The h Bar - 2020-01-25

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3:36 AM

cool fluid dynamics experiment by a very talented undergraduate, for anyone who cares, not terribly far from some long on my mind... _ Accurate Fluid Dynamics By Video Analysis_ physicsforums.com/insights/…

4:08 AM

I'm going to be... a little disappointed if my two 500 point bounties still don't get answers :(

1 hour later…

5:08 AM

@tpg2114 If I knew more I would definitely take a crack at them

5:50 AM

@AaronStevens I was hoping it would incentivize people to come out of the woodwork to answer it. But I think the fluid dynamics community is just not mature enough here... which makes me sort of sad. On the other hand, it was never a robust group anyway and I've been very happy with the increased number of (introductory) questions I've seen on the front page about it

But I also did it because I only have 3 questions asked without accepted answers and I'd like to finish it off so there are zero without answers.

6:03 AM

Happy Lunar New Year!

Yuvraj Singh...

@tpg2114 sir you said fluid dynamics community, does that mean there are very less number of user who are strong in it?

@YuvrajSingh... Correct. It has always been a relatively small subset of people on the site, and it is hard to get a critical mass of people.

Yuvraj Singh...

@tpg2114 why you think, do you have any specific question in your mind, which make you said this?

The folks that are "regulars" in fluid-dynamics are very good. But there isn't very many of them. Not enough that search engines give Physics.SE results as the top answers for fluids questions

@YuvrajSingh... General perception... but, there's only ~4500 questions with fluid-dynamics out of ~152,000 questions total.

So by shear numbers it is a very small component of the site

Yuvraj Singh...

@tpg2114 huge sir!

6:10 AM

~13,000 for newtonian-mechanics, ~20,000 for quantum-mechanics, ~8,000 for general-relativity

So the 4500 is a small subset of "physics," and honestly many of those questions border on engineering.

Yuvraj Singh...

@tpg2114 sir what I believe is, mostly user who are on the are more interested in quantum mechanics, general relativity, black holes, string theory, and that make such thing.

Do you have any idea how do we improve it?

@YuvrajSingh... Definitely -- those are the classic "physics" things, and also are popular in the general public. Fluid dynamics is often thought of as engineering and so we don't seem to attract that crowd here as much. We also don't attract much in the experimental-physics community either... that was something I wanted to improve, and @dmckee---ex-moderatorkitten was very supportive

I don't know how to improve it, other than making sure we have good, high-quality content in that area so search engines turn up Physics.SE pages for almost any combination of words in fluid dynamics that somebody may search for

Which can only happen by having content

Yuvraj Singh...

@tpg2114 agree sir!

Maybe the folks who are in that area need to post more. I know I haven't asked very many questions in general -- perhaps I should start seeding questions

Yuvraj Singh...

@tpg2114 yes sir!

6:18 AM

Not out of a need to know the answer myself, but to start filling in the fundamental questions and answers that will lead to searches pointing people here

Yuvraj Singh...

@tpg2114 we should start from basic.

Like good question on bernoulli equation.

I mean more conceptual.

Sure -- but, it takes a very concerted effort to do that if somebody is coming from a position where they already know the answer

Like, it's hard for me to be motivated to formulate well-posed entry level questions because I don't have those questions anymore.

Yuvraj Singh...

@tpg2114 If you want I have a good user on site.

@Guru vishnu brilliant boy.

You can see his recent question.

Guy who approach the physics in more logical way.

@YuvrajSingh... What happened? BTW Thanks for the compliment!

It's a model that is a flaw of StackExchange in general -- we've discussed before why people answer questions, and it's hard for "experts" to post new questions without making a concerted effort to seed questions

6:26 AM

@YuvrajSingh... If that referred me, then I'd say there are many people (not me) who have already written even more excellent questions and answers! This site is full of great people which is tremendously helpful for learning new stuff everyday :-)

Yuvraj Singh...

@Guru vishnu you got in a wrong way, our aim is build strong foundation for full dynamics.

@tpg2114 correct sir!

@YuvrajSingh... I think I'm still not understanding the context of the conversation. Shouldn't that be "fluid dynamics" instead of "full dynamics"?

Yuvraj Singh...

