The h Bar

11:00 AM

hmm

Solutions of Schrodinger equation aren't in the syllabus but these AITS papers love to mix olympiad syllabus with the IITJEE syllabus.

anonymous

It is in syllabus. Such questions came in our school cbse mock test paper also.

Also it came in AIEEE or JEE main some years back in the online paper

Our teacher said that the orbital graphs psi, psi squared and 4 pi r^2 psi^2 dr are very important.

Also, it is damn easy :P

Yashas Samaga

You are talking about NCERT textbook I guess

those formulas which everybody commits to memory without understanding

n-1, l, n-l-1?

anonymous

Correction: not "everybody"

I know the meaning of each one

Yashas Samaga

The olympiad syllabus has "real" solutions of the SE

they will ask for peaks, zeros, etc.

anonymous

11:06 AM

Ya ya I know. They aren't anything complicated.

It is available on Wiki.

The SE solutions

Schrödinger equation

In quantum mechanics, the Schrödinger equation is a mathematical equation that describes the evolution over time of a physical system in which quantum effects, such as wave–particle duality, are significant. The equation is a mathematical formulation for studying quantum mechanical systems. It is considered a central result in the study of quantum system and its derivation was a significant landmark in developing the theory of quantum mechanics. It was named after Erwin Schrödinger, who derived the equation in 1925 and published it in 1926, forming the basis for his work that resulted in Schrödinger...

Yashas Samaga

You haven't solved FIITJEE papers, have you?

anonymous

On the contrary, I have.

Yashas Samaga

JEE Main or Advanced?

anonymous

Both.

Yashas Samaga

Olympiad?

anonymous

11:08 AM

No not olympiad. I don't have them.

Yashas Samaga

Do you manage to complete the FIITJEE Advanced papers in time?

I can't even solve half of the questions in time

anonymous

Complete? I don't think anyone can complete them in time.

Yashas Samaga

but the questions are nice though

anonymous

They are just for practice

Yashas Samaga

have to think

anonymous

11:10 AM

Find the coefficient of $x^5$ in $(1+2x+3x^2+...)^{-3/2}$

Yashas Samaga

2hr 7min 38sec

anonymous

This was a good sum I found today :P ^

Yashas Samaga

I have to finish the test :P

anonymous

You are giving a test now?

Yashas Samaga

yea

I check the solutions after solving each question though

Main paper

anonymous

11:11 AM

You are chatting or giving test :P ?

Yashas Samaga

both

The main paper is always stupid

anonymous

LOL XD

Yashas Samaga

I can afford to waste some time

anonymous

Don't be the rabbit. Or else the tortoise will overtake you :)

Yashas Samaga

-_-

anonymous

11:13 AM

-__-

The two curves $x^3-3xy^2+2=0$ and $3x^2y-y^3-2=0$ cut each other at what angle? Try this poblem ! @YashasSamaga

Yashas Samaga

-,-

calculus problem which is so direct

anonymous

Is there any shortcut to do this?

Yashas Samaga

enjoy finding the solution

anonymous

x replaced by y

Yashas Samaga

o0

anonymous

11:22 AM

@YashasSamaga I want to know how you solve it. What would be the shortest method possible ?

I already solved it

Yashas Samaga

I have to finish my test :/

anonymous

Using a shortcut

@YashasSamaga I thought you are taking a sleep break like the rabbit :P

Okay good luck

Yashas Samaga

math problems will take time

and I have already wasted sufficient time :p

I have 2 hours to do the math + half of chem

anonymous

@DHMO You there ? :)

DHMO

@anonymous yes

if you don't mind, where do you come from?

anonymous

11:25 AM

@DHMO Means? Country?

DHMO

yes

anonymous

Indian who lives in both Kuwait ( as an expat) and India.

@DHMO

DHMO

I see

anonymous

Can you solve that problem in a short way ? @DHMO

7 mins ago, by anonymous

The two curves $x^3-3xy^2+2=0$ and $3x^2y-y^3-2=0$ cut each other at what angle? Try this poblem ! @YashasSamaga

DHMO

sure

anonymous

11:27 AM

Do tell me how you do it :)

I am looking for some creative shortcut!

