The h Bar

bolbteppa

17:00

You mean a random unfunded 'thesis' with some person with no qualification just work on a project?

Slereah

I mean, I already have a master degree :p

bolbteppa

Taught masters or research masters?

Captain Bohemian

@Slereah you mean to get a PhD position your master thesis has to be a topic which has many offers in PhD postions?

Slereah

Get a funded thesis from a university while not being currently part of that university

ACuriousMind

@bolbteppa He means getting a PhD position while not currently enrolled in a masters degree.

@bolbteppa That distinction doesn't really exist in Europe

bolbteppa

17:02

What is the usual procedure, be enrolled in a masters and get a phd offer?

Slereah

yeah

often you just continue what you did for your master thesis

ACuriousMind

Typically your master's advisor knows someone who knows someone... :P

bolbteppa

Ah haha

vzn

@Slereah cool, hes into interpretations o_O whats your take on RQM? lots of refs to RQM in here (quitie a few by you) but not sure how many are Relativistic QM vs Relational arxiv.org/abs/quant-ph/9609002

Slereah

@vzn shoo shoo

4

bolbteppa

17:03

Honestly, there are no rules here, it's a vicious fight and the only rule is to survive

Slereah

I'll go get me knife

bolbteppa

The stakes are completely, scarily, different to undergrad/masters for getting a place

Slereah

I know, look at me now!

This is what happens when you don't get the thesis

Also I think I'm looking at the wrong time because the 2018 thesis are done

Gotta wait more for the end of the year for the 2019 thesis

vzn

@Slereah thx for ref gotta do a physics + ML blog soon with various links, have you seen this? think youd like it

Jul 26 at 1:09, by danielunderwood

hmmm https://arxiv.org/abs/1803.08823

bolbteppa

Two paths I'd say: one is to send e-mails with results + vague proposal to these guys now asking if it would be possible to apply, second path is prep for the huge wave of applications that will open in the next 3 months and send 30 to multiple countries, send e-mails asking the people can you apply to them or would they consider the application you sent in

Slereah

17:07

Well it's probably best to do both, really

Quite often nobody takes the thesis and they are just put up again next year

bolbteppa

Another is ask your undergrad/masters project advisors if they have any recommendations on what to do, who to apply to

Slereah

Oh man

That dude was not very good at like

office politics

part of the problem, rly

bolbteppa

Another is go to every big uni page and look at the offers, you'd be surprised at the ones they put up

Slereah

yeah that is what I'm doing rn

Gonna try to look at all the interesting ones

Try to read up a bit on the bibliography

Captain Bohemian

@bolbteppa making a proposal is necessary? That's very difficult if you don't know a field sufficient enough.

bolbteppa

17:09

Another is a self-funded research masters in a place that offers it, or offer to do one etc

Slereah

and send them a letter

I don't think self-funded research is allowed here

bolbteppa

Vague proposal

Slereah

that was why I couldn't get mine

I had a PhD topic, just no funding

bolbteppa

(Lots of people go abroad for phds for experience + offers)

Slereah

One thing that is unfortunate is that Nguyen, the guy at the local university who did QFT stuff, moved away

I totally wanted to do a thesis with that guy

@bolbteppa Well I just bought a house

4

bolbteppa

17:10

Another idea is GRE and US applications :p

Slereah

a bit awkward!

vzn

@bolbteppa re "here", it would be great if you clarified that somehow/ someday, ie where

Slereah

I'd rather not be in the US when it collapses :p

bolbteppa

Yeah this is a real fight + sacrifice

Slereah

More Europe / Canada

Captain Bohemian

17:11

@bolbteppa why is vauge proposal? I once sent a mail to a professor telling him I want to do research with him about quaternion-Kahler geometry though I don't know much about that, but he replied me he has no position to offer and he is currently not doing that topic now.

bolbteppa

@Slereah I'd say you'd get one from that list alone tbh edpif.org/en/recrutement/prop.php#view13

Slereah

yeah I found a few interesting looking ones

The hard part is getting picked

Secret

vzn: I don't think Slereah can see you

Slereah

Oh I can

Secret

he does not see me either

bolbteppa

17:13

@CaptainBohemian that's probably what you'll get most of the time, all you need is one, usually web pages say when they have potential offers, even worse, they will offer but funding is not certain so it's a fight

Slereah

But I'm not having a conversation with @vzn

Semiclassical

"can see" != "willing to interact with"

vzn

@Secret join the ghost club dont be afraid :P still waiting for you to follow up on misc physics ideas also :P

