Today I Learned

[fresh_42]

Yeah, stick with the wife... .

One of these mysteries in the universe: they are always right and we have absolutely no clue how they manage it.

 

[OCR]

One of these mysteries in the universe: they are always right and we have absolutely no clue how they manage it.

That's one of the major unsolved problems that is theoretical... meaning, that existing theories seem incapable of explaining a certain observed phenomenon or experimental result.

 

[mfb]

Today I learned about lithium fluorine (+hydrogen) as rocket propellant.
It has a higher specific impulse (exhaust velocity) than all other tested chemical propellants, even higher than hydrogen+oxygen. It has some minor disadvantages, however:

- It needs liquid fluorine, at a temperature below -188 °C (85 K, -307 °F) to prevent boiling.
- It needs liquid lithium, at a temperature above 180 °C (453 K, 356 °F) to prevent freezing.
- It needs liquid hydrogen, at a temperature below -252 °C (21 K, -423 °F) to prevent boiling.
- Liquid fluorine is extremely corrosive and reacts with nearly everything.
- Liquid lithium is extremely corrosive and reacts with a lot of stuff, including spontaneous ignition when in contact with air, water or organic substances
- Liquid hydrogen, when in contact with air and a flame, can explode.
- Fluorine will spontaneously react with both hydrogen and lithium, and lithium and hydrogen together will also react (but slower).
- Fluorine is toxic.
- Hydrogen fluoride is toxic and part of the exhaust stream.
- All three propellants must be combined in a suitable ratio at the same time for a proper reaction.

It has been https://www.flightglobal.com/pdfarchive/view/1967/1967%20-%200069.html, but then it was considered to be too impractical for rockets.

 

[yecko]

Today, I've learned the reason why does a comet's tail always face away from the sun.
Comet is made up of a nucleus (solid, frozen ice, gas and dust), a gaseous coma (water vapor, CO2, and other gases) and a long tail (made of dust and ionized gases). The tail develops when the comet is near the Sun. Its long ion tail of always points away from the sun, because of the force of the solar wind.
http://www.enchantedlearning.com/subjects/astronomy/comet/

 

[Grands]

Today I learned that everyday a lots of people die because there are economical interests, which for some riches are more important then life.

 

[stephenkohnle53]

Today I learned that mercury is not nearly as dangerous as many people think, although it still is dangerous

 

[Best Pokemon]

TIL that the long term average of IQ points (tested on Finnish recruits, and then found in the data-sets of other countries, too) has been increasing until the mid nineties and is decreasing ever since by 2 points per decade.
During my search for some quotable data (I saw it on TV, however, it was a serious channel), I found that scientists assume a correlation of those scores to the average temperature. I really wasn't expecting this as a result of CC. (The last statement is my conclusion and an exaggeration. It is not claimed by anyone. They assume a correlation based on their data of scores versus location, not CC. But a strange coincidence anyway.)

Warm weather makes it harder to think: https://www.scientificamerican.com/article/warm-weather-makes-it-hard-think-straight/

 

[BillTre]

TIL that this exists:

 

[AbstractlyAlgebraic]

Today I learned that I really don't want to go to graduate school in math anymore. It just don't like it as much as I thought I did.

 

[OmCheeto]

TIL that a packet of "Top Ramen" is supposed to feed two people.

It's no wonder I'm so fat.

 

[stephenkohnle53]

That the solar light my mom threw out just needed a new battery, good thing I got it from the recycling bin

 

[Posy McPostface]

Today I learned that I really don't want to go to graduate school in math anymore. It just don't like it as much as I thought I did.

That's unfortunate. Was it theoretical or practical application? Your nick seems to imply the former, so why not try the latter?

 

[fresh_42]

I just learned that the English "town" and the German "Zaun", which means fence, are of the same origin, meaning something within boundaries. This sheds a completely new light on towns.

 

[epenguin]

I just learned that the English "town" and the German "Zaun", which means fence, are of the same origin, meaning something within boundaries. This sheds a completely new light on towns.

I didn’t know that! We think of towns in the Middle Ages is having as being enclosed by walls, The walled enclosure being almost the definition of ‘town’ . I’d picked up somehow the wrong idea that the very common English place name suffix ‘-ton’ just meant “a place” or ‘settlement’. Now a fence may not being much of a, hey, defence, compare to town on or castle walls, but people in the dark and the Middle Ages needed to live in groups, not isolated farmhouses, Were keen for their communities’ space to be delimited, marked. Outside the fence was the Marsh or Mark, if you were there you could have arrows trained on you, you were a marked man.

 

[Rx7man]

Wasn't *today* but I learned a lot about myself recently, dug up courage and strength I didn't know I had... Matters of the heart don't come easy to logical, analytical people!

 

[jim hardy]

Matters of the heart don't come easy to logical, analytical people!

Before one let's his head overrule his heart, he should make sure it is the wiser of the two. I think women have an advantage there.There's lots of country songs written about such mistakes. I'm contemplating one myself.

old jim

 

[OCR]

I'm contemplating one myself.

That's too horrifying to contemplate... .

 

[jim hardy]

That's too horrifying to contemplate... .

