Today I Learned

[strangerep]

Engineers?
From experience a Beer of Engineers would be a fit and it also has a ring to it.

Hmm. A "Brewery of Engineers" is probably closer to the correct scale.

Or maybe a "Chunder of Engineers"?

 

[Gocalc]

Today I learned you can use vinegar in place of fabric softener. I tried it and surprisingly it works. It's the first time my towels have been soft since living in my current place which has no drier.

 

[Tom.G]

Today I learned you can use vinegar in place of fabric softener. I tried it and surprisingly it works. It's the first time my towels have been soft since living in my current place which has no drier.

Vinegar also helps remove the laundry detergent residue and perfume that never seems to be completely rinsed out.

(speculation: That might even be why it softens the fabric.)

 

[Ibix]

Today I learned that you can adjust the step speeds of stepper motors (such as those found in old floppy drives) to make different pitches of buzz. You can probably see where this is going:

(0:45 to skip the overlong intro)

 

[rsk]

Today I learned how to open a tin can without a can opener (the ring pull snapped off in my hand). All you need is a teaspoon.

 

[DaveC426913]

Today I learned how to open a tin can without a can opener (the ring pull snapped off in my hand). All you need is a teaspoon.

Or a hand grenade.

 

[epenguin]

Today I learned how to open a tin can without a can opener (the ring pull snapped off in my hand). All you need is a teaspoon.

You must tell us how sometime.

 

[rsk]

You must tell us how sometime.

It works! It works!

 

[berkeman]

TIL that some drag races are held 4-wide! I've never seen that before...

https://www.nhra.com/schedule/2021/...acing-series/ngk-ntk-nhra-four-wide-nationals

https://www.nhra.com/nhra

 

[DaveC426913]

TIL that some drag races are held 4-wide! I've never seen that before...

https://www.nhra.com/schedule/2021/...acing-series/ngk-ntk-nhra-four-wide-nationals

https://www.nhra.com/nhra

View attachment 283122

This photo is miscaptioned.
This is actually a picture of highway 400, in Toronto, on a Saturday around 11PM.

 

[Astronuc]

This man was stung seven times by murder hornets while trying to save Vancouver Island's honeybees
https://www.cbc.ca/television/this-...o-save-vancouver-island-s-honeybees-1.5971560

zoobyshoe's prescient thread on Asian giant hornets (Vespa mandarinia) from 2013.
https://www.physicsforums.com/threads/the-coming-hornet-apocalypse.714207/

6th Asian giant hornet to be discovered in B.C. found in Fraser Valley
https://www.cbc.ca/news/canada/brit...vered-in-b-c-found-in-fraser-valley-1.5797706

Destroyed 'murder hornet' nest near U.S.-B.C. border contained nearly 200 queens, scientists say
https://www.cbc.ca/news/canada/brit...ornet-nest-washington-bc-200-queens-1.5798631

I know that one or two have been found in Washington State. "In December 2019, WSDA received and verified two reports of Asian giant hornet near Blaine (Whatcom County). These are the first-ever sighting in the United States. Canada had also discovered Asian giant hornet in two locations in British Columbia in the fall of 2019.

In 2020, both Washington and Canada have had new confirmed sightings of Asian giant hornet and in October of 2020, WSDA conducted the first-ever eradication of an Asian giant hornet nest in the United States."
https://agr.wa.gov/hornets

https://invasivespecies.wa.gov/priorityspecies/asian-giant-hornet/

https://www.opb.org/article/2021/03/16/washington-state-canada-try-to-kill-asian-giant-hornets/
I knew of the October 2020 sighting, but not the early sightings.

 

[strangerep]

TIL that some drag races are held 4-wide! I've never seen that before...

Here's a photo of those 4-wide drag drivers look like in real life...

 

[Keith_McClary]

It is claimed that trees did not evolve wood so that they could better access sunlight (than shorter plants).

​

 

[pinball1970]

This man was stung seven times by murder hornets while trying to save Vancouver Island's honeybees
https://www.cbc.ca/television/this-...o-save-vancouver-island-s-honeybees-1.5971560

zoobyshoe's prescient thread on Asian giant hornets (Vespa mandarinia) from 2013.
https://www.physicsforums.com/threads/the-coming-hornet-apocalypse.714207/

6th Asian giant hornet to be discovered in B.C. found in Fraser Valley
https://www.cbc.ca/news/canada/brit...vered-in-b-c-found-in-fraser-valley-1.5797706

Destroyed 'murder hornet' nest near U.S.-B.C. border contained nearly 200 queens, scientists say
https://www.cbc.ca/news/canada/brit...ornet-nest-washington-bc-200-queens-1.5798631

I know that one or two have been found in Washington State. "In December 2019, WSDA received and verified two reports of Asian giant hornet near Blaine (Whatcom County). These are the first-ever sighting in the United States. Canada had also discovered Asian giant hornet in two locations in British Columbia in the fall of 2019.

