The h Bar

hadsed

00:03

so if a question is migrated, does it keep its upvotes?

Astrum

@hadsed yes, I think so

hadsed

oh ok. my question got 3 upvotes then, but 8 would've been nuts

considering i posted to TCS once and got shitted on

(to be fair it wasn't a great question.. it did much better in normal CS)

Astrum

shitted or shat?

hadsed

lol

Astrum

I never can decide which to use XD

hadsed

00:11

well thanks to you, now im in the same boat :P

Astrum

welcome to the club. shat sounds more natural to me, so I usually stick with that. But in formal settings it's hard to know which to use

hadsed

formal settings.. you are lucky if you can say shat in formal settings

Brandon Enright

I can imagine any of "i posted to TCS once and got {shit, shitted, shat} on" sounding correct

So I looked it up at en.wiktionary.org/wiki/shit

Scroll down to the verb section under "simple past" which says "shit (third-person singular simple present shits, present participle shitting, simple past shit, shitted, or shat, past participle shit, shitted, shat, or shitten)"

hadsed

excellent

Astrum

so, IOW they're all correct?

Brandon Enright

00:24

Yeah it seems they all get used that way.

Astrum

cool

sigh, I need to go and work on a some linear algebra problems

Brandon Enright

This Wiktionary entry is amazingly detailed.

Astrum

wiktionary is really useful for learning another language

better than any "official" dictionary I've found

I just checked, there are even SEs for individual languages

Crazy Buddy

03:18

Soooo... Dear @Brandon has come back :)

Welcome to our chat (You do remember me I guess) :P

Brandon Enright

03:47

@CrazyBuddy hey there

user54412

05:48

@LoganM though I do notice that links in the multicollider have the "hq=1" component, which I always assumed was for (partially) negating that feedback

user54412

not that anyone seems to know what the formula for question "hotness" is

user54412

@BrandonEnright yes welcome back

user54412

you made a grand entrance, complete with dusty light beams :P

Brandon Enright

@ChrisWhite thank you :-)

Yeah not even that great an answer. I'm a bit embarrassed by the attention it got.

user54412

I think my Best Answer Ever is either at +1 or +3 depending on which one I have in mind

user54412

05:52

such is the nature of internet hoards

Brandon Enright

Yeah apparently my answer is one of the 31 best this site has ever seen. I need to find those horses and thank them :-p

Now I understand why there is a 200 rep per day cap. One hoard could really throw things off.

It seems there is a small movement by Dimension10, Dilaton, and maybe others to start up a theoretical physics question site. Interesting.

user54412

I suppose if one has the money (which isn't much), one can always host a website without concern for traffic

Brandon Enright

This site seems like the ideal place for it. I never understood the friction that caused a bunch of people to leave or get frustrated.

user54412

I'm trying to imagine convincing the profs in my department to check out any website - they're too busy doing research to chat about research

Brandon Enright

Yeah plus if they want to answer questions and "make a difference" they can just hold more office hours or do seminars or survey courses.

They're already in an ideal framework (a University) for such things.

Or like Ben Crowell and write a whole bunch of books for students.

user54412

06:01

and if they want to ask questions to stay abreast of current issues, well then they use their grant money to travel to conferences ;)

Brandon Enright

Hey @ChrisWhite, I have a simple question probably too basic to ask on the site. Photons are massless and travel at c so their momentum and energy is proportional to their frequency. For gravitons though... they're massless and travel at c. Do they always have zero energy and momentum? Can their energy vary? Does that mean they'd oscillate in some way?

Or is that what is meant by "we don't have a quantum theory of gravity" because we just have no idea?

user54412

I always thought (travels at c) <=> (E = p) and implicitly that energy could be anything

user54412

which of course it must be, because one can always shift reference frames

Brandon Enright

I thought the point of something traveling at c is that you can't boost to a reference frame where it's traveling at anything but c

user54412

i think the idea of a graviton is pretty well fleshed out by now - it's just a spin-2 particle (ok so that's weird but not unworkable)

Brandon Enright

06:09

although I guess moving your reference frame does change (for light) the observed frequency

user54412

@BrandonEnright exactly - you can change p (=E) by boosting, but not v

Brandon Enright

TBH I don't really have any feel for how a spin-2 particle is any different than a spin-1

user54412

of course I come from the GR camp, not the QFT camp - give me nontrivial metrics over "particles" (whatever those are) any day

user54412

@BrandonEnright Neither do I

Brandon Enright

Hmm well I seem to ask a lot of questions that are probably obvious to folks with a background in QM but I guess this is something I should ask on the site then

user54412

06:14

I can talk about the math, with all these "transforms like a blah blah blah" definitions, but it never seems intuitive

user54412

@Transmissionfrom cc @Arc676 physics.stackexchange.com/q/72656

Brandon Enright

Nice answer ;-)

user54412

06:30

@ManishEarth I'll match your un-commented-on arxiv link: arxiv.org/abs/1311.2558

Astrum

06:44

I need money -_-

user35386

Could use some physics expertise over here: skeptics.stackexchange.com/q/18338/5582

Brandon Enright

06:59

@Articuno It looks pretty clear to me that the flower pot won't help the candles heat the room.

But the question seems to be about efficiency and I don't really see how to define efficient in the context of heating a room with a candle. The candle will output the same total amount of energy regardless of the flower pot.

