Today I Learned

[RonL]

The appearance of Bandersnatch here prompted me to finally look up the term. I have never read any Lewis Carroll stuff. So today I learned that, all linguistic cues to the contrary, a "bandersnatch" is not in fact a chastity belt. I now take my leave.

I suspect that this is Danger's last post, he was in very poor health as I understand, does anyone know if he is still alive ?
I kinda miss him

 

[Stephanus]

I suspect that this is Danger's last post, he was in very poor health as I understand, does anyone know if he is still alive ?
I kinda miss him

Truly sorry, if this is true. It's sad to have a friend in trouble. My prayer to Danger, I hope he/she will get well soon. Amen.

 

[Astronuc]

TIL How a Guy From a Montana Trailer Park Overturned 150 Years of Biology
Biology textbooks tell us that lichens are alliances between two organisms—a fungus and an alga. They are wrong. Lichens are formed from three organisms.

http://www.theatlantic.com/science/...er-park-upturned-150-years-of-biology/491702/
Lesson 1 - if the path is blocked, find an alternative path.

At 19, he got a job at a local forestry service. Within a few years, he had earned enough to leave home. His meager savings and non-existent grades meant that no American university would take him, so Spribille looked to Europe.

Thanks to his family background, he could speak German, and he had heard that many universities there charged no tuition fees. His missing qualifications were still a problem, but one that the University of Gottingen decided to overlook. “They said that under exceptional circumstances, they could enroll a few people every year without transcripts,” says Spribille. “That was the bottleneck of my life.”

Lesson 2 - we don't have all the answers; there's always more to learn

In the 150 years since Schwendener, biologists have tried in vain to grow lichens in laboratories. Whenever they artificially united the fungus and the alga, the two partners would never fully recreate their natural structures. It was as if something was missing—and Spribille might have discovered it.

He has shown that largest and most species-rich group of lichens are not alliances between two organisms, as every scientist since Schwendener has claimed. Instead, they’re alliances between three. All this time, a second type of fungus has been hiding in plain view.

“There’s been over 140 years of microscopy,” says Spribille. “The idea that there’s something so fundamental that people have been missing is stunning.”

Lesson 3 - don't give up. If necessary, find a mentor with an open mind.

The path to this discovery began in 2011, when Spribille, now armed with a doctorate, returned to Montana. He joined the lab of symbiosis specialist John McCutcheon, who convinced him to supplement his formidable natural history skills with some know-how in modern genetics.

Pretty amazing story.

 

[Astronuc]

I suspect that this is Danger's last post, he was in very poor health as I understand, does anyone know if he is still alive ?
I kinda miss him

Danger was last seen: Mar 12, 2015. He browsed the forum but did not post since 2014.

 

[Stephanus]

Today I learned that
The French revolusion caused https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure
How can NASA be so foolish?
Metric system

 

[Pepper Mint]

Danger was last seen: Mar 12, 2015. He browsed the forum but did not post since 2014.

Is Danger someone I know ?

 

[Astronuc]

Is Danger someone I know ?

No, he was before your time at PF.

 

[Astronuc]

Today I learned that
The French revolusion caused https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure
How can NASA be so foolish?
Metric system

It wasn't only NASA.
https://en.wikipedia.org/wiki/Gimli_Glider

As they communicated their intentions to controllers in Winnipeg and tried to restart the left engine, the cockpit warning system sounded again with the "all engines out" sound, a long "bong" that no one in the cockpit could recall having heard before and that was not covered in flight simulator training.[4] Flying with all engines out was something that was never expected to occur and had therefore never been covered in training.[6] Seconds later, with the right-side engine also stopped, the 767 lost all power, and most of the instrument panels in the cockpit went blank.

In line with their planned diversion to Winnipeg, the pilots were already descending through 35,000 feet (11,000 m)[3] when the second engine shut down. They immediately searched their emergency checklist for the section on flying the aircraft with both engines out, only to find that no such section existed.[4] Captain Pearson was an experienced glider pilot, so he was familiar with flying techniques almost never used in commercial flight. . . . .

What luck!

Expect the unexpected.

 

[Borg]

It wasn't only NASA.
https://en.wikipedia.org/wiki/Gimli_Glider

That is an amazing story. Even more amazing to me is that the plane was repaired and flown again for many years.

The aircraft was temporarily repaired at Gimli and flew out two days later to be fully repaired at a maintenance base in Winnipeg. Following the successful appeal against their suspensions, Pearson and Quintal were assigned as crew members aboard another Air Canada flight. As they boarded the aircraft, they realized that airplane was the same one involved in the Gimli incident. After almost 25 years of service, the aircraft flew its last revenue flight on January 1, 2008.

