Today I Learned

  • Thread starter Greg Bernhardt
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In summary: Today I learned that Lagrange was Italian and that he lamented the execution of Lavoisier in France during the French Revolution with the quote:"It took them only an instant to cut off this head and a hundred years might not suffice to reproduce it's...brains."
  • #4,131
ergospherical said:
...porridge...

...actually tastes nice...
You've put these two phrases in the same sentence, and I'm having trouble parsing that.
 
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  • #4,132
ergospherical said:
It's recently come to my attention that some people use milk instead of water in the cooking of porridge oats; now I wonder whether this is a popular practice and whether it actually tastes nicer than using water?

One of the primary reasons I got my instant pot at the urging of several friends. Put in steel cut oats, milk, maybe some fruits (fresh or dried) and push the "porridge" button and walk awy. Come back later (half hour) to perfect oats. The milk sugars make it much more delicious.
These cookers are really good IMHO: hi or low pressure, very even heat up the sides, and also very smart sensors. Great for stews, dried beans, rice, braised meat. The rest of my kitchen is black cast iron: pretty much old school. I use it thrice weekly typically.
 
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  • #4,133
hutchphd said:
Come back later (half hour) to perfect oats.
Half an hour! I usually just bung it in the microwave for a few minutes.
 
  • #4,134
DaveE said:
TIL that train wheels aren't cylindrical, and why they do that.


Richard Feynman was asked this question as part of his fraternity initiation.
 
  • #4,135
ergospherical said:
It's recently come to my attention that some people use milk instead of water in the cooking of porridge oats; now I wonder whether this is a popular practice and whether it actually tastes nicer than using water?
Steel cut oats made with 2/3 milk, 1/3 water with pecans, maple syrup and frozen (coldness provides contrast) fruit (usually blueberries, but cherries or pomegranate seeds are a treat)
 
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  • #4,136
ergospherical said:
Half an hour! I usually just bung it in the microwave for a few minutes
Philistine! Time is ours to use. Worth every minute.
 
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  • #4,137
hutchphd said:
Philistine! Time is ours to use. Worth every minute.
No one on their death bed ever wished they took more time for oatmeal
 
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  • #4,138
They were probably busy frantically smelling the roses. I'll take edibles.
 
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  • #4,139
TIL about Zsigmondy's theorem.
If a>b>0 are coprime integers, then ##a^1-b^1##, ##a^2-b^2##, ..., ##a^n-b^n## will always have a new prime factor not present before, with just three exceptions:
  • If a=b+1 then ##a^1-b^1=1## which is not a prime (trivial)
  • If a+b is a power of 2 then ##a^2-b^2=(a+b)(a^1-b^1)## does not introduce a new prime factor as a-b is even. Still pretty easy to see.
  • If a=2, b=1 then ##a^6-b^6 = 63 = 3\cdot3\cdot7##, both 3 and 7 appeared before (e.g. at n=2 and n=3). Why does this weird exception exist?

I also learned about Skype's new account creation captcha which looks like a joke.
 
  • #4,140
BWV said:
No one on their death bed ever wished they took more time for oatmeal
That might be partly because they never had it cooked right, and served with milk and a generous helping of brown sugar. I quite liked that breakfast as a child, though not without the brown sugar.

But since you said that, I'll now try to remember, on my death bed, to ask for porridge with milk and brown sugar. :oldbiggrin:
 
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  • #4,142
ergospherical said:
It's recently come to my attention that some people use milk instead of water in the cooking of porridge oats; now I wonder whether this is a popular practice and whether it actually tastes nicer than using water?
I'm one of those some. I use standard oats and add steel cut oats; the latter takes a little longer. The oats will absorb water or milk, so I add enough to keep soft. My parents would use water, then add milk for eating the porridge. I skip the water and add milk.

With the oats, I'll mix granola, berries (often blueberries, especially from May to August when our bushes produce), walnuts and/or pecans, honey or maple syrup. If I feel really hedonistic, I'll add eggnog after the oatmeal is cooked.
 
