The h Bar

Sir Cumference

1:54 AM

my internet gives out when everything goes online...

Yuvraj Singh...

4:03 AM

@PM2Ring hi

Can you help?

Yuvraj Singh...

6:13 AM

@JohnRennie hi.

John Rennie

@YuvrajSingh... hi :-)

Slereah

6:49 AM

Secret

7:21 AM

@skullpatrol @ACuriousMind ok to clarify why that particular post lead to so much facepalming. It is because of the non mainstreamness implicated due to relating dipoles with dimensions and then only extrapolating the tangential meaning of these analogies, despite the whole thing is not meant to be interpreted as there is such thing as "dipoles in negative dimensions". Thus that paper quoted does not do my post justice

The importance is what new users think when they first saw that

They don't know me and my weird quirks, and will end up as Acuriousmind said it will give a bad professional reputation for h bar

Thus the true system you cannot fight is not the mods, but the way normal people react to weird things

and the mods in this case are innocent

as PWring elaborated previously

PM 2Ring

7:36 AM

A strangely meta MSE question for the 1st of April:

11

Q: Why does this very Meta question lack a duplicate target?

The question https://meta.stackexchange.com/q/345815/336163 (asked less than ten minutes ago) was closed as a duplicate less than five minutes ago, but it lacks any semblance of a duplicate target. The header shows: This question already exists: The expected link to the duplicate target is...

Yuvraj Singh...

@PM2Ring hi how are you? I saw you pin me yesterday related to my question!

Secret

This is now an example of a question which itself demonstrates the bug it's reporting :-D — Rand al'Thor 16 hours ago

lol

also typo PM2ring, not PWring

Speaking about April fools...

Can you make April fools fool itself?

PM 2Ring

@YuvrajSingh... Hi. I'm ok today, but for the past 4 days I had very bad back pain. Even trying to stand up straight was agonising.

@YuvrajSingh... Which question was that?

Yuvraj Singh...

@PM2Ring bottle water one!

PM 2Ring

@YuvrajSingh... No, I didn't respond to that question. Your question is not very clear, but I think you have a water bottle with small holes or cracks, and it doesn't start leaking until you open the lid of the bottle. Is that correct?

Yuvraj Singh...

7:51 AM

@PM2Ring it was leaking a bit, and bottle cap was closed earlier.

John Rennie

18 hours ago, by Yuvraj Singh...

Hi guys today I was on my terrace with bottle filled with water, and bottle had holes in its bottom, and earlier the bottle was sealed pack but some amount of water was coming out, and I open the bottle Cap and water start coming out from the holes at very fast rate. And suddenly the bottle had felt down.

@YuvrajSingh... this question?

Yuvraj Singh...

@JohnRennie yes.

Yes as I saw that water just stopped coming out from the bottle as it falls.

It is like the gravity vanishes

@PM2Ring

John Rennie

If the bottle is falling then the bottle and the water inside it are in free fall i.e. the gravitational force they feel is zero.

ACuriousMind

I'm confused why the bottle is "suddenly" falling down. Are you just holding the bottle and letting go of it?

Loong

www1.grc.nasa.gov/wp-content/uploads/…

Yuvraj Singh...

7:57 AM

@ACuriousMind yes.

ACuriousMind

Ah. Well, "suddenly" and the passive voice sort of implied surprise on your part about this happening...

Yuvraj Singh...

@loong yes sir!

I read some where this was the bass of Einstein GR theory.

John Rennie

@YuvrajSingh... it is!

Loong

Free Falling Leaky Bottle -- xmdemo 017

►

John Rennie

@YuvrajSingh... see for example:

17

Q: If gravity isn't a force, then how are forces balanced in the real world?

Consider a simple situation like this- an object is sitting on a table. In classical mechanics, we say that the net force on the object is zero because gravity (treated as a force) and normal reaction force are equal and opposite to each other, and hence, it's acceleration is zero. But according ...

newtonian-mechanics general-relativity forces spacetime

Yuvraj Singh...

8:00 AM

What confuse me us "Einstein think Newton apple drop experiment. Is Newton head rushed towards the apple and they collide.

John Rennie

@Loong wow, it's remarkable how suddenly the water flow cuts off. Well ... not remarkable really ... but still very striking.

@YuvrajSingh... check out the question above, because that's exactly what it is about.

PM 2Ring

John Rennie

Home schooling in the grip of the virus outbreak:

Though if it was me I think I'd chloroform myself and let the children get on with it.

Loong

8:18 AM

in The Periodic Table, Oct 14 '16 at 12:24, by Loong

That reminds me how some students I was supervising tried to anaesthetize a fly with chloroform.

in The Periodic Table, Oct 14 '16 at 12:25, by Loong

Capture a fly in a test tube, add a few drops of chloroform, close the tube, and let the chloroform evaporate.

in The Periodic Table, Oct 14 '16 at 12:25, by Loong

That actually worked! So they could put the fly under a microscope.

in The Periodic Table, Oct 14 '16 at 12:27, by Loong

However, when they tried to do that again, the fly dropped into the liquid chloroform.

in The Periodic Table, Oct 14 '16 at 12:27, by Loong

And then we learned that fly is soluble in chloroform.