Horrifying ?
Which one ? The erreurs du coeur or country music ?

 

[OCR]

Which one ? The erreurs du coeur or country music ?

Uh, no... writing one...? But if you insist, use some good backup... like this. .

Or... like this . .

Or, just sing along with... Emmylou ..

 

[fresh_42]

Uh, no... writing one...?
But if you insist, use some good backup... like this. .
Or... like this . .
Or, just sing along with... Emmylou ..

Seems to prove one of my favorite quotes about country:
"Three chords and the truth." (D.Parton)

 

[jim hardy]

Uh, no... writing one...?But if you insist, use some good backup... like this. .

Or... like this . .

Or, just sing along with... Emmylou ..

Good choices all.

I'm thinking along a theme Reflections on erreurs du couer, to effect "I'll never get into heaven all my Mother-In-Law's are there".

old jim

 

[AbstractlyAlgebraic]

That's unfortunate. Was it theoretical or practical application? Your nick seems to imply the former, so why not try the latter?

Well, I kind of failed real analysis, and I got a C- in complex analysis, so... my grades just aren't high enough to get in, honestly. And I hated both of those classes. I got an A in physics though. I might try to go for statistics or do a minor in physics or something. I like math, but the math major is just making me miserable.

 

[Posy McPostface]

Well, I kind of failed real analysis, and I got a C- in complex analysis, so... my grades just aren't high enough to get in, honestly. And I hated both of those classes. I got an A in physics though. I might try to go for statistics or do a minor in physics or something. I like math, but the math major is just making me miserable.

Ah, I see. I'm at my limits of what I can advise, perhaps someone else cares to chime in?

 

[Psinter]

Anders Celsius. Can you guess what I learned by the name?

He founded the Uppsala Astronomical Observatory in 1741, and in 1742 proposed the Celsius temperature scale which bears his name.

I also learned

Celsius conducted many geographical measurements for the Swedish General map, and was one of earliest to note that much of Scandinavia is slowly rising above sea level, a continuous process which has been occurring since the melting of the ice from the latest ice age. However, he wrongly posed the notion that the water was evaporating.[3]

But hey, I don't blame him. My logic would have told me same. I would have hypotethized: "I think the rise is due to evaporation... But how can I experiment and test?" Logic can be wrong.

 

[stephenkohnle53]

Today I unfortunately learned how hot a soldering iron truly is. On the bright side I now know how to use a soldering iron and the importance of always wearing protection.

 

[Lisa!]

TIL some stuff about Handicrafts!

 

[berkeman]

Today I unfortunately learned how hot a soldering iron truly is. On the bright side I now know how to use a soldering iron and the importance of always wearing protection.

LOL. When I was about 10 years old, I was learning how to solder using a Weller Soldering Gun, and I wondered to myself whether the shiny rods that hold the tip were hot. Yep, they were!

http://www.stevenjohnson.com/soldering/pics/weller-8200n.jpg

 

[berkeman]

Today I learned two things about dribbling my new basketball down the hall at work (do not ask me why I am at work on a Holiday weekend, and don't ask why I'm dribbling down the hall please...)

We have a nice thin springy carpet at my work, and surprisingly, the basketball rebounds up about 20% higher than it does on hard asphalt or concrete. I did not expect that!

And it turns out dribbling a basketball down the hall on this type of carpet generates a huge amount of static electric buildup on the ball (and me, unfortunately). When I grabbed the doorknob to dribble out into the lobby, KABLAM! (must have been close to a 30kV shock!)

 

[Ibix]

And it turns out dribbling a basketball down the hall on this type of carpet generates a huge amount of static electric buildup on the ball (and me, unfortunately). When I grabbed the doorknob to dribble out into the lobby, KABLAM! (must have been close to a 30kV shock!)

https://m.xkcd.com/242/

 

[jim hardy]

https://m.xkcd.com/242/

Great one.
This might belong in "Random Thoughts" , but following @Ibix's lead
http://www.cvaieee.org/html/humor/marry_not_an_engineer.html

Marry Not An Engineer
[I first saw this on a little yellow card distributed by Schweber Electronics in the late 1960's. I can't find that card anymore but I found this on the Internet and it agrees with my memory. - LH]

Verily, I say unto ye,
marry not an engineer.
For an engineer is a strange being
and possessed of many evils.

Yea, he speaketh always in parables
which he calleth formulae.
He wieldeth a big stick
which he calleth a slide rule.
And he hath only one bible,
a handbook.

He thinketh only of strains and stresses,
and without end of thermodynamics.
He showeth always a serious aspect
and seemeth not to know how to smile.
He picketh his seat in a car by the springs thereof
and not by the damsels.

Neither does he know a waterfall
except by its horsepower,
Nor a sunset
except that he must turn on the light,
Nor a damsel
except by her weight.

Always he carrieth his books with him,
and he entertaineth his sweetheart with steam tables.
Verily, though his damsel expecteth chocolates when he calleth,
She openeth the package to discover samples of iron ore.

