The h Bar

4:14 PM

Going back to this comment yesterday, I've figured out days = int(Timestamp) - 40968. Now I need to figure out hours and minutes, then I can get back to doing some mining

Well that's pretty hot:

4

Q: why is my motherboard temp constant 123 degree celsius?

checked with Piriform Speccy. checked with open hardware monitor checked with hardware sensor monitor(this one shows different statistics)

windows-7

JokelaTurbine

@KyleKanos I think you can solve it (timestamp) by excel? Just copy paste it there and change the format to date&time.

Kyle Kanos

It does not appear to be in any common format

0celo7

@KyleKanos Holy shit, my laptop runs at 75 degrees when gaming and it's (figuratively) boiling.

Kyle Kanos

@0celo7 It's not actually 123 C. It's either displaying a value from a sensor that doesn't exist or can't understand the value being read

Jims Bond

@KyleKanos interesting side note, 40968 days is exactly $112\frac{1}{6}$ years

0celo7

4:18 PM

@KyleKanos I read it.

@JimsBond Who the hell uses mixed fractions...

3

Jims Bond

@0celo7 People who want to stress the exactness rather than say #.1666666666

0celo7

@JimsBond My first thought was 112/6 years, but that's not right.

Jims Bond

That question now is, what is the significance of that? What does int(Timestamp) give you?

Kyle Kanos

@JokelaTurbine Actually...it does seem to be converting it to reasonable dates.

W.T.H.!!

ACuriousMind

lol...you've been outwitted by Excel?

Kyle Kanos

4:22 PM

I have been

Imma go in the corner for a few minutes

ACuriousMind

Googling says the stamp is the number of days since 1.1.1900, btw

0celo7

Huh

Is that 1.1 in American date format or wrong euro format

Jims Bond

@ACuriousMind so then how does subtracting 112 years give the correct number of days?

skill patrol

More importantly how do you adjust for the leap years?

Jims Bond

@skillpatrol 1 year = 365.2422 days

skill patrol

4:28 PM

Ok

0celo7

Leap seconds?

Jims Bond

no

0celo7

Then it's not worth much, is it?

skill patrol

Leap frogs?

:D

Jims Bond

@0celo7 I assume the international reference is updated, but I don't account for it unless it cumulates to at least 1 full day

0celo7

4:30 PM

@KyleKanos You're that ugly, eh? I'm sorry.

@JimsBond We have enough leap seconds to be a full day?

That's like 24x60x60 seconds.

Jims Bond

@0celo7 I don't think we've had 86400 leap seconds yet

ACuriousMind

@JimsBond the other dates were in the first quarter of 2012 - fits perfectly.

yesterday, by Kyle Kanos

All (human-readable) dates are between Mar 08 2012 and Mar 22 2012. The first few of the non-readable format are 40983.91072, 40983.95396, 40983.94837, 40983.90378, 40983.87797

Jims Bond

@ACuriousMind Then there it is. They were using julian dates

JokelaTurbine

Well, if you want to be really precise in time; our day lenght was

19.5.2015 86400.0013649 seconds

and 12.12.1973 86400.0030290 Seconds

If you calculate the difference in inertia, you get nice pile of Joule's (not the beer)

Day length fluctuations

For related longer-term variations, see ΔT. The length of the day, which has increased over the long term of Earth's history due to tidal effects, is also subject to change on a shorter scale of time. Exact measurements of time by atomic clocks and satellite laser ranging have revealed that the length of day (LOD) is subject to a number of different fluctuations. These tiny fluctuations have periods which range from a few weeks to a few years. They are attributed to interactions between the dynamic atmosphere and Earth itself. The International Earth Rotation and Reference Systems Service monitors...

0celo7

I have no clue what you guys are on about.

We have reached the "this chat makes sense to about half the participants" stage.

Kyle Kanos

4:36 PM

Well that solves one problem

Now I have another one: how to calculate the bounce rate

0celo7

???

ACuriousMind

@0celo7 You are not "half the participants" :P

2

skill patrol

Half of ?

JokelaTurbine

-> my comment; forget the leaps seconds, there is about 25 of them "ever since", yet if you want to have exact time, you need some other measurements

ACuriousMind

@skillpatrol I think "half the participants" is perfectly fine grammar.