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  • #4,143
BASE in BASE jumping is an acronym, I thought it meant jumping from a BASE rather than plane but no so.

B = Buildings

A= Antennae

S = Spans (bridges)

E = Earth (cliffs)I was interested to find our what kind of speeds they achieve and also how they maintain height for the ones who wear wing suits.
Some of them seem to able to maintain a certain height from the ground like they are actually flying like a bird.

Anyway I learned that over xmas, TIL that Swimming is the number 2 most dangerous sport after Base jumping.
 
  • #4,144
This probably isn't the safest of skydiving activities either.
 
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  • #4,145
 
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  • #4,146
Borg said:
This probably isn't the safest of skydiving activities either.


That is nuts.

Volcano, sky dive, wing-suiting.

Because normal skydive, wing-suiting over mountains is just not dangerous enough.
 
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  • #4,147
pinball1970 said:
Volcano, sky dive, wing-suiting.

Because normal skydive, wing-suiting over mountains is just not dangerous enough.
But, it has a built-in thermal updraft!
 
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  • #4,148
Keith_McClary said:
But, it has a built-in thermal updraft!
And in case an accident nobody has to bother with the burial either.
 
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  • #4,149
TIL that converting a word document to pdf does not necessarily elimate all the metadata.
 
  • #4,150
Today I learned that the Earth was (ever) tidally locked to one of our (Indonesian) satellite?

https://en.wikipedia.org/wiki/Garuda_1

Leave it to Lockheed Martin to construct such a powerful satellite. Too bad they don't build F22 anymore after so many were destroyed by Godzilla and Ironman.
 
  • #4,151
KingGambit said:
Today I learned that the Earth was (ever) tidally locked to one of our (Indonesian) satellite?
You jest.
 
  • #4,152
What's special about that random GEO satellite? There are ~500 satellites in geostationary orbit. Some have a mass of about 7 tonnes.
 
  • #4,153
KingGambit said:
TIL from this previous TIL link about an old geostationary satellite that one goal for satellites at the end of their operational life is to either de-orbit them (which I knew about), or move them to "Graveyard Orbits":

https://en.wikipedia.org/wiki/Graveyard_orbit

Overview

A graveyard orbit is used when the change in velocity required to perform a de-orbit maneuver is too large. De-orbiting a geostationary satellite requires a delta-v of about 1,500 metres per second (4,900 ft/s), whereas re-orbiting it to a graveyard orbit only requires about 11 metres per second (36 ft/s).[1]

For satellites in geostationary orbit and geosynchronous orbits, the graveyard orbit is a few hundred kilometers beyond the operational orbit. The transfer to a graveyard orbit beyond geostationary orbit requires the same amount of fuel as a satellite needs for about three months of stationkeeping. It also requires a reliable attitude control during the transfer maneuver. While most satellite operators plan to perform such a maneuver at the end of their satellites' operational lives, through 2005 only about one-third succeeded.[2] As of 2011, most[clarification needed] recently decommissioned geosynchronous spacecraft were said to have been moved to a graveyard orbit.[3]
 
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  • #4,154
TIL about Acapella Science. :oldbiggrin:

 
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  • #4,155
TIL about high and low temperature hot spots in the US over the last 20 years (from NY Times):

Screen Shot 2022-01-15 at 10.57.38 AM.png
 
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  • #4,156
Melbourne Guy said:
TIL that Skype is still a thing 🤔
I also learned this recently. It's a very long time since I used my Skype account and I can't remember the password.

Sadly, I also learned that some time back when I updated the email address in my Skype account because the old one was expiring, it didn't actually update the recovery address. Yes, I learned that Microsoft will allow you to change your email address, but will continue sending password recovery information to the old address.

I also learned that Microsoft Support is pretty much useless in such cases because they just keep suggesting things I could only do once logged in.
 
