The h Bar

0celóñe7

12:00 AM

@Blue I was perfectly fine with graduate level QM and basic GR

Reading the books I've told you to read

And Susskind's lectures

Anonymous

I see. Seems like the same case with Balarka

Anonymous

That's because you didn't have to spend years learning advanced Chemistry and Physics :)

heather

oh, come on...

0celóñe7

@Blue I never said one of us is smarter.

heather

i just found the answer to the problem, and it says

0celóñe7

12:01 AM

@heather what

dmckee

@heather You can get it using the velocity form. You just have to figure out how fast the head and the feet are traveling so you can use the proper $v$ for each $r$.

heather

> centripetal force is directly proportional to radial distance from the hub. At half the radial distance, the $g$ force will be half that at his feet.

Anonymous

@0celóñe7 I was just thinking about the differences...not comparing man

Anonymous

I'll probably be more of an applied physicist than a mathematical physicist anyway

dmckee

@heather Which is correct, but unless they told you that explicitly somewhere using it for an answert is a bit of a cop-out.

0celóñe7

12:03 AM

@Blue I know, which ties in to my earlier "You're never going to know all that I know, and vice-versa"

heather

@dmckee, welp, at least i know now.

0celóñe7

@Blue Why are you learning analysis then?

dmckee

To convince yourself using the $v^2/r$ form note that tangential velocity is proportional to radius to. Because the size of the circle traveled in one cycle is proportional to radius.

Anonymous

@0celóñe7 Heh. I might need it someday

0celóñe7

@Blue I think that a course on general topology is better for general mathematical maturity.

Anonymous

12:04 AM

(Most importantly it's in my syllabus)

heather

@dmckee right...

0celóñe7

It's less fussy

Anonymous

@0celóñe7 I'll take it next year perhaps

0celóñe7

@Blue A serious suggestion: springer.com/us/book/9783540258308 chapters 0-7 after your single variable class

Anonymous

@0celóñe7 Okay. I'll check!

0celóñe7

12:06 AM

@dmckee tips on seasoning a cast iron pan?

was gonna try southernliving.com/food/how-to/…

heather

i think arnold is over my head @0celóñe7

0celóñe7

@heather I was afraid of that, but he really does explain this stuff well

maybe when you're a grad student

heather

yeah.

perhaps i'll ask a new resource-recommendation question.

anyway, what's your math recommendation list @0celóñe7?

dmckee

@0celóñe7 That's about what I do. Cook Country recommends letting the sahortning sit a while then wiping off any excess before baking.

skullpatrol

12:22 AM

How's the baby? @dmckee

and, of course, the proud new parents :-)

dmckee

The baby is growing well, but feeling needy and doesn't want to be put down. The parents are sleepy.

Bernardo Meurer

I am now in the same room as @DanielSank, we're taking over the hbar soon

Anonymous

Hey!

Anonymous

@BernardoMeurer

Bernardo Meurer

@Blue Heya

Anonymous

12:28 AM

How's new college going on? :)

DanielSank

Hey, @BernardoMeurer, get back to work!

heather

@BernardoMeurer hello!

how have you been?

Anonymous

Lol, are you guys in the same room and chatting via hbar? :'D

DanielSank

This bar is now the property of the Santa Barbara usership.

2

@Blue No, that would be silly.

Bernardo Meurer

Yep

DanielSank

12:29 AM

>.>

traitor

2

Bernardo Meurer

@heather Been good, just getting settled

@DanielSank I don't have a job

DanielSank

Our conquest begins with the star board.

9

heather

done.

0celóñe7

@BernardoMeurer Michelle is going to be a day late

where are you

DanielSank

@0celóñe7 He's in my apartment.

Bernardo Meurer

12:31 AM

@0celóñe7 in CA

I actually have no classes this week

heather

@DanielSank: uber-introductory highschool-level classical-mechanics book - what would you recommend?

Bernardo Meurer

When's Michelle heading there?

0celóñe7

why are you not with michelle then?

Bernardo Meurer

Dunno

0celóñe7

@BernardoMeurer she's 100 miles away

Bernardo Meurer

12:31 AM

Huh

DanielSank

Ha, I have six on the star board. Is that a record? Where's my prize? @dmckee?

