Today I Learned

[BillTre]

 

[Ivan Seeking]

View attachment 329636

Even the climate change deniers are starting to wilt away.

I worked very hard for most of my life to try to help avoid this. Now part of me is glad I will die before it gets much worse.

 

[Borg]

Even the climate change deniers are starting to wilt away.

Don't bet on it.
https://www.gocomics.com/tomthedancingbug/2023/07/21

 

[BillTre]

Even the climate change deniers are starting to wilt away.

I worked very hard for most of my life to try to help avoid this. Now part of me is glad I will die before it gets much worse.

There are still enough around here to get posts on the subject removed or censured.

 

[Ivan Seeking]

Don't bet on it.
https://www.gocomics.com/tomthedancingbug/2023/07/21

The extended temps of 110 degrees F and greater are starting to get peoples attention. For example, Phoenix has been 110 F or more for I think 25 days now.

I have seen the doubt in their eyes for the first time. My boss caught himself complaining that we never needed air conditioners around here before.... then he stopped himself and changed the subject.

 

[Borg]

I'll agree that I haven't seen as many stories (or tweets) about it being fake but I do have a friend who still belives that the science is all made up because "someone in England, deleted their data". Explaining to him that there are far more than one person researching it, didn't really matter.

 

[pinball1970]

I'll agree that I haven't seen as many stories (or tweets) about it being fake but I do have a friend who still belives that the science is all made up because "someone in England, deleted their data". Explaining to him that there are far more than one person researching it, didn't really matter.

No longer tweets. They are now called "X's"

 

[pinball1970]

I'll agree that I haven't seen as many stories (or tweets) about it being fake but I do have a friend who still belives that the science is all made up because "someone in England, deleted their data". Explaining to him that there are far more than one person researching it, didn't really matter.

Also, no one in England deleted their data, I asked them. We are a tiny little country and I know them all. Trust me.

 

[topsquark]

Even the climate change deniers are starting to wilt away.

Naw. Just wait for record cold temperatures this winter and they'll be back because cold temperatures and global warming can't possibly be related.

-Dan

 

[BillTre]

It was too cold in a local swimming hole (38˚F):

that would be:
https://www.kezi.com/news/officials...cle_f7d1ad1c-2b42-11ee-99eb-e7933b44d814.html

 

[pinball1970]

TIL https://phys.org/news/2023-07-nasa-lab-life-blocks-asteroid.html

"A precious cargo is currently aboard OSIRIS-REx, a US space probe launched in 2016 to Bennu, which orbits the Sun..."

"scheduled to land in the Utah desert on September 24, carrying an estimated 8.8 ounces, or 250 grams of material"

For analysis:

",,,,,precursors that may have fostered life in our solar system and on Earth."

 

[Hornbein]

It was too cold in a local swimming hole (38˚F):
View attachment 329649

that would be:
https://www.kezi.com/news/officials...cle_f7d1ad1c-2b42-11ee-99eb-e7933b44d814.html

? The hike is dangerous so they are going to unenforceably ban swimming in order to discourage hiking.

 

[BillTre]

? The hike is dangerous so they are going to unenforceably ban swimming in order to discourage hiking.

That's what it sounds like.

The hike is not that dangerous, but it takes a while to get there and EMs probably don't want long delays in treating people. There also cliff areas involved which would make transporting injured people out more difficult.

There are also some nude beaches on some isolated river areas.
You aren't supposed to be nude there, but no one there is going to stop you.
Seems the same.

 

[Hornbein]

TIL that the Nazis had a TV station in 1935.



The first television broadcasts in the UK were in 1929. The BBC stopped at 11pm so a private company used BBC radio transmitters after then. In 1930 they got simultaneous picture and sound and broadcast a play.

My mother told me that all US TV had at first was professional wrestling. People would watch for the novelty of it. Sort of the ChatGPT of that day.

George Burns wrote "when they brought a television up onb the stage so the audience wouldn't miss Amos and Andy I knew vaudeville was finished."

Desi Arnez Jr. was largely responsible for getting television out to Hollywood. Even though the most popular star on television Lucille Ball got in serious trouble for having joined the Communist Party. She got off because she had only done it to please an uncle and had never attended a meeting or given them any money. Lucille said McCarthyism was worse under the Truman administration.

 

[Bystander]

TIL:

I don't know about Bridge, but in casinos I often see the dealers "washing" the cards, ie, mixing them up the way a kid who can't shuffle would.

 

[DaveC426913]

Even the climate change deniers are starting to wilt away.

Wilt away? Or retire to their private islands now that they've made their money off the lie...

 

[Ivan Seeking]

Wilt away? Or retire to their private islands now that they've made their money off the lie...

Through my personal interactions, I have observed a subtle but significant change in how deniers react to this subject. My impression is that their confidence has been shaken.

 

[Hornbein]

TIL that the largest known galaxy has a diameter of 1,764,000 light years.

 

[PeterDonis]

TIL that the largest known galaxy has a diameter of 1,764,000 light years.

Which galaxy?

 

[Ibix]

Which galaxy?

