The h Bar

heather

20:00

be right back

Bernard Meurer

Man, this server is fast

Kyle Kanos

@Student404Mus There is no such thing as "relativistic mass"

DanielSank

@KyleKanos some of the older books talk about it.

Actually, I never really understood why that idea has nowadays been abandoned.

Bernard Meurer

@KyleKanos Wrong. My mother says I'm fat and my grandmother says I'm not.

Kyle Kanos

@DanielSank Because if you travel fast enough, you should become a black hole

Student404Mus

20:01

@KyleKanos what is your level?

rob

@KyleKanos I've heard that before, but never computed how fast :-)

Student404Mus

Sorry about that anyway

Kyle Kanos

@Student404Mus Post-graduate

Student404Mus

In physics?

DanielSank

dang

gtg

Kyle Kanos

20:02

@Student404Mus Yes?

Student404Mus

Your domain in physics right?

Kyle Kanos

Yes

Bernard Meurer

This is such a weird conversation

Kyle Kanos

Well, was. I graduated last year, with a PhD in physics, and now work in a non-physics field

Student404Mus

Tli mean the branch you graduated in

Bernard Meurer

20:04

@KyleKanos Is now the CEO of Citibank, Wells Fargo, and Bank of America

Student404Mus

Ok

Bernard Meurer

*and CTO

Kyle Kanos

@BernardMeurer Haha, if only...

Student404Mus

What about statistical mechanics

Bernard Meurer

He's also nostalgic of the 70's baby boom

Student404Mus

20:05

I have another question if u don't mind

Kyle Kanos

@BernardMeurer Wasn't the baby boom in the 40's?

Bernard Meurer

@KyleKanos Not in Brazil :P

Kyle Kanos

@BernardMeurer I'm not in Brazil

Bernard Meurer

@KyleKanos Me neither

Kyle Kanos

@Student404Mus I passed my mandatory classes on it, but it never was my strong suit

rob

20:06

@Student404Mus What's your question?

Student404Mus

If we consider an ultra relativistic particle with energy almost is pc means momentum times light speed...

In quantum statistics of bose Einstein..

koolman

Student404Mus

We write the distribution expression Ni=1/exp(-beta(epsilon_I - mu))

koolman

Why in this question mgcos is not considered in net force

Student404Mus

i mean epsilon_i

Can we ignore mu for this type of particles

i.e ultra relativistic particle?

rob

20:12

@Student404Mus Your mu must have units of energy ... it is chemical potential?

Student404Mus

Yes

That is.

In a short question can we always eliminate mu for ultra relativistic particles?

rob

@Student404Mus You can ignore if it's small compared to the energy epsilon_I :-)

Student404Mus

But as you see its velocity almost the light one

@rob so we can consider it as a photon. Right?

rob

@Student404Mus I admit that I've always been a little shaky on the chemical potential.

Emilio Pisanty

@Qmechanic No, but there's no need to have two identical copies.

Student404Mus

20:19

@rob anyway could you tell me an open website that archives documents of students in physics and it's branches?

rob

@Student404Mus No ideas there either. Sorry.

Student404Mus

No problem.

Bernard Meurer

@rob I have a borderline moral question, are you okay with that?

It's still about science though

rob

@koolman Are you asking about the component of the weight that's parallel to the rod?

koolman

@rob yes

rob

20:21

@koolman That's cancelled exactly by the tension in the rod --- otherwise the rod would stretch or contract as the pendulum swings.

koolman

So net force is mv^2/r

rob

@koolman That's the force along the direction of the rod --- otherwise it wouldn't be moving in a circle about the pivot.

@koolman Net force includes any tangential component, that lets you speed up or slow down.

koolman

Ohk

I got it

@rob thank you

rob

@BernardMeurer Sure, what's on your mind?

@koolman No trouble at all

Bernard Meurer

@rob Today I was studying in the study rooms at university, and in the one I was in were a bunch of people from my year, freshman, and in particular people who have the same schedule as me, so we know each other to a degree

@JohnRennie This is directed at you too now that you joined

rob

20:31

@BernardMeurer Sharing a study room with your classmates is clearly immoral

Glad I could help you :-)

dmckee

We found a student in a study room with classmates. May we burn them?

Bernard Meurer

I was working on my digital systems lab report with my lab mate when a kid from my class started explaining his "theory" to others, which was about how you could go back in time by travelling to another dimension with a wormhole and then back. Which is clearly bullcrap. Other things he said were:

"QC's are faster than classical computers"
"You can go backwards in time by traveling to another dimension using a wormhole"
"A Qubit is 1, 0 or 0&1" (as opposed to properly saying that it's a gradient between 0 and 1.

