Today I Learned

  • Thread starter Greg Bernhardt
  • Start date
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."
  • #2,801
fresh_42 said:
A non associative algebra is a baric algebra if and only if it has an ideal of codimension one.
+
More generally it can be shown that Lie algebras cannot be baric algebras.

This sounds reasonable each on its own, but what about solvable Lie algebras which do have an ideal of codimension one? E.g. ##\mathcal{A} = \langle X,Y\,|\,[X,Y]=Y\rangle##.

https://de.wikipedia.org/wiki/Baric-Algebra
I would feel like a fraud just liking your post as that would suggest I understood it so I will say thanks for explaining this way first. Then like it.
 
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  • #2,802
mfb said:
There is an "edit" button (or "Seite bearbeiten" in German). The syntax is a bit different from forums but the basics are easy to learn. Or use the discussion page. Don't worry about the formatting - others will take care of it if there is a problem. Fixing content errors is more important.
Otherwise the error will stay in there and confuse more readers.
Done. We'll see.
 
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  • #2,803
TIL you can smoke meat in a gas oven.

 
  • #2,804
fresh_42 said:
Done. We'll see.
Not much to see, now it is fixed. You helped Wikipedia to become better!
 
  • #2,805
mfb said:
You helped Wikipedia to become better!
Yes, you did. . . .:thumbup:

See. . . . :ok:

1556435784665.png


.
 
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  • #2,806
TIL the majority of Americans don't think Arabic numerals should be taught in schools.
244646

Comments have been (Roman) numerous, such as this one from NY Times.
 
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  • #2,807
BillTre said:
TIL the majority of Americans don't think Arabic numerals should be taught in schools.
View attachment 244646
Comments have been (Roman) numerous, such as this one from NY Times.
Then it is a great luck that the ciphers actually originated in India. The Arabs took them from there, and then brought it to the Mediterranean countries.

Edit: ... and the sad part is, that it was again accounting why they dropped the Roman numerals, not insight. The Italian dealers simply saw it was faster and easier.
 
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  • #2,808
TIL that mid 90's Jeeps have a pesky security feature.

If you've had the battery out
the Engine Control Unit computer (ECU) expects the door to be unlocked with a key before driving - else it presumes a grand theft auto in progress.
So it disallows driving.
It let's the engine start and run for about two seconds
then it shuts off all the fuel injectors by discontinuing 'ground' pulses to their "low " sides..("High" sides receive battery power)
So the engine coasts to a stop.
Then the camshaft position and crankshaft position sensors obediently report to computer that engine is no longer turning,
and the computer obediently de-enerizes the Fuel Pump Relay as well an 'ASD' Relay that controls battery power to the fuel injectors.

That takes about two seconds.

symptom is it'll start and run for two seconds then die. And a little light on the dash says "Security".

Way to fix a '95 Grand Cherokee is to lock then unlock the passenger door with a key.
Computer somehow senses that and on the next start the engine continues to run just fine.
Had me going all afternoon ,
Using a test light i'd figured out that the ECU was intentionally shutting down the engine but not why... it's not in the service manual so thank goodness somebody posted it on a Jeep forum !

I wonder how many of the Jeeps in junkyards are there because of that ?
It'd likely be mis-diagnosed as faulty Engine Control Unit which is a really expensive part.
I noticed in the Denver junkyard almost all the Jeep ECU's were gone.

i really dislike computers in cars...

old jim
 
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  • #2,809
Not exactly related, but in a similar vein, I rented a van once, back when I had little enough stuff that I could DIY a house move. Got it back to my place and discovered there was no keyhole in the cargo door. No amount of prodding anything revealed a hatch cover that might conceal one, so I rang the rental place. Turned out you unlocked the cargo door by unlocking the driver's door twice. They did apologise for forgetting to mention that...

Edit: today is not the first day you could have learned this. I appear to be running short on personal anecdotes o0).
 
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  • #2,811
I noticed that I am a pf molecule the other day and I thought it was very sweet. We are all just molecules in the wonderfully rich tapestry that is physics forums. However, when checking where posters were from on another thread I realized this is not the case. Checking out the big hitters we have a mountain, an ocean, a moon and Fresh42 is a singularity!
 
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  • #2,812
pinball1970 said:
Checking out the big hitters we have a mountain, an ocean, a moon and Fresh42 is a singularity!

And I'm an Armchair Scientist. o0)
 
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  • #2,813
TIL that I am what? A singularity?
Drakkith said:
And I'm an Armchair Scientist. o0)
You can still become a Couch Potential, a Big Bangjo Player, a Rocking Chair Asteroid, a SOFIA astronomer ...
but me, as a singularity ... my only hope is they will find a white hole some time. :frown:
 
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  • #2,814
jim mcnamara said:
I've been here so long I have no designation.
Probably Titan.
 