Secret

secret just got pwned

Semiclassical

unlike in QM, you can observe others here without interacting with them :P

vzn

17:13

@Slereah ?!? dont know how got on the ignore list, hard to keep track around here :( :P

Slereah

HE KNOWS WHAT HE DID

Secret

@vzn Don't worry, at the current rate of political degeneration by Trump, ghosting will die once earth reached the Hothouse state

Captain Bohemian

@bolbteppa USA application is very money consuming.

vzn

@Slereah responded to your misc p**** joke(s)? guilty, hang him :P

Semiclassical

@bolbteppa hmm, following up on what we were discussing earlier: One should have $J^+=J_1^+ + J_2^+$ annihilating $|00\rangle$

Secret

17:16

anyway <insert huge paragraph of hate speech that will be censored>, thus I am going to maths check to do some maths. Also this conversation is interesting, I don't want to derail it

vzn

@Secret dude, "chin up!" self esteem check :P yeah have been looking elsewhere myself for engaging conversations on SE, feel like turning up emptyhanded more often :(

Semiclassical

Is that enough to ensure that the probability amplitudes are equal in magnitude but alternating in sign?

bolbteppa

Hmm... the thing about the alternating signs is your argument has to generalize to 3j symbols as well, that requires a separate argument to why the amplitudes are the same I think

Does Shankar give this stuff?

Semiclassical

this kind of stuff is in shankar, yeah, though he doesn't do 3j stuff

Secret

vzn: Will reply to that later as anything I said in respond to that will contain extreme hate speech. and I seriously don't want to derail the conversation here because it is so interesting

ACuriousMind

17:18

@Slereah There's your mistake. If you want to do academia, don't settle down until you got tenure! :P

bolbteppa

It's one thing to be interested in an offer, it's another to get an offer, and another thing to accept it, and the people you apply to go on the assumption that you might not take it and are ready for it, so you actually have a bit of freedom to apply and see what one works out

Secret

Do Germany still have tenure systems?

ACuriousMind

@Secret Sure.

Secret

cool, so I am still up to date on academia knowledge

Captain Bohemian

@bolbteppa is there such kind of website? On websites only funded PhD positions are posted. Nonfunded positions are probably not counted as positions, but who can afford them?

ACuriousMind

17:19

It's getting even worse because more and more non-tenured positions are additionally only getting rather short time-limited contracts these days.

And there's some kind of weird incentive structure that means that universities won't renew the same contracts more than a few times

vzn

← enjoys very much "derailing" conversations... just like riding a 18 gear bicycle :P

Semiclassical

I think the only kind of tenure track position I'd be willing to pursue nowadays would be at a liberal arts college, working with undergrads

Secret

well, guess that's the trend for the whole job industry really. Here in Australia, very few PhDs made it to professors and a lot more graduates cannot find any jobs in 6 months

bolbteppa

@CaptainBohemian the thing is with the non-funded ones, you have to ask if there's a chance, e.g. internal funding one could apply to, so then you give it a go, which is why multiple applications are vital

Semiclassical

and I'm not sure even that would be the right fit for me

ACuriousMind

17:21

@Semiclassical So, what'cha gonna do? Postdoc positions for the rest of your life? :P

Semiclassical

f*** if I know

bolbteppa

Another thing which I know people have done is take an unfunded one and hope funding will come up

haha

Craziness

Semiclassical

I think academia as an institution is just kind of f'd up these days

bolbteppa

inspirehep.net/collection/Jobs

vzn

@ACuriousMind internet chat :P

ACuriousMind

17:23

@Semiclassical It is, but too many are more than willing to submit to it for there to be any strong pressure for change.

Semiclassical

@ACuriousMind yep

bolbteppa

@Slereah Here: inspirehep.net/…

vzn

@Semiclassical why sour? did you have some kind of bad experience? seems like it went smoothly to Phd from everything youve said in here

Secret

@ACuriousMind I wonder if that has something to do with academia competition becoming more fierce in recent years, as well how no German Unis have subscription to Esivier anymore

Semiclassical

as long as grad students are a commodity, uni's will use them

@vzn tbh it's probably a lot of sour grapes, reflecting the fact that (for various reasons) I don't consider myself suited to academic research as a profession

which is frustrating, since I do very much enjoy research as an activity

Slereah

17:25

Didn't know inspirehep did thesis proposals

Semiclassical

and the teaching/learning/communicating involved

bolbteppa

Now you're an insider :p

Semiclassical

but research as a career is different

Slereah

Though considering the deadlines

I think what I said :p

vzn

@Semiclassical a phd is academic research. think its ok to change your mind about life goals, academia can be darwinian/ brutal place at times as this conversation is pointing out...

