The h Bar

@0celo7 No. The people who run it are reputable scientists. But they—by design—do no gatekeeping so the posters include all the folks who can't post to more regulated fora.

0celo7

Wait for the price to drop

Slereah

12:29 AM

aight

0celo7

I was craving some AC

So I bought it

But if you can wait, wait

It's still buggy, etc.

Slereah

no surprise

Sasso creedo is famously buggy on release

0celo7

optimization is awful

uses 100% of GPU and CPU for 60fps

Slereah

then again

If you're playing a game

0celo7

@dmckee I posit that only mentally ill people think it's a good idea to post on there, given the other obviously insane people on there.

Slereah

12:31 AM

Do you really need your GPU for anything else

Yeah, posting on Vixra is probably not a good move for credibility

0celo7

@Slereah no, but I would like more than 60fps!

What Sam said.

Slereah

If you really can't post anywhere else, you might as well make a blog

0celo7

If you're a healthy, well-adjusted human being, you look at viXra and say "yikes". If you have some pet theory, you put it on a blog or something.

To want to be associated with viXra requires some amount of insanity.

Slereah

Isn't researchgate the one that's in between Vixra and Arxiv

or something like that

There's also like

AcademiaSomething

I think ResearchGate only requires being at a university

It's less restrictive than Arxiv but that requirement filters some of the cranks

dmckee

@0celo7 Ah. Uhm. Well ... I have no comment on that.

0celo7

12:53 AM

@dmckee do you admit there are some insane people there?

Semiclassical

do delusions of grandeur count?

Slereah

there are literally articles by Jesus Christ on vixra

Semiclassical

some of that may be trolling...but not all of it

Slereah

I think they deleted the article by Jesus Christ

Sad!

0celo7

1:16 AM

@Slereah that just gets my MAGA blood boiling

Why do they hate Jesus?

Slereah

I wonder what the articles on politics are like

let's see

dmckee

@0celo7 I figure that some pretty around-the-bend people who post here, and viXra accepts papers from people who can't form a coherent stack exchange post.

Slereah

"Analysis of Beggars in Modern Nepal"

Boring!

Trump's Political Manifesto

Authors: Adolfo Kitler

YES

dmckee

I actually approve of the basic idea and get the point that outside voices need to have a channel lest science fall into an echo chamber.

Slereah

It's actually just a copy of mein Kampf

dmckee

1:17 AM

But man, it's hard to find any signal in all that noise.

Slereah

vixra.org/abs/1707.0105

0celo7

@dmckee I agree, but the people who can’t post on arXiv tend to be not be in academia for reasons such as delusions of grandeur, etc. I’m not saying it’s a guaranteed thing, but it seems close to it.

Slereah

"The Perils of New Atheism"

"Kings’ Dirty Operation: Concise Memos of My Cooperation with the CIA and Illuminati's Hell"

"Gays in the Military"

dmckee

@0celo7 Well, if you come from the wrong sub-field you may be initially unable to post to arXiv for lack of history.

But the endorsement mechanism is suppose to take care of cases like that as long as the would-be poster has done their homework.

And it is suppose to rebuff people who haven't done the ground work.

0celo7

But no academic would dare post on viXra!

dmckee

1:22 AM

Never having been on the outside it is hard for me to judge complaints that it is too hard for good scientists to penetrate.

Slereah

Well vixra isn't really for academics

Academics have their own channels

dmckee

@Slereah The people who run viXra think of it as an academic repository; just one without quality filters. It's worth reading their page on 'Why viXra', the FAQ and browsing the blog once.

Slereah

They think so, but how many academics do they actually have?

Why would an academic use vixra rather than any other site

dmckee

And a small number of established academics do use it as a place to put their pre-prints as a protest against what they see as overbearing policies on arXiv.

MInd you, I would strongly discourage any early-career scientists from trying that. You need a solid reputation on your own merits to ensure that you name will be more important to a viewer than the name of the pre-rpint site.

Semiclassical

posting on viXra under your own name seems a pretty good way to burn your bridges as far as credibility goes

Slereah

1:30 AM

Sorry I only post my papers on Above Top Secret

abovetopsecret.com/forum/22/pg1/srtpages

"man is abducted by dwarfs bebedouro brazil 1969"

nothing but quality posts

"October Cattle Mutilations"

Mockingbird

3:09 AM

@eranreches Really, a harmonic oscilator?

