The h Bar

Q: Schrödinger's "Award bounty" button

8:00 AM

Whenever I see that mod's name, it reminds me of the Muddy Waters song en.wikipedia.org/wiki/Mannish_Boy

user351417

8:11 AM

@PM2Ring It's an extremely common Indian name.

user351417

4

Let's play a small game first: Illustration: Has the bounty been awarded? Here are two images cut from two screenshots. One of them has an active bounty, while the other has an awarded bounty. Make your guess base on the images! Haha I bet you can't, so here's the answer: Actually they l...

bug design bounty mobile-web

user351417

I don't see any superpositions there.

8:32 AM

@Chair Ok. I used to know an Indian guy named Manesh, I've just never seen it spelt with "i" before.

8:42 AM

I don't see any supetposition either. Just blurry, barely readable screenshots. I guess that could be due to the HUP. ;)

Actually, my friend's name was Mahesh; I haven't seen him for about 20 years.

user351417

@PM2Ring There was one manish in the same classroom as me when I sent my last message, and there's a different manish in the classroom I'm presently in (same spelling in both cases) :P

apt45

9:15 AM

Do you know if it is possible to quantize solition excitations in D=3+1?

10:27 AM

Curzon solutions are kind of hard to find good introductions to

Q: HELP:They say I am going to die on 2054. I can't sleep now?

10:37 AM

-1

I completed a questionnaire on this website (not disclosing it). The result said that I'll die on 2054. Only bad thing I had to choose there (in the website) was that 'I sit for more than 6 hours'. Am a student, I spend more than 6 hours in a library. I do not play sports, but I watch a lot....

health lifespan

The dude's name is literally lmao

Why is anyone taking him seriously

sci-hub seems to be down

PANIC!

Working for me

digital.library.adelaide.edu.au/dspace/bitstream/2440/19586/2/…

Nice B)

sci-hub still won't load

11:03 AM

"For straight line trajectories $z = cr$, $c \in \mathbb{R}$ to $R = 0$, the behaviour of $\alpha$ was seen to be $\alpha \to \infty$ as $R \to 0$. However for approaches along the $z$-axis where $r = 0$, it was found that $\alpha \to 0$ as $R \to 0$."

Help

I hate GR now

"Our result for the Curzon metric shows one of the alternate topological peculiarities that can occur: an event horizon of infinite area on which an invariant of the Riemann tensor becomes singular."

Aaaah

Damn you Curzon

11:30 AM

I don't even know what's the bloody topology this is supposed to be

11:55 AM

@Slereah faun sees John looking hunger and panics

do not touch the Bambi

"Stachel's result suggests that there might be in general a correspondence between equipotential surfaces approaching a non-zero area and directional singularities"

Bambi bourguignon

Nevermind the Geroch weird spacetime

I think this might be the worst metric

"If anything, the entire concept should be referred to as a trajectory singularity rather than a directional singularity"

It keeps getting worse

"By the criterion of Gautreau and Anderson, one might be led to call the termination point in the z-axis direction both singular and non-singular. We feel that it is more reasonable to simply call it singular alongwith every other termination point"

12:14 PM

any Indians around?

I could use some help parsing a name

user351417

@EmilioPisanty ya?

user351417

(though I don't understand what you mean by "parse" in this case :P)

@Chair specifically, how to handle the abbreviation Md

user351417

"mohammed", if I'm not mistaken. It's more like a prefix.

His email reports his name as SURNAME Md Name, and the address is md-name.surname

@Chair yeah, that's what I gather

I was wondering to what extent it's required to use it when in correspondence with them, and to what extent it's optional when other people use it

user351417

12:24 PM

I don't think you ever actually address anyone as "muhammad". But when writing, I think it's usually included.

ok, thanks

user351417

But that's not actually an Indian name, per se... India (in most parts, including mine) is primarily made up of hindus, and that's a muslim title. So I wouldn't exactly relate it to any nationality.