Yea, he holdeth her hand
but to measure the friction thereof,
and kisseth her
only to test the viscosity of her lips,
for in his eyes shineth a far away look
that is neither love nor longing,
but a vain attempt to recall formulae.

Even as a boy, he pulleth a girl's hair
but to test its elasticity.
But as a man,
he deviseth different devices.
For he counteth the vibrations of her heartstrings
And seeketh ever to pursue his scientific investigations.

Even his own heart flutterings
he counteth as a measure of fluctuation.
And his marriage is but a
simultaneous equation involving two unknowns.
And yielding diverse results.

Verily, I say unto ye,
marry not an engineer.

Fair Anne puts up with me though.

old jim

 

[berkeman]

Fair Anne puts up with me though.

 

[Posy McPostface]

Milton Friedman forsaw the internet form of Bitcoin, eons ahead of anyone else.

 

[fresh_42]

Milton Friedman forsaw the internet form of Bitcoin, eons ahead of anyone else.

You're far too focused on it. Be careful, it's a high risk, very volatile investment and other forms already entered the stage.

 

[Posy McPostface]

You're far too focused on it. Be careful, it's a high risk, very volatile investment and other forms already entered the stage.

Yeah, I agree. That boat has sailed already.

 

[Psinter]

One can have a bigger foot than the other.

I started measuring my feet and noticed that one measurement was larger than the other and I was like: "This cannot be, I must be doing something wrong." Although the difference wasn't much.

I spent half an hour measuring my feet again and again until someone told me that people can have one foot bigger than the other.

That moment when you think you are doing something wrong, but you are not.

 

[PetSounds]

TIL (through experimentation and observation) that no matter how long you spend working on an essay, you can never determine how it's going to be received.

 

[Psinter]

There is a galaxy named Triangulum: https://en.wikipedia.org/wiki/Triangulum_Galaxy

In my astronomical illiteracy (pun fully intended), I laughed when I heard the name. It sounds like a Harry Potter spell. Triangulum!

 

[Jonathan Scott]

We recently had a couple of dense showers of dry little balls of snow, smaller than a pea and white rather than clear ice, falling slower than normal hail, resembling tiny little balls of snow, landing quietly and looking very similar to some polystyrene packaging beads. I didn't know what to call it, so I searched online for an appropriate term. Today I learned that the correct term is "graupel", a term of which I was previously unaware, and it is also sometimes described as soft hail.

I also learned that the term "sleet" (which here in the UK means a slushy wet mixture of rain and snow) is used in other places such as the USA and Canada as a general term for precipitation in the form of ice pellets.

 

[Drakkith]

I also learned that the term "sleet" (which here in the UK means a slushy wet mixture of rain and snow) is used in other places such as the USA and Canada as a general term for precipitation in the form of ice pellets.

Yep. We actually use "sleet" to refer to both.

 

[fresh_42]

TIL that things can explode in a microwave.

Before you laugh and write things like "I could have told you", I bet you wouldn't had expected to be goulash in that category either!

 

[Drakkith]

Before you laugh and write things like "I could have told you", I bet you wouldn't had expected to be goulash in that category either!

I've had spaghetti "explode" and coat the inside of my microwave with sauce. The key to cooking in a microwave is to have a microwave with an inverter and to use it at a lower power when heating most foods.

 

[fresh_42]

I've had spaghetti "explode" and coat the inside of my microwave with sauce. The key to cooking in a microwave is to have a microwave with an inverter and to use it at a lower power when heating most foods.

Yes, but the problem wasn't the sauce, I had the plate covered, it was the beef which was torn into parts and lifted the cover.

 

[Drakkith]

Yes, but the problem wasn't the sauce, I had the plate covered, it was the beef which was torn into parts and lifted the cover.

Chicken commonly does that to me.

 

[lekh2003]

I've had particularly smooth microwave experiences. What do you guys do that dangers it up?

 

[Drakkith]

I've had particularly smooth microwave experiences. What do you guys do that dangers it up?

No idea.

 

[lekh2003]

No idea.

Oh, but I did forget to mention the time my sister put a chocolate with metal wrapping in the microwave. We heard sparks followed by smoke and my sister ran out of the kitchen screaming.

 

[Borg]

TIL that things can explode in a microwave.

Before you laugh and write things like "I could have told you", I bet you wouldn't had expected to be goulash in that category either!

I've seen it with various types of food. Beans can really explode if you cook them too long.
I knew someone who put a hot dog on a plastic plate for 10 minutes in a microwave. It didn't explode but it really shriveled up and welded to the plate.

 

[Tom.G]

We usually keep a jar of peanut butter in the refrigerator so it doesn't separate. Occasionally the peanut butter will get too thick to spread, in which case a 10 second zap in the microwave is applied. Now the jars have a paper and foil laminate seal which gets removed upon opening. Occassionally a small scrap of the the seal will stick on the rim of the jar. Well, {thin metal foil} + {microwave oven} = {impressively bright plasma cloud} + {LOUD buzzing sound from oven}.

No further tests are planned.

 

[jim hardy]

Never try to hard boil an egg...

 

[DrGreg]

Today I learned that Barry Manilow's hit record "I Write the Songs" was not written by Barry Manilow.