The h Bar

danielunderwood

12:03 AM

Huh I never thought of determinants as functions

Though my linear algebra course was a bit lacking

Semiclassical

12:03 PM

@danielunderwood how easy it is to see the above depends on your definition of the determinant of course

(Also, 12 hours since the last message? wtf)

Slereah

everything is a function

Semiclassical

Not everything is linear tho

I forget which definition of the determinant is the ‘textbook’ one tbh

Anonymous

1:03 PM

@Semiclassical We're setting new records everyday ;)

Anonymous

The h Bar has been comparatively inactive lately tbh

Anonymous

A lot of members have either left or have gotten busy due to jobs/uni

danielunderwood

1:15 PM

Don't worry. We have the huge chat event today lol

Semiclassical

1:30 PM

huzzah

Emilio Pisanty

2:09 PM

And in a classic episode of "@ACuriousMind forgets that Incognito Mode exists",

4

A: Why was my self-answer accepted, and why did I get +5 rep?

You didn't get +5 for the accept - that was just an unrelated upvote today. The answer was accepted by you yourself back on Apr 10 '16 four minutes after you wrote it, as can be seen from the timeline.

Akash. B

3:16 PM

hi

rob

@Akash.B Greetings

Akash. B

@rob wassup?

rob

@Akash.B Oh, just chilling.

Nog Shine

3:50 PM

Greetings to everyone.

ACuriousMind

@EmilioPisanty Oh...right.

enumaris

chat sesh...

ACuriousMind

Well, I guess I could also have just logged out, but apparently I was lazy :P

Anonymous

The chat session begins 🥁🥁🥁

Anonymous

I am acting dumb.

enumaris

3:55 PM

quick, someone say something physics-y

ACuriousMind

@danielunderwood ...you're a GR book?

That raises more questions than it answers.

enumaris

blinks

vzn

Hamilton quaternions exactly 1¾ century old today! maths.tcd.ie/pub/HistMath/People/Hamilton/Quaternions.html

ACuriousMind

And yet, to a Platonist, they have existed forever.

vzn

or rather the bridge graffiti/ defacement by a respected physicist/ scientist is exactly 1¾ century old today lol :P ... which reminds me what does everyone think of the banksy stunt? :P

ACuriousMind

4:11 PM

::sigh::...How many times must we have a flat earth question hit HNQ?

vzn

← +1 lol! :P

@enumaris so did you get your GPU setup working?

danielunderwood

@ACuriousMind I thought we were all books here

ACuriousMind

That's a ridiculous idea

::sound of paper bristling::

enumaris

4:27 PM

@vzn what GpU setup? Are we talking like 2 months ago stuff?

If so, yes, it's works

danielunderwood

I found an interesting new data title "Data Analytics Analyst"

vzn

take a look at the idea of glider guns in life en.wikipedia.org/wiki/Gun_(cellular_automaton) ... one idea is that particles are like 3d gliders. velocity (eg of a glider) is not exactly encoded into the system directly, its an emergent property of the CA update rules. more discussion try chat chat.stackexchange.com/rooms/71/the-h-bar see also en.wikipedia.org/wiki/Digital_physics — vzn 37 secs ago

@enumaris are you using nvidia?

enumaris

yes

1080Ti

ACuriousMind

@vzn Please do not use comments to direct people looking for discussion of non-mainstream physics to this chat room.

vzn

@enumaris cool, so what are you using it for?

John Rennie

4:32 PM

@vzn UR Stephen Wolfram and I claim my five pounds

vzn

@ACuriousMind digital physics isnt nec nonmainstream etc... anyway barely anyone responds to those invitations anyway :|

enumaris

currently, the GPU enhancement is used by my deep spell corrector to clean data :D

vzn

@JohnRennie UR? 5 pounds? sorry not following

ACuriousMind

@vzn In that case, if you cannot tell the difference, err on the side of caution and do not direct people whose question was closed as off-topic here at all.