@Chair yeah, I realized that after the initial ping

"it stands for Muhammad" does heavily imply that it's m,ore associated with Pakistan and Bangladesh than it is with India

user351417

You could try checking with @Blue, since I think he's in west bengal, where the population of muslims is higher

@Chair nah, it's OK

I'll just keep it in, it's no big deal

thanks =)

user351417

12:27 PM

@EmilioPisanty =)

homework-and-exercises power

12:49 PM

Md may just stand as an abbreviation for their middle name or something

I wouldn't go as far as saying it's Muhammad

My grand parents use

user351417

::enormous sigh::

user351417

-4

Q: power generation

Someone can help and show how to calculate this task

Td Rd and vr

user351417

@AvnishKabaj I dunno... md for muhammad is pretty standard, right? I've seen it around quite a bit.

user351417

@PM2Ring I think you may be interested in this question, which is related to that question about kinetic energy and momentum (same OP).

Q: Should I walk or run to my towel when naked and wet?

1:14 PM

"Furthermore, it will also be seen that different approaches to $R = 0$ in the same direction (e.g. different curves asymptotic to a particular direction), can sometimes correspond to approaches to different limiting points on the infinite surface $R = 0$"

Kill me please

user351417

1:45 PM

What the hell is happening?

user351417

0

This morning when I got out of the shower, I realised I had left my towel in the bedroom. Naked and wet I ran as fast as I could to get the towel. On my way back I didn't run, but rather walked, and it felt a lot less cold. In this scenario, what is the optimal strategy to make this experience a...

thermodynamics energy everyday-life evaporation heat-conduction

3:10 PM

"This metric was first derived by Bach and Weyl, and is occasionally referred to as simply 'the metric of Bach and Weyl'. "

Catchy name

A: Attack of 3-methylbutan-1-ol on benzene in acidic medium

3:23 PM

0

Your answer seems absolutely correct according to the given question. It seems impossible with the following reagents to degrade one Carbon atom. I think answer should be the answer you found out. Thank You.

ಠ_ಠ

@Slereah Not as catchy as Jump, Jive an' Wail.

Did you make a sock to prove your point

user351417

@AvnishKabaj nope :P

A: Should I walk or run to my towel when naked and wet?

I don't believe in coincidences

-3

The optimal strategy is to lie down and slither like a snake as this presents the least surface area for evaporative cooling. The exception is if you are bald in which case you should go feet first as there is no insulation gain from the hair on your head. If you are well bearded you also have th...

user351417

@AvnishKabaj I don't see how that proves the point I was trying to make anyways...

3:30 PM

Heh, the +1 is enough for me to get off your case.

@Chair Commented. I guess I could edit the question into something coherent and then answer it... :D

"The true geometry of the sources for the Zipoy-Voorhees metrics remains an open problem."

Every time I think I understand GR I uncover some more weird shit

"However in 1968, some thirty-two years after Einstein's paper on this subject, Szekeres [27] demonstrated that static; two-body solutions do exist in general relativity. In his solutions, at least one of the two point masses is endowed with a multipole mass structure, which allows equilibrium to be achieved without the need for an intervening strut.
The simplest example is that of a pure mass monopole (a Curzon particle) balanced by a mass monopole-dipole, where the mass of each particle (as represented by the monopole moment) is positive."

This paper is a real horror show

"The source for the Curzon solution is a ring singularity with finite radius and infinite circumference, and the space-time has a doubled-sheeted topology inside the ring"

dies

This also invalidates an answer I gave on PSE

user351417

3:48 PM

@AvnishKabaj Huh, that wasn't me (if you're talking about the vote on your question which your rep history indicates). That could either be the chat-effect or the fact that your question was bumped to the top of the front page of chem SE.

user351417

(if you want proof, I'm quite sure that I've cast 0 votes on Chem SE today :P)

So anyway this paper constructs the wormhole by taking the Schwarzschild in Weyl coordinates, which is sourced by some kind of rod

Doubling that rod

and then identify a sphere around them

Which sounds extremely tricky to do

I'm not even 100% sure what solution doubling that rod will do

user351417

4:07 PM

If there're any mods about, I have a flag about another annoying rollback war on the main site... something to do with charge and the possibility of negative physical quantities.

Anyone aware of any experiments involving testing the speed of light when passing through a casimir cavity?

How hard would it be to construct an experiment where light would pass through several such casimir cavities which combined would be like a kilometer long?

or even set it up such that they would form a ring and you could send light several times around?

"Owing to the Dirac sea, an empty space which appears to be a pure vacuum is filled with virtual subatomic particles. These are called vacuum fluctuations. As a photon travels through a vacuum it interacts with these virtual particles and is absorbed by them to give rise to a virtual electron–positron pair. This pair is unstable and quickly annihilates to produce a photon like the one which was previously absorbed. The time the photon's energy spends as subluminal electron-positron pairs lowers the observed speed of light in a vacuum.