Bernardo Meurer

She's in LA?

DanielSank

What are the mods doing if not giving out star-prizes!?

Bernardo Meurer

I thought she was in SF

0celóñe7

@BernardoMeurer d(LA,Knoxville) >> 100 mi

Bernardo Meurer

12:32 AM

Yes, I agree

heather

@DanielSank all hail the rulers of the hbar! Planck himself salutes you!

DanielSank

Holy cow, really? From the grave?

Amazing.

0celóñe7

@DanielSank he is only 50% dead

DanielSank

lol

skullpatrol

What about the 2pi? @heather

dmckee

12:34 AM

@DanielSank That's a lot, but we have some users who will star anything so I doubt it is a record. On the prize front I can probably stretch to a a gold star sticker.

Get it? Get it?

0celóñe7

no

@BernardoMeurer you know this was your chance to get Shankar and meet bob

Bernardo Meurer

@0celóñe7 I know. I'll text M

0celóñe7

@BernardoMeurer about?

heather

@skullpatrol ?

Bernardo Meurer

@0celóñe7 Where is she?

0celóñe7

12:35 AM

@BernardoMeurer 100 mi away!

In TN somewhere

skullpatrol

The "bar" in hbar @heather

0celóñe7

@heather hbar is Dirac's constant, actually

heather

@0celóñe7 yeah, well.

dirac and planck both salute you @DanielSank

DanielSank

@dmckee Yes I get it.

skullpatrol

Yeah, like the Euler constant is actually gauss's

DanielSank

12:38 AM

@heather Dirac, eh?

Good chap.

heather

@DanielSank direc? never heard of him.

0celóñe7

Dirac's ghostwriter brother

heather

@skullpatrol $h$ is planck's constant; hbar is $h/2\pi$

not really comparable.

$\hbar$ is a form of $h$

DanielSank

Bernardo in his happy place, with an FPGA dev board.

Bernardo Meurer

Long live Xilinx!

0celóñe7

12:40 AM

@dmckee I wrapped the pan in foil and placed it upside down. I figured putting the foil on another rack would make a terrible mess as stuff drips down. Do you think the limited airflow will ruin it?

@BernardoMeurer Do you need a GTX 1080 for that thing

I'm thinking about upgrading

Bernardo Meurer

@0celóñe7 If you offer me a GPU I'll take it. I want to break some hashes

0celóñe7

@BernardoMeurer it can be yours for $550

skullpatrol

That's like saying circumference is a form of radius @heather

Bernardo Meurer

@0celóñe7 Thanks, I'll code my FPGA

skullpatrol

C = 2pi*r @heather right?

0celóñe7

12:44 AM

@skullpatrol did you assume the metric of my space?

heather

@skullpatrol yes

dmckee

@0celóñe7 Don't know. You're burning the shortening down to leave mostly carbon-rich stuff by combining oxygen with the hydrogen in the fat and carrying the water away. SO I suppose you need some access to air.

0celóñe7

@dmckee It's certainly not airtight...

dmckee

Only one way to find out, I guess.

0celóñe7

@dmckee ...look at it when it's done?

dmckee

12:46 AM

You can always scrub off the residue of a failure and try again.

Well, that and cook on it.

0celóñe7

@dmckee Never used one at home, not sure what to expect

I was going to make sausage on it for breakfast

skullpatrol

Cbar = C/(2pi) = r

C

€ the euro is a double bar

0celóñe7

$\bar C=r$

nice theorem

Secret

Multipath contributions to quantum interference being constrained under new experiments using phthocyanin molecular beams

Anonymous

@skullpatrol wut

skullpatrol

12:54 AM

C = 2pi*r

Anonymous

I'm asking about the euro

skullpatrol

It has two bars in it.

Anonymous

That's not an overline bar

skullpatrol

(2pi)^2

0celóñe7

@skullpatrol illuminati confirmed?

heather

12:58 AM

good night =)

skullpatrol

"C bar equals r" has a nice ring to it.

