Today I Learned

[jim hardy]

The hot air engine uses the Stirling Cycle which I believe is a reasonable practical approximation. It chugged away beautifully for ages this afternoon, although it needed occasional oil to help seal the piston. My son was quite interested in it, but my daughter not so much; I think she's more into the theory than the engineering.

I remember reading about Ford's experimental Stirling-engined automobile.
Looks like there were several others...

http://blog.hemmings.com/index.php/...-drops-stirling-engines-in-some-odd-vehicles/

http://stirlingengineforum.com/viewtopic.php?t=1618

Hobbyists of the day liked the old Chrysler sv2 automobile Freon compressor for DIY Stirling projects because it is a 90 degree V giving you the offset you need...
http://diystirlingengine.com/sv-2-stirling-engine-generator/

old jim

 

[epenguin]

Today I learned that I share the same birthday as Erno Rubik.

Today I learned that Tumblr is considered social media.

Today I noticed that Chaplin and Hitler have the same type of mustache, but I still prefer the mustache of Poirot better.

Well Chaplin had it a long time before Hitler - and Hitler was often referred to as soon as anyone noticed him as the 'man with the Charlie Chaplin moustache'.

I am sure that fact this made him faintly comical helped the underestimation of how dangerous he was.

TIL "Chaplin's son Charles Jr. described his father as being haunted by the similarities in background between him and Hitler; they were born four days apart in April 1889, and both had risen to their present heights from poverty." (Wikipedia article).

The thing came weirdly together in Chaplin's film 'The Great Dictator' which would not have been the same thing without the already widely noticed resemblance, which I wonder whether it was total concidence.

 

[jtbell]

Today I learned that from 1978 to 1989, skateboarding was banned in Norway.

http://www.bbc.com/news/magazine-36077122

 

[Hornbein]

Today I learned that Dwight Eisenhower thought that dropping the atomic bomb on J was a terrible idea.

 

[JorisL]

TIL I hadn't installed gcc when I reinstalled my system back in the beginning of november (!)

So it's been almost 6 months without programming in C...

 

[jim hardy]

Today I learned that Dwight Eisenhower thought that dropping the atomic bomb on J was a terrible idea.

Waiting for the Russians to ravage J wouldn't have been very kind either.

It would be interesting to speculate how, were their roles swapped, MacArthur would have handled European and Ike the Pacific campaigns .

 

[1oldman2]

Today I learned that 4/22 is J. Robert Oppenheimer's birthday.

 

[ProfuselyQuarky]

Today I learned that 4/22 is J. Robert Oppenheimer's birthday.

Happy Birthday J.R.O. (yeah, I'm talking to a dead person, I know )

TIL how to convert a mp4 into a mp3. Yeah, baby!

 

[ProfuselyQuarky]

Today I learned that from 1978 to 1989, skateboarding was banned in Norway.

http://www.bbc.com/news/magazine-36077122

Those must have been dark days.

 

[1oldman2]

TIL how to convert a mp4 into a mp3. Yeah, baby!

That was a watershed moment in my life also, I keep all my music in MP3.

 

[ProfuselyQuarky]

That was a watershed moment in my life also, I keep all my music in MP3.

Most audio files I've got are either flac or mp4, unfortunately, but when adding music to a video for an upload, Camtasia only allows mp3 so I can't get around that.

Ever since six hours ago, I feel so accomplished

 

[Hornbein]

Today I learned that maple sap collection ceases when the tree buds. The sap turns bitter.

 

[Pepper Mint]

I learned today Clara Immerwahr, Fritz Haber's wife, killed herself to oppose his work in chemical warfare during WW I by shooting herself in the heart. She'd been buried in Dahlem at first but later her remains, upon her husband request, were moved to Basel where she was then buried next to him. He remarried after her death but still made such a wish at the end of his life.

 

[Hornbein]

Today I learned that the secret police of Russia use Oracle databases.

 

[andrewkirk]

Today I learned some a very useful trick that can be used to reduce the amount of typing needed when typing latex code:

It is based on the fact that when a command like \sqrt requires arguments that are usually put in braces {...}, you can omit the braces if the argument is an 'atom', where an 'atom' is either a single character or (in some cases) an argumentless command (like \partial).