Slereah

17:25

Better to wait like

october

right now everything is over

bolbteppa

The ones that come up now are more likely to have funding but more sparse/random

Semiclassical

given that I've gone through a phd, I've got a pretty good idea of the difference between a research as an activity and research as a career. they're not the same

bolbteppa

How so

Semiclassical

you only have to justify research 'as an activity' to yourself.

you have to justify 'research as a career' to institutions and the community

Slereah

Well yeah but a boring job as a career, you have to justify to yourself

and it's a lot harder!

vzn

17:30

the system involves humans and is imperfect. surprise! :P

ACuriousMind

@Slereah So get a fun job! :P

Secret

I wish the day where jobs to survive is a thing in the past...

Slereah

I also tried!

Semiclassical

@ACuriousMind get a satisfying job that gives you reasonable compensation

vzn

"fun job" ← often an oxymoron :(

Slereah

17:31

Not a lot of jobs at the puppy petting factory

ACuriousMind

@vzn Your sarcasm reflects precisely the kind of attitude that lets bad situations fester. Of course perfection is unattainable, but does that mean we can't do better?

Secret

<Insert democratic socialism proposal here>, thus no more need to work to survive

vzn

@ACuriousMind (ouch) :( did not see it as sarcasm really. am all for improving life, strive for that myself :)

John Rennie

I worked for a decade or so at a large company that I eventually left because it stopped being fun, but then worked at a number of small companies that gave me much less job security but much more fun. The decade at a big company built up enough savings that I felt comfortable taking the risk.

Secret

I also like small companies. They are less rigid in the way they do things

Semiclassical

17:34

i think one thing i'm tired of with academia is the sense that "your research defines your life"

John Rennie

If you find a small company that's growing fast you get the opportunity to really make a difference.

Secret

Large companies tend to get locked in routines and hence harder to have new ideas

despite being more secure

Semiclassical

i'd much rather have a career that gives me the scope to define my life outside of it as I see fit

Secret

I prefer to do "freestyle research". that is research absolutely anything you like without need to care about yielding results to someone else

John Rennie

On one occasion I and the head programmer discussed an idea in the bar ona Friday night (until about 1 a.m. :-) then worked all weekend and had it implemented by Monday morning. There's a terrific sense of accomplishment when you can do that.

vzn

17:36

(lol) lets all figure out to get MBI (Min Basic Income) installed, am sure it could happen somewhere on earth in only a few decades :)

Semiclassical

@Secret yeah

Secret

In fact, I once asked my chemistry professional association, and they said my description sounds like something between a research consultant and a project manager

John Rennie

@Secret that's an option if you're already rich ...

Keep these mind

@Secret But why would anyone (except perhaps for a philosophy department) pay you to do that?

Secret

yeah, it is always money...

In fact, I don't like spending money so much that, some of the programs I am using are build from source code instead of downloading their comercial license

I think I will soon find a way to bypass the need of money if I push my head hard enough

then I will be able to do anything I like without being ultrarich

danielunderwood

17:39

Does anyone do academic research as a side activity and have a career that's outside of academia? Or is that not really a thing?

Semiclassical

I think it’s tough to sustain that

Secret

Industry with academia linkages are pretty common, there are many consultant agents shared in a career talk how they go back and forth and keep publishing to keep the door to academia open

bolbteppa

Having a boss < < < < < < < having no boss

Secret

"put one's leg against the door of academia to prevent it from shutting" they say

Semiclassical

it depends on the industry you’re in

Keep these mind

17:41

@danielunderwood Einstein

John Rennie

@Secret I think the reality is that those people are attractive to academia because of their contacts and potential for funding.

@Keepthesemind that was a very different era. I think it would be much harder now.

Semiclassical

If you’re not working in that context, then I think the only way to sustain a credible independent research hobby would be to have prior connections in the area

vzn

@danielunderwood yes have been doing that for years but its indeed rare :) :|

Secret

@JohnRennie They are also attractive because companies often stumble upon interesting fundamental problems that otherwise not seen in academia settings, and companies won't have enough time and resources to understand them in detail as they have products to deliver to clients, thus they send those problems to academia. Industry and academia is kinda a mutual system nowadays

Keep these mind

There are plenty of people who pursue, eg, PhDs while working 'commercially'. Generally takes a bit more time to finish, but still.