Cya @heather

Workin on it @0celóñe7

0celóñe7

@skullpatrol don't say in chat when you have

they'll do things to you

skullpatrol

True dat, pal.

The terminator bots are watchin

Anonymous

I need to print the text in a pdf without the background colors. Any idea how to do it?

Anonymous

This pdf

0celóñe7

1:06 AM

copy it by hand

Anonymous

heh

Anonymous

My hand is not a printer

0celóñe7

what time is it in India

Anonymous

6:37 am

0celóñe7

seems to be early for an Indian in the chat

lol

Anonymous

1:07 AM

I woke up at 3 am

0celóñe7

ever heard of going back to sleep?

Anonymous

Got college in few hours

Anonymous

Can't sleep now

0celóñe7

@heather bookmarking for later

@BalarkaSen Galois theory might be the first interesting bit of algebra I've learned

skullpatrol

1:33 AM

0

Q: Was Selma Lagerlöf a Nazi supporter?

While reading about Selma Lagerlöf online, I was somewhat surprised to learn the following fact: At the start of World War II, she sent her Nobel Prize medal and gold medal from the Swedish Academy to the government of Finland to help raise money to fight the Soviet Union. The Finnish governm...

I think they're skating on "thin ice" with a title like that.

But then again, even Mohammad Ali threw his Olympic gold medal in the Mississippi and football players today sit during the national anthem, so who knows.

micsthepick

1:59 AM

If a metallic object moves perpendicular to a constant magnetic field, I believe that a charge separation is induced, but why?, isn't there no change in magnetic flux?

0celóñe7

2:38 AM

@rob apprently the kids have school monday

I tried to convince their mom that 1st grad/preschool is optional but she didn't buy it

rob

@0celóñe7 Mine have school (4th/6th grades). I'm taking them out.

0celóñe7

@rob Good for you/them

@rob was Vol Hall around back in your day?

rob

2:53 AM

@0celóñe7 Doesn't ring a bell.

skullpatrol

4th/6th grades is the perfect age to witness such an amazing event

Is it amazing?

Have you seen one?

nope

I've seen several eclipses

but not solar eclipses

skullpatrol

3:01 AM

There was a lunar eclipse like 10 days ago

rob

I've seen several lunar eclipses, and two or three partial solar eclipses, but this will be my first totality

John Rennie

3:17 AM

@0celóñe7 That looks a pretty good solution to me :-)

Secret

[A small ramble about politics] I think the issue of politics is very similar to quantum interpretations:

e.g. What socialist called state capitalism may be what conservatives called socialist induced big country

They all identify the same issues, but use different terms to describe it.
Perhaps, like the issue of blind people working out the shape of the elephant, they might be onto the same thing, and that what they said may be either both true or is the same thing in different guise

O, and btw, the more extreme the political position is located in the ends of the spectrum, the generally less receptive they are to the opposing view. That is ok, for that has the effect of maintaining the purity of their worldviews, for they can see things the opposing party did not

and, should things gets too toxic, nature has a way to deal with toxic disruptive worldviews:

3

Q: How are beliefs restricted by an objective reality?

Consider the following belief A human can survive if they don't drink water for 1000 days We knew from biology that this is practically improbable as there are very few people who can survive for 18 days without water (Andreas Mihavecz in 1979). However, there are also beliefs that are unr...

epistemology metaphysics belief

To me, I am my own side. all that matters is as long every worldview don't obstruct The Plan it will be fine

0celóñe7

@JohnRennie you being up means it's time for an SSD benchmark

still crap

oh well

John Rennie

@0celóñe7 another benchmark :-)

0celóñe7

@JohnRennie upon inspection, I think that each benchmark writes ~25GB on the drive

that's why I have an outrageous usage

John Rennie

Remember that SSDs have only a finite life and each time you run a benchmark you use up some of that life ...

0celóñe7

3:32 AM

@JohnRennie what good is that life if I have a lemon?

John Rennie

It's not a fracking lemon! That is the fastest PC I have ever seen!

Emilio Pisanty

@JohnRennie what time is it where you are?