@eranreches Have you looked at the question properly!

Semiclassical

4:48 AM

@Mockingbird what strikes me as tricky about this example is that the stated equation is dx/dt, not d^2x/dt^2. so this isn't an equation of motion in the sense of being equivalent to F=ma.

aaactually. suppose $m$ is taken to be very light, so that $m\approx 0$.

then you can interpret that equation as $m\ddot{x} \approx 0 = -\dot{x}+\sin x$, which is a (massless) pendulum with an extra force term.

(i'm not completely sure that works. the test will be if it helps answer part b or not.)

Lagranian

@ACuriousMind That was my bad. I'm sorry for all

Lagranian

5:10 AM

Two identical glass rods $S_1$ and $S_2$ (refractive index is $1.5$) have one convex end of radius of curvature $10$ cm. They are placed with the curved surfaces at a distance $d$ as shown in figure with their axes (shown by the dashed line) aligned. When a point source of light $P$ is placed inside rod $S_1$ on its axis at a distance of $50$ cm from the curved face, the light rays emanating from it are found to be parallel to the axis inside $S_2$.

here is my diagram as seen below

Might I take your hints?

Also, my thinking is to use Gaussian formula.

Semiclassical

my hint is to ask someone who knows optics

(so uh not me)

Lagranian

I hope there's someone who knows it

0celo7

@JohnRennie My SSD speeds are back

it's the schroedinger benchmark

Semiclassical

@0celo7 now i'm curious what that means

0celo7

@Semiclassical SSD speeds decrease over the lifetime of the drive, but mine oscillates

hence it's random

and probably wrong

so idk

Semiclassical

5:16 AM

huh.

0celo7

@Semiclassical SSD speed is kind of meaningless anyway because you never use 100% of the drive

I think it can read faster than the processor can open

Sir Cumference

6:20 AM

@Lagranian Hey JR

eranreches

7:08 AM

@Mockingbird Yes I've looked. The idea is to start with a pendulum, and to observe what force you need to add to it in order to have the first derivative term in the equation.

In your case you want to add a damping force, proportional to the velocity.

Then you should approximate the equation in the over-damped limit, when the inertial term becomes negligible.

@Lagranian Have you learned geometrical optics? There are formulas for curved interfaces.

Sir Cumference

God I'm tired

John Rennie

God doesn't care ...

@Lagranian That is in effect a lens i.e. the two curved surfaces are the two sides of a lens.

Bernardo Meurer

7:48 AM

@JohnRennie Morning John!

@dmckee Heya

John Rennie

@BernardoMeurer Morning :-)

Bernardo Meurer

@JohnRennie How's the weather looking over there?

John Rennie

It's nice and clear, but frakking cold :-)

There was a frost this morning so it's aound 0ºC. It was cold in my office first thing this morning!

Bernardo Meurer

It's kind of cold here too, I was outside and had clouds coming out of me mouth!

John Rennie

I didn't realise it got cold in Santa Barbara ...

Bernardo Meurer

7:51 AM

Alas, 10C isn't that cold

But cold enough for me to want to go home to Rio and get drunk

John Rennie

10ºC - luxury!! :-)

Bernardo Meurer

Hehehe, Luxury is home 34 in the day, 25 at night

Just 4 more weeks and I'll be back in the land of ~~milk and honey~~ beer and lead

John Rennie

beer and lead - that sounds awfully like large areas of the US :-)

Bernardo Meurer

Except in Brazil there's no age restriction to enjoy the ride!

John Rennie

Europe generally takes a sane view about drinking. In theory there's an age limit of 18 in the UK but in practice it's widely flouted and no-one really cares.

We're not so keen on guns though :-)

Bernardo Meurer

8:03 AM

We're not keen on guns in Brazil either

the drug cartels beg to differ though

Emilio Pisanty

14

Q: How can I prove my publication list is mine?

In some of the questions regarding author name, it is mentioned that people can use whatever they like, however, they must be consistent across their publications. When it comes to being hired by a university for a tenure track position or by another principal investigator as a researcher, how c...

'Protected by Community'?