DHMO

add them together to obtain $(x-y)^3=0$

so $x=y$

and substituting gives $2x^3-2=0$

so their intersection point is (1,1)

anonymous

@DHMO I guess if function and its inverse cut they always cut on y=x. And after that you will find the angle between them using the tan(A-B) formula?

DHMO

@anonymous oh it's its inverse!

anonymous

Yep. Replace x by y!

DHMO

I was going to differentiate both functions

now I only have to differentiate one lol

so 3x^2 - 3y^2 - 6xy y' = 0

I see that y' = 0

@anonymous is this correct?

anonymous

11:32 AM

Seems okay

DHMO

then the angle is 90 deg

anonymous

@DHMO How can you say that by differentiating only one function ?

DHMO

@anonymous inverse function... reflect by x=y...

anonymous

Good...you know it ;)

Well done :)

DHMO

thanks

anonymous

11:36 AM

I've got one more problem for you

3D and vectors

Will you do?

DHMO

depends on what the problem is

anonymous

The center of circle given by $r.(i + 2j + 2k) =15$ and $|r-(j+2k)|=4$ is ? ($i,j,k$ are the usual unit vectors along x,y,z axes). $r$ is a vector.

@DHMO

DHMO

alright

are you sure that it is a circle?

anonymous

The first one is the equation of a plane and the second one is equation of a sphere. They cut to form a circle.

DHMO

oh, I had the wrong intuition

anonymous

11:51 AM

@DHMO Need hint ?

Secret

[Random sci-fi idea] what if the Big Bang is extremely cold instead of extremely hot, yet it has very low entropy. Then theoretically we will end up with entropy increasing as the universe expands and warm up to slightly above absolute zero, and heat will behave bizarrely as it spontaneously flow from cold to hot

Kenshin

Many of the great questions on this site come from John Rennie

Perhaps I should just make a book called the best of @JohnRennie

Secret

en.m.wikipedia.org/wiki/Cold_Big_Bang

And therefore, our Big Bang must be hot

anonymous

Just take a line passing through center of sphere and parallel to the normal of plane. Then place it in the equation of plane to find its intersection point. @DHMO

I got to go now. Cya!

Slereah

12:24 PM

"In the 6th century, John Philoponus partly accepted Aristotle's theory that "continuation of motion depends on continued action of a force," but modified it to include his idea that the hurled body acquires a motive power or inclination for forced movement from the agent producing the initial motion and that this power secures the continuation of such motion."

Good old Philoponus

Secret

"Probing the possibility of a contradiction in backwards time travel, the American philosopher John Earman has described a rocket ship that carries a very special time machine.

The time machine is capable of firing a probe into its own past. Suppose the ship is programmed to fire the probe on a certain date unless a safety switch is on. Suppose the safety switch is programmed to be turned on if and only if the “return” or “impending arrival” of the probe is (or has been) detected by a sensing device on the ship. Does the probe get launched"

Moses

@JohnRennie Yeah that's what I was referring to. I think it makes no sense for anyone to guess that your question is homework, regardless of how it appears. It's just a baseless assumption.

Secret

Solution d) 1. Launch the probe 2. Probe send light signal back to ship as it travel to the past 3. Probe arrived at the past 4. Light signal reached the ship, but not before the probe is launched

Solution d) is thus similar to solution b), except that the paradox is averted by having all the events arranged in a consistent cyclic order, hence predestinate itself.

John Rennie

@Moses The issue is not whether a question was actually given as homework. All that matter is whether it is homework-like. See my reply here for more on this

Secret

This solution is based on that computer calculation of the pont(forgot) deutsch spacetime like geometry as a solution to the grandfather paradox reported in an arxiv some time ago

John Rennie

12:37 PM

Although in this case I don't consider your question to be even homework like.

0celo7

@Kenshin he would sue you

Kenshin

12:55 PM

@0celo7 na John's nice

and plus the content is under the CC licence

0celo7

@Kenshin lol

Secret

"Some dynamic theories imply that the flow is a matter of events changing from being indeterminate in the future to being determinate in the present and past. Time’s flow is really events becoming determinate. Thus dynamic theorists speak of time’s flow as “temporal becoming.” Another dynamic theory implies that the flow is a matter of events changing from being future, to being present, to being past. This is the kind of flow associated with McTaggart’s A-series of events."