0celo7

4:38 PM

@ACuriousMind Yes I am.

@ACuriousMind I agree.

Kyle Kanos

Hmm. Should I sort by UserID then Timestamp or Timestamp then UserID?

skill patrol

It is perfectly fine grammar, I just wanted to know the precision of the word "about?" @ACuriousMind

Jims Bond

@KyleKanos If each user has a lot of entries, do it by UserID first. If you have more users than average number of entries per user, then do it by Timestamp first

Kyle Kanos

Users count ~ 38k, Total Entries ~ 420k

Jims Bond

so each one has ~11 entries?

Timestamp it

and if you don't like the result of that, then stop taking suggestions from me

0celo7

4:43 PM

Could someone please fill me in??

@ACuriousMind I am the representative of the half that does not understand.

Kyle Kanos

The way I planned on computing the bounce rate involved going through each User & checking times between successive entries, so I'm thinking UserID first

skill patrol

@0celo7 You forgot the word "about" :D

Kyle Kanos

But that's for the global rate. I need a per-subsite rate as well. Which would probably require sorting by site first, then user, then time

@0celo7 What part is confusing you?

0celo7

@skillpatrol Good point. By my estimates, only 3/9 people understand what is going on.

Jims Bond

@KyleKanos You could probably make a data structure to store this in that contains pointers to the next data point arranged first by userID, time, and site. It'd be like a linked list with a head and multiple links to all the same data points

0celo7

4:49 PM

@KyleKanos What the heck are you talking about?

Kyle Kanos

@JimsBond: Did you do your undergrad + MS at UToronto?

Jims Bond

nope

York

Kyle Kanos

@0celo7 Data Science stuff. The test thing I mentioned a couple days ago? This is all related to it

0celo7

@KyleKanos Is Jim better at it than you?

Jims Bond

not enough data for an accurate comparison

Kyle Kanos

4:50 PM

@JimsBond Did you ever meet our recent user here, Dr. Ikjyot Singh Kohli

Jims Bond

Yes, I knew him personally

nice guy

Kyle Kanos

@0celo7 Well I'd say I know a drop in a bucket, so if he says he knows two drops, then yes.

@JimsBond He does seem nice. I've had a few interactions with him (mostly involving formatting stuff for his posts)

0celo7

0

A: Do virtual particles actually physically exist?

I think one has to be very careful when talking about "particles popping in and out of existence". This interpretation is only sort of fine in flat-spacetime QFT, where the Minkowski metric is time-invariant, so has a global timeline Killing vector. The definition of a particle depends on the n...

Jims Bond

@KyleKanos He knows what he's talking about. He's a mathematician that specializes in cosmological applications

0celo7

Pretty much word-for-word from the cited text.

Jims Bond

4:53 PM

usually very good at explaining concepts

not great at overlooking misuses of technical terminology

Kyle Kanos

@JimsBond That seems rather typical for mathematical physicists (from what I've seen anyways)

ACuriousMind

@JimsBond I like him already

Jims Bond

I once made the mistake of calling a manifold locally flat instead of saying it's a $C^\infty$ manifold

I won't make that mistake again

0celo7

@ACuriousMind I can use the uncertainty principle to explain virtual particles, right?

That's not a misuse, I think that's just plain wrong, lol.

ACuriousMind

@0celo7 May a thousand horrible diseases befall you :)

skill patrol

4:57 PM

But you won't be certain of the answer ;)

Kyle Kanos

@JimsBond Probably will sound dumb: what's the difference?

0celo7

@KyleKanos In a $C^\infty$ manifold, the transition maps are all smooth.

Jims Bond

@KyleKanos I'm still not sure. A $C^\infty$ manifold is continuously differentiable infinitely, so locally it is smooth and should approximate a flat minkowskian space

Kyle Kanos

@0celo7 smooth = differentiable (more or less), right?

0celo7

In a locally flat manifold, the metric can take the flat form in a neighborhood.

@KyleKanos Infinitely differentiable.

Jims Bond

5:00 PM

But I was lectured on how it's not the same and how the manifold metric would have $g=\eta+h$ where h would be small but non-zero

0celo7

$C^n$ means $n$-times differentiable.

$C^0$ is continuous.