Secret

Judge Doom intensifies

John Rennie

@Loong Skin is soluble in chloroform as well. At Unilever we used a mixture of ether and chloroform to extract skin lipids for analysis, but keep it on the skin for more than a minute or so and it feels as if your skin is on fire.

I have tried it, and I can vouch for the intensity of the pain it causes.

PM 2Ring

@JohnRennie That's a lovely answer.

Secret

suffice to say an accident that involve falling into a tank of chloroform will be an agonising way to go

John Rennie

@PM2Ring though notice that he who shall not be named was unconvinced. There's just no getting through to some people.

Secret

8:24 AM

The only thing that bothers me about chloroform is why it is not light green in color as its name imply

also... chloroform has a watery smell with a sharp ending at least in lab atmosphere

still much less pungent than benzyl chloride

Slereah

Colour Forms Simpsons

►

Loong

@Secret described like a wine connoisseur

PM 2Ring

When I was a kid, there was a popular brand of over-the-counter throat lozenges (LLC) which contained a small amount of chloroform.

Slereah

@Loong I prefer this review

Fear and loathing in Las Vegas - Ah, devil ether

►

John Rennie

The temptation to sniff whatever you're working with can be irresistible, though if it smells of almonds you might be well advised to back away.

Loong

8:27 AM

I still like the smell of benzene. Smells like old ball pen ink.

Secret

interestingly, propane-1-ol smells like strawberries to me

John Rennie

I have in that past inadvertently sniffed hydrogen fluoride and phospine (at very low concentrations). Sometimes I wonder how students ever survive the lab work.

PM 2Ring

@JohnRennie I noticed. Stuff like that is bound to trigger his "argument from incredulity" circuit. But to be fair, it is pretty mind-blowing the first time you encounter the notion. :)

Slereah

Here is a handy smell chart :

jameskennedymonash.files.wordpress.com/2014/01/…

John Rennie

@Slereah Excellent :-)

PM 2Ring

8:30 AM

@Loong Toluene's got a nice smell too.

Secret

formaldehyde has a watery smell, though I don't want to go blind thus I immediately move away from the area when I smelled it

Loong

@Slereah Ah, so methanal smells like formaldehyde. ;-)

Slereah

Apparently iodo-ethane smells "ethereal"

I'm not sure what kind of smell that is

Perhaps if you smell it you go to the astral plane

Secret

ethanol has a "deep watery" smell
diethyl ether smells like drowning

I felt like someone is putting gassy oil into my lungs when I smelled ether

and if I don't get out of the area in 5 s, I felt dizzy and drowning like

Slereah

that's ether for you

All the thiols smell terrible it seems

Secret

8:34 AM

skunks extraordinate

Slereah

Lactones are the good stuff

John Rennie

Asparagus doesn't smell of anything much until it has been through your kidneys, when it suddenly produces the characteristically rank thiol smell.

Loong

If you go outside after a long day in the organic laboratory, you have adapted and now the clean fresh air has a taste.

PM 2Ring

I like the smell of diethyl ether, but it gives me a headache within minutes, even at low concentrations.

Slereah

@Loong Novelty detection

@PM2Ring Do you smell it from an American flag

Secret

8:36 AM

oxfordreference.com/view/10.1093/oi/authority.20110803095759217

PM 2Ring

@Slereah No. :D

Slereah

Smelling dimethyltryptamine will actually send you to the astral plane

PM 2Ring

When it comes to stinky, thiols are just appetizers. Go down the periodic table to selenium & tellurium for the serious contenders. ;)

Slereah

@PM2Ring does the moon stink

ACuriousMind

Sure, it's made of cheese after all

Slereah

8:39 AM

oh apparently there isn't a particular large quantity of selenium on the moon

lame

John Rennie

@Slereah I'm sure I remember reading somewhere that dust collected from the Moon does smell bad.

Loong

futurama.fandom.com/wiki/Smell-O-Scope

Slereah

@JohnRennie I also seem to remember that due to a lack of erosion, dust on the moon is like tiny knives

and will shred your lungs like asbestos

PM 2Ring

From Things I Won’t Work With: Selenophenol A few years ago, Gaussling at the Lamentations on Chemistry blog referred to it as “The biggest stinker I have run across. . .Imagine 6 skunks wrapped in rubber innertubes and the whole thing is set ablaze. That might approach the metaphysical stench of this material.”

John Rennie

Maybe that's what causes the unpleasant smell i.e. a physical mechanism rather than a chemical one.