John Rennie

@vzn UR = you are

Lobby Lud

Lobby Lud is a fictional character created in August 1927 by the Westminster Gazette, a British newspaper, now defunct. The character was used in readers' prize competitions during the summer period. Anonymous employees visited seaside resorts and afterwards wrote down a detailed description of the town they visited, without giving away its name. They also described a person they happened to see that day and declared him to be the "Lobby Lud" of that issue. Readers were given a pass phrase and had to try and guess both the location and the person described by the reporters. Anyone carrying the...

vzn

4:35 PM

@ACuriousMind understand your pov but theres also this "loophole". also the questioner is not proposing any theory etc

> ...specific questions evaluating new theories in the context of established science are usually allowed...

ACuriousMind

@vzn I don't see what that's got to do with your comment. If you think this "loophole" applies to this question, then vote to reopen it! You still shouldn't use comments to give half-answers to closed questions or to invite the asker to chat.

vzn

@ACuriousMind bummer. thought it was constructive. the question will probably be deleted by the roomba at some pt anyway with no answers right, zapping any comments etc? afaik dont have the rep to vote to (re)open. think its 1K or something.

ACuriousMind

It's 3k, same as to vote to close.

vzn

@JohnRennie wolfram has a Phd in physics, maybe some think it should be revoked lol ... from Caltech! same school as Feynman...

John Rennie

He's a new kind of physicist

vzn

4:45 PM

looking at his wikipedia bio, Feynman was on Wolframs thesis committee wow. also Feynman has spoken positively of Fredkins digital physics in Feynmans paper inventing quantum computation... Feynman wrote letter of recommendation of Wolfram for MacArthur grant... Wolfram youngest winner at age 21...

bolbteppa

5:11 PM

@vzn nice spot of the date

danielunderwood

@Blue have you done dynamic learning in that course you're going through?

vzn

@bolbteppa (thx) some ppls main accomplishment drinking beers 1st time (legally) at that age :P

bolbteppa

If we had adopted quaternions, how would we go to higher dimensions :o

danielunderwood

to octonions!

though I really have no idea about them aside from somehow managing to lose associativity

bolbteppa

Have quaternions actually done anything that couldn't be done better otherwise, beyond exist, hmm

Maybe I should say, in physics

You don't need to know what they are in su(2) they are just there as a special case right

If Hamilton was our lord and savior it could potentially have held physics back

danielunderwood

5:26 PM

They're used in 3D graphics for rotation, but that's not really physics

bolbteppa

Physics FAQ: Maxwell and quaternions

►

That guy tried to make a unified theory with quaternions

Anonymous

@danielunderwood .....what is dynamic learning? o_o

ACuriousMind

@danielunderwood There's nothing special about using unit quaternions for that, they're just one of several convenient representations of SO(3),

bolbteppa

Pretty hilarious, his justification iirc came down to something like how cool it was that they square to minus 1 and so you can link this to the invariant interval and how it 'cannot be an accident' etc

Anonymous

Do you mean dynamic programming?

bolbteppa

5:29 PM

Things like this are great examples of how easy it is to get lost in this stuff, how viciously self-critical one must be (hint hint @vzn)

danielunderwood

@ACuriousMind it's not computationally less expensive or anything?

enumaris

quaternionsssss

ACuriousMind

@danielunderwood That's an implementation detail :P

I'm sure you could find different coordinates for SO(3) that do equally well

danielunderwood

@Blue yeah that's my question. It seems kind of like upside-down recursion, but I can't quite get my head around it. Supposedly it's the hardest thing in the course I'm doing and they have much less info on it than any of the other topics

@ACuriousMind something something Euler angles?

speaking of which, are Euler angles something useful to understand? My mechanics professor decided to skip them when we were doing rigid body stuff

Anonymous

I'm now going through part 3 of the course and it's mostly graph theory. The theory part is pretty easy. But the programming exercises are really really hard (but really fun!). You feel like banging your head against the floor.

enumaris

5:32 PM

pretty useful for rotations

Since they are the standard way to describe rotations

Anonymous

@danielunderwood Link? Or could you tell me the lecture number?

danielunderwood

@Blue ahh I think the first course of this sequence doesn't cover graphs unless it's in the last exercise. I'm pretty interested in learning graph algos though

bolbteppa

I wonder how Hamilton's argument for ending up with quaternions could be phrased in the language of representation theory

danielunderwood

coursera.org/learn/algorithmic-toolbox/home/week/5

Like one of the examples is to calculate the Fibonacci sequence starting from the bottom and just doing the sum of two numbers. That makes perfect sense, but it just gets opaque after that