John Rennie

17:44

@Secret colour me unconvinced. From my experience of both sides of the divide what academia wants from industry is funding.

vzn

@Secret its called roughly "industrial research" and yes is still widespread but maybe off its heyday...

ACuriousMind

@danielunderwood Between the job and reading papers to keep up to date, there's realistically no way you're going to have any kind of life outside of that

@JohnRennie Also works with a large company if you get into the right place :P

danielunderwood

How many papers do people in research typically read?

bolbteppa

Inspire stuff is not really in France, that huge list is all France, also that list should update for next year probably by/after? Christmas

ACuriousMind

@danielunderwood As many as they humanly can, in my experience :P

Keep these mind

17:46

@ACuriousMind I'm not sure they asked for a money-making job, research, and a life.

John Rennie

@ACuriousMind your fairy godmother has been working overtime then :-)

ACuriousMind

@Keepthesemind Ah, well, undeath is nice, too

vzn

← lol wonder if fairy godmother split at birth :P

@Secret google is probably the 800lb gorilla example of this.

Captain Bohemian

@danielunderwood I recently saw a physics faculty website listing a person with name and picture with the title voluntary collaborator.

I wonder how he finances himself.

Keep these mind

@CaptainBohemian Probably with a job.

Slereah

18:01

is that how they call interns now

Captain Bohemian

@Keepthesemind but I feel it's very difficult to have a job and do research work at the same time. I feel very awkward at multitasking.

vzn

unpaid work, the pinnacle of capitalism o_O

Keep these mind

@CaptainBohemian Not if your well-paying job doesn't take much effort, intellectually or otherwise.

vzn

@Keepthesemind lol who has one of those...

Captain Bohemian

I know a person who is also a volunteering researcher in Hasselt and his financing source is depression aid from Netherlandish government.

Keep these mind

18:05

@CaptainBohemian That's brilliant. Also: 'Dutch', not 'Netherlandish'.

Secret

Well, I guess funding is still the major motivator, but my chemistry seminars have gave examples like developing a hair product that ends up triggering AFM investigation in some hydrogen bonding of those molecules. Perhaps those are still rare in comparision
(I will get back to you with the link later, cause the details of that past seminar is in my notebook which is in my office)

bolbteppa

Can arrange that list by the green lights

ACuriousMind

@Keepthesemind I'm doubtful that having severe enough depression to be on financial aid is adequately characterized as "brilliant".

bolbteppa

'The physics of myelin and myelination' awesome

Anonymous

@ACuriousMind Well, something like "depression aid" existing is 'brilliant'. Not all countries offer such a thing :)

Anonymous

18:12

Also, the fact that the aid amount is sufficient for research, is quite surprising

Captain Bohemian

I don't think a depressor in my country can get that kind of aid from the government.

Keep these mind

@ACuriousMind And I am doubtful that the Dutch government sponsors research in Hasselt (Belgium) to help against depression of the researcher.

Captain Bohemian

He gets the aid enough for him for basic living and the needed medical treatment; his research doesn't require any extra money, I think, because it's theoretical research.

@Keepthesemind no, his nationality is Hollands, but he goes to Belgium to do research.

Anonymous

@CaptainBohemian Same here! BTW small nitpick: It's "depressive" not "depressor" afaik :)

ACuriousMind

@Keepthesemind I don't think that's the claim here. I think the claim is that the aid simply enables him to spend what effort he can on voluntary research instead of making money. Then again, any other form of social security income would fulfill the same function.

Keep these mind

18:16

@CaptainBohemian Yes, but I would assume that he receives 'benefits' or some 'allowance' no matter what. IMO, there cannot be any requirement for him to do research to receive it.

Captain Bohemian

he originally had a postdoctoral position in Hollands, but lost it due to lack of funding, then after some search, he found a professor in Hasselt agrees to let him help her research without funding.

Keep these mind

I think we all agree.

Captain Bohemian

@ACuriousMind well, I think that depression aid is given to him whether he wants to do voluntary research; it's give him due to his depression.

ACuriousMind

4 mins ago, by Keep these mind

I think we all agree.

Physics Meta

0

Q: Physics' updated site theme is ready for testing!

As part of implementing the new unified themes across the network, we're gradually rolling out updated site themes for each site. As of today, we have enabled your updated site theme for testing. If you can't see it right now, that's by design! We're hoping to get feedback from you before rolli...