Kyle Kanos

@0celo7 This makes sense

0celo7

$C^{-n}$ means $C^n$ and Lipshitz.

ACuriousMind

@0celo7 That one's not very standard

Kyle Kanos

Lipshitz means this?

0celo7

5:01 PM

@ACuriousMind HE uses it.

ACuriousMind

E.g. I know $C^{n,\alpha}$ for $C^n$ functions with Hölder exponent $\alpha$, so Lipschitz would be $C^{n,1}$.

0celo7

@KyleKanos Yes.

Kyle Kanos

@0celo7 This still bothers me, the use of HE in place of Hawking & Ellis. Or even H&E

Jims Bond

All I know is that it's too misleading to say it's locally a good approximation of flat space

That said, he was very nice about the whole exchange

0celo7

@JimsBond The official definition is that there is a local isometry to flat space.

Jims Bond

5:04 PM

@0celo7 Perhaps I had said locally minkowskian

0celo7

This is more stringent than the "homeomorphism" from the manifold definition, I think. @ACuriousMind pls verify?

Kyle Kanos

Oh, I got to report a SCRAPER to SE yesterday.

0celo7

Another definition can be: A space is locally flat if and only if the curvature vanishes locally.

ACuriousMind

@0celo7 Yes. A local isometry is one globally defined function for which every point has a neighbourhood such that it is an isometry

Kyle Kanos

That was fun. They ask you to fill out the URL, the SE original & how you found it. I wrote that I searched Kyle Kanos in google and added (pls don't judge :() to it

I hope I got a smile out of someone this morning when they read it

0celo7

5:07 PM

@ACuriousMind Wait, every point has a flat nbd?

ACuriousMind

@0celo7 I believe so, yes

0celo7

@ACuriousMind Would that not be just "flat"?

Why "locally" then?

@KyleKanos Huh?

Kyle Kanos

Scraper site

A scraper site is a website that copies content from other websites using web scraping. The purpose of creating such a site can be to collect advertising revenue or to manipulate search engine rankings by linking to other sites to improve their search engine ranking. In the last few years scraper sites have proliferated at a high rate for spamming search engines. Open content is a common source of material for scraper sites. A search engine is not a scraper site itself; sites such as Yahoo and Google gather content from other websites and index it so that the index can be searched with keywords...

205

Q: Updated procedure for reporting SCRAPERs

Since day one of Stack Overflow, all content posted on Stack Exchange sites by their users (i.e. you wonderful people) has been provided to the whole universe under the CC-BY-SA license. For my fellow non-lawyers, that license basically means: Anyone can use any Stack Exchange posts at any time...

discussion seo attribution copycat-sites screen-scraping

@badp "Stack Content Republishers Attributing Poorly and/or Excelling at Ranking" — Pops ♦ May 27 '14 at 13:43

ACuriousMind

@0celo7 I have no idea what a "locally flat manifold" is, I just replied to your question about a local isometry :P

Kyle Kanos

SE content is protected by CC-BY-SA which means anyone can take the content, so long as they (1) maintain the license and (2) attribute the original source

ACuriousMind

5:10 PM

According to Wikipedia, local flatness is not a (pseudo-)Riemannian concept at all

Kyle Kanos

A scraper is someone who just republishes it without attribution and/or the same license

0celo7

@ACuriousMind Wrong thing.

Flatness is meant in the curvature sense.

Or maybe that's not wrong...

Kyle Kanos

The message I got from SE said something along the lines of it being a difficult and long process to get the scraper fixed (either by attribution or removal of content), but they were working on it

I don't think the answer here is right: physics.stackexchange.com/questions/192674/…

ACuriousMind

@0celo7 My searches indicate that manifolds with vanishing curvature are usually just called "flat", and that having a local isometry to flat space is equivalent to that, so "locally flat" is not a useful notion in Riemannian geometry I'd say.

Kyle Kanos

Or at least he goes on tangents that makes it seem not right? IDK now....Imma need to think about it some more

0celo7

5:18 PM

@ACuriousMind I'm now trying to work out Theorem 15.6 in Straumann. I don't get the first equation.

Is that from the Cartan equations?

Jims Bond

@KyleKanos The question asks which classical forces are attributable to gravity. He says most forces that look like gravity is the cause are attributable to a combination of gravity and EM. There's nothing overtly wrong that I could see

Kyle Kanos

Yeah maybe. I guess just maybe I got thrown off by some of the wordiness of it.