If the argument uses alphabetic characters, you need to leave a space between the command and the argument. If it's non-alphabetic, you don't.

So
\frac12 gets you $\frac12$, instead of having to type \frac{1}{2}
\vec v gets you $\vec v$, instead of having to type \vec{v} [the same approach works for \tilde, \bar etc]
\sqrt x\sqrt2 gets you $\sqrt x\sqrt2$, instead of having to type \sqrt{x}\sqrt{2}
\mathcal T^i gets you $\mathcal T^i$, instead of having to type \mathcal{T}^j
\mathbb R gets you $\mathbb R$, instead of having to type \mathbb{R}
\frac\partial{\partial x} gets you $\frac\partial{\partial x}$, instead of having to type \frac{\partial}{\partial x}

Maybe it's just me but my fingers are not very quick at finding those curly braces on the keyboard, so not having to type them speeds me up a lot!

 

[jim hardy]

testing

\frac nd
\fracnd
\frac n/d

\frac numerator denominator

\frac12

computers are just that way.

 

[jtbell]

You still need the delimiters at the beginning and end of the LaTeX code. $$\frac nd$$ gives you $$\frac nd$$ in a separate "paragraph". $\frac nd$ gives you $\frac nd$ in-line with the surrounding text.

andrewkirk probably didn't show the delimiters because they normally disappear and make the LaTeX code be rendered as LaTeX. To make them visible as in my examples above, select the delimiters (only), click the "Text Color" icon in the formatting palette, and choose black (or some other color if you want to make them stand out!). The color tags hide the delimiters from the LaTeX processor.

 

[JorisL]

I learned the Vivaldi browser is awesome, it uses way less RAM than either chromium/firefox/opera or so it seems.
The flash-plugin is worse though.

What's even better is that you can stack tabs!
For example you have 7 PF tabs open (certainly possible), you can stack 'em and only take up the space of 1 tab!

 

[jim hardy]

testing $$\frac nd $$

try numbers $$\frac 23 $$

how would one make a fraction with text or numeric strings for numerator & denominator ?

$$\frac numerator denominator $$

 

[DrGreg]

how would one make a fraction with text or numeric strings for numerator & denominator ?

$$\frac numerator denominator $$

That's when you have to use braces (curly brackets)

\frac{numerator}{denominator}

$$\frac{numerator}{denominator} $$

 

[jim hardy]

Thank You !

My ancestors are all from Missouri, the Show-Me state... I'm not incapable of learning just slower than most folks.

$$ \frac {dividend} {divisor} $$

This should make me a better PF contributor . Thanks again .

 

[JorisL]

You now know the basics of $\LaTeX$

Whenever you find yourself in need to do something just google and you'll 99% of the times find exactly what you look for.

 

[jtbell]

If you haven't seen it already, check out our LaTeX primer:

https://www.physicsforums.com/help/latexhelp/

 

[jim hardy]

If you haven't seen it already, check out our LaTeX primer:

Thanks.
It's chaotic. itex ## $$ seem to do same thing
parentheses vs curly brackets
when do you need or not need \
too many permutations
i've spent hours trying every combination to make a fraction with terms in between parens in numerator and denominator
got frustrated and gave up on latex

but i will plod forward from here
thanks for the jump start .

old jim

 

[Hornbein]

Today I learned that Direct TV was charging my 88-year-old mother for Playboy TV.

 

[Pepper Mint]

Today I learned about Coronary Stenting and what metal materials can be "digested" in our blood stream after some time. Very interesting huh ? at least so to me.

 

[Astronuc]

Today I learned about the Insurgent territory - Minnesota, Iowa, Kansas, Wisconsin and Indiana - heart of the Progressive movement in US political history in the first two decades of the 20th century.

From Doris Kearns Goodwin's book, "The Bully Pulpit: Theodore Roosevelt, William Howard Taft, and the Golden Age of Journalism"
https://www.amazon.com/gp/product/141654786X/?tag=pfamazon01-20

 

[jim hardy]

From Doris Kearns Goodwin's book, "The Bully Pulpit: Theodore Roosevelt, William Howard Taft, and the Golden Age of Journalism"
https://www.amazon.com/gp/product/141654786X/?tag=pfamazon01-20

From the reviews it sounds like an interesting book for these times.
Breaking up abusive corporate monopolies ?