In 2020, both Washington and Canada have had new confirmed sightings of Asian giant hornet and in October of 2020, WSDA conducted the first-ever eradication of an Asian giant hornet nest in the United States."
https://agr.wa.gov/hornets

https://invasivespecies.wa.gov/priorityspecies/asian-giant-hornet/

https://www.opb.org/article/2021/03/16/washington-state-canada-try-to-kill-asian-giant-hornets/
I knew of the October 2020 sighting, but not the early sightings.

I am terrified of bees and wasps, I am not sure I have ever seen a hornet. My worst night mare being attacked by them.

 

[Frabjous]

I am terrified of bees and wasps, I am not sure I have ever seen a hornet. My worst night mare being attacked by them.

How do you feel about cicadas?
https://www.cicadamania.com/cicadas/periodical-cicada-brood-x-10-will-emerge-in-15-states-in-2021/

 

[Ibix]

How do you feel about cicadas?

He'll be cicadem by de end of de year if he lives in one of those states...

 

[Ibix]

How do you feel about cicadas?
https://www.cicadamania.com/cicadas/periodical-cicada-brood-x-10-will-emerge-in-15-states-in-2021/

More seriously, I thought these periodic insects tended to operate on prime number of year cycles, but if I'm reading right those ones are on a ten year period.

 

[pinball1970]

How do you feel about cicadas?
https://www.cicadamania.com/cicadas/periodical-cicada-brood-x-10-will-emerge-in-15-states-in-2021/

I do not feel good about anything with more than 4 legs.
Is there a thing with cicadas and primes?

 

[Frabjous]

I believe it is 17 years. See this for primes in predator-prey interactions.
https://www.cicadamania.com/downloads/prime-PRL.pdf

See also
https://www.washingtonpost.com/dc-md-va/2021/04/01/cicadas-come-out-2021-brood-x/

 

[Ibix]

Is there a thing with cicadas and primes?

I read on one of Dawkins' books, I think, that long period cicadas tended to have prime periods because things that ate them couldn't emerge on factors of their period and eat something else - e.g. this ten year cicada could be predated by the five-year-cicada-eating-beast that emerges every five years. But a thirteen year cicada can only be eaten (except opportunistically) by a thirteen year cycle creature.

Misleading popsci, maybe.

 

[dlgoff]

This man was stung seven times by murder hornets while trying to save Vancouver Island's honeybees
https://www.cbc.ca/television/this-...o-save-vancouver-island-s-honeybees-1.5971560

This makes me cringe, as I was hospitalized once from bumblebee stings. Freely flowing liquids from both ends simultaneously.

 

[collinsmark]

Is there a thing with cicadas and primes?

Oh, yes.

The Cicada’s Love Affair With Prime Numbers​

 

[mfb]

Today I found two examples of weird large derivatives appearing:
A particle bouncing inside a convex region can be a chaotic system. But the motion cannot be chaotic if the 553rd derivative of its boundary is continuous (Lazutkin, 1973). Later work improved that requirement down to the 6th derivative. Discussed by @john baez in 2016: Blog article

If you take the Minkowski sum ($\{a+b:a\in A,b\in B\}$) of convex subsets A, B of $\mathbb{R}^2$ with real-analytic boundaries then the boundary of A+B is guaranteed to be "6+2/3" times differentiable.

 

[strangerep]

I do not feel good about anything with more than 4 legs.
Is there a thing with cicadas and primes?

Cicadas are cute and harmless -- as a child we used to catch them, trying to collect as many different varieties as possible. There were quite a few names, but now I only remember "Green Grocer", "Black Prince", "Yellow Monday(?)", "Pizz Whacker" (don't ask) ...

 

[rsk]

Today I learned that if you don't have a spare CR2032 battery handy, two CR2016s, stacked, will do the job nicely.