Slereah

8:42 AM

Asbestos crystals look very threatening

The Moon is made of green cheese

"The Moon is made of green cheese" is a statement referring to a fanciful belief that the Moon is composed of cheese. In its original formulation as a proverb and metaphor for credulity with roots in fable, this refers to the perception of a simpleton who sees a reflection of the Moon in water and mistakes it for a round cheese wheel. It is widespread as a folkloric motif among many of the world's cultures, and the notion has also found its way into children's folklore and modern popular culture. The phrase "green cheese" in the common version of this proverb (sometimes "cream cheese" is used)...

it's on wikipedia

it must be true

John Rennie

They cause pneumonoultramicroscopicsilicovolcanoconiosis.

Slereah

Adverse health effects from lunar dust exposure

The respirable fraction of lunar dusts may be toxic to humans. NASA has therefore determined that an exposure standard is necessary to limit the amount of respirable airborne lunar dusts to which astronauts will be exposed. The nominal toxicity that is expected from ordinary mineral dust may be increased for lunar dusts due to the large and chemically reactive surfaces of the dust grains. Human exposures to mineral dusts during industrial operations and from volcanic eruptions give researchers some sense of the relative toxicity of lunar dust, although the Earth-based analogs have serious limitations...

PM 2Ring

@Slereah Yes, it's all produced by shattering, with virtually no processes happening that can round stuff off.

Slereah

That's it, no more doing lines of moon dust for me

John Rennie

The Mysterious Smell of Moondust

Slereah

8:46 AM

"Feel it—it's soft like snow, yet strangely abrasive."

No, don't feel it!

PM 2Ring

Mars dust gets a little bit of rounding by being blown in the wind; OTOH, it contains all sorts of fairly active chemicals (like oxides) that are very happy to absorb any water they can get.

Slereah

One thing I wonder is

What do individual smell receptors smell like?

Because smell doesn't work via individual receptors for each smell

Each chemical activates every receptor to some degree, and the smell is just the set of all those potentials

So we never really smell anything that activates a single receptor

PM 2Ring

Actually, some of the moon dust isn't produced by shattering. Really big impactors will splash up molten rock, and you will get some smooth droplets forming when the rock re-solidifies. But you'll also get some very jagged stuff too.

Slereah

this means that, much like impossible colors, there are impossible smells

PM 2Ring

How Brian O'Brien's lunar dust detector sketched on a whisky coaster made it to the moon

Q: What does chlorine trifluoride smell like? A: It smells like your nose is on fire.

Secret

9:00 AM

do you seriously smell that?

John Rennie

Q: Why does it smell like your nose is on fire? A: Because it is.

Secret

that thing burns concrete in seconds

hmm impossible smells...

problem is unlike the eye which is mostly 3 cones and tons of rods, the nose have over 1000 receptors

so it is very hard to isolate the effect of just one receptor

I have yet to found any scholarly research on single ofactory receptor response

Slereah

9:17 AM

Impossible smells could possibly be generated by hallucinations, but there aren't a lot of drugs that give you olfactory hallucinations

Apparently Diphenhydramine does

Johan Liebert

This

Slereah

9:38 AM

One of the most terrifying thing I've ever seen is the test they administer to dementia patients where they ask them to draw a clock

This is how you know you're going mad

Secret

...indicates a reduction in the ability of coordinating motor movements, and distortion of the sense of space and time...

that's my thought when I look at those diagrams

the way they are distorted though, seems to suggest some things are emphasised while some things are lost

makes me wonder what that guy who drew the multihand clock in 3III is thinking

Slereah

No, that's not the issue

The point of using a clock is just because it tests a variety of abilities

Shapes, sequences, positions, etc

PM 2Ring

@Slereah My maternal grandfather suffered from Alzheimer's for the last 5 years or so of his life. I didn't see him very much towards the end, it was just too distressing, and he didn't recognise anybody anyway. :( He stayed with my mum & step-dad, until he got too difficult for them to manage.

Slereah

it is not very fun

Secret

Yeah that was what I am thinking, Alzhimers usually recall very old memories but not stuff in the recent past, so I am suspecting that whatever features in the clock that looks remotely normal may be a hint of memories they still retain

Slereah

9:52 AM

Dementia doesn't just affect memory

Secret

e.g. perhaps the person in IV4 love sequences, so that part don't get degraded alot

Emilio Pisanty

Novel approach to Room Temperature Superconductivity problem. I. Timokhin and A Mishchenko, arXiv:2003.14321 (2020).

3

↑ makes the annals, for sure

Slereah

It can get fairly bad

PM 2Ring

He was a builder, and specialised in roofing for most of his career. When he was in the nursing home he gave the staff a hard time because he was such a good escape artist, and had no qualms about climbing out of windows & strolling around on the roof. :)

My niece Bianca has done some work on genetic markers for Alzheimer's, eg researchgate.net/publication/…

Emilio Pisanty

seriously, no stars for high-TC superconductors?