Have we had a question about the 4 fundamental forces and GR saying gravity isn't a force?

Jims Bond

I think so

it's hard to tell if what I remember is from a question, the chat, or a back-and-forth in comments

Kyle Kanos

23

Q: Why do we still need to think of gravity as a force?

Firstly I think shades of this question have appeared elsewhere (like here, or here). Hopefully mine is a slightly different take on it. If I'm just being thick please correct me. We always hear about the force of gravity being the odd-one-out of the four forces. And this argument, whenever i...

general-relativity gravity forces

alarge

@JimsBond I get that, but it is still not clear to me what the role you'd be applying to is with those study topics. I mean KyleKanos was reading up on and aiming at a standard quant role, but I doubt he read or would have needed to read stuff on risk management.

Kyle Kanos

5:33 PM

I'm pretty sure there was a Chapter in Hull about Risk Management that I skimmed

Jims Bond

@alarge The job would be in risk management. Updating models, predicting market risk, calculating credit risk of new clients, mitigating operational risk of various products, etc

Physicists are suited for it because we deal with using math and computers to model the patterns and dynamics of physical systems. This is using math and computers to model the patterns and predict outcomes of financial systems

Gaurav

I was just thinking about something, about how we could help non-English speakers participate on stackexchange sites. I'm not talking about localised sites for them, I'm talking about a common stackexchange for all language speakers because then it'll be a truly universal community.

Perhaps something on the lines of making non-English content community translatable, and what keeps it going would be rewarding rep or badges to those members of the community who help translate them.

Jims Bond

@Gaurav Who gets to vote on if a translation is good or not?

Kyle Kanos

@JimsBond One easy mechanism is via upvotes after the fact

NB: it was posted on MetaSE:

-5

Q: Community translation : Creating a SE for all

I was just thinking about something, about how we could help non-English speakers participate on stackexchange sites. I'm not talking about localised sites for them, I'm talking about a common stackexchange for all language speakers because then it'll be a truly universal community. Perhaps som...

discussion feature-request

Currently not well received

(found by searching to see if was previously suggested)

Jims Bond

-5 in 4 minutes

That has to be a record or something

Gaurav

5:48 PM

@JimsBond Perhaps Stack Exchange can hire some professional translators ?

lol the first comment already got 6 upvotes

Jims Bond

@Gaurav SE could never afford that kind of thing on their business model

Kyle Kanos

@JimsBond: Learn Latin does not satisfy DeerHunter's advice

Jims Bond

How so?

0celo7

movies

Jims Bond

..... I'm not going to search but I bet there's at least one all-Latin movie

alarge

5:54 PM

@KyleKanos Given the target audience of the book is MBA students and the like, that's hardly surprising, though.

Jims Bond

and even if there isn't, sometimes Latin is spoken in movies. Learning it helps you experience more of those movies

alarge

@JimsBond Ah, so you were thinking of being an actuary then?

Jims Bond

@alarge I've never heard that term before

0celo7

@JimsBond oO

Jims Bond

but yes, something like that

giulio_hep

5:57 PM

Are you there Jims?

Jims Bond

sometimes

giulio_hep

well, you asked this question: "That's another person in the last little while to say "I don't care about the answer". What is going on? Don't people realize that asking the question means you must care about the answer?"

are you interested in a answer or your question is just fake?

Jims Bond

I got my answer to that, as well

0celo7

From me I hope.

Jims Bond

yup

2 hours ago, by 0celo7

@JimsBond They don't care if the answer is one way or another, they just want the correct answer.

0celo7

5:59 PM

:D

Gaurav

@JimsBond Earlier mother meta posts to similar questions suggested that all questions non-English should be translated by professionals, which would obviously require a huge number of such translators, thereby making it unviable economically. My proposal eases the load on the necessity to have a large number of professional translators. All they have to do is to verify community translations, and we'd need far less of such professionals compared to the earlier case.

0celo7

@JimsBond High school diploma at work.

giulio_hep

where are you from Guarav?

Gaurav

India

Jims Bond

@Gaurav I have not enough data to agree or disagree with that statement

giulio_hep

6:01 PM

why do you think that my English is a problem?