This wonderful book frames the man's character by presenting Roosevelt as a man making a stance by enforcing the Sherman Act of 1890 (an antitrust law) that was basically over looked while the big business bosses established their vast monopolies & power in the late 19th to earlier 20th century...
...Ms. Goodwin has cleverly developed the story of these two men by showing the path of Taft as President to push congress to reform big business through regulatory amendments and measures to enforce them, while Roosevelt who regretted not pursuing another term wishes to take action on child labor and women's work issues. Roosevelt advocated social engineering measures such as income & inheritance taxes, food safety, political reform, and direct primaries. Too big of a step for President Taft & leader of the Republican party. The discontented Roosevelt tried to regain the nomination of his party and failed to unseat Taft who was backed by the old guard Republicans. Roosevelt the perpetual fighter dislodged the continuity of his former party by forming the Bull Moose Party. The fractioned Republicans lose - leading to a win for the Democrat Woodrow Wilson in 1912.

History might be warming up for another rhyme.

900pages ? I'll have to wait for the movie - been working on "The Sun Kings" for a month now, Carrington and his sunspots. Delightful history of early astronomy .

 

[Hornbein]

Today I learned about the Insurgent territory - Minnesota, Iowa, Kansas, Wisconsin and Indiana - heart of the Progressive movement in US political history in the first two decades of the 20th century.

From Doris Kearns Goodwin's book, "The Bully Pulpit: Theodore Roosevelt, William Howard Taft, and the Golden Age of Journalism"
https://www.amazon.com/gp/product/141654786X/?tag=pfamazon01-20

Back in those days the government was even more corrupt than it is now. Political parties existed solely to bring money to the party members. The most lucrative job in the country was that of the head of the New York Port Authority. It was possible to make millions of dollars per year.

When FDR first became a state legislator in New York the hottest issue was child labor. Whether to ban child labor? Nope. Whether child labor should be limited to 50 hours a week.

Business owned the Senate. Many Senators were appointed by state legislatures, so Senate seats were often for sale to the highest bidder. The Senate did the bidding of the trusts. Once a proposition passed by something like 500 to 6 in the House only to fail in the Senate.

The Western states went to popular elections for Senators. Eventually the states threatened to convene a constitutional convention to make a change. To avert this Congress passed an amendment requiring popular elections for all Senators.

Impoverished farmers attempted to form a union or cartel to increase the price of their crops. Bankers and railroads united against them. Many farmers couldn't afford the $1 a year dues, so that was the end of that.

The farmers took over the Democratic Party and ran William Jennings Bryan for President. No luck. Most voters were OK with the railroads and bankers getting all the profits from farming.

It was pure luck that TR became President. He'd been made Vice President to get him out of New York City, where he had been too effective in fighting corruption. Then McKinley was assassinated.

In my opinion TR didn't do all that much. He blocked J.P. Morgan from taking control of all the railroads from Chicago to the West Coast. His biggest accomplishment was regulating railroad fees. The other oligopolies (trusts and holding companies) went on as before. It may not have been much, but it was a lot better than nothing and enough to get him onto Mount Rushmore. Note that in contemporary USA he does not share in the veneration according (rightly or wrongly) to Washington, Jefferson, and Lincoln. Both parties avoid mentioning him.

A Socialist party was formed and got 15% of the vote. Wall Street was bombed. The Socialist candidate was imprisoned for speaking out against World War One.

The people made a lot of noise and got a few reforms but things didn't really change until Wall Street defrauded the nation of its money and the economy collapsed. Then there were more losers than winners, so reform was possible.

 

[Astronuc]

TIL why owls are so quiet

 

[Ibix]

Today I learned that the oldest known surviving moving picture is "Roundhay Garden Scene", a handful of frames of "does this thing work? Can you guys just move around a bit in front of the camera?" It was filmed about a mile from where I grew up.

https://en.m.wikipedia.org/wiki/Roundhay_Garden_Scene

 

[Astronuc]

TIL one can make a vase from Crayolas

 

[Hornbein]

Today I learned that the oldest known surviving moving picture is "Roundhay Garden Scene", a handful of frames of "does this thing work? Can you guys just move around a bit in front of the camera?" It was filmed about a mile from where I grew up.

https://en.m.wikipedia.org/wiki/Roundhay_Garden_Scene

They don't make 'em like they used to.