Astrum

the dailymail, doesn't surprise me that they promote BS

user35386

That's what some answers mentioned... and guessed that they must have meant something else by "efficiency" rather than the technical definition

Brandon Enright

It's conceivable that the flower pot spreads the heat more uniformly but heat is heat. It's 100% efficient at putting heat into the room.

user35386

One comment speculates that having the pot heat up and then radiate heat means more heat stays in the room than if convection simply brought the heat up to the ceiling and then lose it through the roof

Brandon Enright

I don't think it's really the sort of question that can make use of physics expertise. If anything it seems like an engineering question. All that really matters in heating a room is what the occupants feel. Sklivvz's response looking at BTUs and how many candles it would take is spot on.

user35386

07:07

okay that's good then. even just some extra eyes to catch any blatant errors is helpful

Astrum

07:19

@BrandonEnright you solved that wicked hard cube puzzle?

Brandon Enright

Are you referring to the 4D Rubik's cube analog?

Astrum

yeah

that's insane

Brandon Enright

It's wicked intimidating at first but it's not wicked hard.

Astrum

how'd you do it? is there some sort of technique?

Brandon Enright

Yeah like most things, there are some basic techniques or algorithms for finding a technique that can break the problem down into simple steps. In the case of pretty much any "twisty puzzle" like the 3x3x3x3 you borrow a trick from group theory called a "commutator".

Astrum

07:24

commutator?

like in linear algebra? XD

Brandon Enright

Yeah so in group theory, elements in a group don't necessarily commute. So ab may not be the same as ba. If ab == ba then a and b are said to "commute"

Astrum

ah, so it's the same, cool

did you use a computer to help?

Brandon Enright

But if two group elements don't commute then if you to aba'b' where a' is the inverse than the effect of this aba'b' sequence is called the "commutator of a and b"

Well I used a computer in the sense that you can't really see or manipulate a 4D object without one. I also used a computer in that I pre-made a bunch of useful move sequences and then pasted them in whenever I needed them as a macro

But I did not use a computer to find any of the sequences and in principle I could have performed every move click by click rather than recording macros of useful moves

Astrum

I see

Brandon Enright

For twisty puzzle commutators are especially useful because they allow you to build 3-cycles of pieces. Once you can cycle around just one piece type without affecting anything else on the puzzle it's not too hard to solve all of the pieces of that type without affecting anything else

About 2 years ago I made a 2-part video on youtube on how to find nested commutators that would allow you to solve the 3^4. I've been thinking of reprising that video to show how to find shorter, more direct commutators for solving it.

Astrum

07:29

you're talking above my head, i know pretty much nothing about group theory

user35386

do you have any opinions on using feynmanlectures.caltech.edu to learn physics?

Astrum

bad idea

Feynman lectures are great for reading, but bad for learning for the first time

Brandon Enright

@Astrum I have several videos on basic commutators too. I try to avoid too much math theory in my videos so I don't spend a lot of time talking about group elements or multiplication of elements, etc.

Astrum

what's your channel

?

Brandon Enright

@Astrum youtube.com/user/bmenrigh

Twisty puzzles are my primary hobby. They take up most of my time and money.

Astrum

07:37

money?

Brandon Enright

Yeah most "exotic" puzzle designs need to be 3D printed which is a very expensive process. Then, because I'm crazy, I polish the printed parts using a technique I developed which requires a reasonable amount of equipment.

Well I really need to call it a night :-) See ya.

Astrum

alright, see ya

interesting knowing about your obsession with twisty puzzles! =D

ManishEarth

08:21

Its @BrandonEnright! Welcome back!

@ChrisWhite whoa, interesting method

@BrandonEnright "shitten"? I must start using that.

@ChrisWhite yeah, it costs less than ten dollars a month for hosting, and it's not hard to set up a FOSS alternative to SE software (Did that once for the heck of it and had fun)

The larger problem is getting people interested.

And keeping people on board.

@ChrisWhite exactly .

ManishEarth

08:43

@BrandonEnright maybe the feynman diagram is wigglier? But there isn't much of a different iirc. Except for deep theoretical stuff I have yet to learn, I bet.

@BrandonEnright You should make a RepRap. Or get your own printer. I work with one group in the institute (or used to, not so much now) on robotics, and they used to buy time on the 3D printer of a prof. They got their own and now they're saving lots of money. And if you don't want to get your own, you can make one using RepRap :)

@MarkBooth on Robotics (he ought to be around in the chatroom) knows quite a bit about these if you want more info.

@BrandonEnright I was always surprised that we had folks like Shor and 't Hooft active on the site (with quite a bit of rep). These guys are at a university and have a lot of things they can do, yet they spend a little time here :)

Well, 't Hooft is less active these days, but he used to be here.

And then we do have a significant number of active researchers (eg dmckee).

What dilaton&dimension want to do is recreate TP.SE, a site for research level questions only. And they want to be free from some of the SE rules (civility, the issues with list questions, moderation in general). I personally don't think it'll work, but it sounds like an interesting plan nevertheless.

ManishEarth

09:03

While the question isn't so great, it's actually the seed of a good question

0

Q: How can we write the wave function in quantum mechanics?

In quantum mechanics, while writing the wave functions we can take a product of the spatial and the spin parts.But what does it means? What is the meaning of the spatial wave function and the spin wave function?

Even I used to wonder for a while what the actual form of the spin wave function (as well as the actual form of Dirac's psi) was.

Now I know, but it took pretty long.

Natanael