0celo7

Why can't people just learn English?

giulio_hep

I have a CAE

0celo7

Curious Aero Engineer?

Capillary Auto Endgame?

Colloquial Automorphic Endomorphism?

Cun... forget that one.

Jims Bond

Creative Acronym for Everybody?

Kyle Kanos

Computer-Aided Engineer?

giulio_hep

6:04 PM

is the first google search results

i.d.i.o.t.s.

0celo7

Cobordism on Automorphic Earls?

Kyle Kanos

First result for me: cae.com

0celo7

^^

ACuriousMind

Mine: de.wikipedia.org/wiki/CAE

Kyle Kanos

@ACuriousMind That's mostly in a fake language

giulio_hep

6:06 PM

ein Sprachzertifikat der University of Cambridge

0celo7

@ACuriousMind I can recognize some words...everything else looks like gibberish.

You should get that checked out, I think your PC is borke.

giulio_hep

I have studied also German and Russian

ACuriousMind

BTW @giulio_hep, where did Gaurav (or anyone else) say that your English was a problem? The translation discussion was wholly unrelated to you.

giulio_hep

ok, I was asking something to Jims and I couldn't understand his answer

0celo7

@ACuriousMind I am needing helping with the first unnumbered equation on Straumann page 658...I is distracting from my intern duties.

ACuriousMind

6:11 PM

@Gaurav: Making English non-obligatory would make it poosible that there are groups of users incapable of communicating with each other because they lack a common language. That would be the very opposite of a community.

@0celo7 I believe you should use 15.72

Jims Bond

@giulio_hep Sorry, did I miss a question you asked? I'm trying to do 3 things at once and I fear talking on chat is the one that is suffering for it

0celo7

@ACuriousMind I don't think so. I just re-found the first equation on page 617.

I know I've proved that one explicitly.

I need to show the first two terms on the RHS vanish.

AH

The inner products are deltas!

Glorious.

@ACuriousMind Thanks~ ;)

Gaurav

@JimsBond @ACuriousMind It's obviously some random idea that just popped into my brain. I just thought I'd convey it to the community. I mean, it must be of some use right ? Like setting the record for the highest rate of downvotes ? :D

0celo7

Found someone with last name Lulz.

giulio_hep

@JimsBond the point is that when I (people) ask why my (a) question is rated as unclear you don't have to answer to me... you can just answer the specific question... period Also it is very strange that physicsts find a question about time in special relativity so unclear

Kyle Kanos

6:23 PM

Well, I doubt there's a lot of rap written in Latin. So you win this round — Jims Bond 30 mins ago

Gaurav

@ACuriousMind Uh, I'm trying to say that we need to remove that barrier that is set because of the absence of a common language, not the converse.

0celo7

@Gaurav The common language is English.

Why is that so hard to understand?

Kyle Kanos

I'm pretty sure the galactic standard is English

Gaurav

@0celo7 What's so hard to understand ?

0celo7

Military spending dictates the language.

@Gaurav English is the common language here.

Those who don't speak it are not conforming to the common language (of PSE).

Gaurav

6:28 PM

Did you read my post on the mother meta ?

0celo7

Yes.

Gaurav

Did you actually edit that to put a full stop ?

0celo7

No, but that's not unimaginable.

I edited it from "maybe" to "yes".

ACuriousMind

@Gaurav The issue I see is that translation is only necessary if not everyone speaks a common language. It follows directly that there must then be subsets of users who are unable to communicate with each other except through someone translating for them, which I see as undesirable for a community.

0celo7

@ACuriousMind Are the subsets closed, open, or both?

Someone initialed the petition -.-

@ACuriousMind Are you saying translation will disincenivise learning English to participate on SE?

ACuriousMind

6:46 PM

@0celo7 I'm saying it would lead to users unable to talk to each other (e.g. in comments), naturally fracturing the site into the subgroups sharing a common language, intended or not.

Gaurav

@ACuriousMind You're right in a way, that you can't translate each and every comment. But for many students, just the opportunity to ask a question in their native tongue and receiving a quality answer in their own language is a great deal, since there might not even be people (who speak the OP's tongue) being able to give a decent answer.

0celo7

@ACuriousMind Hmm, but if they can't speak with us already, what would translation do if not what I said.

