip that didn’t buy FTs later became big EMC customers; based on the tests, eight other railroads bought FTs for a total of 1,096 units. By 1947 the now-Electro-Motive Division of General Motors was cranking out four to six diesel locomotives a day. It’s appropriate in this 75th anniversary year of that fateful tour that the original FT, No. 103, is still with us. After a career of lugging freight on Southern Railway, No. 103 was donated in the early 1960s to the Museum of Transportation in St. Louis. The locomotive, “the diesel that did it,” took a place of honor during this year’s “Streamliners at Spencer” festival, celebrating the sleek, smooth look of early American diesel locomotives. Norfolk Southern is repainting the unit at its shop in Chattanooga, Tenn., before returning it to the museum St. Louis. No. 103 is a prized artifact in the history of American railroad technology, one of the true forces of technological change.

 

[berkeman]

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.

 

[Hornbein]

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.

 

[Hornbein]

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.

 

[Ivan Seeking]

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

 

[Hornbein]

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.)

 

[Hornbein]

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.

 

[Ivan Seeking]

YIL where we get tartaric acid and cream of tartar.

 

[DaveC426913]

YIL where we get tartaric acid and cream of tartar.

Having just been to the dentist, I really don't want to know...

 

[jack action]

TIL that the first-ever webcam was set to watch a coffee pot.

 

[Ivan Seeking]

TIL that the first-ever webcam was set to watch a coffee pot.

View attachment 289288​

And the darned thing still won't boil.

 

[Keith_McClary]

TIL that the first-ever webcam was set to watch a coffee pot.

View attachment 289288​

if they’d make the trip to the Trojan room to refuel on coffee only to find an empty pot, they’d be very disappointed indeed.

Because it would be their turn to brew another pot.

 

[collinsmark]

TIL that the first-ever webcam was set to watch a coffee pot.

View attachment 289288​

Yep, there's a lot of history between the web and coffee.

There's also this:

Hyper Text Coffee Pot Control Protocol​

 

[BillTre]

Avast, its International Talk Like a Pirate Day, Matey.

 

[BillTre]

Avast, its International Talk Like a Pirate Day, Matey.

 

[Ivan Seeking]

Avast, its International Talk Like a Pirate Day, Matey.

Man, Pittsburgh sucks. I want to be traded! The coach is drunk again and he won't let me pitch!

 

[mfb]

TIL: Out of three people in space who later became NASA administrators, two have been on the same flight, STS-61-C.

* Charles Bolden as astronaut, who became NASA administrator under Obama
* Bill Nelson, then member of the House of Representatives, who became NASA administrator under Biden.

(the third one with spaceflight experiments is Richard H. Truly, who flew two very early Shuttle missions)

 

[NTL2009]

TIL about SIGSALY. https://en.wikipedia.org/wiki/SIGSALY

This was an encryption method used in WWII between the highest levels of US and Allies.

It follows the method that was familiar to me (and in common use today, I think): digitize the voice, then modify those values with a pseudo-random number generator before transmitting. On the receiving end, the complementary arithmetic is applied with an identical pseudo-random number generator.

Today, digitizing speech is easy, cheap and common in 8 bit ~ 16 bit precision.

Today, creating a pseudo-random number stream is easy, cheap and common. Start both generators ( a few lines of code?) with the same 'key', and you will get an identical random appearing number stream.

But in those days, neither was so easy.

To digitize the voice, and limit the amount of data required, they used a 10 band vocoder, quant to 6 values (not 6 bits!), and measured the frequency of the voice ( 6 course and 6 fine - 36 values), and set a bit for 'voiced' or 'unvoiced' (a pitch with harmonics was used on the receiver to simulate a voice, white noise to simulate consonants like "s", "t", etc), sampled every 50 msec. If I did this right, that would be a data rate of about 1,460 bits per second. Take that mp3! Though I wonder what that level of fidelity would take for mp3 (to be fair, mp3 is not optimized for speech)?

For test purposes, a big relay based device was used as the programmable pseudo-random number generator. Here's the most amazing part to me: to provide a matching pseudo-random number to the receiving end, they made two copies of an analog white noise source with a phonograph record. One record was used at each end. They had to carefully sync the records (within 50 msec!) at each end to decode the transmission. Only two copies of any particular recording were made.

Though, getting the exact speed would not be hard, a synchronous motor does that. And if you get close with the start times, you could 'hunt' a bit with a test pattern which would jump from white noise to intelligible speech when you got it synced. But you'd be eating into the 12 minutes of recorded noise.