Now, those are really bad, wrong statements for the most part

John Rennie

Why is it immoral to study with classmates? Is there some in joke I'm missing?

Bernard Meurer

@dmckee This is for you too

But it's none of my business

dmckee

@JohnRennie I think we're just killing (or burning) time until he writes out the issue.

Bernard Meurer

20:33

however I feel like it's immoral to let the guy teach people wrong things when I'm there to help

I intervened and called him out on it, but should I have done that?

rob

but in real life

dmckee

I don't intrude on random conversations in public for such purposes, but you were in the circle.

Bernard Meurer

Should I fight against this kind of spreading of misinformation? Or is it none of my business, even though I knew better to help those he was doing a disservice to?

dmckee

But I try to be diplomatic even if I speak up.

John Rennie

You'll never be able to out-talk the committed fanatic. We have, or rather had, our very own example of this right here in this chat room.

dmckee

20:35

It helps to know enough on the subject to ask them the deep, troubling issues that are current in the field and then talk about the diversity of opinion among the acknowledged experts.

Bernard Meurer

All I said is, quote, "NAME, unless you can show me the maths and consistent theory behind all of this you're saying in a logical way it's as credible and as right as a disney movie man. Rigor cleans the window through which intuition shines"

dmckee

And about the lack of diversity on things that are settled.

But you may be stepping into a tar pit.

So it's a judgement call.

Of course, I'm still waiting for Amazon's to ship me some more judgement. I never seem to have enough.

John Rennie

Talk quietly but with authority, I.e. don't bullshit, and those who really want to learn will listen.

Bernard Meurer

I felt good at first, because I got the people to not blindly believe his crap, but then I felt bad for interrupting someone else

heather

"NP just means complexity is exponential" (::winces::)

Bernard Meurer

20:38

@heather That one almost killed me

Emilio Pisanty

@BernardMeurer there's a certain point at which that stops working with the person themselves

the question there is: is there an audience that I can help inform

heather

hmm, I'm having trouble git pull ing

Bernard Meurer

Wait, my german neighbor needs help with the new box of cigars he just got, brb

rob

A college study room is the ideal place to interrupt a conversation like that, to be honest.

dmckee

^ That's a point.

No better time in life for some serious thrashing out of things.

Kyle Kanos

20:40

@rob That's why I invested in music & headphones

heather

ah, never mind, it worked now

dmckee

@KyleKanos My place has a "quiet" study room (best view in the library, too) if you don't want to listen to that kind of thing.

There is also one reserved for faculty, but I rarely both getting them to let me in because the main one is so nice.

rob

I certainly learned new and interesting things in college at a much faster pace than I properly assimilated them, and explored lots of interesting permutations of those facts and their consequences.

heather

yes! got it to build @DanielSank

rob

... which means that I said some dumb stuff which eventually got corrected

Physics Guy

20:42

BOOH !

rob

but I also made some insightful connections that other people hadn't noticed.

It took conversations with peers for me to figure out which sort of observations were which.

2

dmckee

We could start a "I said some dumb stuff" club. The membership would be self-selected: those who recognize their past failing and might, just might, therefore be open to the possibility of future failings as well.

But would we really want to keep minutes?

rob

item 1: "I can't believe I suggested we start this club"

2

dmckee

::chuckles::

heather

hmm, I have a new problem now

okay, so I cloned my calculus notes file on the linux side of my computer, and opened the main file in texmaker

Emilio Pisanty

20:48

ooooh, hey, btw, now that @rob and @dmckee are both here

heather

except, even though it downloaded the images, it doesn't like them, and I don't know why

Emilio Pisanty

has anti-deuterium been observed?

dmckee

Oh. Oh.

Emilio Pisanty

or anything multi-hadronic

dmckee

Can't recall hearing about it.

Emilio Pisanty

20:49

@dmckee ok, fair enough

rob

@EmilioPisanty STAR found anti 3He and anti 4He --- there was a Nature paper

dmckee

You'd need a reliable anti-neutron beam to start. I think that's been done.

Emilio Pisanty

Alfred Centauri just pointed me to dipositronium and I was mighty surprised

dmckee

@rob And I know I guy who worked on that project, too.

Did we mention saying dumb stuff?

rob

I remember it vividly because the on-paper version of the Nature paper had a botched printing job and didn't make any damn sense. I was so relieved by the erratum.

Emilio Pisanty

20:50

@rob gotcha, that'll be this one english.cas.cn/resources/archive/research_archive/rp2011/201502/…

I imagine anything bigger is out of the question

@rob wait, the... what?

who reads Nature on paper?

this was 2011, right?

not the 1990s

::grin::

rob

@EmilioPisanty I had it sent to my house for a few years. I like reading on paper.