PM 2Ring

9:57 AM

These days, she's got a baby to look after, but she has done some work with her husband Nathan on respiratory viruses. hmri.org.au/news-article/…

Slereah

Isn't room temperature superconductivity old news by now?

Secret

processing stars in progress

Slereah

If it's cheap room temperature, that would be great

Emilio Pisanty

@Slereah go and look at the preprint

Slereah

Does he have to work from home because of the virus

Emilio Pisanty

9:58 AM

you did look at the date, right?

PM 2Ring

@EmilioPisanty Cute, I assume that's an April Fool's Day paper.

Emilio Pisanty

@Slereah presumably, yes

Slereah

The date isn't actually on the paper, but yes I got it

ahah

Oh also 2003

Wait, is it 2020 or 2003

Oh 2003 is submission number

Secret

@EmilioPisanty The non April fools response to that is: assuming we don't die first, the amount of liquid nitrogen needed will leave our earth with no atmosphere

Slereah

Also april fool doesn't excuse papers made in MS Words :p

Secret

10:00 AM

yup

Emilio Pisanty

> Acknowledgements | The authors acknowledge unprecedented circumstances of at home lockdown due to COVID-19 outbreak.

Slereah

I don't follow at all the superconductor scene

PM 2Ring

@Slereah Probably not, but I haven't spoken to him for a while. I figure he's kinda busy right now. His lab is equiped to handle pretty dangerous stuff. Eg, the air pressure is kept below ambient, so nothing nasty can accidentally leak out.

Slereah

how are superconductor nowadays

Emilio Pisanty

@Slereah arXiv IDs are of the form YYMM.nnnnn

Secret

10:03 AM

Speaking of COVID-19, I am still annoyed that having more phenomenologists at home still failed to give new physics

Emilio Pisanty

@PM2Ring huh. attoscience labs are normally kept above ambient pressure (when possible), so dust doesn't get in.

Secret

Surely for a virus that can take down economies and whatnot, physics is no match to it lol?

@PM2Ring that sort of thing I talked about indeed

PM 2Ring

@EmilioPisanty Indeed. Nathan's lab may suck a bit of dust, but that's better than potentially infecting the neighborhood with some respiratory bug.

Emilio Pisanty

yeah, that's fair.

for us it's more a matter of, if a speck of dust settles on a mirror, and is then hit by an IR pulse at PW peak power, that bit of mirror isn't gonna mirror anything at all at any time in the future.

Loong

@Slereah could also be used as a reCAPTCHA

Secret

10:10 AM

does that part of the mirror become charred when that happens, I don't know but normal char can be wiped by suitable cloths that are not abrasive to the mirrors

but I don't know if laser grade mirrors have specialised wiping cloth

unless, you mean the irradiated dust actually melts that part of the mirror due to the IR output that is concentrated on it

PM 2Ring

@EmilioPisanty Got it. :) What do you make lenses etc out of that can handle petawatts of IR? I know salt (NaCl) is used for some low power IR work.

B. Brekke

I am looking at a propagator in the Hubbard model and my timescale is beta. I see that for longer (imaginary) times tau, the particle can propagate further away.

However, it can't move infinitely far, as the time is limited by beta. If I increase beta I would assume the particle can propagate further away. Now, when I think about beta not as a time scale, but as inverse temperature, I struggle to understand what is going on. If beta -> 0, and temperature goes to infinity the particle can't propagate at all and if beta goes to infinity the particle can propagate far. But is this how temperature works, it is not very intuitive to me.

Emilio Pisanty

@PM2Ring what matters is more the intensity than the power

PM 2Ring

Ok.

Emilio Pisanty

but generally you try to avoid transmissive optics once the pulse has been amplified and re-compressed

i.e. you try to work with reflective optics as far as possible

PM 2Ring

10:15 AM

That makes sense.

Emilio Pisanty

this isn't quite so much about damage thresholds as about dispersion

transmissive optics are generally dispersive, and will tend to mess with the temporal envelope of your pulse

damage is also a concern, but dispersion comes up first

when you do use transmissive optics, you normally pre-compensate for them by adjusting the pulse compressor

... with all of this within the framework of Chirped Pulse Amplification, as described in my answer about it

damage is definitely a concern on clean optics, but mostly within the amplification stage

PM 2Ring

Ok. I'll take a look at that answer. I guess even with a fairly monochromatic beam you still get dispersion with short pulses.

Ah, that was easy to find: physics.stackexchange.com/q/432137/123208

Emilio Pisanty

@PM2Ring "fairly monochromatic" and "short pulse" are essentially antonyms.

"fairly" and "short" are weaselly, undefined adjectives, but as soon as you give them quantitative meanings, there's a strict trade-off between the two.