 

[phinds]

That one of the weirdest things in numerology that I've ever seen is this:

111,111,111 x 111,111,111 = 12345678987654321 [counts up 1 to 8 then down 8 to 1 but with a 9 in the middle)

What has me flummoxed is NOT the math so much as who in hell every happened to SEE it ? I mean, whoever it was has WAY too much spare time on their hands.

 

[jedishrfu]

I think this comes from playing with 1 x 1 = 1, 11 x 11 = 121, 111 x 111 = 12321 ... so naturally someone would extend the sequence to the limit of disbelief.

 

[Keith_McClary]

whoever it was has WAY too much spare time on their hands.

         111111111
        x111111111
        __________
         111111111
        111111111
       111111111
      111111111
     111111111
    111111111
   111111111
  111111111
 111111111
_________________
 12345678987654321

 

[Keith_McClary]

 

[Janus]

That one of the weirdest things in numerology that I've ever seen is this:

111,111,111 x 111,111,111 = 12345678987654321 [counts up 1 to 8 then down 8 to 1 but with a 9 in the middle)

What has me flummoxed is NOT the math so much as who in hell every happened to SEE it ? I mean, whoever it was has WAY too much spare time on their hands.

It's part of a pattern:
11 x 11 = 121
111 x 111 = 12321
1111 x 1111 = 1234321
etc.

 

[DrGreg]

It's part of a pattern:
11 x 11 = 121
111 x 111 = 12321
1111 x 1111 = 1234321
etc.

Or an even more general pattern$$\begin{align*}
(x+1)^2 &= x^2 + 2x + 1 \\
(x^2+x+1)^2 &=x^4 + 2x^3 + 3x^2 + 2x + 1
\end{align*}
$$etc.

 

[fresh_42]

That one of the weirdest things in numerology that I've ever seen is this:

111,111,111 x 111,111,111 = 12345678987654321 [counts up 1 to 8 then down 8 to 1 but with a 9 in the middle)

What has me flummoxed is NOT the math so much as who in hell every happened to SEE it ? I mean, whoever it was has WAY too much spare time on their hands.

Yes, but this is what can be found playing with sequences of ones. However, who the heck found that:
$$2^n+7^n+8^n+18^n+19^n+24^n=3^n+4^n+12^n+14^n+22^n+23^n \text{ for } n =0,1,...,5$$

 

[jedishrfu]

Many genius level mathematicians have an incredible computation skill.

I remember the scene in the Ramanujan movie where one of the Oxford dons could do fast calculations and battled with Ramanujan to test his skill or something like that.

There also was that savant David Tamett who could do remarkable feats of calculation and memorization.

 

[DaveC426913]

Today I learned that if you don't have a spare CR2032 battery handy, two CR2016s, stacked, will do the job nicely.

Only in devices that will tolerate a doubling of the voltage.

 

[Ibix]

Many genius level mathematicians have an incredible computation skill.

You know that puzzle with two trains that start 70km apart and travel in opposite directions, one at 30kph and one at 40kph and a fly that flies backwards and forwards between the trains at a constant 80kph (it's one o' them rocket propelled flies) - how far has the fly traveled when the trains meet? There's a popular theory that mathematicians given this problem spot that there are two geometric series to sum, but physicists shy away from the computation, and then note that the trains meet in an hour so the fly also travels for an hour, hence flies 80km.

There's a story of someone who decided to test that theory, and the first person he happens across is John von Neumann. He quickly lays out the problem and von Neumann says instantly "80km". The guy is a little crestfallen and explains to von Neumann that he had expected him, as a mathematician, to take the series sum solution rather than the easy way. "Ah," says von Neumann, looking a little embarrassed. "You're right, there is an easier way to do it."

 

[rsk]

Only in devices that will tolerate a doubling of the voltage.

I did wonder about this, but it seems to be ok.

FWIW it's the button part of a wireless doorbell in my parents' home.

 

[DaveC426913]

I did wonder about this, but it seems to be ok.

FWIW it's the button part of a wireless doorbell in my parents' home.

Is their doorbell twice as loud now?

 

[rsk]

Is their doorbell twice as loud now?

Button part. The bell part still has its regulation batteries. But now I'm scared that the post man or delivery man might get hurt when pushing the button

(nah, 6V not going to hurt anyone, right?)

 

[Ibix]

FWIW it's the button part of a wireless doorbell in my parents' home.