There was a popular film of a guy sneezing.

Another film featured a man aiming a pistol at the camera. The audience would scream.

 

[ShayanJ]

Today I learned that if you use the (-+++) signature for the metric, the Klein-Gordon equation should be written as $(\partial^\mu \partial_\mu - m^2)\phi=0$ instead of $(\partial^\mu \partial_\mu + m^2)\phi=0$! (I don't like $\Box$ or $\Box^2$!)

 

[Hornbein]

Today I learned that the USA occupied Haiti for nineteen years.

 

[Astronuc]

TIL, Krispy Kreme is being acquired by JAB Holding Co., a European investment fund that owns several brands including Keurig Green Mountain.

Krispy Kreme started out as a single store in Winston-Salem, NC in 1937. It went public in 2000. Stock price surged to a peak of ~$50/share in 2003. They over-expanded. Stock price collapsed to $1.01 in 2009. JAB will pay ~$21/share.

 

[Hornbein]

TIL, Krispy Kreme is being acquired by JAB Holding Co., a European investment fund that owns several brands including Keurig Green Mountain.

Krispy Kreme started out as a single store in Winston-Salem, NC in 1937. It went public in 2000. Stock price surged to a peak of ~$50/share in 2003. They over-expanded. Stock price collapsed to $1.01 in 2009. JAB will pay ~$21/share.

It's pretty funny seeing Krispy Kreme counters in East Asian airports.

 

[Mondayman]

Today I learned I've been pronouncing Poincare incorrectly.

 

[Hornbein]

Today I learned I've been pronouncing Poincare incorrectly.

I learned that Putin is pronounce puTeen. Russian reporters address him as Vladimir Vladimirovich. That like calling W George Georgeson.

 

[Mondayman]

I learned that Putin is pronounce puTeen. Russian reporters address him as Vladimir Vladimirovich. That like calling W George Georgeson.

Yup, pronounced just like the food! And I believe Russian middle names come from their fathers given name. I could be way off on this, however.

 

[Hornbein]

I believe Russian middle names come from their fathers given name.

Right. Scandinavian style. People in Iceland don't even have family names.

To me, Russia/USSR is/was largely about Vikings vs. Slavs.

 

[Hornbein]

Today I learned that the Cultural Revolution included politically motivated cannibalism.

https://www.hongkongfp.com/2016/05/...cultural-revolution-remain-unspoken-50-years/

 

[jim hardy]

Today I learned that the Cultural Revolution included politically motivated cannibalism.

Wow.. that's disturbing.

“This was not cannibalism because of economic difficulties, like during famine,” X.L. Ding, a Cultural Revolution expert at the Hong Kong University of Science and Technology, told AFP.

“It was not caused by economic reasons, it was caused by political events, political hatred, political ideologies, political rituals.”

"Political Correctness" on steroids !
I guess "Lord of the Flies" was in 1960's high school curricula for a reason.

 

[Jonathan Scott]

Today I learned that having recently turned 60 I no longer have to pay for UK NHS prescription medicine. The pharmacist told me that and gave me my money back along with the medicine on having noted that their records indicate that I'm now 60, which I admitted was true.

So far, that's the first thing I've noticed that still changes at age 60 in the UK.

 

[Sophia]

Today I learned that having recently turned 60 I no longer have to pay for UK NHS prescription medicine. The pharmacist told me that and gave me my money back along with the medicine on having noted that their records indicate that I'm now 60, which I admitted was true.

So far, that's the first thing I've noticed that still changes at age 60 in the UK.

Maybe you also won't have to pay for public TV?
And what about public transport?

 

[Jonathan Scott]

I think I'd have to be 75 to get a free TV license (which pays for the BBC). I think that's likely to be going away soon anyway.

The only concession on transport here at age 60 is that if I lived in London I would be eligible for free public transport within the London area. Elsewhere, free public transport mostly starts at state pension age for women, which is currently 63 and rising, and by the time I catch up with it in 2022 the state pension age will be 66 for both men and women.

