Today I Learned

[YoungPhysicist]

Today I learned about what exactly is a parabola

 

[Jonathan Scott]

Today I learned about gallstone problems. I had been thinking that my long-running acid digestion problems had produced some strangely severe spells of discomfort in the last few weeks, but yesterday's was really bad and I started Googling, and found that the symptoms matched a gallstone attack. I'm beginning to wonder whether other longer term symptoms could also be related to gallstones. I'll try to check it out with my doctor.

 

[YoungPhysicist]

Today I learned about gallstone problems. I had been thinking that my long-running acid digestion problems had produced some strangely severe spells of discomfort in the last few weeks, but yesterday's was really bad and I started Googling, and found that the symptoms matched a gallstone attack. I'm beginning to wonder whether other longer term symptoms could also be related to gallstones. I'll try to check it out with my doctor.

Hope getting better soon!

 

[YoungPhysicist]

Today I learned what is a circle equation on another thread!

 

[fresh_42]

Today I learned what is a circle equation on another thread!

Yesterday a parabola, today a circle. May I suggest to investigate cones?

 

[gleem]

Today I learned about gallstone problems. I had been thinking that my long-running acid digestion problems had produced some strangely severe spells of discomfort in the last few weeks, but yesterday's was really bad and I started Googling, and found that the symptoms matched a gallstone attack. I'm beginning to wonder whether other longer term symptoms could also be related to gallstones. I'll try to check it out with my doctor.

Twenty years ago so did I as I went to the ER. In previous years I had symptoms on occasion which I attributed to gas after eating turnips. Then one day the symptoms appeared but intensified to extreme nausea and abdominal pressure. I hand an extreme urge to belch but could not summon it. It was only after a naso-gastirc tube was inserted that relief occurred. Ultrasound exam revealed a blockage of the bile duct. Good Luck.

 

[YoungPhysicist]

Yesterday a parabola, today a circle. May I suggest to investigate cones?

On my list now
Just like @Greg Bernhardt says, random stuff that we learn everyday

 

[phinds]

On my list now
Just like @Greg Bernhardt says, random stuff that we learn everyday

The conics should not be "random stuff" they should be part of a course in mathematics. They are the basis for a huge amount of math.

 

[Spinnor]

Well it was a couple of days ago. If an electron is confined to a path that encloses magnetic flux then opposite moving eigenstates for a given value n have different energies. I knew about the Aharonov-Bohm effect but I did not know about this aspect of the effect, quite marvelous.

From (Google Chrome tells me this link is not secure, whatever that means), http://physics.gu.se/~tfkhj/TOPO/Aharonov-Bohm.pdf

 

[mfb]

Yesterday a parabola, today a circle. May I suggest to investigate cones?

Just don't mistake hyperbolas for hyperboles.

 

[phinds]

Just don't mistake hyperbolas for hyperboles.

Or ellipses from ellipsis

 

[DrGreg]

Just don't mistake hyperbolas for hyperboles.

Or ellipses from ellipsis

That's taking things too far...

 

[YoungPhysicist]

The conics should not be "random stuff" they should be part of a course in mathematics. They are the basis for a huge amount of math.

Yes, I know. I mean “random stuff that show up which are not in your plan) like bumping into circle equation on this forum which is not ,and will not be mentioned in my quadratic function courses.

 

[Ibix]

Just don't mistake hyperbolas for hyperboles.

One results from extremising the action; the other from extremising everything.

 

[fresh_42]

That's taking things too far...

Good that you mentioned it: Don't forget the Von Staudt conic!

 

[Drakkith]

Good that you mentioned it: Don't forget the Von Staudt conic!

I read that as the Von Staudt comic the first time...

 

[phinds]

I read that as the Von Staudt comic the first time...

A good indication of the level of your intellectual abilities.

 

[Drakkith]

A good indication of the level of your intellectual abilities.

It's true. My cone has been truncated.

 

[YoungPhysicist]

Yesterday a parabola, today a circle. May I suggest to investigate cones?

Finish investigating cones!(Not very deep though), but still a great thing to know beside ordinary courses.

 

[jim hardy]

https://en.wikipedia.org/wiki/Coneheads_(film)

one of the better movies i can think of

 

[CWatters]

Today I learned in the newspaper that when there is a leak in the ISS the air 'rushes out slowly'.