It also has stuff about string edit distance

enumaris

edit distance, fun

Anonymous

5:39 PM

@danielunderwood Oh, so you did mean dynamic "programming"

Anonymous

Yes, DP is well known for being a hard topic :P

Anonymous

And it's popular in interviews

Anonymous

Roughgarden will cover DP in week 3. I'm still stuck in week 2

Anonymous

I should be able to complete the exercises by tonight I think

enumaris

Dynamic programming in the reinforcement learning sense?

Anonymous

5:42 PM

@enumaris I don't know if DP and RL are related

enumaris

It's a tabular reinforcement learning algorithm isn't it?

with planning...

I should prolly reread that reinforcement learning book...

danielunderwood

Well my lecture did say he was interested in planning but named it programming to get funding...so maybe it's related

Also quicksort took me a solid day to wrap my head around. So many swaps

enumaris

Dynamic programming was the first RL algorithm introduced in the RL book lol

it uses boot strapping to better estimate state pay-offs right

and you got a table of possible states

and at any one time you have a full state-value pair for every state

the idea is to let the agent interact to better estimate those state-value pairs and then use DP algorithm to plan the play of the agent

Anonymous

@danielunderwood For any type of sorting refer to the MIT OCW lectures. They're excellent (taught by the CLRS guys)

Anonymous

@enumaris Maybe. I just don't know anything much about RL to make sensible comments :P

enumaris

5:51 PM

I need to get back into writing my RL library...

danielunderwood

Maybe I should just skip the course's intro to dynamic programming and do RL lol

enumaris

lol

DP is admittedly pretty limited in terms of RL

since it's a tabular method

it requires you to generate a table of all possible states

which is impossible for even something like Chess and Go...not to mention more complicated RL problems like LoL

danielunderwood

That's kind of what the lecture seems to do

LoL...League of Legends?

enumaris

yeah

danielunderwood

ew

enumaris

5:59 PM

there's a lot more possible states there

vzn

@bolbteppa lol who is "lost"? (oh now see the video thumbnail)

enumaris

like health of all players, and for a RL agent, even like what parts of the map are revealed vs not revealed

danielunderwood

I have certainly been interested in RL-based game AI though

enumaris

in any case, for modern RL applications, it seems like some sort of function approximator (e.g. a neural net) is necessary

Semiclassical

i'm really tired of getting league of legends ads on Youtube.

bolbteppa

6:01 PM

@vzn

GEM blog 01: The Ultra Conservative Fringe

►

vzn

@bolbteppa we already had this discussion in here, dug up a nice ref, nobody read it. they have major use in some formulations of relativity, etc

Semiclassical

I'm not interested in LOL, kindly **** off

danielunderwood

ad blocking my dude

bolbteppa

GEM Blogs: GEM Unification Rescinded, Official

►

Semiclassical

@danielunderwood yeah, that's probably the productive thing

bolbteppa

6:02 PM

@vzn you don't seem to use any properties of the algebra in relativity

vzn

@bolbteppa lol does he have papers or a blog, prefer to start with written material

danielunderwood

If you're really crazy, you could set up a pi-hole. That's what I have and it seems to kill everything. Even ads on mobile apps

bolbteppa

In QM/QFT you do but it's because of group considerations

vzn

@bolbteppa they are useful for those who use them, some dont use them :P

Semiclassical

@bolbteppa In terms of the Cayley construction, I suppose the logic is "If I do this again, I'll get something non-associative and I don't want to deal with that"

bolbteppa

6:02 PM

world.std.com/~sweetser/quaternions/qindex/qindex.html

'I am rescinding my efforts to unify gravity and EM using quaternions and hypercomplex numbers. The quaternions do the work of EM fine and that part of this work is still of value. The hypercomplex numbers were given the chore of doing gravity. Under a rotation, the square of a hypercomplex number changes. As such, when used in a Lagrangian, angular momentum will not be conserved. Gravity most definitely conserves angular momentum.'

