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."
  • #2,171
Today I see...
Firefox said:
Watching the sunrise outdoors statistically increases your odds of having a good day.
Oh...? I need a reference for that one...[COLOR=#black].[/COLOR] :oldgrumpy:
Firefox said:
And needing a nap after lunch.
I'll accept this as fact, though...[COLOR=#black].[/COLOR] :oldtongue:
 
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Physics news on Phys.org
  • #2,172
Borg said:
I think that he may be referring to this Science Daily article that came out last week - Physicists create 'negative mass'

They are sensationalizing a bit but, interesting properties for what was created.
When you follow the link to the journal abstract, you find it is really "negative effective mass", not "negative mass".
 
  • #2,173
DrGreg said:
When you follow the link to the journal abstract, you find it is really "negative effective mass", not "negative mass".
Sounds like the effect demonstrated by a helium balloon in an accelerating car.
 
  • #2,174
Today I learned about a $400 internet-connected juice gizmo. Apparently you must subscribe to get whatever it is you get. Juice as a servce?

This gave me an idea. It should be possible to build a simple metal device that you put over your cup. It has a sort of cone-shaped thing in the middle and there are lots of sharp bits with holes. Sorry I haven't come up with the drawing yet.

Let's say you want some orange juice. You cut the orange in half. Then you place one half of the orange over the cone and push down while turning the orange. The juice comes out and falls through the holes into the cup.

I think this is a very green invention and I think it has great potential. It could even be advertised as "exercise your hands while making juice and keeping your planet healthy."

I don't suppose anyone has contacts with a good angel investor on this? I may need one soon anyway for my AI project.
 
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p.s. in case someone already thought of my revolutionary green juicer technology, I could spruce it up with some LEDs and maybe a tiny video camera connected wirelessly to an app. I see great potential for this sort of video going viral on Youtube. You heard it here first, so I expect full credit if anyone monetizes this idea.
 
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  • #2,176
Aufbauwerk 2045 said:
This gave me an idea. It should be possible to build a simple metal device that you put over your cup. It has a sort of cone-shaped thing in the middle and there are lots of sharp bits with holes
Can't tell if you're being tongue in cheek or not, but I assume you are. The first time I saw one of those was well over 60 years ago and I don't think they were particularly new then.
 
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  • #2,177
phinds said:
Can't tell if you're being tongue in cheek or not, but I assume you are. The first time I saw one of those was well over 60 years ago and I don't think they were particularly new then.

Yes, it's an apparently failed joke.

This is why I fail as a comedian. No matter what I say (or write) people think I'm being serious. That's why I need to just be deadly serious all the time.

Sigh.
 
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  • #2,178
Aufbauwerk 2045 said:
Yes, it's an apparently failed joke.

This is why I fail as a comedian. No matter what I say (or write) people think I'm being serious. That's why I need to just be deadly serious all the time.

Sigh.
It may be more of an internet problem. I don't have it in person but sometimes do on forums. You lose most of the expressiveness we humans have when you do a post.
 
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  • #2,179
This is some hard hitting science.
xVGtqT4.jpg
 
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  • #2,180
newjerseyrunner said:
This is some hard hitting science.
View attachment 197217
Ah, dude ... you have WAY too much spare time on your hands :oldlaugh:
 
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  • #2,181
to day I learned that APT supports zwo ASI1600mm-c
 
  • #2,182
Today I learned, it's all too easy to make your spray lacquer finish run if you aren't extremely careful... Oops! Lesson learned the hard way. Just made myself a little bit more work than I had originally expected.
 
  • #2,183
Today (well, yesterday) I learned about Dynamical Parallax, a method to estimate all sorts of good information about stars in a binary star system using only a limited set of observational data.

Using only [comparitively] easily observable parameters such as the binary system's orbital period, orbital angular separation (angular semi-major axis, as observed from Earth), and each star's apparent magnitude (brightness as seen from Earth), One can use Dynamical Parallax to accurately estimate the stars' actual masses, distance from Earth, and luminosities.

A quick guess might lead one to think that there is not enough information to solve such problems (lacking spectral information, etc): a close star system with small stars would be indistinguishable from a far away system with larger stars. Stellar Parallax works by exploiting the non-linear* relatiship between the stars' masses and corresponding luminosities -- that's what makes it work.

So yesterday I whipped up a program implementing the algorithm. It ignores relative eccentricity and assumes that the system's orbit is viewed flat on from Earth. I can live with that. The program requires inputs of the stars' relative magnitudes, the average angular separation of the stars along the line of their farthest/closest points of orbit (i.e., semi-major axis), and orbital period. It calculates the rest.

Here's a test case with Alpha Centauri that worked out pretty well:

DynamicalParallaxOutput.gif


For comparison, here are more accurate parameters (more accurate measuring techniques) from Wikipedia:

Distance: 4.37 light-year

Alpha Centauri A:
Mass: 1.1 M
Luminosity: 1.519 L
Absolute Magnitude: 4.38

Alpha Centauri B:
Mass: 0.907 M
Luminosity: 0.5002 L
Absolute Magnitude: 5.71

Pretty nifty. The crazy thing is this is the first time I've heard of dynamical parallax. Apparently astronomers have been using this technique for roughly a century.
----
*(The mass-luminosity relationship of a star is nonlinear up to about 20 solar masses, at which point Dynamical Parallax becomes less useful.)
 
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  • #2,184
collinsmark said:
It ignores relative eccentricity and assumes that the system's orbit is viewed flat on from Earth.
With circular orbits, our line of view doesn't matter.
The eccentricity is not hard to calculate if the position of the stars is tracked over one orbital period (or more precisely over a part of it).
 