@Guru vishnu typo.

technology bias:

It seems the current trend of technology makes it increasingly vulnerable to failures

e.g. internet of things vs discrete appliances, the former is so easy to take over just by hacking

@Secret Growing pains. That's all it is. When the car was first invented, there were so many accidents that killed people. It took time to refine it.

Pick any new thing. It takes time to iron out the kinks and make it work safely and reliably.

6:39 AM

I think it is worse than that. For example steam engines rely on water and if there is no water, you only lost access to steam technologies. But for almost every modern technology, once the power grid is out, everything from wifi to mobile phones to electric doors are knocked out

Internet of things drives that central depnedence on one resource to a whole new level: Once it is hacked in, everything from auto driving cars to the entire city can be controlled

But we could still build and use a steam engine. And when that fails, we could still do things by hand. I think given any technology X, we can always fall back to X-1 (with a lot of pain, sure)

I think if society and technology are creative enough to come up with something, then we are creative enough to come up with something else when the original thing fails miserably.

Will it be easy? No way -- what the heck would happen if GPS turned off. We'd all be extremely lost. I don't even know where to buy a paper map anymore

I don't know, but I think it is getting fatal to do so. We are so dependent on mobile phones to do pretty much anything so if its core dependent resource is knocked out, pretty much the whole of modern society is taken down with it. It will be like as if we all all suddenly isolated

This sometimes makes me wonder, is there a way to run a modern technology without reliance on electricty, but a more accessible form of resources that does not need a lot of processing?

I agree with that. But I don't know that it is somehow fundamentally different than what happened in prior generations. We would be "dead" without a cell phone. But some time ago, they would have been "dead" without tractors and trucks to manage the farms and food. And before that, they would have been "dead" without something else.

But humans have survived a long time without whatever technology we're talking about. Would it be the same? No. And it would suck for the transition generations. But maybe we come out better for it, because we can take a step back to take 2 steps forward

I guess you are right. Still, I hope technology can move beyond the electricity paradigm. Even emerging quantum technologies still need electricity to manipulate the quantum states

that might help it to become more robust

I guess at the end of the day, the laws of thermodynamics rule. We need an energy gradient to do work, and work is what makes things happen.

6:47 AM

that's for sure

Electricity isn't the most energy-dense form of work, but the others (nuclear, gravity) would be pretty dangerous to try to use in every device

How we generate electricity is important for our survival. But electricity itself seems to be the most fundamental, most stable, and most available source of work out there

I see

I'm open to being wrong ;)

But there's only so many sources of energy gradients in the universe. And very few of them are usable on the scale of a planet

7:22 AM

platinumelectricians.com.au/blog/…

Ok found something

There is something called mechanical computers, but they are a lot slower

1 hour later…

8:31 AM

Is there any way to align images in questions/answers? I know to decrease their sizes, but not to align them to the centre or something like that. I tried using MathJax but the image itself doesn't get displayed. Thanks!

8:42 AM

@skullpatrol Same to you Pal

Novalium Company

Guys, can we argue that such things as irrationality and nonsensical thoughts cannot actually be that. I mean, our brains work on very precise mathematical models of the shooting neurons. How can such a rigid system think of something irrational or illogical?

Is it possible that such things as illogical and irrational don't exist?

Like, whatever bullsh*t I come up with, it must have logic. My precise mathematical brain functioning is impossible to come up with anything else.

Tell me what you think about that.

please elaborate a bit more on what you mean by "irrational"?

if you push the wrong buttons on a calculator you will get an illogical answer, right? @NovaliumCompany

Novalium Company

8:58 AM

Well, I'm starting to wonder what irrational and illogical actually is. Like, are they subjective concepts?

Or something is irrational or illogical if it doesn't align with the way the universe works?

@NovaliumCompany Since we do not understand how the content of a thought maps to the physical substrate of the brain it exists in, whether or not the neurons of the brain can be described with mathematical models seems to me to have very little to do with whether we would describe the content of the thoughts of the brain as 'logical'.

is 2 + 2 = 4 subjective?

Novalium Company

Yes

why?

Novalium Company

Because I perceive it.

9:01 AM

you don't trust your perception?

Novalium Company

We're entering very deep philosophical waters here.

I don't know what I'm doing... I guess I'm just trying to make being stupid cool.

We've been here before

Jul 14 '19 at 13:39, by ACuriousMind

Radical scepticism is a valid but empty position, since no one really acts as if they believed it.

Novalium Company

Yep, I remember.