It's not like translating will cause people to forget English and form foreign cliques.

Gaurav

Seeya guys, it's night here.

ACuriousMind

@0celo7 I don't care whether it makes people more or less likely to learn/forget English, I'm concerned about a "community" where there are people who can't understand each other.

0celo7

@ACuriousMind I don't understand how translating will change that.

ACuriousMind

6:53 PM

@0celo7 If we don't translate stuff, we force every user to be able to speak English, so everyone can understand everyone. If we translate stuff, this is only of real value to people who can't speak English, so for it to be not useless, we would have to have a sizable fraction of users incapable of speaking English.

0celo7

Incapable of speaking technical English well.

I'm still confused. Are you saying it will be useless because we don't have that sizeable fraction?

ACuriousMind

@0celo7 Either it will be useless because everyone speaks English anyway or it will create "communities" where one part can't understand the other. So it's either useless or counterproductive to how SE communities are supposed to work, imo

0celo7

@ACuriousMind How will it create those communities if not by disincentivising people from learning English?

ACuriousMind

@0celo7 Did I say it does not disincentivise people from learning English?

0celo7

@ACuriousMind "I don't care whether it makes people more or less likely to learn/forget English"

ACuriousMind

7:03 PM

I feel were somehow talking past each other, fittingly for the topic :D

@0celo7 "I don't care" != "It does not"

But I see now how that phrase isn't saying what I wanted to say

0celo7

@ACuriousMind Which is?

I'm confused, because you say you don't care about the cause, only the effect.

ACuriousMind

@0celo7 My "I don't care"

0celo7

No, what did you want to say?

Only a few hundred signatures left!!

ACuriousMind

@0celo7 Stop being confused and assume I just answered "Yes" to your "Do you want to say...". I wanted originally to express that I am not worried about people not learning English as such, but about the particular effect it would have in this case.

0celo7

@ACuriousMind "Stop being confused". Done.

0celo7

7:39 PM

@ACuriousMind Sorry about that.

@dmckee When teaching the quantum double slit experiement, one usually talks about doing it using classical particles first, right? In the diagram in Shankar's book, he ends up with bell curves on both slits and a bigger bell curve when both are open. Why are there bell curves in the classical picture? Don't the particles travel in perfectly straight lines and cause spikes on the sheet in the back, not bell curves?

ACuriousMind

@0celo7 No need to be sorry about anything

0celo7

@ACuriousMind Then my question @dmckee is @ you too.

ACuriousMind

@0celo7 I don't know Shankar, but I think the curves should be the classical distribution of a classical wave passing through the slits.

0celo7

@ACuriousMind With the waves there is an interference.

ACuriousMind

Ah

dmckee

7:46 PM

Feynman talked about it using bullets and classical waves as part of a compare and contrast to the quantum behavior.

0celo7

But why the bell curves for classical particles?

ACuriousMind

What kind of particle source is he considering?

dmckee

I wouldn't argue with that approach, but I don't think it is necessary and I do think that you then need to head off certain misconceptions that will be coming.

ACuriousMind

IAnyway, I'd agree with your statements about "spikes"

dmckee

Those misconceptions are wrapped up in the way most people talk about the "wave-particle duality" as if it is a problem to be solved.

0celo7

7:47 PM

@ACuriousMind Unspecified.

Hmm, he says "varying directions"...but the slits are supposed to be tiny, right?

I think the diagram is not to scale.

dmckee

Students need to understand that quantum things are quantum and that wave- and particle-like behaviors are special case limits. That nature is quantum and they way we're used to things is a feature of our crude, large-sixe and slow-time experience of the world.

0celo7

@dmckee I'm not confused with the quantum experiment.

I would screenshot, but I'm at work.

Page 109, Fig. 3.2 if you can obtain the text.

I was talking to my dad the other day about this experiment and it's been bothering me.

dmckee

Don't have that text. If it follows the pedagogical path Feynmann blazed than there is an assumption that some of the classical particles nick the edges of the slit and are scattered in varying degrees. The distribution is then drawn as a bell curve because all peaks are Guassian unless and until they are shown not to be. I don't think you should take the shape of the peak too seriously.

0celo7

Ah, nicking the edges makes sense, thanks.

Transcript for