I've now discovered one other thing that starts at age 60 here - free eye tests. What would be a lot better would be free spectacles, or at least lenses! I currently need four pairs (reading, office, music, distance) which after a lot of careful adjustment of my prescription are now fairly well optimised. (My eyes have rather limited accommodation because I went somewhat cross-eyed at age 3 through reading too much and it was fashionable at the time to "fix" that by a "squint operation" which deliberately weakened some of the eye muscles. The operation is now considered unnecessary or even harmful in most such mild cases as the child's eyes recover naturally).

 

[Sophia]

I think I'd have to be 75 to get a free TV license (which pays for the BBC). I think that's likely to be going away soon anyway.

The only concession on transport here at age 60 is that if I lived in London I would be eligible for free public transport within the London area. Elsewhere, free public transport mostly starts at state pension age for women, which is currently 63 and rising, and by the time I catch up with it in 2022 the state pension age will be 66 for both men and women.

I've now discovered one other thing that starts at age 60 here - free eye tests. What would be a lot better would be free spectacles, or at least lenses! I currently need four pairs (reading, office, music, distance) which after a lot of careful adjustment of my prescription are now fairly well optimised. (My eyes have rather limited accommodation because I went somewhat cross-eyed at age 3 through reading too much and it was fashionable at the time to "fix" that by a "squint operation" which deliberately weakened some of the eye muscles. The operation is now considered unnecessary or even harmful in most such mild cases as the child's eyes recover naturally).

Here pension is 62 for men and less for women, depending on how many children they had. But it's going to be equal soon. I laughed so much when I read that I'll go to pension when I'm 69! Hahaha!

 

[Jonathan Scott]

Here pension is 62 for men and less for women, depending on how many children they had. But it's going to be equal soon. I laughed so much when I read that I'll go to pension when I'm 69! Hahaha!

I've been nominally allowed to retire and take my company pension since age 55 (with state pension supplement from age 66), but I can't really afford it yet and I'm very annoyed about that, as the "very generous early retirement scheme" was one of the factors originally used to lure me into joining the company in the first place about 28 years ago.

A few years ago they closed the company "defined benefit" pension scheme and replaced it with a "defined contribution" scheme (which actually lost money initially, being less use than just leaving it in the bank) which reduced my pension quite a bit as I had only built up 2/3 of the years needed to get the full amount and the new scheme, even paying extra contributions from my income, didn't build up very much at all. We originally had a small early retirement penalty which that meant our annual pension would be 3% less for each year we retired before age 60 (so at age 55 we would lose 15% and get only 85% of the original pension). Then, just as I reached 55 the company unilaterally changed the rules so that we would have to forfeit 7% of our annual pension rate for each year we retire before age 63 (so at age 55 we would lose 56%, and get only 44% of the original pension - just over over half of what it would have been!). Many employees took the brief chance to retire in the last month of the old scheme before the new one came into effect, which suddenly meant that there were far fewer experienced people left. Some employees took the company to court, and essentially won the case that the company shouldn't have made those changes, but the only correction that has been made so far is that they have canceled the early retirement penalty for age 60 or above, so at least now I could get all of my reduced pension, but it's still only 3/4 of what was originally predicted.

And I've got a daughter who is studying Physics at Imperial College London, which is a brilliant achievement getting there from a local state school, but it costs me about 9,000 UK pounds per year for her to live in London. (If I retired and got a smaller income as a result, the state would increase her student loan to cover more of that, but that would just be more for her to pay back later). And my son is still at school and won't be going to Uni for another four years.

 

[Sophia]

I've been nominally allowed to retire and take my company pension since age 55 (with state pension supplement from age 66), but I can't really afford it yet and I'm very annoyed about that, as the "very generous early retirement scheme" was one of the factors originally used to lure me into joining the company in the first place about 28 years ago.

It must be very disappointing to work hard all your life and than discover that the pension is lower than you expected.
Your children must be glad that have you to help them so they won't have large debt to pay. It's very nice of you that you are so responsible.

I know a doctor who had worked for 30 years as a GP and you know how much she gets? Originally, they were giving her 330€/month and now because we have soooo very social and people-oriented government, it was raised to slightly over 400€/month. No, it's not a typo. No zeroes are missing. For a doctor! It's such a shame. She is one of that unfortunate generation who worked most of her life during socialism (she's about 75 years old). They are people who worked hard and built the country but now they are almost at the bottom of society.

 

[mfb]

Today I learned: For some reason, the night is a popular time to get babies - or at least it has been so 1950.