That's why I stopped :D

I guess for now, logic and rationality break down to whether they align with what the universe tells us.

just remember

user image

never stop leaning

Novalium Company

yep :)

9:09 AM

cya, pal

Yuvraj Singh...

@ACuriousMind please sir change your dp, I like the earlier one!

Novalium Company

bye

9:23 AM

@YuvrajSingh... Please change your dp first, I don't like this one. (Just for fun :-)) I think it's totally up to the person using the account.

@NovaliumCompany Are you around?

1 hour later…

10:38 AM

@skullpatrol I don't see a single child in that orchestra

Lies

@ACuriousMind I am

You just can't tell because your senses are deceiving you

1 hour later…

Shootforthemoon

11:45 AM

@Slereah Classical argument: you can't tell anything, then how can you tell that senses are deceiving?

You can't!

But they MAY

dun dun duuun

the uncertainty!

12:45 PM

I have to prove that $ A \cap A = A$

Here’s what I did: $$ \textrm{Let x belongs A \cap A} \\ x \in \left( A \cap A \right) \\ \implies x \in A ~\textrm{and} ~x\in A $$

Now how can I conclude from the last statement that $ x \in A $

?

1:09 PM

1

A: Can a submerged object in a free falling fluid sink faster than falling?

The question is well answered by Aaron and Emilio. To make the effects interesting, let us visualise the scenario for a particular case - when the object is hydrophilic (water attracting) and air resistance is negligible, in a qualitative manner. The following image shows the system at different...

Is the actually how hydrophilic interactions work?

1:20 PM

@AaronStevens Let me clarify it. I don't think I explained the object seeks towards the centre because of hydrophilic nature, it's because of adhesive forces (force between water molecules and the object). As far as I understood, hydrophilic interactions are a subset of adhesive interactions. I understood that it's not because of hydrophilicity the object seeks towards the centre rather it's because of the net force due to non-uniform arrangement of molecules. I hope you understood my point now.

If I'm incorrect kindly feel free to correct me :-)

For instance, consider this image - i.stack.imgur.com/7PCVt.png - I've not mentioned the net force is due to hydrophilic interactions, but it's because of adhesive forces which I believe could act even when separated by some distance as they are just coulombic interactions (electrostatic force).

What does a tidy Mexican divorce means?

@Knight do you have any ideas on how to find out pal?

1:40 PM

@skullpatrol You mean Abhas?

@Knight nope, i mean if you google "a tidy Mexican divorce" you'll get a lot of song lyrics by Tom Waits which doesn't really help with the meaning

@skullpatrol yes

I want to know why he used that metaphor?

because it was clean and cheap

Mexican divorce

In the mid-20th century, some Americans traveled to Mexico to obtain a "Mexican divorce". A divorce in Mexico was easier, quicker, and less expensive than a divorce in most U.S. states. Celebrities who obtained a Mexican divorce include Johnny Carson, Katharine Hepburn, Richard Burton, Elizabeth Taylor (from Eddie Fisher), Marilyn Monroe (from Arthur Miller), Don Hewitt, Charlie Chaplin (from Paulette Goddard), Jayne Mansfield (from Mickey Hargitay), Stanley Kubrick, and Tom T. Chamales. It was often referred to as a quickie (sometimes spelled quicky) Mexican divorce. Mexico does not require spouses...

come on, you could have found that^ :-)

Yeah

when it doubt, go to Wikipedia

1:48 PM

I want to know one more thing, Tom Waits use that phrase in sad love song so why would he want a Mexican divorce?

he wanted the relationship to be over quickly, i guess

By the way have seen this youtu.be/K8hF7qQE5nQ

cute

Why you didn’t come from so many days? Were you busy or there was some other reason?

just busy

1:54 PM

The main thing is that I get alone without you, as you must be aware that Abhas has left SE

yup

And as you know here “Might is right” policy prevails

the whole network is undergoing a "phase change"

You got examples?

check meta

1:58 PM

Stepping down?

yup

and 3 community managers let go in a week

That’s sad thing, dmckee shouldn’t leave but we know he got a special bond with shog9

@skullpatrol Jon Ericson wasn't 'let go', he left on his own. If you must discuss this here, please at least be accurate.

Did shog9 left for money?