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  • #2,185
Sean Carrol getting stuff nailed again.
 
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  • #2,186
mfb said:
With circular orbits, our line of view doesn't matter.
The eccentricity is not hard to calculate if the position of the stars is tracked over one orbital period (or more precisely over a part of it).
Yeah, the tricky part is those star systems who's line of semi-major axis is pointing more-or-less towards/away from Earth. In those cases, the system's semi-minor axis would appear (sort-of) to be the system's semi-major axis from Earth's perspective.

You can account and correct for that by carefully observing Doppler, etc., and being more careful about observing details of the orbit -- something a bit more complicated than simply observing the min/max angular separation alone. My program doesn't do any of that though. But I'm okay with it. For something I whipped up in a day, I'm happy with it. :smile:
 
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  • #2,188
Today I learned that after just one day of breaking the diet soda habit, I already feel better. No more diet soda for me. No more aspartame and/or sucralose. That makes several bad habits I've eliminated over the last year. These include Facebook, video games, and listening to talk radio.

"I am the Master of my fate,
I am the Captain of my soul."
 
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  • #2,189
Aufbauwerk 2045 said:
Today I learned that after just one day of breaking the diet soda habit, I already feel better.
Don't be surprised if you experience cravings in next few days.
I tried to cut out sweets a year ago , only last three months have been successful. Took a whole year for the craving to subside.
Sugar is addictive. I don't know about addictive-ness of those artificial sweeteners because i never would eat them. Aspartame upsets my vision.

Good luck with eating healthy !
If you can't stream this , search on "Michael Pollan"
http://www.pbs.org/video/2365635287/

old jim
 
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  • #2,190
@jim hardy thank you for your comments. I know it's a struggle.

It was very hard to break myself of the pizza habit. I finally lost all craving for pizza, and in fact it now disgusts me.

I have a really fascinating diet book called Eat To Live by Dr. Joel Fuhrman. The only diet I was ever on that was successful was his strict diet. He backs up his diet with tons of references. I lost more than 20 lbs while eating as much as I wanted. The catch is I could only eat certain types of foods. It was a vegan diet. I ate lots of Romaine lettuce.

I was working from home at that time. Unfortunately it's too hard for me to stay on it when I'm working my current job. I plan to go back on it soon.

Among other things, he bans sweets. He explains that nature gives us our sweet tooth so we will enjoy eating fruit. He is all for eating fresh fruit. Although he does ban fruit juice from his strict diet. He emphasizes eating the whole fruit so we get the fiber and various other good bits from the fruit which are lost in juicing. I broke that rule sometimes.

One of my most interesting experiences was that once I had been off all meat for several weeks, I could no longer stand the smell. All I could think of was why I had been eating all that stinking, rotting animal flesh.

But sadly now that I'm not on the diet anymore, I have gone back to cheeseburgers. Disgusting.
 
  • #2,191
Today I learned that Einstein had really nice legs
 
  • #2,192
Today I learned that deGrasse can be SAVAGE...so funny and with a painful depth of truth lol

His defence of his statement that "Math is the language of the universe".

oh wow...and that Bill Nye can be even more so lol
Wait for his comment after deGrasse opines.

Not long after the Nye comment, Brian Greene's wife Lucy Day, answers a question regarding the importance of getting the stories of science across accurately...hmmm...I wonder if she's read his pop books lol.
 
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  • #2,193
Today I learned that it costs me as much to make a 1.35 litre pot of coffee as it does to mow my neighbors 102 m2 lawn: ≈1¢
 
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  • #2,194
Today I learned quitting smoking isn't so hard.
 
  • #2,195
HAYAO said:
Today I learned quitting smoking isn't so hard.
It isn't. The hard part is not starting up again.
 
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  • #2,196
Borg said:
It isn't. The hard part is not starting up again.
Well I quit smoking and now it's been more than six months, but I don't feel like starting up again.
 
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  • #2,197
Today I learned James Comey got fired.
 
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  • #2,198
StevieTNZ said:
Today I learned James Comey got fired.
Really? Haven't even had the tube on today. OMG
 
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  • #2,199
Today I learned that Jon Bosak, who led the creation of the XML specification, was given the xml name of xml:Father.
In appreciation for his vision and leadership and dedication the W3C XML Plenary on this 10th day of February, 2000 reserves for Jon Bosak in perpetuity the XML name "xml:Father".
:bow:
 
  • #2,200
Today I learned there is a video of some of the 1927 Solvay Conference participants. I see it was posted here in 2010.

Here is a rather beautiful video of de Broglie.

 
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  • #2,201
nitsuj said:
Today I learned that deGrasse can be SAVAGE...so funny and with a painful depth of truth lol
Didn't watch this yet (at work) but I just want to say that I admire NGT so much, not only for his intelligence, but for his charm. I have a really hard time talking to science illiterates. He does it with such grace and wit. -Dave K
 
  • #2,202
dkotschessaa said:
Didn't watch this yet (at work) but I just want to say that I admire NGT so much, not only for his intelligence, but for his charm. I have a really hard time talking to science illiterates. He does it with such grace and wit. -Dave K
I liked Pluto:

 
  • #2,203
Today I learned that when the directions tell you to remove the lid before microwaving, you better remove the lid!

20170516_172345_HDR.jpg
 
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  • #2,204
TIL about the Capgras syndrome: familiar people appear unfamiliar; noted cases involve the patient not recognizing themself in the mirror.
 
  • #2,205
EnumaElish said:
TIL about the Capgras syndrome: familiar people appear unfamiliar; noted cases involve the patient not recognizing themself in the mirror.

That is absolutely terrifying.! :nb)
 
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