Boy, there must be some real stinkers there

NormalsNotFar

9:51 AM

Hi folks, I have a quick question to do with SR and the definition of elementary questions. Is anyone available at the moment?

oops, I meant elementary particles**

Qmechanic

2

Q: How does the human ear guess the source of the sound?

Suppose a sound is produced behind you. You can easily tell that the sound came from behind. Our ear lobes face towards the front and hence traps the sound waves which come from the front. Yet, we can detect that the sound came from behind. We can claim that the sound which was produced behind t...

acoustics reflection biology perception

Off-topic? Roll back bounty?

NormalsNotFar

I'll leave my question here in case someone feels like answering.

We define an elementary particle to be a unitary irrep of the Poincare group, because this is the symmetry group corresponding to SR. The unitary irreps are labelled by mass and spin (m,s). But if a representation (aka a particle) has mass m, then haven't we already stepped outside the boundaries of SR (since the presence of mass implies we are not in flat space anymore)?

I would say not Qmechanic, but I don't know as much about the site rules as everyone else.

ACuriousMind

@NormalsNotFar What do you mean by the presence of mass implying we're not in flat space anymore? Are you thinking of the gravitational influence of said mass? In that case, the answer is that standard QFT simply does not describe gravity, or general relativistic effects.

Sir Cumference

10:10 AM

Howdy

NormalsNotFar

@ACuriousMind I guess I am just a little confused as to the fact that we use SR to define elementary particles, but the presence of a particle curves space-time, so we aren't in SR anymore. It just seems like some sort of oxymoron in my mind.

But as you say, I guess its because the failure to combine QFT and gravity.

John Rennie

@NormalsNotFar not my area, but I guess we assume that the effect of the particle mass on the curvature of spacetime is negligible, which unless we are dealing with Planck scale particle masses seems a pretty good approximation.

@Qmechanic I'd be inclined to let that one go. It is, in principle at least, about the propagation of sound waves.

Secret

vimeo.com/236211411

NormalsNotFar

10:28 AM

@JohnRennie Yeah that sounds quite reasonable. I don't have much experience in this area, so what I am about to say might sound very naive. But shouldn't we define elementary particles to be unitary irreps of the symmetry group of some non-trivial spacetime, like de Sitter space or a Friedmann universe, for example. I imagine that this would be a lot more difficult, if possible though..

John Rennie

@NormalsNotFar For freely moving objects spacetime is always locally flat, so locally Poincaré symmetry is a good approximation.

ACuriousMind

@NormalsNotFar The Poincaré and de Sitter reps are related, cf. this answer of mine and links therein. Your point is not naive, but you probably underestimate how good the approximation of "spacetime is flat" really is when one is not looking at cosmological scales

John Rennie

The point being that when considering collider experiments we don't need to consider the large scale geometry of spacetime.

NormalsNotFar

Right I get what you are both saying, thanks a lot. Is this one of the purposes of the Vierbein formalism? I have been meaning to get into this but I have exams at the moment.

By the way @ACuriousMind , thanks for the link to Boers masters thesis, it looks really interesting.

ACuriousMind

@NormalsNotFar No, the tetrad formalism is simply another formulation of GR.

However, it is the formalism one prefers to use for (effective) quantization

NormalsNotFar

10:46 AM

I haven't really started to learn QFT yet. I want to, but I have heard that it is best to have a solid knowledge of field theory first. Would you agree, or do you think I should get started on QFT sooner rather than later?

ACuriousMind

You should have a firm grasp of ordinary quantum mechanics. Field theory is a plus but not necessary - most courses and books don't really assume that you know classical field theory in any detail, for better or worse.

NormalsNotFar

Ok i'll keep that in mind. Thanks very much for your time @ACuriousMind and @JohnRennie, enjoy the rest of your day.

NormalsNotFar

11:01 AM

As a parting note, if any of you like the idea of alien jazz music, you should give these guys a listen - soundcloud.com/grievousbodilycalm - they're awesome!

Mary Star

Hello @JohnRennie !! Could you take a look at my question: physics.stackexchange.com/questions/368506/… ?

user129412

11:19 AM

How would one go about calculating the Thomas-Fermi screening length for a thin layer of aluminum around 0K (or well, 10mK)?

user129412

11:36 AM

Or to rephrase it, how would one go about estimating the electron density? And by thin I meant from monolayers up to say 10 nm

Emilio Pisanty

@ACuriousMind who the hell learns classical field theory?