0celóñe7

@JohnRennie I get literally half of the advertised speeds

::runs another benchmark::

help me

John Rennie

@EmilioPisanty 04:30 I couldn't sleep :-(

rob

What are you trying to do with this computer that you're so fixated on disk speed, @0celóñe7?

Emilio Pisanty

3:35 AM

if you're in the UK, surely it can't be reasonable

0celóñe7

@rob Everyone seems to be missing the point

If you buy a Ferrari and for some reason it can only go 85 mph, wouldn't you feel cheated?

John Rennie

@EmilioPisanty I've got a bit of arthritis in my leg (happens to us geriatrics :-) and it flares up sometimes. At the moment it's flaring and it's hard to sleep. Oh well.

0celóñe7

Anything above 85 is "reckless driving" in the states, but so what?

You still want the Ferrari to go fast!

I got the Ferrari of SSDs and it's a Corvette.

John Rennie

It's like you bought a Ferrari and it's 10% slower than your Ferrari owning friends claim their Ferraris go. Would that make you throw your Ferrari away?

rob

So why are you measuring it again and again? Looking hard at your Corvette doesn't change what it is.

0celóñe7

3:37 AM

50% slower.

@rob Because it's highly variable

John Rennie

Anyway, I like Corvettes. I always wanted a Sting Ray but they're collectors items now and way out of my price range.

Sir Cumference

Howdy

John Rennie

Morning

0celóñe7

Trying to pin down the cause

John Rennie

Boot Windows off a USB stick so you can run the benchmark on a minimal system.

0celóñe7

3:39 AM

@JohnRennie I did, same speed.

John Rennie

same speed i.e. more than twice as fast as the (allegedly fast) disk I have here :-)

rob

@0celóñe7 Could be the drive is fine, but some part of the bus connecting it to the motherboard is the bottleneck.

0celóñe7

@rob At one point I saw the advertised speeds.

That is what has got my panties in a twist

rob

@0celóñe7 Okay. What problem are you solving that needs high disk throughput?

0celóñe7

If you're going to ignore everything I said, why bother responding?

rob

3:44 AM

You told me that it used to be fast like the sticker says it should be, and now it's not. You didn't tell me why you especially wanted a fast disk.

0celóñe7

No particular reason

But I'm not getting what I paid for

Doesn't matter if I intend to use it or not

rob

@0celóñe7 So you paid for an especially fast disk for no particular reason, and it's fast but not as fast as it says on the sticker.

0celóñe7

@rob I see what you're trying to do here

@JohnRennie has been trying for a while and has failed

rob

@0celóñe7 I'm trying to see what your endgame is.

0celóñe7

@rob my endgame is to have a good boot time

right now it takes fovever

rob

3:52 AM

One option is that the disk suddenly returns to full speed. That makes you happy, yes?

0celóñe7

yes

well, no

why did it slow down?

there are still questions

rob

Another option is that you discover some setting, tweak it, and it returns to full speed. That's better, right?

Like maybe you put some speed holes in the disk or something.

Speed Holes

►

0celóñe7

Some people are saying that a 50% drop is normal

@JohnRennie Clearly the only solution is to buy another one, yes?

A 1TB one this time

Also upgrade the CPU

Sir Cumference

Quick question. For physics, do industrial/government lab researchers usually work on practical things or theory?

0celóñe7

practical

Sir Cumference

3:55 AM

Yeah, as I guessed...

0celóñe7

ideally things that blow up certain things

Sir Cumference

._.

John Rennie

@SirCumference in industry you work on things that will make money for your company

Sir Cumference

@JohnRennie So, not theory

What about a government lab?

rob

@SirCumference A government lab might have several theory groups, but usually they're chosen to work closely with the experimental groups at that facility.

John Rennie

3:57 AM

I can't comment on government labs as I've never worked in on. They don't really exist in the UK except possibly in certain niches.

Sir Cumference

Astrophysics has really no practical purpose. So if I want to be an astrophysicist, the only path seems to be academia...

rob

@SirCumference It takes more people to do the experimental things, so the experimentalists outnumber the theorists.

John Rennie

@SirCumference Yes

Sir Cumference

@rob So like finding particles, for example?