@ACuriousMind feel free to remove

3 community managers ~~let go~~ left in a week

2:07 PM

What’s the different between “let go” and “left” ? If I want to leave then why I wouldn’t be allowed to let go?

@Knight 'let go' means 'fired'.

'left' doesn't really say whether the employee wanted to leave or not.

Who among them got fired for money?

I have no idea what "got fired for money" is supposed to mean.

They left because they wanted money

could part of the reason they "left" be because others were "let go"?

2:10 PM

If you're asking for the reasons the CMs left, read meta and twitter. There's very little official statements and a lot of lines to read in between.

@Knight No, that's certainly not the reason for any of them.

How do you know that?

@skullpatrol Does any member make any money from SE?

@Knight CMs are on a salary

@Knight That's...not the sort of person they are. If you have no idea who Shog, Robert or Jon are, you shouldn't be throwing out random ideas about their intentions.

@Knight mods are completely voluntary

@ACuriousMind Just point out when I asserted that they were money minded. Don’t you try to put false accusations on me!

2:15 PM

4 mins ago, by Knight

They left because they wanted money

@skullpatrol Was shog9 a mod or higher official on SE?

@Knight he was a CM

@skullpatrol that was the explanation of “what fired for money means”

@skullpatrol What’s the full form of CM?

I have no idea what the first sentence in your reply is supposed to mean, sorry. You accused them of leaving because they wanted more money. I'm just saying if you don't know who they are, maybe don't make such assertions.

@Knight Manager of the community

2:17 PM

I never made any assertion I asked whether they got fired for demanding money or was it something else.

4 mins ago, by skullpatrol

@Knight CMs are on a salary

ok ok

@skullpatrol I got your indication

21 mins ago, by skullpatrol

the whole network is undergoing a "phase change"

sorta like water boiling

Novalium Company

It's better to read a book a month, but that book to be a right one. A one that influences you and you really learn something new and useful than reading a book a week but you hardly remember anything from the BS you read. Do you agree?

yes

sounds like common sense :-)

\o @YuvrajSingh...

2:21 PM

No, read as many books as you like.

Novalium Company

I'm just seeing this new trend - "Oh look at me, I'm reading a book a day, I'm so smart". And I'm like... a bit jealous. donno...

Books don't have to teach you something, read pulp fiction, if you like it. Read a silly story a day if you want to. I very much reject the elitist idea that there has to be objective worth in a book for it to be worth reading.

Novalium Company

I'm reading Recursion: A Novel now. Seems cool.

I want to be "an intellectual". I feel like I'm not doing enough.

@NovaliumCompany The Blake Crouch novel?

Novalium Company

ye

2:26 PM

That book has been in my "to read" pile for ages but the pile keeps getting bigger so I haven't got around to reading it. Is it good?

Novalium Company

I'm on page 35. I started it an hour ago so I can't tell from now.

But for now, it's good enough.

Anyways, I gotta go. Be back after 2 hours.

Bye

cya pal

Yuvraj Singh...

@JohnRennie what does that mean.

@NovaliumCompany How to read fewer books

2:34 PM

@YuvrajSingh... Recursion is a novel by a chap called Blake Crouch.

Yuvraj Singh...

@JohnRennie hi sir where we're you today?

@YuvrajSingh... I was out late last night - very late :-)

Yuvraj Singh...

@JohnRennie oh! Party?

@ACuriousMind why is that "elitist"? Is wanting quality only for the "elite"...

2:53 PM

@skullpatrol ever read Tolstoy?

nope

too long for me

@skullpatrol Fyodor Dostovesky

same

@skullpatrol Edgar Allan Poe?

some

3:07 PM

Did you like?

his poetry is amazing

Poetry? He writes macabre

true, that's what he's famous for

What about some movies? Do you wanna tell some movies?

the pit and the pendulum was a good movie

based on Poe

3:21 PM

Should I read it or watch it?

watch it to see if you want to read it

@JohanLiebert We are friends now!

@NovaliumCompany I just mentioned that book here not too long ago. I loved it

@JohnRennie I loved it.

On February 9 Oscars will be awarded !

3:37 PM

On February 2 the superbowl will be played!

Is Brady playing?

nope

Why?

his team lost in the first round of the playoffs

Oh Gosh !

3:39 PM

yeah, ENOUGH of that dynasty

nasty cheaters :P

LOL

Whom you want to be awarded with the best picture of Oscars?

dunno, who do you like?