 

[mfb]

Today I learned that
The French revolusion caused https://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure
How can NASA be so foolish?
Metric system

I would instead blame the only government not pushing to adapt the system 95% of the world population uses.

We would have way more accidents like this if every country would use their own units.

 

[OmCheeto]

TIL that the U.S. distilled alcohol industry converted to the metric system in 1979.
One very common quantity, the "fifth", may have been widely accepted by consumers, as 1/5 of a gallon (0.2 gallons) is very close to the new 750 ml bottles (0.198 gallons).

 

[Stephanus]

I would instead blame the only government not pushing to adapt the system 95% of the world population uses.

We would have way more accidents like this if every country would use their own units.

You tell me. I live in MKS, but I'm having trouble understanding my tyre (tire?) pressure in pascal rather than in psi.

Spoiler: psi to Pascal

1 pound = 0.453
1 inch = 2.54
$Pa = \frac{0.453}{2.54*2.54/100/100} = 702$
$Pa = 702 * 9.8 = 6881?$
$1 psi = 6881 pascal?$

 

[Stephanus]

TIL that the U.S. distilled alcohol industry converted to the metric system in 1979.
One very common quantity, the "fifth", may have been widely accepted by consumers, as 1/5 of a gallon (0.2 gallons) is very close to the new 750 ml bottles (0.198 gallons).

Ahhh, and there are gallons, barel, and all those things. And I also remember. I can picture AUXUSD (the price of gold in US dollar) in how many dollar per troy ounce, rather than how many dollars in gram/kg. Who is troy anyway?

 

[jim hardy]

You tell me. I live in MKS, but I'm having trouble understanding my tyre (tire?) pressure in pascal rather than in psi.

i gave up long ago
went to atmospheres , one of those is within 2% of 100kPa
and quarts, one of those is within 6% of a liter
but i still have to look up hogsheads .

 

[Astronuc]

When I studied physics, we did our work in MKS and cgs. When I did nuclear engineering, it was mostly British units with some SI.

When I started working professionally, we had clients throughout the US and the rest of the world, so we used both systems. I prefer SI, and many codes I have used are written with SI internally (with some models specifically in British units because experiments were done in BU), but the codes would have options to do input and output in British or SI/cgs. Since manufacturing uses dimensions in inches/mils/micro-inches or cm/microns, there were mixed systems.

 

[jim hardy]

Since manufacturing uses dimensions in inches/mils/micro-inches or cm/microns, there were mixed systems.

speaking of mixed systems...
the little diesel engine in 83-84 Ford Rangers is mixed , all the bolts in it have metric heads but inch threads...

it was a Perkins design built in Japan by Mazda.

 

[mfb]

went to atmospheres , one of those is within 2% of 100kPa

One of the weird historical coincidences.

The second is 1/86400 of a day - that is older than the SI.

The two proposed definitions for the meter were:
(a) the length of a pendulum with a period of 2 seconds, fixing $g=\pi^2 \frac{m}{s^2}$ (~9.87) for the point where the definition is applied.
(b) 1/(10 million) times the length from a pole to the equator
Those two independent lengths agree to better than 1%, the latter got chosen.

The kilogram was based on 1dm³ of water, fixing its density (at a given temperature) to 1000 km/m³.

Combining those three units, kPa is fixed. 100 kPa (using the accidental $g \approx \pi^2 \approx 10$) corresponds to about 100,000 kg/m² mass of the atmosphere, or (using the non-accidental density of water) to about 10 meters of water, which is about 1 millionths of the pole/equator distance. Which happens (another coincidence) to be within the small actual range of atmospheric pressure.

 

[jim hardy]

Combining those three units,

I really like little memory aids like that, they give perspective.

A Newton is roughly 1/4 lbf, so i tell beginners "think of a hamburger not a cookie ".

 

[Ibix]

all the bolts in it have metric heads but inch threads...

That's nuts...

 

[Ibix]

One of the weird historical coincidences.

A year isn't far off $\pi\times10^7$s - about 0.5%.

One gravity is approximately one light year per square year, useful for those relativistic rockets.

 

[Stephanus]

When I studied physics, we did our work in MKS and cgs. When I did nuclear engineering, it was mostly British units with some SI.

Today I learned that Americans use British Units, and the British' use metric unit??
That was what was confusing me all this time. I heard that Americans use different units than British.
American use miles, inch, pound.
But what about the British? Surely British would use something else than miles and pound.
But miles and pound are British units.
Argghhh...

That's nuts...