@PM2Ring ;-)

PM 2Ring

@EmilioPisanty Sure, Fourier and all that.

PM 2Ring

10:35 AM

@EmilioPisanty So how do you do that recombining step without blowing stuff up? "Finally, you pass your pulse through a reversed set of gratings which will undo the relative delay between the longer- and shorter-wavelengths of your pulse"

Slereah

@Loong Robots can draw clocks

experiments.runwayml.com/generative_engine

Loong

Is that cuneiform?

Slereah

It's a clock

I think that AI may have dementia

Loong

> suspected frontotemporal dementia

Emilio Pisanty

@PM2Ring you use reflective gratings

and you work with reflective optics after that

PM 2Ring

10:44 AM

@EmilioPisanty Ah, right. And make sure there's no dust on them. :)

Emilio Pisanty

and you consider very carefully the dispersive and Kerr-lensing effects of any transmissive optics you introduce after the compressor

generally, you'll need at least some transmissive optics

most notably including any windows into vacuum chambers

... unless you fit the compressor inside a vacuum chamber, of course, which will be quite expensive and a lot of hassle, but it does happen, e.g. at ELI Beamlines

Secret

do the dust just dispersed the beams or it actually get heats up and damage the mirror since you said dispersion will be a bigger issue compared to damage?

PM 2Ring

@Loong I have a question about tritiated water that I keep meaning to ask you. I understand that it's somewhat corrosive, due to self-radiolysis. I've tried looking for the pH of tritiated water, but with no success. Is pH even useful in this context? Or should I say pT?

Emilio Pisanty

@Secret as I understand it, dust is mostly a problem when it settles on optical surfaces, and not if it's just floating around

(but keep in mind I don't directly work in a lab)

Secret

Ah right

user434058

12:00 PM

0

Q: Breaking the light speed barrier

A question I put to a physicst who didn't know the answer. Assuing that our current understanding that the speed of light can't be matched or breached is correct, if you were travelling at the fastest possible speed in a space ship, say 99.99% of light speed, what would then happen if you were t...

special-relativity visible-light mass speed

user434058

I am quite sure that someone would have surely asked it before ☝️

Novalium Company

Damnit

The answer was Korea, not China

I guess it breaks down to textbook stuff yeah

PM 2Ring

@NovaliumCompany There's still a lot of animosity in China towards Japan due to the atrocities committed during the World War 2 era. See en.wikipedia.org/wiki/Second_Sino-Japanese_War en.wikipedia.org/wiki/Japanese_war_crimes en.wikipedia.org/wiki/Unit_731 Etc

Yuvraj Singh...

12:21 PM

@PM2Ring hi.

PM 2Ring

@YuvrajSingh... Hi, again.

Yuvraj Singh...

Do you agree with physicists like brian Greene that, we live in world of parallel universe. And there are enormous number of universe and big bang we know is only the origin of our universe ;-)

@PM2Ring

PM 2Ring

@FakeMod Re: physics.stackexchange.com/questions/540816/… It's quite appropriate for someone to update their answer in response to comments requesting clarification, etc. But if the comment is asking a follow-up or tangential question, then sure, it's probably better to respond with a comment.

bolbteppa

The third clock in I is a masterpiece

JMac

@YuvrajSingh... Does Brian Greene claim that we actually live in a world of parallel universes, or does he just talk about the possibility and the science that suggests that we may, and how such situations might seem?

Yuvraj Singh...

12:27 PM

@Jmac he didn, t use the word parallel.

user434058

@PM2Ring Yeah! Now seeing my comment again, I admit my comment was too "straightforward" and short and I was just lazy to explain :)

JMac

@YuvrajSingh... I just copied your words.

Yuvraj Singh...

@Jmac but he said our universe is part of these universe.

I am sorry to use parallel I should had remove that!

ACuriousMind

...on what type of keyboard is , next to '?

user434058

@JohanLiebert Why did you delete your answer to that meta question?

JMac

12:30 PM

@YuvrajSingh... Where did he say it though? Was he presenting it as a fact, or a possibility? I don't remember Brian Greene pushing any one interpretation over others as if it were true, but I only read one of his books and it's been awhile.

Yuvraj Singh...

@Jmac it was in some class!

bolbteppa

I'm pretty sure he's careful about what he says about parallel universes, "MAY" etc

Yuvraj Singh...

I have the video!

PM 2Ring

@YuvrajSingh... Maybe. ;) I'm not a fan of the Many Worlds Interpretation, but I did write an answer about it recently: physics.stackexchange.com/a/536580/123208 In that answer, I assume there's a single Big Bang that created an infinite number of universes. In general, I'm not that attracted to theories with multiple Big Bangs, but some of those theories are intriguing, like Lee Smolin's Cosmological Natural Selection

user434058

@ACuriousMind On this XKeyboarCD 👇

user434058

12:34 PM

Yuvraj Singh...