  • #2,815
fresh_42 said:
TIL that I am what? A singularity?

You can still become a Couch Potential, a Big Bangjo Player, a Rocking Chair Asteroid, a SOFIA astronomer ...
but me, as a singularity ... my only hope is they will find a white hole some time. :frown:
If this is a mass thing then you are infinitely larger than me. Greg would not give me details on rankings and suggested I search and work them out. I have to aim for organism next apparently. It could be worse, I could be a baculum.
 
  • #2,816
pinball1970 said:
If this is a mass thing then you are infinitely larger than me. Greg would not give me details on rankings and suggested I search and work them out. I have to aim for organism next apparently. It could be worse, I could be a baculum.
... or even worse: a baubellum!
 
  • #2,817
fresh_42 said:
... or even worse: a baubellum!
Yes that's worse..
 
  • #2,818
Do we have a black hole?
[Designated as such; not "just" 'singularity' ...]
 
  • #2,819
Stavros Kiri said:
Do we have a black hole?
[Designated as such; not "just" 'singularity' ...]
I've not seen one.
I'm checking members mass status out as I read threads...on a Friday night...
 
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  • #2,820
pinball1970 said:
members mass status
Is it a mass thing or more like a "structure thing"? ...
 
  • #2,821
Can I change my moniker to "Spherical Couch Potato" ?
 
  • #2,822
hmmm27 said:
Can I change my moniker to "SphericalCouchPotato" ?
I don't think you can, Greg has the algorithm.
 
  • #2,823
It was mostly rhetorical, while I tried to figure out what an earlier poster meant by "molecules" "black holes" etc.(figured out).
 
  • #2,824
Now I have a different understanding of the pot at the end of the rainbow!

244743


The cars need Dead stickers.
 
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  • #2,825
Stavros Kiri said:
Is it a mass thing or more like a "structure thing"? ...
based mainly on number of posts? ...
@Greg Bernhardt
 
  • #2,826
It is based on trophy points, the increasing levels are in increasing mass and size (until it goes into the speculative region). There is no black hole.
You can see the level in user profiles.
 
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  • #2,827
Stavros Kiri said:
Is it a mass thing or more like a "structure thing"? ...
More structure means more mass though? Also
mfb said:
It is based on trophy points, the increasing levels are in increasing mass and size (until it goes into the speculative region). There is no black hole.
You can see the level in user profiles.
Singularity is the highest I have found so far with a quick search and these tie in with pts (Fresh42)below this multiverse (orodruin, Greg) then universe ( you, Peter Donis) galaxy (mark 44) Star (Dale Russ) then it could be moon (Neumaier, Nugatory,jim) but I suppose planet/gas giant may be in there.

Up from the other end quark, atom, molecule some stuff then mountain ocean.
 
  • #2,828
There is supercluster above galaxy and planet between moon and star. Found with a bit of searching, Greg didn’t release a full list. That also means we don’t know if there is something beyond singularity, no one has 1300+ yet.
 
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  • #2,829
And 'Armchair Scientist' ! ...
 
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  • #2,830
.
Mark Twain said:
Forgiveness is the fragrance that the violet sheds on the heel that has crushed it.
It's a beautiful quote!
.
 
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  • #2,831
OCR said:
.
It's a beautiful quote!
.
That is also true Love! ...
 
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  • #2,832
mfb said:
the increasing levels are in increasing mass and size (until it goes into the speculative region).
pinball1970 said:
More structure means more mass though?
I think size, structure and mass come in all together, but with no hard and fast rule ...
[e.g. there can be a planet smaller than a moon, in general ...]
 
  • #2,834
Stavros Kiri said:
I think size, structure and mass come in all together, but with no hard and fast rule ...
[e.g. there can be a planet smaller than a moon, in general ...]
I will go with that.
A helium balloon has size and not too much mass or structure whereas a plasmid has lots of structure but not so much size or mass and a rock has more mass than both with little structure but much bigger size than the plasmid but much smaller than a He Balloon (it's a big balloon)

Density would be better I suppose but that would be volume and mass rather than 'size' which is a little ambiguous.
So I am probably denser than a galaxy in that case? Definitely supercluster or universe.
Stick with mass otherwise it gets messy.
 
  • #2,835
pinball1970 said:
I will go with that.
A helium balloon has size and not too much mass or structure whereas a plasmid has lots of structure but not so much size or mass and a rock has more mass than both with little structure but much bigger size than the plasmid but much smaller than a He Balloon (it's a big balloon)

Density would be better I suppose but that would be volume and mass rather than 'size' which is a little ambiguous.
So I am probably denser than a galaxy in that case? Definitely supercluster or universe.
Stick with mass otherwise it gets messy.
I mostly agree.
I would rather though stick with the old way ... (for PF members), ... [aside of course, perhaps, possible security and privacy issues ...]
 

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