Yashas Samaga

1:42 PM

0

Q: Exact definition of Law of Conservation of Energy

I have learnt about law of Conservation of energy overtime that " For an isolated system, energy of that system will remain constant with time." I want to know the conditions and constraints under which this law works. Basically i want the exact definition of Law of Conservation of Energy with al...

0celo7

@JohnRennie halp

Yashas Samaga

is that question of the type homework question without any effort?

0celo7

@YashasSamaga maybe he is asking about general relativity

Yashas Samaga

He did not add the GR tag

huh

physics.stackexchange.com/questions/313650/calculating-electric-field-using-volt‌age/313687

He solved it correctly then said "This doesn't seem to be right for some reason"

His answer was correct -_-

Yashas Samaga

2:02 PM

What happens if someone upvotes an answer for a user who has already reached the daily reputation limit?

Secret

Measurement in quantum mechanics seemed to provide the necessary element of "temporal becoming" as observables are not determined until a measurement is done and the state end up in one of the many eigenstates. It is also irreversible as far we knew

However, it is still not sufficient to account for the impression of time flow as a state still evolve in time according to the hamiltonian, one can easily check this by performing quantum state tomography on an ensemble of replicates at different times, and the distribution of observables one obtains will agree with the state at the time of me…

anonymous

@YashasSamaga Their reputation points don't increase on up-voting. However, they will get points if their answer gets accepted (+15) .

Yashas Samaga

I feel bad for those who get +100 votes in a single day lol

anonymous

It is good to have that cap. Sometimes hot network questions earn a lot of undeserved upvotes.

The hot network questions algorithm is pretty awful.

Hey @Kaumudi.H Nice dp :)

user228700

@anonymous Thanks :-) Is it really visible? I'm only able to see the old one.

0celo7

2:13 PM

dp?

Yashas Samaga

What's dp?

I hear it everyday

anonymous

Yeah, it is visible. Refresh your page.

Yashas Samaga

but I don't know what it means

anonymous

"Display picture"

user228700

@anonymous Nope. Huh :-|

0celo7

2:14 PM

must be Indian English

Yashas Samaga

ye

anonymous

It is common in whole Asia.

And Australia

user228700

@0celo7 Nah.

0celo7

this is America

anonymous

And New Zealand too

And even in the middle east

Secret

2:14 PM

9

Q: Is there conservation of information during quantum measurement?

Consider the following experiment. I take a spin-$\frac{1}{2}$ particle and make a $\sigma_x$ measurement (measure the spin in the $x$ direction), then make a $\sigma_y$ measurement, then another $\sigma_x$ one, then $\sigma_y$, and so on for $n$ measurements. The formalism of quantum mechanics t...

quantum-interpretations measurement-problem

measurement problem...

anonymous

@YashasSamaga @0celo7 quora.com/…

0celo7

So, it's un-American.

Secret

2:36 PM

"Suppose you have a movie of a basic physical process such as two electrons bouncing off each other. You can not actually create this movie because the phenomenon is too small"

No, we can now, at least to the level of atoms

Secret

2:49 PM

quora.com/Why-is-linear-motion-relative-but-rotation-absolute

Bucket argument

Isaac Newton's rotating bucket argument (also known as "Newton's bucket") was designed to demonstrate that true rotational motion cannot be defined as the relative rotation of the body with respect to the immediately surrounding bodies. It is one of five arguments from the "properties, causes, and effects" of true motion and rest that support his contention that, in general, true motion and rest cannot be defined as special instances of motion or rest relative to other bodies, but instead can be defined only by reference to absolute space. Alternatively, these experiments provide an operational...

Yashas Samaga

Maybe rotation has to do something with gravity. If you put yourself inside a spaceship which is rotating, you'll feel fake gravity :P

Well, Einstein argued in a similar fashion before developing GR. He used a lift instead of something rotating.

Secret

Indeed, that's the equivalence principle. In the next 5 or so years, a bose einstein condensate microgravity experiment will probably provide more info on how far this principle will hold in the quantum regime given the rocket that contain that experiment has been launched earlier this month into orbit

Yashas Samaga

Oh, interesting. I am going to google for it.

@Secret Japanese rocket?