@bolbteppa he even compare our universe like a sandwich!

JMac

@YuvrajSingh... Right; but it's important to pay attention about the specifics about what people are saying. Especially with QM interpretations. The statement "Do you agree with physicists like brian Greene that, we live in world of parallel universe." implies that Brian Greene openly supports that interpretation over others; but for the sake of accuracy most physicists only talk about that as a possibility, because we have no way to prove that over other explanations.

PM 2Ring

"My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose". — J. B. S. Haldane

Guru Vishnu

@FakeMod: With respect to your comment: Thanks for letting me know that. I was wondering why \Sigma didn't auto resize to the good looking \sum :-)

Yuvraj Singh...

What I feel is physicists try to explore nature, and use his imagination that what is happening and how is thing happening.

So yes he said this words and then said about multiple universe!

user434058

12:37 PM

@GuruVishnu You are welcome! :)

user434058

BTW whoever deleted the comments on the Meta post by insomniac, please also delete my last comment, because now it looks meaningless......

JMac

@PM2Ring That's one thing I find really interesting about physics. It's about such fundamental things that it's really not clear if you could ever possibly get to a good enough level of understanding.

@FakeMod You can delete your own comments (though it might be a pain on mobile).

user434058

@JMac No worries! "the system" did it!

JMac

I saw.

user434058

I was gonna write that I didn't want to sound condescending, but I ran out of space, in other words, the margin was too small....:P

JMac

12:41 PM

@YuvrajSingh... Do you have a link to the video you're talking about?

PM 2Ring

@YuvrajSingh... You're doing that thing again:

Mar 18 at 14:49, by PM 2Ring

@YuvrajSingh... Hi. You said: "that, s what I am saying". But you should write that with an apostrophe ' not a comma , and there should be no space after the apostrophe because it's inside a word. Like this: "that's what I am saying". I notice that you often make this mistake, and it makes your posts harder to read.

ACuriousMind

@FakeMod Flags, not chat for moderator interventions, please

Yuvraj Singh...

I am not sure, because I got just 2 minute clip I searched on YouTube and I find this.

Science Is Everywhere with Neil deGrasse Tyson & Brian Greene | StarTalk @ BAM | Full Episode

►

user434058

@ACuriousMind Sorry! But I have flagged it now!

user434058

You have some work to do :P

ACuriousMind

12:44 PM

I often happen to be looking at chat when I'm on the site, but few other mods will. There is nothing wrong in using custom mod flags, we can handle a few surperfluous flags :P

Yuvraj Singh...

@PM2Ring it is an habit, I must admit I am very weak at literature because from my small town I did not get proper education in literature and grammar.

user434058

Damn! "the system" is really unhappy with me. It constantly keeps on deleting my enlightening comments, arghhhh....:P Jk, do as you please, you make better decisions

user434058

I would advise "the system" to "relax"....... Don't kill me, this was intended as a joke

JMac

@FakeMod I'm personally avoiding writing comments on that question. The OP is clearly heated, and most comments seem to just be making things worse.

PM 2Ring

@YuvrajSingh... Personally, I am fond of Wheeler–Feynman absorber theory and the Transactional Interpretation. Unfortunately, nobody has been able to achieve much with that interpretation of QM.

user434058

12:50 PM

@JMac I doubt that the system is just waiting for the OP to finish everything and then delete all those comments at once...... The system is intelligent

Yuvraj Singh...

@Jmac have you seen that video.

?

user434058

@JMac metoo. I have given up. The system's surely gonna delete my comments

ACuriousMind

@FakeMod I'd advise you to disengage. Snark is not the answer here (it's never the answer).

user434058

4 hours ago, by Slereah

Here is a handy smell chart :

user434058

I keep on reading it as "handy smelly chart"...hahahaha

JMac

12:52 PM

@YuvrajSingh... I think I've seen parts of it before. I don't know where the part about Brian saying we live in a multiverse is though.

user434058

@ACuriousMind Yeah sure! (But was I being snarky?(that's an honest question))

Yuvraj Singh...

@PM2Ring certainly

They are good.

user434058

Snark reminds me of Snarky Puppy ;)

ACuriousMind

@FakeMod The comment about the chat room struck me as snarky. If you meant it in earnest, let me clarify that chat is definitely not the place to have such conversations - meta discussions should stay on meta where people can see them.

user434058

@ACuriousMind Even long winding conversations like this?

Yuvraj Singh...

12:55 PM

We won't agree with strung theory credibility, but it is giving correct result for 20 numbers.

ACuriousMind

On the main site we'd move to chat, but on meta we usually don't do that - it is for discussion, after all.

user434058

@ACuriousMind Oh!!! That's something new! Thanks!

ACuriousMind

Mar 12 '16 at 11:44, by ACuriousMind

"'Multiple exclamation marks,' he went on, shaking his head, 'are a sure sign of a diseased mind.'" - from Eric, by Terry Pratchett.