Scharnhorst effect

The Scharnhorst effect is a hypothetical phenomenon in which light signals travel slightly faster than c between two closely spaced conducting plates. It was first predicted in a 1993 paper by Klaus Scharnhorst of the Humboldt University of Berlin, Germany, and Gabriel Barton of the University of Sussex in Brighton, England. They showed using quantum electrodynamics that the effective refractive index, at low frequencies, in the space between the plates was less than 1 (which by itself does not imply superluminal signaling). They were not able to show that the wavefront velocity exceeds c (which...

4:44 PM

@Chair I'm getting really sick of that kid.

@PM2Ring link?

@JohnRennie This is his 3rd or 4th question on this topic. physics.stackexchange.com/questions/460342/…

@PM2Ring meh, let it go. I've voted to delete the question anyway. A few more votes and it will be gone for good.

I try to make allowances for people who have trouble writing & comprehending English, but not when they get angry & nasty. If someone's English is so poor that we can't understand their questions, and they can't understand our comments and answers, they're wasting their time and ours. IMHO, he needs to work on his English first if he wants to use resources like Stack Exchange.

@JohnRennie I didn't comment on that question. I didn't even bother downvoting it. I guess the question ban will kick in soon.

@pZombie As the Wikipedia article says, testing a variation in photon speed of one part in $10^{36}$ is unfeasible with current technology.

Anonymous

5:15 PM

@PhysicsMeta This isn't a big deal either way. That said, Physics could do with another election in the near future, in case it's getting difficult to manage spam and flags.

This guy, who Chair linked earlier, also has communication problems, but at least he's not hostile.

5:43 PM

@PM2Ring Yes, i read that part but i don't see why it is unfeasible if you were to use multiple cavities and mirrors to run a beam of light in a circle. Surely some photons would make it, wouldn't they? Well, i don't know for sure or i wouldn't be asking but i found it quite interesting nevertheless. It should be impossible to surpass C though as if you could, you could send information back in time or alternative our current theories would need adjustment

Curio

5:53 PM

Is H2SO4 a network solid?

Anonymous

@Curio I don't think so...

Anonymous

I'm not sure. Any reason why you think it should be a network solid?

@pZombie It'd need to be a big circle, or do a ridiculous number of loops. Either way, the errors due to photons exchanging momentum with the mirrors would swamp the Scharnhorst effect.

Anonymous

Network covalent bonding

A network solid or covalent network solid is a chemical compound (or element) in which the atoms are bonded by covalent bonds in a continuous network extending throughout the material. In a network solid there are no individual molecules, and the entire crystal or amorphous solid may be considered a macromolecule. Formulas for network solids, like those for ionic compounds, are simple ratios of the component atoms represented by a formula unit.Examples of network solids include diamond with a continuous network of carbon atoms and silicon dioxide or quartz with a continuous three-dimensional network...

Anonymous

Read the Properties mentioned there. H2SO4 doesn't seem to satisfy those.

6:05 PM

@pZombie I'm not a real physicist, but I see no problem with photons travelling slower than c in a normal (non-Casimir) vacuum. Primarily, c is the space / time conversion factor, The fact that it's also the speed of massless particles in a true vacuum is secondary.

@PM2Ring Hm, i don't know. All we would have to do is to detect a few out of many photons arriving at the other end faster than expected.

@pZombie If the path is long enough to detect that tiny discrepancy the arrival times will be all over the shop because the mirrors are wobbly.

yes, but you are not concerned about all the arrival times but only of those photons that made it through at FTL

a wobbly mirror won't cause a photon to travel FTL

A wobbly mirror varies the path length, so even though you know the travel time you don't know the distance with enough precision.

screw the mirrors then, just make a long line of casimir cavities and shoot a lot of photons through them. Surely a few will make it through.

6:14 PM

Hey @Chair A Manish has just turned up in the Python room. I expect I'll see them everywhere now. :)

Anonymous

@ACuriousMind @Chair @DavidZ The chat guidelines post is 1 week old. Should we add it to the room description and make it official now (by adding the faq tag)?

@Blue I don't think we'll have an election in the "near" future, flag stats are looking good.

Anonymous

@ACuriousMind Ah, that's good to hear.