Semiclassical

@danielunderwood I'm not that crazy, but not having mobile ads would be nice

I mean, ads on mobile apps is annoying but I get it

vzn

@bolbteppa try this apparently built out of a Tegmark analysis theworld.com/~sweetser/quaternions/intro/math_structure.pdf just an element of the "math universe"... reminds me of complexity class diagrams from CS complexity theory... similar to list compiled by Aaronson.

Semiclassical

ads which hijack the page you're on while on mobile, however, can kindly GTFO

bolbteppa

I'd like to understand that proof of the 4 division algebras properly

Semiclassical

the higher one goes in the multiverse classification, the less patience I tend to have

vzn

6:07 PM

@bolbteppa did your read any of the site? some excepts (speaking of "viciously self critical"...)

ACuriousMind

@danielunderwood And then one day someone hacks the pi and reroutes all your queries to ads. Forever.

vzn

> I am rescinding my efforts to unify gravity and EM using quaternions and hypercomplex numbers. ... Simply put, all of the work, claims, and even the t-shirt, that touch on hypercomplex numbers are WRONG. I learned a huge amount of real physics anyway. You might also. Good luck in your studies of this flawed work.

danielunderwood

@ACuriousMind well I do seem to get thousands of attempts to my ssh-exposed machine with default pi credentials...hopefully someone doesn't unknowingly expose their pi with default credentials

bolbteppa

You can represent a 4-vector with a 2x2 matrix, it makes sense you could potentially end up with Maxwell's equations and even the Dirac equation in terms of 2 x 2 matrices, the problem is what any of this means, it's just stuff that makes sense put into matrix language as a game

vzn

↑ not the fault of quaternions that he cant personally (figure out way to) make a ToE out of em... tail wagging the dog™...

Semiclassical

6:11 PM

that sounds like the equivalent of "not the fault of legos that you can't personally make a good house out of them"

i mean, if you're sufficiently creative you can do a lot with legos

but there's no particular reason to expect that legos are the right tool for the job

bolbteppa

Lego house :p

vzn

@Semiclassical lol not sure what you mean someone has built a working car out of em Bugatti Chiron! lego.com/en-us/themes/technic/bugatti-chiron/build-for-real ← not the only one! o_O

Semiclassical

for a certain definition of working, yes

bolbteppa

How do you make a lego radiator/heater/fireplace is an issue :p

vzn

> an inept carpenter blames his tools™

bolbteppa

6:15 PM

The problem was, he was trying to say a certain tool was magic that was special to the weird representation of normal things (four-vectors) he took for no reason

ACuriousMind

@bolbteppa Just burn some LEGOs. The fumes'll make you forget it's cold anyway :P

vzn

@bolbteppa theres his problem right there. magical thinking. no tool is magic. except— any sufficiently advanced technology is indistiguishable from magic™ :P

Semiclassical

That doesn't mean that a good carpenter uses the same set of tools as the inept one. It just means that they doesn't waste time blaming them; if they're not sufficient to the task, they pick something else.

bolbteppa

haha

Semiclassical

It's not enough to know how to use a given tool. One has to know what tools are appropriate for what task, and not waste time trying to make a tool fulfill a task it's not suited for.

vzn

6:18 PM

although, legos are close to magic! you can even make grad students out of legos :P legogradstudent.tumblr.com

Semiclassical

yeah but uh

those tend to be pretty depressing

(so, true to actual grad students I guess)

vzn

@Semiclassical lol!

bolbteppa

I vaguely remember that lego grad student thing getting pretty depressing :p

@Semiclassical yeah

Semiclassical

I haven't looked at a lot of them tbh

vzn

@bolbteppa havent looked at it a lot but didnt seem much different than phd comics...

Semiclassical

6:21 PM

mostly because I didn't really want to bum myself out

bolbteppa

I think it's darker haha

vzn

phd comics can be pretty dark...

← surpreme hardcore geek saw the movie

ACuriousMind

PHD comics has punchlines. The lego grad student just has gut punches :P

Semiclassical

LGS lines you up for punches.

vzn

then its very appropriate for this chat room :P

bolbteppa

6:38 PM

1

A: What is kappa symmetry?