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  • #4,157
I had similar experiences with Google. Had an old Youtube account that I didn't use for a while. Tried to log in again - I knew the password, but Google decided that it doesn't recognize my device and needs extra verification it's me. I didn't give Youtube (back when the accounts were separate) my phone number or any RL information Google would have accepted, so the account is dead.
 
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  • #4,158
mfb said:
I didn't give Youtube (back when the accounts were separate) my phone number or any RL information Google would have accepted, so the account is dead.
Indeed. And to add insult to injury, every time I try to log in it sends me an email telling me someone tried to log into my account and asking me to click on a link to confirm that I'm me - at which point it asks for my password and round we go again.
 
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  • #4,159
It's SO frustrating.
 
  • #4,160
TIL that airlines want 5G technology delayed near airports, as they are afraid that it will interfere with some of their technology.
The representatives of 10 carriers asked the administration in a letter obtained by CNN to further delay the rollout near airports where Federal Aviation Administration flight restrictions take effect once the technology kicks in. The aviation world is concerned 5G signals will interfere with aviation technology including the radar altimeter onboard planes.
"The ripple effects across both passenger and cargo operations, our workforce and the broader economy are simply incalculable," the executives wrote. "To be blunt, the nation's commerce will grind to a halt."
 
  • #4,162
Today I learned that trisection of an arbitrary angle using only a ruler and unmarked straightedge was proved impossible in 1837. In 1980, it was shown to be possible using origami (essentially because folding pieces of paper allows you to add marks to your straightedge). Off the back of that I discovered the Miura map fold, a fold of a piece of paper that allows you to collapse it into a small square and expand it again just by pushing or pulling on opposite corners. It's been used in space programs to store solar panels in a compact form that's mechanically simple to open.
 
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  • #4,163
BillTre said:
TIL that airlines want 5G technology delayed near airports, as they are afraid that it will interfere with some of their technology.
I was a bit alarmed when I heard this as I have to fly long haul next week and this, together with the dust on the fan blades episode, made me a bit nervous. Fortunately I'm not going through US airspace.
 
  • #4,164
TIL not for the first time that I can visualize a problem and possible solutions but have difficulty expressing the answers in English, due to age and injuries.
https://www.physicsforums.com/threads/lock-in-amplifier-with-pulsed-sinewave.1011450/

Specifically, I know or knew methods to measure the requested signal lock but 1) my equipment knowledge is years out of date and 2) exact details are sketchy such as coupler attenuation. I would try using the reference pulse to synchronize the PRF (pulse repetition frequency) and/or alter the carrier pulse width to optimize lock but doubt these generalities would help a working engineer.
 
  • #4,165
Klystron said:
TIL not for the first time that I can visualize a problem and possible solutions but have difficulty expressing the answers in English, due to age and injuries.
https://www.physicsforums.com/threads/lock-in-amplifier-with-pulsed-sinewave.1011450/

Specifically, I know or knew methods to measure the requested signal lock but 1) my equipment knowledge is years out of date and 2) exact details are sketchy such as coupler attenuation. I would try using the reference pulse to synchronize the PRF (pulse repetition frequency) and/or alter the carrier pulse width to optimize lock but doubt these generalities would help a working engineer.
Yes, me too. I was sooo much smarter 30 years ago. I knew a bunch of stuff I never used much, or ever, which has now drifted away.

But, a couple of related points.

1) This is the sort of problem that can have several solutions from simple (buy the right instrument) to complex (PLLs to filter, demodulate and sample etc.). Which are really based on how much you care, how hard is the problem, and how much time and money you have. This causes a bit of confusion to people that understand the options but not the all of the constraints.

Which leads us to:

2) Working engineers are working. They will spend much more time and effort thinking about their specific problems than we will. When I was actually paid for this sort of thing I probably would have spent at least a day thinking about the solution, sometimes much more. OTOH, we won't. We toss out ideas based on our previous experience, learned by actually solving these things. If you cared more because this was your problem, not someone else's, you would sort all of that out.
 
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