Secret

In the rotating spaceship, the artificial gravity is due to the centripetal force as viewed from a nonrotating frame, and a centrifugal force in the corotating frame

@YashasSamaga This one

Secret

3:07 PM

"If Aristotle were correct that the future, unlike the past, is undetermined or open, then the future of people in the time-reversed region would be open, too. But it is like our past. What can we conclude from this? Do we conclude that our past might really be undetermined and open, too? That our past could change"

Actually for me, I think it means there are many possible pasts lead to one present, but we only get to see one at a time
Possible means they don't necessary exists, as in the case of branching timelines

If you think of this in terms of light cones, it kinda make sense. Any events in the past lightcone of any observer can potentially influence the present that the the apex of the lightcone

So in a time reversed world, what we recognised as the future lightcone becomes a past lightcone for that world

"Philosophers are divided into three camps on the question of the reality of the past, present, and future. The presentist viewpoint maintains that the past and the future are not real, and that only the present is real, so if a statement about the past is true, this is because some present facts make it true. Advocates of a growing past argue that, in addition to the present, the past is also real. Reality “grows” with the coming into being of determinate reality from an indeterminate or potential reality. “The world grows by accretion of facts,” says Richard Jeffrey. Aristotle (in De Inte…

Slereah

Secret

I am actually more of the growing block camp in philosophy of time

Secret

@Slereah What does jennifer lawrence had to do with cyclic groups?

Secret

3:29 PM

->Ok, cannot find anything in google, other than it is one of the "That's not A that's B" dank memes

Secret

"The advocates of the block universe counter that only the block universe can make sense of relativity’s implication that, if people are in certain relative motions, an event in person A’s present can be in person B’s future. Presentism and the growing-past theories must suppose that this event is both real and unreal because it is real for A but not real for B. Surely that conclusion is unacceptable, they claim. Their two key assumptions here are that relativity does provide an accurate account of the

John Rennie

@Kaumudi.H aha, you found me on Google+

user228700

@JohnRennie I didn't find you. I updated my details and saw ur profile on my "People you might know" list :-)

Yashas Samaga

o0

Secret

"The principal motive for adopting the Aristotelian position arises from the belief that if sentences about future human actions are now true, then humans are fated (or determined) to perform those actions, and so humans have no free will. To defend free will, we must deny truth values to predictions."

John Rennie

3:38 PM

Ah. I don't use Google+ much. I think my account got created automatically when setting up one of my many Android devices.

user228700

I liked and commented on that infamous videos of yours :-) I also may have subscribed to you, just to increase the number of subscribers you have--that may be how ur name popped up.

John Rennie

Apart from here (of course :-) the only other place I hand out is on Facebook.

@Kaumudi.H Ah, yes, that's probably why Google suggested me because that video is on my Google account.

user228700

@JohnRennie I see. I don't have an account on Facebook, as u know. I don't have an account on any other (apart from Google+, which I updated today after God knows how long) social networking websites.

John Rennie

I only check Facebook once in the morning and once in the evening, so I'm not exactly a fanatical Facebooker.

DanielSank

Speaking of Facebook:

user228700

3:42 PM

@JohnRennie OK, I see :-)

John Rennie

I don't think I've ever updated my Google+ page ...

Secret

The major reason of trying to write a time travel story using a back to the future model is because I want to preserve free will (All GR solutions DON"T preserve free will).
Free will is really one of the more stubborn parts of my thinking process, basically a bias in my worldview.

You gotta have to try very hard to convert me and make me abandon the notion of free will completely, but you might not want to do so. This is because my attitude to truths is I will not only accept them, I will FORCE all worldviews to accept them. In the given context, it is known that when people lose the beli…

DanielSank

I forwarded an event notifiaction email, that came from Facebook, to a friend, and through that email my friend was able to access my Facebook account.

user228700

@JohnRennie Lol, I used to be an active user of Google+ about the time when it was launched--four years ago, IIRC. A small group of us used it for about 6 months before giving up. Since then, I've changed my e-mail id so I've had to set it up again to comment on YouTube videos and such.