Since no other answer has turned up so far, I decided the Lubos Motl's comment is good enough to make a start and I hope he does not mind when I make what he said a CW answer: Be warned, it's a technically very complex thing with limited physical implications. See e.g. [this](Be warned, it's a ...

:(

Emilio Pisanty

@ACuriousMind why would you need to log out, when incognito mode is just a right-click away?

@ACuriousMind so true

I take it that was you in the recent LGS pic about waiting for a job-interview phone call?

@vzn LGS is significantly darker than PhD comics

2

I've been through the entire PhD Comics corpus at one point or another, and I'm pretty sure there wasn't anything this depressing

Green

@EmilioPisanty what's the long name for LGS? I'm always looking for new comics to read.

Emilio Pisanty

@Green Lego Grad Student

Green

@EmilioPisanty thanks.

ACuriousMind

@EmilioPisanty Nope, the hair's all wrong ;)

Emilio Pisanty

6:52 PM

doesn't have a dedicated site last I heard. Posts on various social-media outlets instead.

ACuriousMind

@EmilioPisanty What's this tumblr then?

Emilio Pisanty

@ACuriousMind a social-media outlet?

Semiclassical

PhD comics are basically, well, comic

ACuriousMind

@EmilioPisanty I'm not sure I understand the functional distinction to a dedicated site in this case

Emilio Pisanty

maybe I just don't understand well enough what tumblr is

ACuriousMind

6:53 PM

I...don't think anyone does

Emilio Pisanty

@Semiclassical PhD comics are basically, well, dead nowadays

Semiclassical

True that

But I mean that the strips were intended foremost to be funny

danielunderwood

tumblr seems like people from twitter wanted to blog, but didn't want to put in the effort to write an actual article

or at least that's what I get from it

Semiclassical

It comments on the experience of grad school in order to make jokes about the absurdity

Whereas LGS really isn’t occupied with that

I guess this is just rehashing what ACM said earlier re: punchlines

bolbteppa

7:08 PM

The eerie thing about LGS is the smile on his face in those depressing visuals

danielunderwood

Oh man that HNQ flat earth question...I think I'd just be done if someone said the Earth was flat on a date

Semiclassical

7:26 PM

There’s apparently a guy who regularly stands on a street corner on campus with a The Earth Is Flat sign

danielunderwood

ahh of course

Semiclassical

Not going to pretend I understand the mindset

But it’s out there

danielunderwood

I remember when I first started, I felt I had to be polite and talk to everyone that said "Hey, do you have a minute?"

Yeah I don't really understand it either

Anonymous

It feels so weird that there's just one theoretical computer scientist in India, who works on quantum algorithms/information. Rest are all physicists

Anonymous

Maybe QI isn't quite popular here after all

Anonymous

7:32 PM

(Unlike string theory :P)

Semiclassical

What I find weird is the prevalence of the "spiritual but not religious" category nowadays

invoking God in order to explain natural phenomena seems like such a waste of God :P

danielunderwood

They're religious, but want to feel different

Semiclassical

well, I think there is a distinction

there's an invocation of god or some other spiritual being/matter as some way of explaining mere phenomena in the world. the flat earth mindset is one rather stark example of that

but i'd classify new age stuff like 'the secret' or homeopathy in that vein as well

so invoking spirituality in order to explain or control how nature works

whereas when I think of religion as such I more have in mind invoking god in relation to morality

(not that I'm terribly sympathetic in general to moral systems which say that takes "do X because God says so" either.)

danielunderwood

7:48 PM

Ahh I never really associated it with moral/physical. I always took both to be belief in God or some sort of non-human agent with power over what happens

With spirituality more being towards a different deity than the Christian conception of God

Though I've never really attempted to try to understand much about religion

ACuriousMind

"spiritual but not religious" usually means "I'm not into any organized religion, but I'm not an atheist either", in my experience.

lılostafa

@ACuriousMind it may also mean I don't follow any religion but do believe in something further than the physical dimension of the world and humans

vzn

8:13 PM

@EmilioPisanty point taken... theres an older phd comics character who nearly haunts the venue, "near miss"... pretty dark stuff

Avantgarde

@lılostafa So like, 10 dimensions?