@Ibix is right! But now I truly understand.
It's no wonder that a-200 millions dollars NASA's Mars Climate satelite crashed. We live in a crazy world, no matter what Carl said. We have to understand those units out of the blue in this pale blue dot!

We would have way more accidents like this if every country would use their own units.

I hope we'll be careful in our everyday life.

 

[Stephanus]

A year isn't far off $\pi\times10^7$s - about 0.5%.

One gravity is approximately one light year per square year, useful for those relativistic rockets.

Gosh, you're right!
But it's 9.8 km/s² not m/s²

 

[mfb]

There are many different pounds and different miles. Three miles are still in use - the nautical one, the "normal" one, and my favorite weird unit, the US survey mile, which is about 3.2 millimeters longer than the normal mile.

@Stephanus: the 300,000,000 is meter/second. It is m/s^2.

 

[Stephanus]

There are many different pounds and different miles. Three miles are still in use - the nautical one...

Yep, 40000km/360/60

 

[DrGreg]

Today I learned that Americans use British Units, and the British' use metric unit??

The terms "British Units" and "English Units" are, nowadays, I think, used only by Americans. Here in the UK, if we want to refer to the old units, we call them "Imperial Units" (if anything).

Almost everything in the UK now is officially metric, with just a handful of exceptions, for example:

• draught beer and cider must be sold in pints;
• milk may be (optionally) sold in pints;
  
• distances along roads and railways are still in miles and yards (and chains on the railways);
  
• vehicle speeds are still in miles per hour.

Unofficially, imperial units may be used in everyday life by some people (especially older generations), e.g. stones and pounds for body mass, feet and inches for body height, Fahrenheit for air temperature on a hot day (but Celsius on a cold day!). Vehicle fuel consumption is often expressed in miles per gallon even though fuel is sold in litres!

I just hope that, post-Brexit, we don't abandon the metric system!

 

[DrGreg]

One gravity is approximately one light year per square year, useful for those relativistic rockets.

And, of course, the speed of light is about one foot per nanosecond.

(I suppose, in the spirit of SI, that should really be one gigafoot per second.)

 

[Ibix]

View attachment 103759
Gosh, you're right!
But it's 9.8 km/s² not m/s²

You've slipped up somewhere - I agree that the answer should be c / year, but that should be $\simeq (3\times 10^8 \mathrm {ms^{-1}}) / (\pi \times 10^7 \mathrm s)\simeq 9.5 \mathrm {ms^{-2}}$, about 3% below g=9.81ms^-2.

 

[jim hardy]

Almost everything in the UK now is officially metric, with just a handful of exceptions, for example:

No more Whitworth bolts ?

http://britishfasteners.com/threads/bsf.html

 

[jim hardy]

British anvils are strangely marked ... i ran across a early 1800's " Mousehole Forge" anvil at the metal scrapyard.

Anvils-6: Marked Weight of Anvils
Anvils are marked in a variety of methods but most English anvils were marked using the hundredweight system. American made anvils are marked in pounds. Anvils made in other places (including many Swedish anvils) are often marked in pounds. A few are marked in kilograms and some cast anvils are marked in pounds rounded to the nearest 10 pounds (250# = 25). Cast markings are easy to identify as they are usualy raised figures rather than stamped into the anvil. Then there are the many unmarked anvils. . . If you are not sure and you really need to know then weigh it. English Hundreds Weight (hundredweight) System:
Typically the hundreds weight markings are separated by dots but not always. These figures were stamped into the finished anvil and are often not very deep. The first figure to the left is hundred weights which equal 112 pounds. The next figure is quarter hundred weights which equal 28 pounds and the last number is whole pounds. The three are added together for the total weight. Examples:

1 · 0 · 16 = 112 + 0 + 16 = 128 pounds

2 · 1 · 3 = (112 x 2) + 28 + 3 = 255 pounds

2 · 2 · 25 = (112 x 2) + (28 x 2) + 25 = 305# The second place is never over 3 so if you have difficulty reading the number it is a 1, 2 or 3. The last place is never over 28 and most often is a single digit or less than 20.

The weight of these is usualy +/- 1 pound when measured on an accurate modern scale.

SO. . . how did the English weigh anvils and figure the marking?

EASY, on a balance scale using hundred weight, quarter hundred weight and pound weights.

 

[Astronuc]

American use miles, inch, pound.

And BTUs, BTU/hr, and BTU/ft²-hr. I've seen legacy code with steaming rates in BTU/ft²-hr. W/m² is so much better

Or heat transfer coefficients in BTU/ft²-hr-°F. I much prefer W/(m²K).Still it's better than horsepower/leagues or leagues/fortnight.