Captain Bohemian

18:25

I have once heard from eavesdrops someday in a supermarket that some people talked about someone (probably their friend) in Hollands having depression gets fixed money every month from Nethelandish government enough for living and the Nethelandish government levies very high tax.

Keep these mind

@CaptainBohemian You shouldn't eavesdrop.

Anonymous

@Keepthesemind Really? :P

Captain Bohemian

@Keepthesemind I didn't hear stealthily. That sat near me and talked so loudly that I can hear them naturally.

Anonymous

@CaptainBohemian Well, that's not "eavesdropping" then :P

Anonymous

Nothing illegal

Keep these mind

18:31

Well, then you used the word 'eavesdrop' incorrectly.

Also, which supermarket are we talking about here?

Captain Bohemian

@Blue eavesdrops isn't something done by stealth.

Keep these mind

@CaptainBohemian "Eavesdropping is secretly or stealthily listening to the private conversation or communications of others without their consent"

Captain Bohemian

well, I think my situation is also counted as eavesdrop.

Anonymous

@Keepthesemind The "without their consent" part seems redundant. You can't possibly "secretly" listen to a conversation with their permission. ;)

Captain Bohemian

they didn't perceive that I was listening to their conversation.

Keep these mind

18:38

Why don't you two figure it out amongst yourselves? I have some video tapes to return.

Captain Bohemian

when I am listening to strangers' conversation, I never let them perceive that I am obviously listening because that looks very impolite.

Anonymous

@CaptainBohemian The fact that they spoke loud enough, that any passer-by could listen to them, makes it evident that their conversation wasn't something they necessarily wanted to keep "secret" or "private". Anyhow, "private", "secret" are all pretty vague terms and probably not worth our time to even try to make clear demarcations!

Anonymous

This was some good procrastination for me though. Should prolly get back to work XD

vzn

lol this seems to be approaching lexicology. or like trying to define insider information/ trading...

Captain Bohemian

18:54

@Keepthesemind Wellcome. We have supermarkets everywhere and some have chairs and tables for customers to sit.

bolbteppa

Print off a paper, read every line, tick each line you're happy with it, skip around/go nuts on bad sentences, and you zoom through it, life lessons

Secret

I have met two kinds of people: One kind which will not care if you are listening near them, and one kind will say they are having a private discussion and basically tells you to move away in a very rude bureaucractic robotic way

vzn

← sometimes worries about secret o_O

Anonymous

@Secret lolol

Secret

I have negative tolerance to any perceived estrangement, if I encounter them enough in a small room, I will want that whole room of people to die

why are people so inefficient. Can they save all that estrangement and pretentious c888 for something more meaningful?

vzn

18:59

some things not so funny these days dailymail.co.uk/news/article-6101729/…

Anonymous

From my observations, some people tend to give off the gullibility vibes, and they're supposedly easier to shoo off, compared to those who don't.

Captain Bohemian

@Secret I don't particularly like to listen to eavesdropping from the street because they are mostly boring. I usually hear them due to the impossibility of avoidance because they really speak too loudly. You know ears, unlike eyes, can't be closed.

Secret

@CaptainBohemian Well, most of those conversations are really slice of life, and I am neutral towards them

vzn

← works in 21st century ~~sweat shop~~ open office now & dislikes/ cringes over loud talkers, alas friendly one sits feet behind me, doesnt get the hint

Captain Bohemian

well, when I am thinking about physics problems, I would feel those who speak too loudly near me so annoying.

Anonymous

19:09

I live on the first floor of our building. There used to be a middle-aged guy in the 4th floor who used to converse with his driver (who normally loitered in the parking area).....via shouting! All the residents were very relieved when he left the flat, for good :P

Anonymous

@CaptainBohemian Yeah, that is annoying

Captain Bohemian

@Blue there is a person living in the building next to my room who often talks on phone in the balcony. His sound is so loud that I can hear very clearly. I could even know he is an undergraduate student from his conversation though I have never seen him. His talking on phone is often disturbingly loudly.

vzn

@Blue re that, actually this is not well remembered (& quite to the contrary picture of corporations with a conscience) but the 5-day work week can be seen as partly resulting from widespread labor/ union strikes in the 20th century generally against oppressive conditions esp wrt modern standards...

Captain Bohemian

besides speaking on phone disturbingly loudly, he also often smokes in the balcony with the second smoke drifting into my room; it's really annoyingly stinky.