Secret

My philosophy is as follows: I accept truths very readily once it is proven and checked, and I do not like the false hope and the notion of delaying the inevitable if it is going to happen anyway. Anything that is not well explained (including ambigurity between A and B) is to me, a complete waste of time

The side effect of this philosophy is I accept the death of my grandparents very readily and seemly without emotions, as mentioned earlier

The cool thing about reality is, it makes proving something is a false hope increadibly difficult, thus you will still do it because it might not be a false hope at all

MartianCactus

3:49 PM

evevevent!!

s.harp

how come I got pinged aobut this event in the mathematics chat room?

Riker

because it pings you wherever you are

Secret

@s.harp You must have bookmarked it somehow

Riker

if you've been in this room in the last couple days

you don't have to have bookmarked it

s.harp

last time I was here was jan 24 D:

ACuriousMind

3:51 PM

I thought it only pinged you if you were either in here or had signed up for the event here

rob

@s.harp Because we were hoping you would join us. Welcome!

David Z

@ACuriousMind that's what I thought too

DHMO

hi everyone

@JohnRennie is not here though

s.harp

@rob :D ok

David Z

What shall we put on the agenda today?

Terry Bollinger

3:57 PM

Greetings all!

David Z

Greetings

Terry Bollinger

@ACuriousMind, your icon is looking particularly scary lately. What character is that?

John Rennie

@DavidZ I'm mildly, not insanely, curious about the new question blocking feature.

David Z

@JohnRennie Ah OK, we'll spend a few minutes on that. Good idea

Tony Stewart

1st time to the h bar. Is it all-inclusive?

ACuriousMind

3:59 PM

@TerryBollinger It's the protagonist from Planescape: Torment

@TonyStewart Nah, you gotta pay for your drinks individually ;)

David Z

@TonyStewart yep!

@ACuriousMind ah, true

OK, welcome to the chat session everybody!

Yashas Samaga

^_^

David Z

Please hold off on unrelated discussion until we've gotten through our prepared topics (of which there are few this week)

Terry Bollinger

So what is this new feature for question blocking?

David Z

Here's the agenda for today's session:

1. Intro, welcome newcomers, site questions (5m)
2. Recent physics developments (10m)
3. New question blocking feature (5?m)

and after that back to open discussion as usual

@TerryBollinger we'll get there

Terry Bollinger

4:01 PM

:)

David Z

To start off, is anyone other than @Tony new to chat, new to chat sessions, or new to the site?

(and willing to admit it? :-P)

BTW welcome @Tony!

s.harp

I'm new I guess

Tony Stewart

@DavidZ thanks

David Z

@s.harp Hello then, and good to see you!

Tony Stewart

< retired EE since '75

David Z

4:03 PM

@TonyStewart cool, I do hope you like it here

Tony Stewart

muchos gracius

David Z

For those who aren't familiar with it, these chat sessions are a biweekly event we do to bring the community together and sometimes to discuss site policy or important issues

Tony Stewart

so far it seems far more intel on this stack than the EE one

David Z

We're not having much of a formal policy discussion today, but if anyone does have any general questions about site policy (except the new question blocks, which we'll get to later), this would be a good time to ask them

Tony Stewart

how important are references to opinions based on personal experience in answers?

David Z

4:07 PM

@TonyStewart Hm, well speaking for myself, I'd say we prefer calculations and references to opinions, but if an informed opinion is all you've got, it can be better than nothing

Tony Stewart

perhaps more relevant to the experimental and practical ones

gotcha

David Z

Maybe other people can also weigh in

I know those other people are here somewhere :-P

ACuriousMind

@TonyStewart For most questions, I cannot see how personal experience would be relevant at all. It may play a role for questions about specific experimental setups, but many questions are of a theoretical nature where knowledge is much more relevant than experience.

Terry Bollinger

@TonyStewart actual paper refs are always helpful, e.g. to back up opinions.

John Rennie

@TonyStewart I think it depends. I occasionally see questions that relate to my time as a colloid scientist and there I can often help because I have the experience.

David Z

4:08 PM

(let's defer current physics until 10 minutes in, i.e. 2 more minutes of this)

John Rennie

But if I'm being asked some fairly deep technical question then I'd expect to provide a detailed theoretical background to make my point not just my best guess.

Terry Bollinger

@JohnRennie I'm currently finding a deep dive I once did on polyacetylene quasiparticles relevant to work I'm doing on a very different area... sometimes the math carries...