Emilio Pisanty

@rob no, to be fair, that's a plenty reasonable course of action

dmckee

@EmilioPisanty You can get a rough idea of how quickly the cross-section (in heavy ion collisions) drops just by comparing the number of He-4s to He-3s in the STAR paper.

Emilio Pisanty

I'm considering a subscription to nature phys

dmckee

Maybe the LHC has enough luminosity to find a few slightly heavier things, but it is certainly a diminishing returns approach.

Emilio Pisanty

20:53

@dmckee is it exclusively a cross-section issue, though?

or mightn't you have issues gathering and selecting them and whatnot

rob

@dmckee I doubt it. There isn't anything stable with mass 5, and lithium is fragile.

dmckee

@EmilioPisanty Well, effective cross-section.

Emilio Pisanty

I guess cross-section completely dominates

@rob yeah, you kinda want to make it to carbon, right?

dmckee

@rob Doesn't have to be stable. Just needs a half-life comparable to the time to travel through one radiation-length of detector. More or less.

Emilio Pisanty

@dmckee I'm mostly interested in stables

as in

stable nuclei

not

you know

horses n stuff

rob

20:55

@dmckee Mass 5 minimum width is 0.5 MeV ...

Emilio Pisanty

But nuclear decay lifetimes might make a nice testbed for matter/antimatter asymmetry

dmckee

Well. Yeah. But none of those are actually long-lived in the detector environment. Too much ordinary matter. But I agree things that are nominally stable are better.

rob

@EmilioPisanty There's anti-tritium, presumably.

Emilio Pisanty

@rob sure, but you already have helium there

I guess the driving question is - how crazy is it to think of an anti-molecule

rob

@EmilioPisanty Yeah, I noticed that comment by you earlier.

Emilio Pisanty

20:57

di-antihydrogen sounds reasonable, I guess

but could you at least make something heteronuclear?

$\mathrm{\bar{Li}\:\bar{H}}$, maybe?

rob

@EmilioPisanty My thoughts exactly: no higher than anti-hydrogen, which is boring-looking in bulk.

Emilio Pisanty

@rob nah, forget about how it looks like in bulk

but could you run molecular spectroscopy on it?

heather

maybe do I need to put the directory they are in?

Emilio Pisanty

probably not that interesting, since you can get much more valuable data from precision antihydrogen spectroscopy

dmckee

Related: nature.com/nphys/journal/v7/n7/pdf/nphys2025.pdf

and: ncbi.nlm.nih.gov/pubmed/16090392

Emilio Pisanty

21:00

@dmckee yeah, I remember that

dmckee

@EmilioPisanty Anti-H-2 is probably your best bet for that.

Just cool the heck out of a anti-H beam.

And hope you can prove it.

Radio excitation of molecular states, I guess.

Emilio Pisanty

@dmckee molecular and atomic hydrogen are way different spectroscopically

the challenge'll most probably be getting enough of the stuff to get anything measurable

but once you do there'll be plenty of unique signatures

dmckee

Yeah. But you want to the gentlest possible touch to not disrupt the system as it is forming.

Because you're going to have to do this in beam.

Emilio Pisanty

sure

well, yeah, I guess, and if you're doing spectroscopy then you probably want some nice long just-under-cw probe

so that might actually take a nontrivial amount of time you don't have between making them and them hitting a wall

dmckee

Yikes. I hadn't notice that I can't steer them!

Emilio Pisanty

21:05

I guess I'm kinda spoiled by attosecond spectroscopy where you can have your experiment be over in well under a picosecond and still get valuable spectroscopy

dmckee

Maybe anti-H_2^- ions?

Emilio Pisanty

@dmckee yeah, that's not a bad thought at all

put them in an ion trap, maybe?

dmckee

@EmilioPisanty I saw some talks on that while I was at KSU. Very cool stuff.

Kyle Kanos

Well that was a good game, OSU vs Mich

Emilio Pisanty

@dmckee oh, yeah, you mentioned you had a stint in Manhattan

I can't find the exact reference, but I thought it was pretty funny. "ATTO is the leading conference on attosecond physics. It has been held in Dresden, Manhattan, Sapporo and Paris."

It looks harmless enough, until you realize that if it had been in Manhattan NY then it would probably say New York City instead

though maybe @dmckee will defend KSU as a more lively place than NYC? ;-P

rob

21:13

Maybe they're all place names which are more famous elsewhere. I used to have family in Paris, Kentucky

Dresden, Ohio

heather

21:25

@BernardMeurer, is it worth it to customize chromium? I was reading this website and it said that I can "build" chromium myself.