(by which I mean to say I don't see what's so exciting about this information that it's worth a '!!!' :P )

Yuvraj Singh...

@ACuriousMind what about a separate chat room for meta only?

user434058

@ACuriousMind Ouch ~~!!!~~

ACuriousMind

12:58 PM

@YuvrajSingh... what about it?

user434058

@ACuriousMind I am not meticulous enough to weigh the worth of exclamation marks before typing them!!!!!!!!!!

ACuriousMind

Don't get me wrong, mods can move meta comments to chat just as well as they can main site comments. We just don't usually do it because "comments are not for extended discussion" doesn't really apply on meta.

Yuvraj Singh...

@ACuriousMind room which directly meta site related problem.

ACuriousMind

that sentence no verb

JMac

@FakeMod The easy solution to that is only ever use one. It seems to work very consistently.

user434058

1:00 PM

Why has "the system" stopped working? Why is "the system" no longer deleting comments? PSE wants to know!!!! :P

user434058

@JMac Hmm..I am willing to try that!

user434058

@ACuriousMind that's a nice reply stating the mistake using the mistake!

ACuriousMind

Thank you for pointing out my Very Clever Rhetorical Device.

user434058

@ACuriousMind You have a comment flag to handle. Please check it! Even if you don't act, still the custom text is worth checking out!

ACuriousMind

@FakeMod Moderator flags can be seen by all mods and should not be used in jest. Also, please stop using chat to try to get me to take moderator actions. I don't want to repeat that a third time.

user434058

1:06 PM

2 mins ago, by FakeMod

@ACuriousMind You have a comment flag to handle. Please check it! Even if you don't act, still the custom text is worth checking out!

user434058

Just don't get angry...

PM 2Ring

Also, "And all those exclamation marks, you notice? Five? A sure sign of someone who wears his underpants on his head." — Terry Pratchett, Maskerade.

user434058

@ACuriousMind oh! You did get angry. Why am I so bad at humour?

user434058

@PM2Ring Your comment made me imagine stuff which I would never like to see :)

ACuriousMind

@FakeMod Knowing when to be funny and when not to be is a non-trivial skill, don't beat yourself up over that, just try to learn for the next time

user434058

1:10 PM

@ACuriousMind I would rather be serious always. That never hurts.

Emilio Pisanty

2

Q: Groenewold's derivation of the star product (On the principles of elementary Quantum Mechanics)

$\newcommand{\dd}{{\rm d}}$ In the paper "On the principles of elementary Quantum Mechanics" am trying to get from equation EQN 4.25 to EQN 4.27. I need help on exponential identities and integration by parts. Basically I need to get from part (9) to (10) of my calculations (Full details after th...

homework-and-exercises mathematical-physics phase-space wigner-transform deformation-quantization

ooooffff

what happened there?

that's odd

hmmmmmmmmm

it was showing MathJax errors but they disappeared when I reloaded the page

ACuriousMind

looks like error-free MathJax to me :P

Emilio Pisanty

¯\ _(ツ)_/¯

ah well

Reusing \f from the post instead of \fracing like you should've? tsk, tsk. — Emilio Pisanty 12 secs ago

ACuriousMind

I don't support \fracking

Johan Liebert

@FakeMod actually the answer there didn't added much to the other answers there. Also I thought of it as a clarification to the OP (and by the time he had seen it I deleted it).

user434058

1:25 PM

@JohanLiebert Well, that's absolutely your choice, but if it were me I wouldn't have deleted that answer.

Physics Meta

3

Q: The scope of \newcommand changed

It was pointed out earlier today on chat, by Martin Sleziak, that the scope of MathJax new commands changed at some point in the (recent?) past: it was switched for Math SE in January of last year and on this site at some point in the intervening months. The short of it is that answers now start...

discussion mathjax

Johan Liebert

1:41 PM

@FakeMod I un-deleted the answer. Though I believe that the OP should be suspended to cool down.

PM 2Ring

@JohanLiebert I think we should leave the modding to the mods. That's what we elected them for.

ACuriousMind

@JohanLiebert Please do not call for the suspension of specific other users publicly.

PM 2Ring

But I agree that a quiet word from a mod to that user might be useful.

ACuriousMind

If you have concerns about moderation of a specific post you are, once again, welcome to raise a flag.

user434058

@JohanLiebert Yeah I saw. Most probably the OP has "self-suspended" (disengaged) him/herself. There's a high chance that they may have requested for account deletion as the hate was evident from their comments.

ACuriousMind

1:46 PM

But let me assure you that the moderators are well aware of this post and do not need another reminder that it exists every 5 minutes :P

Emilio Pisanty

3

Q: How to check $\renewcommand{\vec}[1]{\mathbf{#1}} \vec{v'}\cdot\vec{V}$ and $\vec{v}'^2$ are time derivatives of some other functions?