Tony Stewart

e.g. say someone has a question about testing fragility boundary (v vs g vs t) of a device and I have lots of test experience but little on the theoretical side. Would this be ignored?

John Rennie

@TonyStewart Your experience would certainly be welcome, and you should answer if you think you can help.

Tony Stewart

gotcha

John Rennie

4:11 PM

But I have to say that those types of question aren't that common here.

David Z

Yeah, practical experience is definitely a valid basis for an answer.

Terry Bollinger

@TonyStewart hands-on gives insights, for sure...

David Z

Let's move on to recent physics news. What's new in the world of physics?

John Rennie

We don't seem to have a large experimental community so we don't often get the more practical questions.

Terry Bollinger

Q: Anything going on in emergent space-time papers? I have a few now...

Secret

4:12 PM

Field pattern models

The maths looks solid in the paper, but it is unsure if it can account for quantum things as they claimed in a future extension

Terry Bollinger

@Secret wow, cool, thanks!

Oddly, some of my current work might add a lot more mathematical specificity to the approach they appear to be advocating (I think).

David Z

Working directly with probabilities in quantum field theory caught my eye while browsing arXiv, but I haven't gotten to look over it in detail yet.

Not related to emergent spacetime, just possibly interesting

Akoben

@TerryBollinger I'm a fan of this paper: arxiv.org/abs/1005.3035

John Rennie

I would guess this doesn't apply to many people here, but for anyone looking for an educated amateur approach to GR this seems to be a nice book:

amazon.co.uk/…

Terry Bollinger

@DavidZ hard to get the gist immediately, but intriguing...

David Z

4:18 PM

@TerryBollinger indeed

Terry Bollinger

@Akoben thanks that is exactly the paper I was indirectly mentioning!

Akoben

Ahh heh

Terry Bollinger

@Akoben he hasn't seemed to follow up on it much though...

Secret

Beating the rayleigh resolution limit not via intensity, but by modulating the phase

Terry Bollinger

@Secret interesting, though I thought similar ideas were already in use? Maybe this goes deeper still?

DHMO

4:21 PM

@JohnRennie is back

Secret

Well they say past methods use intensity. This one uses phase instead

Akoben

@TerryBollinger there are some interesting examples of emergent spacetime from entanglement in tensor networks, i.e. arxiv.org/abs/1209.3304

Terry Bollinger

@Secret definitely worth a closer read, thanks!

David Z

OK, let's move on to spend a moment on the new low-quality question blocks.

161

Q: Comprehensive question quality blocks now enabled everywhere

Questions are the lifeblood of any Stack Exchange site. But asking good questions can be difficult, and while most people start off doing it poorly, some never get better. For years now, when sites reached traffic levels that made manual review and filtering of questions burdensome for the good f...

discussion asking-questions post-ban

John Rennie

This seems as if it was imposed by fiat, with very little consultation.

David Z

4:23 PM

@JohnRennie Perhaps so.

John Rennie

I wonder how relevant it is to us, though i note there was one site member complaining in the Meta that they had been banned.

Is there any way of seeing how many people on the PSE are being affected by it?

Tony Stewart

the phase info is great for improving resolution on coherent waves is old but application may be new to optics?

David Z

@JohnRennie Not directly, but the SE people have revealed that information to the mods. I'm not sure if I should give exact details in public but the number is very small.

Terry Bollinger

@Akoben nice, thanks! I am deeply intrigued by the space-as-entanglement theme. My own phrase for it from years ago (2006? have to look) is the Boltzmann fabric...

ACuriousMind

@JohnRennie No. The number of affected accounts is in the lower two-digit range, though.

John Rennie

4:26 PM

I guessed there wouldn't be many people affected, since I don't recall seeing many persistently bad questioners.

David Z

@JohnRennie If you're talking about this post, that was different.

John Rennie

Was any indication given of the reason why the new controls were introduced?

@DavidZ Ah, OK, my mistake.

ACuriousMind

@JohnRennie One reason I heard was that many sites are now large enough that the SE team felt it was unreasonable to expect moderators to dole out low-quality suspensions individually

Terry Bollinger

Must go, a bit hard to type right now (transient flare up of a condition). Thanks to several for the excellent paper refs!