Anonymous

@CaptainBohemian Go and confront them (if you have the patience i.e.)! :P

Anonymous

19:22

@vzn The union strikes thing....yeah, it does make sense!

bolbteppa

@Slereah first 20 pages of Scherk basically written up linearly no jumps of logic except the no ghost theorem and covariance of quantization and skipped lightcone stuff overleaf.com/read/bntchqsfhgnq

If you want to explain his way of doing no ghost and covariance that would be great ;)

3

Q: Spinors on algebraic plane curves

I'm interested in parameterizing spinors on Riemann surfaces. For my purposes, it's best to represent the Riemann surfaces as immersed in $\mathbb{C}P^2$, i.e. as algebraic plane curves. Apparently, mapping the Riemann surface to $\mathbb{R}^3$ via immersion is equivalent to equipping the RS with...

spinors algebraic-geometry

What is this madness

Emilio Pisanty

19:54

FYI, it turns out "...because I haven't figured out whether he would be my brother-in-law or not" does NOT qualify as a "reason why these two should not be wed."

hmmmm

that's failing to onebox

Munroe was born speaking the wrong language

concuño

Noun: concuño m (plural concuños, feminine concuña, feminine plural concuñas)

Alternative spelling of concuñado...

Slereah

@bolbteppa thx

Emilio Pisanty

also while we're here

my comment section worries me

►

danielunderwood

I just found a blog post about website security on a website that has broken SSL...hmmm

Emilio Pisanty

@danielunderwood is it hackyourselffirst?

(hack-yourself-first.com)

vzn

xkcd discovers family tree / "human family" en.wikipedia.org/wiki/Family_tree

danielunderwood

20:08

Oh neat I think I saw a website lack that a while back like that if it's one that's meant to be open to attacks. But it was redotheweb.com. Maybe he wants to redo SSL too

Novalium Company

khanacademy.org/science/physics/… This thing only works if we consider the target charge with a small charge or the two main source charges static, like they are pinned down, otherwise, if the charge of the target charge was big, it would effect the source charges, and also, the sources charges must be like pinned down, otherwise they will effect each other and that will cause problems?

danielunderwood

Although it looks like the blog isn't really maintained anymore, so maybe it's just an old cert

Captain Bohemian

how to find the publications of a person in Inspire Hep if this person's name is common? When I key in the name, there are thousands of publications of people with similar names.

danielunderwood

@EmilioPisanty wow I wonder how many of his youtube comments he actually reads and how they haven't driven him insane

Captain Bohemian

I mean entering the name in inspirehep.net/?ln=en

Emilio Pisanty

20:13

@danielunderwood to be completely honest I didn't get it until the reveal, I thought it was just a jokey way to say his brother got married

... but what I didn't do was to then go on to inflict that stupid interpretation on the rest of internetdom

Sir Cumference

My blood boils when textbooks don't write arrows over the vectors or bold them

Emilio Pisanty

@SirCumference learn to live with that.

danielunderwood

The end was just him saying that it was his wife's sister. But who knows how many ridiculous comments he read other than those

And I don't think I've ever seen a book that didn't do either unless it was talking about tensors

Emilio Pisanty

boiling blood is bad for you. Notation like $x\in \mathbb R^3$ is not.

Sir Cumference

@EmilioPisanty shivers

danielunderwood

20:16

I will say that $x^2$ messed with me for a solid couple of weeks

Sir Cumference

It's just kind of inconvenient when I can't immediately look at a letter and know it's a vector

Emilio Pisanty

In fact, it is an inevitable fact of daily maths once you get past a certain point.

Sir Cumference

@EmilioPisanty Sigh

Emilio Pisanty

@SirCumference what if it is a vector... in a vector space... whose elements are actually functions?

Sir Cumference

@EmilioPisanty You're not going to convince me that this textbook is rational :P

Emilio Pisanty

20:19

@SirCumference you're fighting to swim upstream against a very strong current

seriously

danielunderwood

Then it's a ket because obviously QM is the only places such vector spaces exist!

Emilio Pisanty

take any mathematician's-perspective textbook on linear algebra

Sir Cumference

Yeah I know. I had a math textbook on linear algebra and hated the lack of vector hats

But now I'm seeing physics books with that

danielunderwood

Wait if you have a vector space with vectors that can be parameterized, is that technically a vector space of functions? Like having $x(t)$

Emilio Pisanty

treat it like baked beans when you're living in England

Sir Cumference

20:22

I thought physicists were keen on keeping vector hats, hell they even write $\vec{\nabla}$ sometimes

Emilio Pisanty

you can either learn to live with it, and lead a contented life

or keep on hating it and be miserable for no real reason

Sir Cumference

I know ;-;

Emilio Pisanty

@SirCumference depends on the context

Sir Cumference

@EmilioPisanty Is it ever justified?