Several years ago I learned that if you buy a wireless doorbell and select one of the sixteen channels it can transmit on at random, your neighbour will also buy the same model and select the same channel. Neither of you get loads of unexpected visitors, so the one who actually has a visitor will usually be ready and let them in before the other has found his front door keys. So it will take some months for you to work out the cause of occasional "nobody there" bell rings...

 

[pbuk]

Only in devices that will tolerate a doubling of the voltage.

Yeah, don't try this at home kids. Youd be better off jamming some aluminium foil wrapped round cardboard in there.

 

[mfb]

However, who the heck found that:
$$2^n+7^n+8^n+18^n+19^n+24^n=3^n+4^n+12^n+14^n+22^n+23^n \text{ for } n =0,1,...,5$$

What computer found that?
Prouhet–Tarry–Escott_problem

 

[rsk]

Only in devices that will tolerate a doubling of the voltage.

Yeah, don't try this at home kids. Youd be better off jamming some aluminium foil wrapped round cardboard in there.

Heeding these warnings, I decided to rummage through my foreign coin collection to see if I had anything approximately battery sized and thin enough and yes, it works!

The odd thing about this is that the coin is a US dime and the only time I ever set foot in the USofA was to transit through Atlanta airport. I don't even know what a "dime" means.

But anyway, it's working, presumably at 3V instead of 6V and with a spare battery returned to the blister it came from.

 

[jedishrfu]

A penny is one cent, a nickel is five cents, dime is ten cents, a quarter is 25 cents, and a half dollar is 50 cents vs a US dollar which is 100 cents.

There may be some other more obscure US coins that are no longer in use But I don’t remember them.

oh yeah we even have a two dollar bill which my coworker would use to be different when shopping. They weren’t popular and caused havoc at the cash register because there weren’t enough drawer slots for all the common bills 1, 5, 10, and 20 and this one.

 

[rsk]

Interesting fact, Cuba actually has notes worth 3 pesos. 1, 3, 5, 10, 20, 50 ... no 30s or 300s, just the 3.

This applied in both their CUP and CUC, but the latter (the convertible one pegged to the US$) has recently been removed from circulation - the currency, not just the 3 peso note.

 

[JT Smith]

But anyway, it's working, presumably at 3V instead of 6V and with a spare battery returned to the blister it came from.

Hang onto that extra battery. The cr2016 is less than half the capacity of the '32 so you'll be fiddling with it a lot sooner than if you just went to the store and bough the right battery.

 

[berkeman]

dime is ten cents

A dime is also an assist in basketball...

https://basketballword.com/in-basketball-what-does-dropping-dimes-mean-explained/#

Many of us know basketball terminology but have no clue where terms may have come from or how they originated. Such is the case with the saying dropping dimes.

What does dropping dimes mean in basketball? In basketball, the term dropping dimes refers to an assist, in which a player will make a pass to a teammate which leads to scoring a basket. The dime we are talking about is the ten-cent coin that was needed to use a payphone. Putting a 10 cent coin into the payphone was known as dropping a dime.

A dime may be an easy or difficult pass that would lead to a score in basketball. The saying would usually come from the player that acquired the assist, or by fans watching the player do so. “He’s dropping dimes”.

 

[JT Smith]

Interesting fact, Cuba actually has notes worth 3 pesos. 1, 3, 5, 10, 20, 50 ... no 30s or 300s, just the 3.

Apparently the U.S. used to have a three cent coin, way back when. Half penny, two cent, and twenty cent coins as well.

 

[rsk]

Hang onto that extra battery. The cr2016 is less than half the capacity of the '32 so you'll be fiddling with it a lot sooner than if you just went to the store and bough the right battery.

Just as soon as it stops raining.

 

[mfb]

A penny is one cent, a nickel is five cents, dime is ten cents, a quarter is 25 cents, and a half dollar is 50 cents vs a US dollar which is 100 cents.

Is the half dollar actually used?
There are 1 dollar coins.
https://en.wikipedia.org/wiki/Dollar_coin_(United_States)

For some reasons your 5 cent coin is larger than the 10 cent coin, and apparently 50 cent is larger than 1 dollar as well.

 

[JT Smith]

Is the half dollar actually used?

Not very often. Dollar coins are also not seen frequently. For that matter, who uses cash anymore? Since the pandemic shut down I think I've paid in cash about five times.

The $2 paper bill is also kind of rare. You can get them at the bank if you want. A friend owed me a couple hundred dollars and paid me with 100 of them just for fun!