 

[Stavros Kiri]

Today I learned that this thread exists ...

 

[Phylosopher]

https://en.wikipedia.org/wiki/Coneheads_(film)

one of the better movies i can think of

Oh My God, what a weird poster. It is scratched in my head. I can't get it out!

 

[jim hardy]

The movie is a delightful sci-fi comedy about an alien family sent as a 'fifth column' for conquest of earth.
But they come to like the place.

If you've raised teenagers you'll love it. It's light hearted and well done.

old jim

 

[OmCheeto]

TIL that tiltmeters can measure tilt to a nanoradian.
Then I learned that a nanoradian is the equivalent of a nickel's thickness difference when viewed from a distance of New York City to San Francisco.

 

[Tom.G]

TIL that tiltmeters can measure tilt to a nanoradian.
Then I learned that a nanoradian is the equivalent of a nickel's thickness difference when viewed from a distance of New York City to San Francisco.

...And they can be purchased where?

On second thought, the price tag probably has too many digits. How about: ...And the plans are available where?

 

[OmCheeto]

...And they can be purchased where?

On second thought, the price tag probably has too many digits. How about: ...And the plans are available where?

As far as I can tell, they are strictly DIY.
You can contact Rex Flake of Central Washington University for the plans.

Btw, the ones he built were about a kilometer long, and I'm wildly guessing that they cost $50,000+ each.
Kind of a niche market for these things.

-------
ref:
discussion about the tiltmeters starts @ ≈21:00

further reading:

Slow Earthquakes in the Pacific Northwest

Michelson Tiltmeters​

 

[jim hardy]

Hmmm. Do they work by gravity, like this one ?

Great. Now i'll be worrying about effect on them from planetary alignment and barycenters... please tell me there is none...

 

[mfb]

Superconducting gravimeters levitate a sphere in vacuum and measure the electric current necessary for that. They achieve 10^-12 g precision for the local gravitational attraction. They should be able to measure sidewards forces in a similar way. A pendulum interferometer is great if you don't have local seismic noise.

Sub-nanorad tiltmeter with a pendulum

10 picorad resolution for angle measurements (relative to a given reference)

 

[OmCheeto]

Hmmm. Do they work by gravity, like this one ?
View attachment 230230

I'm not really sure.
Interestingly, the device was designed 99 years ago by A.A. Michelson, of "the Michelson–Morley experiment" fame, but one wasn't built until a couple of decades ago.

As far as I can tell, they just measure the difference in the height of water at the two ends, based on the change from when the devices are originally installed.

The data in the info-graphic doesn't quite match what the interviewee was describing, so I would ignore that.

Great. Now i'll be worrying about effect on them from planetary alignment and barycenters... please tell me there is none...

Good point! I hadn't even thought about that. Might be something to calculate.

The interviewee did discuss "earth tides" @ 09:00, something I just recently learned about.

Earth tide [wiki]

Earth tide (also known as solid Earth tide, crustal tide, body tide, bodily tide or land tide) is the displacement of the solid Earth's surface caused by the gravity of the Moon and Sun. Its main component has meter-level amplitude at periods of about 12 hours and longer.
...
The development of a systematic theory of Earth tides was started by George H. Darwin in 1879, and was then furthered by numerous authors, most notably by William Kaula in 1964.​

hmmmm... Sometime in the past, I think I mentioned that if I were to post here everything I learned every day, it would become the "What did Om learn today" thread.

So I'll close this out with;

Did you know that starfish don't have blood? They use seawater to transport their nutrients around their bodies.
Imagine how cool that would be.

Nurse; "Doctor! OmCheeto's leg has been cut off! He's lost huge amounts of blood! The blood bank says they're all out of O, A, and whatever blood types! What do we do??"
Doctor; "No problem. Om is a starfish. Just go out to the bay and collect some seawater. He'll be fine."​

ps. Ok, I'll close this again with:

Superconducting gravimeters levitate a sphere in vacuum and measure the electric current necessary for that. They achieve 10-12 g precision for the local gravitational attraction. They should be able to measure sidewards forces in a similar way. A pendulum interferometer is great if you don't have local seismic noise.

Sub-nanorad tiltmeter with a pendulum

10 picorad resolution for angle measurements (relative to a given reference)

I don't even want to know how expensive those suckers are.