@Blue I'd personally give it another week - we've done without it for pretty long, no need to rush it now.

Anonymous

I think the moderation team is doing fairly well. What we need is more active reviewers and editors.

Anonymous

6:26 PM

@ACuriousMind Sure, that's fair.

@Blue aren't you part of the moderation team?

Anonymous

@pZombie No, not on Physics.

Anonymous

I'm a Quantum Computing mod.

I wonder how many quantum computer programmers are out there

last time i checked, classical computers would be faster than quantum computers still

Is AutoComments script broken for anyone else?

The auto link doesn't appear for me anywhere

Anonymous

6:36 PM

@ACuriousMind Yes...

Dammit

And the thing isn't being maintained

Q: Is quantum computing just pie in the sky?

@Blue are there any problems which can be solved on current quantum computers that CANNOT be solved on the current fastest supercomputer, faster than on current quantum computers? Or cannot be solved at all on classical computers but can be solved on CURRENT QCs?

Anonymous

@pZombie No and no. Quantum computing is still in the nascent stages and it can't do anything more than what your laptop already can.

Anonymous

123

I have a computer science degree. I work in IT, and have done so for many years. In that period "classical" computers have advanced by leaps and bounds. I now have a terabyte disk drive in my bedroom drawer amongst my socks, my phone has phenomenal processing power, and computers have revolutioni...

classical-computing applications history

Anonymous

Obligatory link. ^

6:41 PM

Nice, apparently it's maintained enough, a fix has been merged to master: github.com/Benjol/SE-AutoReviewComments/pull/164

But they didn't update the version number so Tampermonkey doesn't auto-update

@Blue "Molecules behave quantum mechanically, and simulating quantum mechanics is not efficient on classical computers, but is on quantum computers." - This seems to contradict your former statement a little

@Blue Reinstalling the script from the current GitHub version fixes it

Anonymous

This is where some knowledge of JS comes handy.

Anonymous

@ACuriousMind Right, trying...

You'll probably have to restart the browser, too

6:46 PM

@Blue Does the current fastest QC simulate molecule interactions faster than the current fastest supercomputer at about 200 petaflops or more efficiently?

Anonymous

@pZombie No, there are a lot of engineering hurdles we have to overcome for that.

Anonymous

Current day QCs are pretty useless.

@pZombie When people say that quantum computers are "faster" than classical ones, they do not mean that a particular quantum computer manages a particular computation in less actual time than a particular classical computer. They mean that for certain problems, there exist algorithms for quantum computers that have lower run time complexity than any known algorithm for a classical computer, e.g. Shor's algorithm

Anonymous

Jan 18 at 20:13, by Blue

Note to future self: I personally have a strong feeling that P=BPP=BQP and that quantum computing is moot. (Blue - 2019) :P

10 years from now we will probably get QCs that are faster than any classical computer... about the same time we will crack human level AI

Anonymous

6:57 PM

Well, 10 is a bit too optimistic.

Anonymous

For me the most interesting outcome would be being able to show that all quantum algorithms can have equivalent classical algorithms (of similar complexity). One of the reasons Ewin Tang's work caused such a brouhaha in the QC community.

Anonymous

Not saying that the other outcome won't be interesting. It's just that I don't care about the development of quantum computers as much as I'm interested in the math. I like to view it from a theoretical CS perspective. And such a proof would have huge impacts on theoretical CS.

@enumaris OpenAI put a lot of GPT-2 output samples here, along with a pared-down version of their model

Anonymous

Didn't have to restart. Was a one-line fix. :)

The samples are pretty interesting for their literary value, imo.

Where else can you get a machine telling you, in response to a passage about the growth of computing power, that "The next great computer science breakthroughs will allow computers to understand, analyze, and make sense of the world around them. These breakthroughs will enable computers to perform in ways that human brains cannot.", and then just repeating "The next big computing breakthrough will be the one that will make the world a better place." under different headlines a dozen times?

enumaris

7:04 PM

@ACuriousMind thanks for pointing me to it :D

@pZombie That'd be a long line. The best atomic clocks can currently get down to around a femtosecond, and may soon do $10^{-16}$s. so to measure the predicted speed difference the path needs to be $10^{20}$ lightseconds long, over 3 trillion lightyears, which is much larger than the diameter of the observable universe. Now there may be a better way to do the timing, eg via interference, but you'd still need an enormous pathlength, and to eliminate errors from external factors like gravity.