Emilio Pisanty

@rob hah, could be

dmckee

@EmilioPisanty I actually got roped into driving an invited speaker from that conference back to the airport in Kansas City (I was going that way anyway, so it only took me about twenty miles out of my way).

heather

the website was this: androidcentral.com/…

dmckee

Nice guy. Wish I had time to really dig into the subject.

But no, The Little Apple is not really a happ'in place. And that made me a happy person.

Emilio Pisanty

@dmckee you call it the little apple?

lol

dmckee

21:28

I like to live near enough to serious cities to take advantage of the art museums, and what not without having to live in them.

@EmilioPisanty There is even a sign on the interstate put up by the city using that phase.

Emilio Pisanty

@dmckee what serious cities are near manhattan?

heather

kansas city has a great art museum

dmckee

None. Really.

Kanasas City is two hours away.

Topeka is only an hour but it doesn't really count as serious.

heather

wait, where is this, exactly?

Emilio Pisanty

@heather Manhattan, Kansas

dmckee

21:30

@heather Several, but you are probably thinking of the Nelson-Atkins.

Which is indeed a very nice museum.

heather

@dmckee, yep, I went to the Nelson-Atkins

dmckee

Not only is it nice, but the main exhibits are free.

DanielSank

@heather define "doesn't like"

dmckee

Compared to the cost of admittance at the Chicago Art Institute that is outstanding.

heather

@DanielSank it gives an error saying file not found

Emilio Pisanty

21:32

@dmckee there's actually an associate professor spot open on the KSU atto group, my supervisor was pushing me to apply

but if the nearest big city is KS at two hours away, it's not for me

dmckee

But The Art Institute has a superb impressionist collection.

heather

@dmckee, yeah, we were in KC for the weekend because I had a rock climbing competition, so we went to the nelson-atkins and the WWI museum, it was fabulous

dmckee

@EmilioPisanty Sorry to hear that. Manhattan is nicer than a town of 70,000 people in the middle of the prairie has any right to be, but ...

... it is still a town of 70,000 in the middle of the prairie.

Emilio Pisanty

@dmckee the smallest city I've lived in is Berlin

by a pretty wide margin

heather

how about iowa? ISU is a pretty great university, so's university of iowa and university of northern iowa

sorry, iowa state university is the first

dmckee

21:34

Yikes. I liked on the outskirts of Chicago for a year and that we close enough for me.

heather

(because I'm not pro-iowa at all =P)

Emilio Pisanty

@heather KSU is relevant for me because Chii-Dong Lin is there, along with a strong attophysics / strong-field physics group

dmckee

Grew up near San Antonio, which is the biggest place that I've ever felt comfortable.

DanielSank

@heather You're a competitive rock climber?

dmckee

At the time around 3/4 of a million people.

heather

21:35

@DanielSank, yes? I'm not super good, but yeah, I compete.

It's super fun =)

Emilio Pisanty

@dmckee I was in San Antonio for the APS March meeting last year

dmckee

@EmilioPisanty I thought I hated that place. Until I moved away. Now I get why visitors usually like it.

Emilio Pisanty

though to be honest I spent most of my time in the conference centre

dmckee

@EmilioPisanty Once you reach the hotel, every conference is in Cleveland...

Emilio Pisanty

@dmckee goodness, yes

the APS meeting was a whole other level, though

50 parallel sessions at any given time

pretty intimidating tbh

DanielSank

21:39

@heather Cool. Sounds fun.

@dmckee I was surprised at how bad the food was there. I must have gone to all the wrong places.

@EmilioPisanty It's a madhouse. You can't even go to all the superconducting qubit sessions anymore because they overlap.

dmckee

@EmilioPisanty I took three undergrads to the April meeting in Baltimore a couple of years ago. I tried to talk them into some regional meeting because that place is a zoo, but Kris insisted.

They. Were. Stunned.

rob

@EmilioPisanty Literally fifty??

Emilio Pisanty

@rob literally fifty

dmckee

@DanielSank I haven't lived there in twenty year, so I can't say for sure, but I still visit and there are good places to eat.

Emilio Pisanty

it thins out a bit to maybe forty at the very end

heather

21:41

geesh

too many people

dmckee

All three of the students came away from that conference with a whole different attitude about what constituted hard work and doing well in their classes.