Emilio Pisanty

yes.

danielunderwood

20:24

@EmilioPisanty is there something wrong with baked beans in England?

Emilio Pisanty

@danielunderwood wrong question

"is there ever anything actually right with baked beans?"

No.
Absolutely not.
Why are you even asking that?

is more like it

baked beans are an abomination

... which, nevertheless, one must make one's peace with, if one wants to live in the UK and not be miserable.

danielunderwood

They're a pretty common food here. Every summer cookout has them

Though I do question how much sugar people like to put in them for some strange reason

Emilio Pisanty

@danielunderwood yeah, I understand that Brits are not the only people whose childhoods left them culinarily damaged enough to think that baked beans are reasonable food

danielunderwood

So how do you eat beans?

well not physically how, but how the beans are prepared

Emilio Pisanty

any way that doesn't involve ketchup?

or sugar, more generally

danielunderwood

20:33

Yeah I'll give you that one. We have some sort of sugar problem over here

user2236

Diabetes is an epidemic.

danielunderwood

I feel like we have a bunch of kids getting addicted to soda from the sugar and caffeine and people haven't really noticed it

Well adults as well

user2236

> The “Diabesity” epidemic (obesity and type 2 diabetes) is likely to be the biggest epidemic in human history.

Novalium Company

Guys, when we have one negative and one positive charge, the biggerthe distance between them, the more potential energy. If they start attracting and get close to each other, they will lose potential energy and convert is into kinetic?

danielunderwood

If you just had an electric interaction. Really some of the energy will be converted to radiation and go into fields

Novalium Company

20:48

Ok, but I'm not trying to understand that. I don't know why but it confuses me, when we have two positive charges, when they are close to each other they will have high potential energy, and when we release them, they will repel and some of that potential energy will be converted into kinetic. What's the case with a positive and negative?

bolbteppa

The Coulomb force between them is F ~ 1/r, the smaller r is, the larger F is pushing them away from each other

danielunderwood

If you wanted to look at an attractive 1/r potential without the complication of magnetism, you could look at Newtonian gravity

Novalium Company

I just want to know how the potential and kinetic energy increases/decreases as the distance between a positive and negative charge increases/decreases.

As far as my understanding goes, when we have one positive and one negative charge, as they get far apart, their potential energy increases and decreases when they get close to each other?

bolbteppa

The closer they are, the larger the force pushing them away from one another will be, implying the 'potential' for the charges to move is larger the closer they are

Novalium Company

Thanks, but I was wondering about positive and negative charges? (1 pos. and 1 neg.)?

bolbteppa

21:00

Novalium Company

Does that mean that when we have one positive and one negative charge, when they get closer to each other, the potential energy will increase?

So it is complicated to determine what happens with the potential energy in an attractive charge system?

Anonymous

@NovaliumCompany As far as potential energy is concerned, you have $$\text{Potential Energy $(A_+,B_-)$} = \frac{kQ_AQ_B}{r}$$, where $A$ is your positively charged particle and $B$ is your negatively charged particle. Since $Q_A$ and $Q_B$ will have opposite signs, the potential energy is negative. Also, notice the $r$ is the denominator (it denotes the distance between the particles).

Anonymous

So, as they get closer, $r$ decreases and the potential energy decreases in "magnitude", but increases overall (if you consider the sign).

bolbteppa

Oh wait, F ~ 1/r^2, U ~ 1/r

Anonymous

@NovaliumCompany Increase in the sense that $-1>-2$. But decrease in the sense that $|-1|<|-2|$.

danielunderwood

21:07

But note as they start to move, you'll have a current and electrostatics no longer applies

Though as long as they're moving fairly slow, it won't be a huge difference

Novalium Company

@Blue Thanks, I like to get into count the sign, so as they get closer and closer, their potential energy will increase?

enumaris

cool beans

Anonymous

6 mins ago, by Blue

So, as they get closer, $r$ decreases and the potential energy decreases in "magnitude", but increases overall (if you consider the sign).

Anonymous

Sorry, I made a silly error here.