From Landau, Lifshitz Mechanics p.127 $\renewcommand{\vec}[1]{\mathbf{#1}}L'=\frac{1}{2}m(\vec{v}'^2+\vec{v'}\cdot\vec{V}+\vec{V}^2)-U $ He states that "$\vec{V}^2(t)$ can be written as the total derivative with respect to $t$ of some other function.". I understood that but the point that I cou...

classical-mechanics lagrangian-formalism

goodness

that's some awful MathJax-ing right there

any ideas?

luckily nothing is explicitly broken

ACuriousMind

\renewcommand in the title?

4

good lord

Emilio Pisanty

but still, it feels like the kind of extraneous MathJax that needs to go

@ACuriousMind yes.

change all \vec's to \mathbf's?

ACuriousMind

sounds reasonable

On the other hand, is anything lost just deleting the \renewcommand and just leaving the standard $\vec{v}$?

Emilio Pisanty

3

Q: How to check $\mathbf v' · \mathbf V$ and $\mathbf v'^2$ are time derivatives of some other functions?

From Landau, Lifshitz Mechanics p.127 $$ \renewcommand{\vec}[1]{\mathbf{#1}} L'=\frac{1}{2}m(\vec{v}'^2+\vec{v'}\cdot\vec{V}+\vec{V}^2)-U $$ He states that "$\vec{V}^2(t)$ can be written as the total derivative with respect to $t$ of some other function.". I understood that but the point that I...

classical-mechanics lagrangian-formalism

@ACuriousMind consistency with the question body

ACuriousMind

1:53 PM

I'd just have deleted it everywhere. I mean, intention of the author is all fine and good but I doubt anyone really cares whether vectors are arrowed or bolded in a post they wrote six years ago :P

Emilio Pisanty

eh

too late

ACuriousMind

But this is fine too

Emilio Pisanty

if you want to edit then go ahead =)

I've just gone through 120 posts, I'm not spending more time on that one =P

Yuvraj Singh...

@ACuriousMind please it will help us if we have a new chat room for meta!

ACuriousMind

Whom will it help? What will improve?

Yuvraj Singh...

1:59 PM

For user who have queries related to their meta post!

ACuriousMind

You're free to make a coherent argument for whatever exactly your proposal is and post it on meta to see what other users think.

Yuvraj Singh...

@ACuriousMind OK cool, do I need to add some specific tag for such kind of post!

ACuriousMind

Meta has done fine - within the restrictions of the SE system - for the last decade or so. Please consider any change to our meta habits carefully and present evidence for its necessity.

Emilio Pisanty

@YuvrajSingh... In what ways is the current combination (this room plus the backup room) insufficient for the purposes you're describing here?

ACuriousMind

@YuvrajSingh... If you don't understand enough about our meta habits that you need to ask what to tag proposals with, maybe you should re-evaluate whether you understand meta enough to make a proposal for changing it.

Emilio Pisanty

2:05 PM

@ACuriousMind you misspelled ~~maybe~~

Yuvraj Singh...

@ACuriousMind yes?

ACuriousMind

Is that a question? The result of a (very fast) evaluation? A random reply not related to my post?

Honestly, I'm getting very frustrated with the way you're communicating here. Please try to talk in complete, coherent sentences that one can understand without having to try to read your mind.

I understand English is not your native language (neither it is it mine) but that's not really an excuse for not even trying.

I'm sorry to be so blunt about it but you've ignored all my (and others') more subtle attempts at this so far.

Nanashi No Gombe

2:25 PM

What does one mean by the phrase "scaling solution" in physics?

ACuriousMind

2:38 PM

@NanashiNoGombe That's not a generic term from physics, and a quick Google (e.g. books.google.de/…) suggests that it's a term in cosmology for some solutions of cosmological equations that scale with the Hubble parameter

Yuvraj Singh...

@ACuriousMind sorry for incomplete sentence I was about to right the upcoming part, there was a Internet issue in my area, and I am shocked by this.

This mean your claim regarding my incomplete sentences

I would say it is not your fault may be my poor hold on language and grammar error make me feel hard to convey what I want to say some times but there were a only few incidence where I wrote four words sentence and I am sorry for that.

Nanashi No Gombe

2:52 PM

@ACuriousMind I am curious, what exactly did you search with Google? I use DuckDuckGo and I searched for <meaning of "scaling solution" in physics> and got nothing. 🤔

ACuriousMind

@NanashiNoGombe I just searched for physics "scaling solution", this was on the first page for me

The quotes are important though, I only get irrelevant things when searching for physics scaling solution

PM 2Ring

Here's a lovely sweet acoustic guitar song by 60s rockers, Pete Townsend from The Who, and Ronnie Lane from The Small Faces. April Fool.

April fool - Ronnie Lane

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