Anonymous

8:49 PM

@lılostafa And I simply avoid thinking of all that lest it cause an ~~identity crisis~~ existential crisis...

Emilio Pisanty

@vzn what, you mean Mike Slackenerny?

phdcomics.com/comics/aboutcomics.php

Semiclassical

9:14 PM

eh. he's got a postdoc in the comic

tbh I'd say he's a light take on that

he's got a wife, a kid, and an academic job

whereas LGS has the grad student wanting despondently to get a call about a career

vzn

@EmilioPisanty think in the movie slackenerny seems to be a very tragic character, showing up at end, almost like a ghost... trapped in a kind of nearly endless academic limbo... maybe less tragic in the strip... movie left out his "sugar mama" part lol phdmovie.com

Semiclassical

yeah, in the strip he ends up staying around so long that they give him a postdoc

Emilio Pisanty

@Semiclassical eventually graduated to a postdoc

Semiclassical

well, yes

vzn

anyway the strips are very similar in spirit/ theme, agree there is some minor )( difference in tone... the profs in phd are rather unempathetic to say the least...

Emilio Pisanty

9:25 PM

I mean, this isn't anywhere near 'dark'

ha, found it!

now that I look at the archives, though, it's kind of confusing

he defended in March 2005, but submitted in 2007?

the US is weird

Semiclassical

Yeah, that’s a bit goofy

Anonymous

@EmilioPisanty ...are they meant to be in chronological order? (just curious, I don't follow that comic series)

Semiclassical

I mean, the characters in PhDC do get stressed out

But there’s not that level of inner turmoil that LGS seems to exhibit

Emilio Pisanty

@Blue phdcomics.com/comics/archive_list.php

Anonymous

Wow, so it begins from the "prospective grad student" and goes on to the "postdoc" stage?

Semiclassical

9:35 PM

Different characters I think

The one we’re talking about was already a long-time phd grad student at the start of the strip iirc

Anonymous

Oh

Emilio Pisanty

exactly

Anonymous

Seems like I just found another way to procrastinate: reading PhD comics :)

Emilio Pisanty

Nameless Grad Student (the protagonist) will almost certainly remain as a PhD student forever

Semiclassical

so It’s not so much a long arc for a single character as a bunch of shorter arcs for the ensemble

Emilio Pisanty

9:38 PM

though he did leave academia for a while

Semiclassical

Well, unless he decides to end the strip

Emilio Pisanty

@Blue and you're only 20 years behind the curve! =P

Anonymous

Better late than never :P

Emilio Pisanty

I mean, now you can binge on 20 years of material

and when you're done with that, it will become painfully obvious just how slow the pace of updates is nowadays, as compared to its heyday

hence

3 hours ago, by Emilio Pisanty

@Semiclassical PhD comics are basically, well, dead nowadays

Semiclassical

The funny thing is that’s not the longest running webcomic out there, even among the ones I follow

(Sluggy Freelance started in August 1997, whereas PhDC was October 1997)

vzn

9:52 PM

seems like both phdcomics + LGS have a lot of what is sometimes called gallows humor. one can argue how "lighthearted" it is... yes LGS at times maybe needs to see a therapist... o_O

depression rates phds insidehighered.com/news/2018/03/06/… nature.com/articles/d41586-018-03803-3 qz.com/547641/…

Emilio Pisanty

@vzn I guess the difference is that PhD Comics sees the gallows are there, from a few hundred meters away, with some lazy guards making some vague motions in that direction

whereas LGS writes with the noose around his neck

Semiclassical

One mines grad school’s absurdities for humor, the other for dread

I mean, part of this is the medium. A comic strip lends itself to humor, given the expressiveness of the medium

Whereas with LEGO you can’t do something as simple as facial expressions

as such, it instead plays that up by contrasting the LEGO face with the internal turmoil

Emilio Pisanty

10:15 PM

@Semiclassical that's pretty harsh

I'd say LGS is simply trying to deal with the otherworldly harshness of grad school by turning up the gallows humor to 11 21

I mean, it just started with the guy getting his thesis completely demolished and needing an outlet

Semiclassical

oof

I guess it’s the fine line between gallows humor and being ghoulish

It’s hard for me to find even gallows humor in that “despondency” one you showed earlier

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