Anonymous

If $r$ decreases, the magnitude of potential energy should increase in magnitude

Anonymous

21:12

Because say $1/0.5>1/2$

Anonymous

@NovaliumCompany So if you count the sign, then it decreases

Anonymous

So basically the statement is: "As two oppositely charged particles get closer the potential energy of the system decreases." :P

Novalium Company

Pff, this "decreases in "magnitude", but increases overall (if you consider the sign)" confuses me. I like to think of numbers this way: 3, 2, 1, 0, -1, -2, -3, and it will increase like this -3, -2, this is increasing. Sorry, it's midnight, my mind is overloading as always :D

Anonymous

Same here :P

Novalium Company

It makes sense to decrease (in my way), meaning, will go down and down in the scale (e.g -3 to -4 to -5...). That is the decreasing you mean, right? (not in magnitute)

Anonymous

21:17

@NovaliumCompany Exactly

Anonymous

Yes, I'm including sign

Novalium Company

@Blue Cool, thanks. How is uni going?

Anonymous

Remember as a rule of thumb that potential always tends to decrease for spontaneous processes (i.e. those which tend to happen by themselves). For example, opposite charges tend to move closer to each other by themselves....so that's sort of a spontaneous process and potential energy tends to decrease for the system as a whole

Anonymous

You must have heard the statement "nature tends to minimize potential energy" several times over ;)

Novalium Company

Yep, also repeling of charges happens by itself, so again, decreasing. Ok, I better go to bed, my eyes are closing by themselves, meaning my eyes experience decrease in potential energy xD Goodnight.

Anonymous

21:20

@NovaliumCompany Three days holiday for the time-being (including Monday), yay! Getting some rest finally :D

Anonymous

@NovaliumCompany That's correct. But if you push together opposite charges that's something which you are doing by force and thus potential energy will increase!

Novalium Company

It makes sense for the universe to tend to minimize it's potential energy, because potential energy just means that it can do work, so why not do it, nothing is stopping it. This means that we live in a hard-working universe :D Ah, it's really late... what am I talking about... Goodnight everybud :-3

Anonymous

Tbh I don't really know the entire process of how minimization of potential energy mathematically arises from the basic axioms of classical mechanics (or for that matter quantum mechanics)

Anonymous

@NovaliumCompany Goodnight!

Anonymous

21:37

Hmm, I'm confused now. Is minimization of potential energy a statistical phenomenon?

Anonymous

27

Q: Why does a system try to minimize potential energy?

In mechanics problems, especially one-dimensional ones, we talk about how a particle goes in a direction to minimize potential energy. This is easy to see when we use cartesian coordinates: For example, $-\frac{dU}{dx}=F$ (or in the multidimensional case, the gradient), so the force will go in th...

newtonian-mechanics lagrangian-formalism potential-energy

Anonymous

Or is it just due to $\vec{F} = -\nabla U$ (i.e. by definition)?

Anonymous

(Or maybe they're both equivalent....which seems possible)

Anonymous

@trysis Why the model exists is "because it fits the data", that is the only reason that a model exists. Physics does not answer ultimate "whys", and this is not a question that can be answered within physics. We have defined the potential energy so as to fulfill the law of conservation of energy and the result is that systems tend to minimized potential energy by construction, within the theory. It is a tautology. Because we have observed it, we construct the model. — anna v May 18 '14 at 18:47

Anonymous

Hmm, so my question boils down to: "Potential energy tends to be minimized by construction. Explain how" I'm not very clear on the "how" part yet :/

enumaris

21:54

meh, the "minimize potential energy" thing has never held much appeal to me

just solve the equations of motion

or the equations of state

The principle of stationary action is much more of a principle (and much more precise and well defined) than "things tend to minimize potential energy"

after all, if you look at an elliptic orbit, the potential energy is constantly fluctuating from higher to lower then back to higher again.

and to first approximation that motion carries on forever

Anonymous

@enumaris Sure, but the very fact that we observe the latter to be true in many instances demands an explanation...and why so

Anonymous

It surely is necessary to be clearly able to demarcate which situations follow the observed principle and which do not

enumaris

You can explain it individually in each case you see it's true by applying the equations of motion

If you truly want to do some sort of "demarcation" then you have to actually rigorously defined the principle. What's your rigorous definition of "things tend to move to lower (potential) energy states"?

Anonymous

I'm looking for a generalization though. I can solve most differential equations numerically by plugging them into mathematica but that doesn't mean mathematicians should stop studying "classes" of DE's ;)

enumaris

Well I guess if you can provide a rigorous definition and then find some utility in the principle, that's all well and good.

I haven't found any to date.

Anonymous

22:03

@enumaris It's more like I'm trying to find a precise definition. Maybe I should ask this on the main site. And where is @ACuriousMind when you need him!

enumaris

22:18

ask it :D

Transcript for