The internet has broken the poor machine, though - it thinks "Advertisement - continue reading below" is something that should occur throughout a text a random places

enumaris

nice

Also, "<|endoftext|>" is an apparently an acceptable thing to say in order to suddenly and randomly switch topic :D

@PM2Ring I see. Guess it isn't that easy after all. Yet i could swear i saw some time ago some experiment where someone was testing the speed of light going through a casimir cavity. Unfortunately, back then i did not pay much attention to it

enumaris

7:13 PM

@Blue differential geometry is fun :)

Anonymous

@enumaris Yes it is! Several times more fun than analysis. I'm hoping to cover this playlist after I'm done with the GR one. :)

Anonymous

The nice mechanics lectures by Schuller are all in German though. ;_;

Anonymous

Heck, I'm even willing to learn German to understand his lectures. They are par excellence, well motivated and extremely clear. That's something not found in any textbook.

"The Unruh effect would also cause the decay rate of accelerating particles to differ from inertial particles. " - Now that is an experiment i would like to see confirmed

Curio

@Blue In fact I didn't think so either

Thanks

7:29 PM

On second thought, this needs a rewrite. It is not really clear what is meant. There are many inertial particles all traveling at different speeds and having different decay rates when observed by a given non-accelerating observer. What exactly would an accelerating particle having a different decay rate mean in this context?

the acceleration itself changes the decay rate rather than its current velocity relative to some observer?

Or would someone carrying a bunch of myons in a bottle while accelerating, observe the myons decay at a different rate than normal?

then i guess we would have to use something other than an atomic clock to measure it, as the atomic clock surely would be subject to the same effect

Anonymous

Hmm, it helps that the German alphabet set is somewhat similar to English. I can just type what's written on the board into Google Translate and understand at least 50% of the lecture.

Anonymous

I need to get someone to dub it for me. :P

@Blue this is one of the occasions where I am happy to be German :P

Anonymous

7:47 PM

@scaphys I'm so jelly. $$\Huge{😤}$$

@Blue are these lectures on YouTube aswell? If so, maybe there are auto-generated English subtitles. They are usually quite good.

Anonymous

@scaphys No, they're not on YouTube. However, they're downloadable. I wonder if I can auto-generate English subtitles for it somehow.

Anonymous

There's this. Dunno if it works...

No idea. Maybe it would be enough to extract the audio and use Google's Speech-To-Text engine. I've never used it, but I'd assume the quality is rather good, considering it's Google. :P

Anonymous

@scaphys Could be worth a try. :P

Anonymous

8:06 PM

I could try this: download the video -> upload it to YouTube as a private video -> generate the subtitles and then translate the subtitles.

@Blue good idea

Anonymous

Man, this is why we need AIs.

Anonymous

2019 and we still can't translate videos easily...such a shame.

8:23 PM

@Blue soon, very soon. :P

8:52 PM

In 1954, researchers believed "machine translation would be a solved problem within three to five years". See en.wikipedia.org/wiki/History_of_machine_translation

@PM2Ring true. however, the technology to transform speech to text and translate it already exists (e.g. YouTube's auto-subtitles)

vzn

9:19 PM

@PM2Ring lol off by only 10x ... much of those early rosy predictions came out of the legendary dartmouth 1956 conference. but rosy predictions like that were typical of the era for many other technologies eg transportation, robotics etc... and some have now come true. others prove elusive. and (almost) nobody predicted mass income inequality... except marx. etc

@scaphys both the speech recognition and translation are not good enough though for Blue's use case. It is already hard enough to understand physics on this level without any translation and speech recognition errors

At least machine translation has made better progress in the last 6 decades than fusion power.

Mo_

"While many people think that email, smartphones and the internet have made proximity less important to the creative process, in reality the opposite is true. Location is more important than ever, in part because knowledge spillovers are more important than ever." (nytimes.com/2019/02/20/opinion/amazon-hq2-new-york.html)

Anonymous

9:51 PM

Phew, every alternate day there's someone on QCSE who's totally confused about tensors and tensor products and their properties. Not that I blame them. This topic is usually not taught well to physics and CS students.

vzn

10:18 PM

@PM2Ring fusion power is starting to click lately. there are some new innovations and private initiatives. think controlled over unity fusion at research level is on 10 yr horizon. :o :)