John Rennie

But don't plan your entire life just yet. When I started at university I wanted to be an academic but ended up in industry and enjoyed it.

rob

3:58 AM

@0celóñe7 So that's a third option. Suppose you discover that the disk has developed some flaw and won't run at full speed any more. What do you do in that case?

0celóñe7

@dmckee It failed miserably

the stuff is rubbing off

John Rennie

You never know how your views will change over the years of doing a degree then a PhD

0celóñe7

tastes quite good

@rob Hari kari

Sir Cumference

@JohnRennie Right. But I'd rather not be midway through a PhD program and then realize I want to do something else instead...

John Rennie

@SirCumference so do your degree first then see how you feel

rob

4:00 AM

@0celóñe7 You wouldn't try to return it if it were defective?

Sir Cumference

@JohnRennie Huh. I was thinking that I have more doors open to me while I'm getting a bachelor's

John Rennie

Well yes, I agree. So do your bachelors and after the four (is it four?) years see if you're still driven to study astrophysics.

0celóñe7

@rob I got the speeds at first

Sir Cumference

@JohnRennie All right. Thanks :)

0celóñe7

and there are multiple people who say a performance drop is normal

idk what to do

John Rennie

4:03 AM

@SirCumference honestly, the degree will be so much fun!

rob

@0celóñe7 How long have you had the thing?

0celóñe7

@rob 2-3 weeks

some people say a performance drop after 8 hours of use is normal

I want to buy a new one to test that

rob

@0celóñe7 Call the manufacturer. Tell them it broke and you want them to send you one that stays fast.

0celóñe7

just run a benchmark for days

@rob won't they say I should format it and try again?

rob

@0celóñe7 Why don't you try that?

0celóñe7

4:06 AM

@rob my computer is in use right now

doing a clean install takes a whole day

rob

@0celóñe7 Like a 24-hour day, or an eight-hour workday?

0celóñe7

like 8 to midnight

and @JohnRennie told me not to put that wear on the drive

rob

@0celóñe7 So four hours?

0celóñe7

@rob 24-8=16

rob

That was the other option, yes.

0celóñe7

4:11 AM

I probably shouldn't worry

a more immediate concern is how much I can put on this shelf after my modiciations

rob

Sheesh.

0celóñe7

@rob what now

rob

@SirCumference So the astrophysics groups I have worked with have had a nuclear physics interest. They talk about element production in supernovae, they do supercomputing fluid dynamics simulations, and they work with experimental nuclear physics folks to identify nuclides whose excitation structure would play a role in r-process and s-process evolution.

Just one example.

Sir Cumference

@rob Okay, but does this necessarily have to have practical applications?

rob

@SirCumference Not as a short-term goal, no.

Sir Cumference

4:17 AM

:39480096 Bad example, hold on

@rob Well actually, their end goal wouldn't predominantly be studying the universe, but rather seeing how to make use of these things?

John Rennie

@0celóñe7 are you tempering a frying pan?

rob

@SirCumference No, the official on-paper end goal can totally be to understand the universe better.

0celóñe7

@JohnRennie yes

it failed, I will have to try again tomorrow

rob

@SirCumference Let me find some examples.

0celóñe7

there wasn't enough air, the oil just cooked

it didn't burn

Sir Cumference

4:21 AM

@rob OK. Thanks btw

0celóñe7

turned into a sludge

John Rennie

There is a really good video showin how to temper a pan on Youtube somewhere

The trick is to use a tiny, tiny amount of oil and keep repeating it to build up the non-stick layer.

rob

Here's the US DOE long-range plan as of 2015

0celóñe7

@JohnRennie I have a feeling I used way too much oil

4:25 AM

@rob Hmm, some people are saying that industrial research is meant to benefit a company. I don't see how an end goal of studying the universe would typically accomplish that.

John Rennie

@0celóñe7 I think this is the one. I used this method and it worked really well. The trick is that you need a really thin film of oil.

0celóñe7

@SirCumference No, it is to please whoever is giving you paychecks.

rob

Astronomy's decadal plan (2010), surely it's been updated since.

John Rennie

Too much oil and it just goes black, sticky and really revolting. I speak from experience :-)

rob

@SirCumference These are plans for the government labs in the US.