The Irishman

@skullpatrol Do you want Abhas to come back?

@Knight yup, but he's gotta do what's right for his self-respect, just like dmckee, right?

Yes,

3:47 PM

thanks pal

You and I can understand what really he's feeling now

I watched the whole thing...

You know after that somebody even said that I'm supporting his views by asking him to comeback. What a pity!

yeah, I know

We got very logical people here, so logical that you'll not find in any part of the world

3:54 PM

i haven't been to all parts of the world :P

That's a very good point. Means there are chances where people will be more logical than here.

@Slereah perhaps, one day there will be...

@skullpatrol How to search for messages in transcript which were sent 2 days earlier?

use the "search" window in the upper right corner

beside "site rooms"

What should I type? the actual message?

4:08 PM

yes

Yuvraj Singh...

4:50 PM

@skull patrol thanks for correcting me good!

@YuvrajSingh... where?

5:06 PM

@YuvrajSingh... thanks for taking away my access to your room

did you see that^ @Knight?

@skullpatrol What access?

@Knight to his room

means? I’m not getting you

you can see the evidence in the room

@skullpatrol Please say clearly what has happened

5:08 PM

@Knight I have a few messages posted in there

@skullpatrol in general chat?

@Knight no

♦ Physics.

General physics problem.,

@Knight here^

@skullpatrol what he did?

first he gave me access to speak, then he took it away

Why you asked him access? He is a political guy, you should have asked me first

5:13 PM

you don't have access either pal

in Physics. , 11 hours ago, by skullpatrol

I was starting to think you didn't want me around...

I never asked for it. Why should I go in a such trashy place, I can talk to John Sir whenever I want in the h bar

Or the problem solving strategies

true

@skullpatrol Please give the whole transcript

nvm, it is over

2 hours later…

Novalium Company

7:22 PM

@AaronStevens I'm on page 124 of Recursion: A Novel. Would you mind clarifying some things for me because I'm a bit confused on how the 4-dimensional memory travelling thing works. (So I can understand the rest of the book properly)

learning the art of rereading books is a big part of the understanding process @NovaliumCompany

Novalium Company

I reread the part where my confusion arises a few times. I'll go back through it again I guess.

“Thermodynamics is a funny subject.The first time you go through it,you don't understand it at all.The second time you go through it,you think you understand it,except for one or two points.The third time you go through it,you know you don't understand it,but by that time you are so used to the subject,it doesn't bother you anymore..”

― Arnold Sommerfeld

Novalium Company

Actually, my questions about the book are related to things they don't explain in it.

I guess they are answered later in the book.

go forward with that assumption pal

Novalium Company

7:36 PM

yep :P

Novalium Company

8:23 PM

All the details are getting clearer and holy smokes that book is one of the best sci-fi books I've ever read in my life.

@AaronStevens book is amazing dude

I'm looking for a movie based on the book but I can't find :(

see, sometimes you just have to get

> so used to the subject,it doesn't bother you anymore..”

:P

@NovaliumCompany I feel like explaining it (or even talking about it) is a spoiler. I agree, it gets confusing. The best way to get used to it is just to keep reading though.

@NovaliumCompany The book came out fairly recently. Blake Crouch said that if someone wants to make a movie then he won't be too involved with it though.

Honestly, I feel like a movie would mess it up

Novalium Company

8:38 PM

I'm on the most confusing untied part of the book. Part 3 if you remember.

Anyways, all of my questions are being answered as I keep reading.

@NovaliumCompany Yeah. It gets pretty crazy. I think he does a great job at using the premise in different, interesting ways

The only other book I have read by him, "Dark Matter", is also really good

Novalium Company

Reading from the description of Dark Matter, it looks pretty similar to Recursion.

It's not.

@skullpatrol I thought this applied to QM.

8:55 PM

that's the original quotation

@Knight In the future you might want to avoid referring to other rooms as “thrashy”. Maybe you don’t like it (and you’re entitled to not liking it) but surely it’s a bit condescending to make such a comment.

von Neumann said pretty much the same thing

...you just get used to it

> it doesn't bother you anymore

@ZeroTheHero the problem is most people call the beginning stages of "getting used to it" rote memorization

1 hour later…

Shootforthemoon

10:24 PM

@Slereah XD Then the uncertainty is certain!

Paradox!

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