ACuriousMind

@EmilioPisanty Exactly.

Emilio Pisanty

btw quick question, can you see how many closevote reviews are pending?

ACuriousMind

@EmilioPisanty Queue shows 33 for me, and since I haven't used the queue in ages, that's likely the total number of reviews pending

Emilio Pisanty

@ACuriousMind ok

thx

it'd be useful to have those statistics a bit more widely available

i.e. total number of questions in the queue

Phase

11:45 AM

@0celo7 what's the expectation value of ACO corruption, immediately after it melts large parts of your SSD

Emilio Pisanty

and minimal number of reviews that would be needed to clear it

those are not user-dependent so they're cheap, and they'd be in low-traffic pages

but oh well

ACuriousMind

I agree

Emilio Pisanty

so even you can't see the totals?

SE is bizarre sometimes

ACuriousMind

@EmilioPisanty Not that I'd know, no

John Rennie

@Phase Assassin's Creed Origins presumably? Why would playing the game melt your SSD?

Phase

11:52 AM

@JohnRennie @0celo7 had to take the top off of his case. It uses 100% of his CPU even overclocked

It will just melt his entire PC

It's horribly optimised. Because of it's DRM it seemingly emulates scripts inside the DRM itself, which eats up CPU's

John Rennie

ACO has the reputation for being poorly optimised so it takes a lot of CPU, but you don't have to run it at the highest graphics settings.

Phase

@JohnRennie nah dude it's worse than that

With mid range CPU's some people cant even get it to 60 fps on low

+ you're talking about someone who complains that 60fps is an eyesore

John Rennie

You young things. Back in the days of playing Doom on a 386 any frame rate in double figures was considered acceptable :-)

Phase

"ooo back in my day we used to draw paintings on rocks and switch out the rocks to make cartoons, the framerate was about 0.005 but it was a fun time ooo..."

:P

Time's have changed old man!

John Rennie

@Phase ah, sarcasm ...

Phase

11:57 AM

Was that around back in 20BC?

x)

Besides

Ahhh I cant remember the name

There was a game like doom ages ago but had magic and stuff, I feel like it had "hex" in the name, it was way better imo

Hexen?

John Rennie

Yes, probably Hexen. It used the Doom engine.

Hexen was good fun. Less action oriented than Doom but with puzzle solving.

And it introduced the hub model for games.

Or do you mean Heretic?

Phase

Pretty sure I meant Hexen but I'm not sure

I remember playing them years and years ago

Doom was fun but I just didn't really find the aesthetic or setting very engaging

SigmaAlpha

@EmilioPisanty So you don't rate classical field theory either, or was that sarcasm... I can't tell xD

John Rennie

You can play Hexen (and other contemporary games) using modern 3D engines like JDoom. They are still surprisingly enjoyable, though some of that is down to nostalgia.

Phase

Nice, might give that a try, next on my list is Planescape tho

Also

does anyone know of any papers where they measure motion of the earth using the vertical coriolis effect?

I wanna explain it to someone but they keep asking for proof : /

John Rennie

12:08 PM

I think I meant Doomsday rather than JDoom

ACuriousMind

@Phase Are you talking to flat earthers again? :P

Phase

n....no?

I'm actually talking to the Roundies

But most of the time they prove to be just as bad

There I go thinking I'm sharing an interesting fact and suddenly everyone hates me because I implied you don't land exactly where you start, in ideal conditions

I cant find any RIP

Slereah

@Phase Planescape is p. good

Phase

@Slereah ACM recommended it

I'll probably play it after I get back from lectures today but my drawing tablet is also arriving so who knows

Slereah

I'll bet

Most of his avatars are from it

Phase

12:21 PM

That's how I found out about it's existence : P

Slereah

Tip : invest a lot of points in charisma and wisdom

One of the rare game where that's a good idea

Phase

Oh nice

I like talking my way out of stuff

part of the reason FO NV was so fun

@Slereah what does Comoving mean in relativity? Does it just literally mean two frames that wouldn't see each other move?