2

rob

Wow. April meetings are usually about a dozen parallel sessions. Even if all the parallel sessions are sparsely attended, that's an awful lot of people.

dmckee

I'd love to get all of my students to a conference like that, but there is not way in hell.

heather

I visited NYC once, we got stuck in traffic

in iowa, my idea of getting stuck in traffic is waiting 15 extra minutes, max

i wondered if we were ever going to get out =P

dmckee

@rob There were 18 room in Baltimore. And usually circa 16 in use. But I've heard from other people who go to the March meeting.

Emilio Pisanty

21:43

@rob meetings.aps.org/Meeting/MAR15/APS_epitome

A1 through A53

dmckee

@heather My wife and I like to joke about it being rush hour and maybe taking twenty whole minutes to get across town.

DanielSank

@rob Dude, one year I remember the local cafes ran out of pastries.

Emilio Pisanty

B1 through B53

repeat

dmckee

That is a joke we've carried with us from Tuscaloosa through Manhattan, KS and to Joplin.

heather

@dmckee, exactly, that's what its like in iowa =)

Emilio Pisanty

21:44

@dmckee what, like a school trip to the heart of the jungle? yeah, that sounds like a no.

heather

and then I go to NYC and I'm like geesh, how do you live like this?

DanielSank

@heather Driving a car in NYC is often a mistake.

The public transit is fantastic though.

heather

yeah, the subway was much better

DanielSank

@heather You take the subway :-)

Emilio Pisanty

@heather I can introduce you to plenty of people with three-hour-plus commutes back home

heather

21:45

@EmilioPisanty, !!!!

DanielSank

@EmilioPisanty :-(

Emilio Pisanty

well, ok, three hours for a regular commute is maybe a bit too much

heather

my dad's got a 10-15 minute commute

Emilio Pisanty

two hours on a daily basis, 2.30 if its bad

DanielSank

@EmilioPisanty That wouldn't leave much time for working.

heather

21:46

!!!!

2 HOURS!?

that's nuts!

Emilio Pisanty

@DanielSank well, you do what you can with what you've got

DanielSank

^ True

Emilio Pisanty

my mom does have students with 3h+ commutes each way

on public transport

heather

::shivers::

DanielSank

Each way? I guess they do their homework?

Emilio Pisanty

21:47

probably bus>bus>metro>bus

@DanielSank you read as much as you can

heather

@DanielSank, that long, I could do my homework, take a nap, review for a test, do some coding, and finish my book =P

DanielSank

Why not just sleep at school at that point?

heather

and that's just on the way there

Emilio Pisanty

writing on a mexico city bus is a non-starter

even on the metro it's not really that much there

DanielSank

@heather Yes well, no need to boast about it.

:P

heather

21:48

@DanielSank oh, it wasn't meant as boasting, i was just joking that that was a long time =)

DanielSank

I know. I was teasing you.

heather

oh, okay =)

Emilio Pisanty

these are people of extremely limited economic means, generally the first in their families to go to college

DanielSank

I understand. It's just that with so much transit time I wonder at what point it's better to sleep in the library or overoccupy an apartment.

I guess the rent must just be that much higher in the city.

Emilio Pisanty

@DanielSank it's complicated

dmckee

21:56

^ It always is.

heather

@DanielSank, DHMO and meow-mix on mathematics chat kindly read through my calculus notes - let's just say there are more than a few errors =/ plus all the other issues already raised

github.com/physicsnerd/calculus-notes/issues/6

^the 6th issue has all the notes they raised

DanielSank

Heh. Note that those are largely saying to be more precise.

Balance precision against clarity.

It's easy to write very precise but very unreadable math exposition.

dmckee

^ That.

And easy to sacrifice important precision in the hopes of clarity.

::sigh::

DanielSank

Yeah. Writing is hard.

heather

22:16

ah, well, clarity is my primary goal, but I do want it to be applicable, so. I'll keep working on it =)

dmckee

Writing is a process. You write something, see how well it works, think it over then go back and revise it.

Sure, eventually stuff has to go out the door, but even that doesn't mean you've actually come to the end. Check the edition numbers on your textbooks.

If it important, you'll be looking at it again sometime. That's when you make it better.

DanielSank

"An author never finishes a book. They eventually abandon it."

heather

thank you for the advice.

Sir Cumference

23:20

Howdy

heather

@SirCumference, hello

rob

23:51

Is there a known bug where the post previewer tries to update continuously, rather than doing the LaTeX preview every few seconds?

3

Q: Formulas are flickering in the preview as I type

When I typing my post MathJax re-render the preview after each key press, leading to an annoying flicker in the preview area as I'm typing. When there are lots of formulas it also slows down the entire thing making my characters appear in the editing window with a noticeable delay as it renders. ...

Transcript for