0celóñe7

4:26 AM

my kitchen smells like a gas chamber

rob

The government labs, and the universities, are willing to support blue-sky research because it is interesting. Practical applications that arise are seen as a bonus.

Sir Cumference

@rob So are government labs typically research based? It seems like the vast majority of astronomers work in academia.

John Rennie

@SirCumference in industry you have to contribute more to the company's profits than they pay you otherwise what's the point.

rob

Industrial researchers in the private sector tend to have shorter time horizons.

0celóñe7

@JohnRennie So, should I tempt fate now and load this thing with books or not?

rob

4:29 AM

@SirCumference Yes, but many of the academics are grant-funded, and the biggest issuers of grants are government organizations: DOE/NSF for nuclear physics, NSF/NASA for astrophysics

Sir Cumference

@rob I assume those jobs are far more competitive than academia, which itself is already competitive...

John Rennie

@0celóñe7 The post you put in seems a great engineering solution. I'd say go for it.

rob

So the long-range plans put out by the funding agencies are crafted with the help of academics, and shape the sorts of things that academics get funded to do, in addition to the folks who works for government laboratories directly.

John Rennie

But I'd still be inclined to move your screens then deliberately overload the shelf to test it.

rob

It's a pretty complicated ecosystem.

0celóñe7

4:31 AM

@JohnRennie two posts

John Rennie

That looks fine to me.

Columns worked for the Greeks :-)

0celóñe7

I bet the Greeks had better SSD speeds...

John Rennie

That's a good size of coffee mug BTW :-)

0celóñe7

@JohnRennie sarcasm?

it's a normal size mug

John Rennie

It is? I thought it looked like a pint mug ...

Or did you mean that's normal?

0celóñe7

4:35 AM

idk, the large Keurig size fits perfectly in it

John Rennie

Well this is what I use, and it looks about the same size as yours:

And that's a pint mug.

0celóñe7

that looks way bigger

John Rennie

I need a pint of coffee at 4 a.m. :-)

0celóñe7

do we have any books in common?

rob

Goodnight, all

0celóñe7

4:39 AM

@rob night

@JohnRennie do you have Wald

John Rennie

Only as an ebook

To be honest I don't have the time or energy to read deeply into anything these days.

I use Wald, MTW, etc only as reference books when I want to double check something in one of my answers here.

skullpatrol

cya @rob

What happened to your new mouse pad? @JohnRennie

0celóñe7

@JohnRennie I have a ruler

3.75" tall and 3" diameter

John Rennie

@skullpatrol I ate lunch on my desk yesterday, and I didn't want to get food on the new mouse mat so I removed it.

@0celóñe7 give me a mo and I'll measure mine ...

0celóñe7

434 mL?

skullpatrol

4:48 AM

Inches into mL?

0celóñe7

inches^3 to mL

John Rennie

@0celóñe7 Ah, OK, mine is about 4" wide by 3.75" tall (external measurements) so yes it is bigger than yours though not hugely bigger

But standard coffee mugs in the UK are about half that volume, so your mug is still a goodly size by UK standards.

0celóñe7

UK people are small

I'm heading to bed, cheers

skullpatrol

cya

John Rennie

One thing I love about the US is you chaps are sensible about portion sizes.

Goodnight.

0celóñe7

4:53 AM

@JohnRennie you should always take home leftovers!

And if you'be got a big hunger, eat up!

John Rennie

There are no leftovers when I eat :-)

GPhys

Is this good enough for the solar eclipse?

John Rennie

Yes, that'll be fine. Be sure to gaze at the Sun long and hard :-)

GPhys

:)

0celóñe7

Oh fuck, where do I get some eclipse glasses

Wrichik Basu

4:58 AM

You people will be able to see the eclipse, but we in India won't get a view. Please send photos of the eclipse.

John Rennie

@WrichikBasu no eclipse here in the UK :-( The last one was about 20 years ago.

And it was cloudy!
(Cloudy skies in the UK? Who would have believed it?)

Wrichik Basu

@JohnRennie still, with the net, we'll be able to see the eclipse through the eyes of the camera :-)

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