Slereah

"moving with"

Emilio Pisanty

@SigmaAlpha I just don't know of any real reason why anyone would learn classical field theory other than just gearing up to do QFT.

but maybe you can set me to rights

Slereah

Comoving coordinates are coordinates in the FRW metric such that galaxies are at rest

@EmilioPisanty Electromagnetism is classical field theory

John Rennie

12:28 PM

@Phase in what context?

Phase

Idk, just any? I figure that for special relativity two frames are instantaneously comoving if they have the same instantaneous velocity, and that you can use that describe acceleration, but in an expanding universe would two continually comoving objects need to be accelerating against expansion?

John Rennie

When using the FLRW metric we generally use coordinates in which everything is stationary and the proper distance between points changes with time. These are called comoving coordinates because they move along with the expansion.

Phase

oh ok

John Rennie

In this metric comoving observers have zero proper acceleration i.e. they are all in free fall

Phase

So if you have a volume of space

John Rennie

12:31 PM

This is why it's often said that distant galaxies aren't really moving away from us but instead the space between them and us is expanding.

Phase

where the only forces particles in the space are subject to are inertial

then they're comoving?

Or is it just that the zero proper acceleration is a consequence of it, rather than a part of it's definition

John Rennie

I think the term comoving would generally mean that the coordinate distnce between the observers involved is constant.

That isn't necessarily the same as the proper distance. In any case it depends on your choice of coordinates - objects that are comoving in one set of coordinates are not necessarily comoving in a different set of coordinates.

Phase

In SR, is comoving just literally two frames that move with the same velocity?

John Rennie

I'm not sure the term has a precise definition, but yes in SR I'd interpret it as having the same velocity.

Phase

nice

thanks

Balarka Sen

12:37 PM

Why would Kim Jong-un insult me by calling me "old," when I would NEVER call him "short and fat?" Oh well, I try so hard to be his friend - and maybe someday that will happen!

Tweeted by realDonaldTrump on November 12, 2017 at 12:48 AM

Emilio Pisanty

@Slereah sure, but I've never seen it studied in a larger framework that could also be used to study, say, classical $\phi^4$ theory

Balarka Sen

... clap. clap. clap.

Phase

What a lad.

Slereah

Scalar field theory is useful for like

Fluid mechanics

Phase

as comically missuited to politics as he may be

I feel like the media dogpile him unnecessarily 99.999% of the time

Emilio Pisanty

12:40 PM

@Slereah sure. Now show me a textbook that just does classical field theory as such.

John Rennie

@Phase Much if not most of the authority of a head of state depends on the respect in which they are held. That's why most heads of state don't behave like truculent teenagers.

Slereah

@EmilioPisanty I would but I really hate MHD

Actually

I think I have one

Yes, there it is

"Exact solutions and scalar fields in gravity"

Balarka Sen

Why would WSJ insult me by calling me "a nazi," when I would NEVER call them "fake news" Oh well, I try so hard to be their friend - and maybe someday that will happen!

Tweeted by pewdiepie on November 12, 2017 at 9:49 AM

Phase

Nice.

Emilio Pisanty

@Slereah that's a GR book

Slereah

12:42 PM

yes.

Phase

@BalarkaSen the damn geralt pic too

Slereah

All classical, though

Emilio Pisanty

I guess if the point isn't clear now it's not worth arguing over

Balarka Sen

@Phase It's missing a Viking beard tho

Phase

Why would Jacksepticeye insult me by calling me "a swedish meatball," when I would NEVER call him "green and Irish?" Oh well, I try so hard to be his friend - and maybe someday that will happen!

Tweeted by pewdiepie on November 12, 2017 at 9:19 AM

Balarka Sen

12:45 PM

idubbbz retweeted the realDonald tweet

this is like the next great meme

Make Memes Great Again

Slereah

heh

that book includes string theory modifications to Maxwell's equations

Secret

If there's one thing good about trump, is he is a lot less inaction when it comes to do things, so if any group can nudge him in the right direction, things can happen a lot more efficiently

(ceditability nt guarenteed, as I don't know enough US politics)

ACuriousMind

@Slereah What does that mean?

Slereah

The correction of the form of Maxwell's equations given by string theory?

ACuriousMind

I don't know what sort of corrections "string theory" would make to Maxwell's equations

Slereah

12:59 PM

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