David Z

@JohnRennie it's a fair mistake to make. My understanding is that the new question block is basically permanent (it allows posting one question every six months or something), and is reserved for the most egregious cases of consistent low-quality posters.

@TerryBollinger see you later!

John Rennie

4:28 PM

I wonder if this is being driven by sites like Stack Overflow, in which case any effect on us is an accidental by product.

s.harp

If you write lots of crappy questions and get banned there is little stopping you from making another account

ACuriousMind

@JohnRennie It was active on SO long before this

David Z

@JohnRennie Well, this particular ban was already enabled on SO and 7 other sites. The SE team had enough data from other sites (including this one) that they concluded it would make sense to implement it here, and everywhere.

s.harp

on the mathematics stack exchange there were some people writing lots of crappy operator theory questions, after while they stopped getting answers and suddenly a new account appeared asking the same kind of questions

ACuriousMind

@s.harp The system is not that dumb - making a new account rarely allows you to evade the system restrictions for long.

David Z

4:30 PM

@s.harp ACM is right, though it's a legitimate point to bring up if you're not familiar with the system.

s.harp

I see

David Z

SE does not reveal a whole lot of detail on the algorithms behind these blocks, to avoid giving people a template for how to beat them - but again, these are targeted at the most extreme cases of low-quality posters, and they come after the poster is subject to temporary blocks and warnings; it's not a surprise.

Anyway, that's more than our allotted time for the question blocks, so let's move on to open discussion. If anyone else has questions about the new blocks, you're still welcome to ask them of course! Otherwise back to "business" as usual.

Tony Stewart

It makes sense to force newbies to learn the ropes slowly before noise cluttered questions unless there is a means to elevate on credentials

ACuriousMind

I'm pretty sure that most new users will never run into any of the quality bans - many ask a question or two that are moderately well-received, then are never seen again. That's just my impression though.

David Z

@TonyStewart We do have a gradual system of warnings in place to try to catch people who are likely to ask bad questions and steer them in the right direction. But what do you mean "means to elevate on credentials"?

Tony Stewart

4:37 PM

such as a greater initial point system when sponsored by an admin

who knows the new person's experience

ACuriousMind

SE is intentionally egalitarian in that respect - we do not care who you are in the real world, or who you might know. Expertise in your subject area does not mean that you will be a good contributor to SE

David Z

Plus it's so rare that an "administrator" (or even a moderator) actually knows a new member that it would not be very useful for those people to get a bump in reputation.

Interesting idea, I just think we have our reasons for not doing it that way. (Or rather, I should say the SE team, since they're the ones who designed the system without that feature.)

Tony Stewart

ok

ACuriousMind

I think it's important to realize that reputation does not actually measure skill or expertise but rather how much your contributions are valued by the rest of the users. You can get the same amount of reputation from one brilliant post or ten good posts or a hundred average ones - or even just from one that was lucky enough to be seen by many users even though it is not all that good.

It's tempting to see reptuation as a straightforward measure of knowledge or skill, but it's more complicated than that.

David Z

Indeed, and it's an imperfect measurement at that.

Tony Stewart

4:43 PM

yes but the votes are all weighed equally by those with little or great experience, so there may be an egalitarian skew to value

but then those are the realities of egalitarian free choice

David Z

@TonyStewart Yeah, that does pop up occasionally. There have been proposals to weight votes according to some metric like the reputation of the voter, but the details get really complicated and nobody's been able to figure them out. It would tend to lead to more of a "club" where high-rep users get more rep more quickly, and low-rep users have a hard time "breaking in".

Tony Stewart

yes and harder to maintain. ty all ciao

David Z

Thanks for stopping in

Anything else to cover before we close out our chat session?

skullpetrol

How about the next AMA?!

David Z

Oh, yes - and before that, the previous AMA! In case anyone didn't notice, we had a very successful (right?) AMA with heather yesterday.

4

I don't know anything about the next one; @vzn and @DanielSank are handling that project, I believe, so they're the ones with the information to offer.

skullpetrol

4:58 PM

Sign up people everybody is welcome :-)

David Z

Well, hopefully there will be more information about AMA upcoming, here and/or on meta.

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