ESO 383-76 according to Wikipedia.

 

[DrGreg]

TIL that the largest known galaxy has a diameter of 1,764,000 light years.

To put that into perspective, that's about 20 times the diameter of our own galaxy (again according to Wikipedia).

(Caveat: all these numbers are estimates, and different estimation methods can give substantially different answers, yet again according to Wikipedia -- this is a subject I know nothing about.)

 

[BWV]

To put that into perspective, that's about 20 times the diameter of our own galaxy (again according to Wikipedia).

(Caveat: all these numbers are estimates, and different estimation methods can give substantially different answers, yet again according to Wikipedia -- this is a subject I know nothing about.)

Or over half the distance to Andromeda

 

[pinball1970]

Or over half the distance to Andromeda

68%!
First thing I did!

 

[DaveC426913]

Or over half the distance to Andromeda

To put that in perspective...

 

[Ivan Seeking]

TIL that the largest known galaxy has a diameter of 1,764,000 light years.

What is the centripetal force acting on an object on the outermost edge of that galaxy?

 

[DaveC426913]

What is the centripetal force acting on an object on the outermost edge of that galaxy?

I should clarify that - despite my deliberate artistic licensing - it's actually an elliptical galaxy.

The force shouldn't be too hard to approximate (by pretending it's of uniform density).
Mass: 2.3×10¹⁴M☉ (230 trillion Sols) = 4x10⁴⁴kg
Distance: 882kly = 8.3x10¹⁸km

(I'm doing something wrong; I get like 7x10²⁰Newtons). I'll show my work...

$$M = 2.3 x 10^{14}\\D=8.8x10^5 light years\\ (1 light year = 9.4 x10{12} )$$

_{(OK, I give up on LaTeX or MathJax or whatever it is. The commands they say work don't work.)}

 

[strangerep]

I should clarify that - despite my deliberate artistic licensing - it's actually an elliptical galaxy.

The force shouldn't be too hard to approximate (by pretending it's of uniform density).
Mass: $2.3\times 10^{14}$ M☉ (230 trillion Sols) = $4 \times 10^{44}$ kg
Distance: 882kly = 8.3x10¹⁸km

(I'm doing something wrong; I get like 7x10²⁰Newtons). I'll show my work...

$$ M = 2.3 x 10{14} ~~;~~ D=8.8x10^5 \mbox{light years} $$
(1 light year = 9.4E12 ?what?

I don't know what you're trying to do. Were you trying to use $a = GM/r^2$ ?

Regardless, you'll have to use a MONDian modification of the Newtonian formula to get anywhere near the actual physical result.

(OK, I give up on LaTeX or MathJax or whatever it is. The commands they say work don't work.)

They do work if you RTFM. I fixed yours a bit.

 

[strangerep]

What is the centripetal force acting on an object on the outermost edge of that galaxy?

If it were a spiral, you should be able to get a reasonable approximation to the outer tangential velocity using the Tully-Fisher/MONDian formula $v_{\text{tan}}^4 = GM a_0$, where $a_0$ is the Milgrom constant. From that you can calculate centripetal acceleration.

Elliptical galaxies are a bit different, however. One must use the Faber-Jackson relation between velocity dispersion and luminosity, but I won't attempt to explain that here since it involves some tricks such as the Virial theorem.

 

[DrGreg]

What is the centripetal force acting on an object on the outermost edge of that galaxy?

To be pedantically and relativistically correct, the answer is zero.

(Gravity isn't a force in relativity, but of course in Newtonian theory it is a force.)

 

[Ivan Seeking]

To be pedantically and relativistically correct, the answer is zero.

(Gravity isn't a force in relativity, but of course in Newtonian theory it is a force.)

Heh. I doubt we get into velocities great enough or gravity strong enough to require GR. But if the word "force" doesn't apply at all, perhaps it should be dropped altogether. Why are we teaching false physics?

Teaching Newtonian physics makes sense because it is accurate enough for most applications. But calling something a force when it isn't actually a force is another matter.

 

[DaveC426913]

I don't know what you're trying to do. Were you trying to use $a = GM/r^2$ ?
They do work if you RTFM. I fixed yours a bit.

I was just trying to show my work - one equation per line. I RTFM'd and it said that "\\\" starts a new line but it does not.

 

[Ibix]

I was just trying to show my work - one equation per line. I RTFM'd and it said that "\\\" starts a new line but it does not.

You need the eqnarray* environment. It's basically a three column table with the columns right, center, and left aligned. Within that environment, & delimits the columns, \\\\ ends rows. Like this:$$\begin{eqnarray*}
F&=&ma\\
&=&\frac{GMm}{r^2}
\end{eqnarray*}$$Omit the asterisk in the environment name if you want your equations to be numbered.

 

[Ivan Seeking]

Easier

i

 

[pinball1970]

TIL Euclid has released first light commissioning images.

https://www.esa.int/ESA_Multimedia/Images/2023/07/Early_commissioning_test_image_VIS_instrument

 

[BillTre]

The Great Carrier Reef; probably mostly dead now due too high water temperatures off Florida.