Some of my friends on a mailing list are calculating how fast 5g of peanut butter would have to be moving to kill a person

I just closed like 5 or 6 low-effort homework questions... :-/

@DavidZ Did they come up with a number?

And yeah... september, ain't no time like it

@Danu there's some disagreement over just how the peanut butter would kill

I also wonder

Btw, do you think 'bra-ket-notation' could be a valuable tag?

I don't think we need it as a separate tag

The combination of quantum-mechanics notation should usually cover it

although I don't feel particularly strongly about it either way

notation already exists, ah

Does anyone know what the deal is with a so-called "Godzilla particle"?

This article mentions it

sciencenews.org/article/…

but I can't find any other mention and I can't see past the second paragraph.

@EmilioPisanty: I think that they mean that there's no big obvious particle to be discovered, now that the Higgs boson has been found.

Not that there's a particle named the "Godzilla particle."

@KyleKanos Yeah, I guess that's what they mean. I just wondered where they got the term.

(And shame on them, really, if they're making it up. I think it's terrible.)

Definitely not the best term, but I don't think I'd be able to invent a better phrase

So quiet...

What is this madness?

Um...shouldn't you know, given that you posted it?

Where is it from?

It's from my simulation

There are strange lines sticking out like a sore thumb there

They don't look like they belong, certainly

Definitely not

The output of the previous time-step does not show this

And, strangely, the expected run-time of the simulation jumps from about 2 hours just before 10 to about 14 hours immediately after output 10 (and over the next 20 $dt$'s, jumps to 8.8 days)

99 bugs in the code, 99 bugs...take one down, run it again, 127 bugs in the code...

Lol

As I've no clue about simulations, that's all I can think to that :P

One of the code developers recently noticed a strange behavior in the solver in his simulations

I wonder if this is a related issue

@ACuriousMind Hah, I thought for a second that what you said was starred 99 times

Guys, in the context of general topological spaces, an isomorphism is defined as a bijective bicontinuous function. But in the context of Hilbert spaces/QM, one says two spaces are isomorphic iff there is a map that preserves the inner product between the two. Is it obvious that this is the same thing?

@Danu Is isn't (in the sense that not every top. space iso is an Hilbert space iso)...and it is: An isomorphism is an invertible morphism of a category. In the category of topological spaces, morphisms are continuous maps. In the category of Hilbert spaces, morphisms are isometries (or sometimes, linear maps)

I meant to ask whether it's the same in the context of Hilbert spaces

i.e. does every bicontinuous bijection preserve the norm?

or are you saying that the definitions are different even when restricting to Hilbert spaces?

@Danu No. Take the same Hilbert space as source and target. Take the bicont. bijection that multiplies everything with 2. It is not an isometry

Right, I figured (oh yeah, a norm preserving morphism is an isometry

Then isn't it very strange that these definitions are different?

@Danu Not really, when we adopt the viewpoint that, in the context given, morphisms are those maps that preserve the structures that interest us, and that isomorphisms are those of these that are invertible

ahh

okay, so a morphism is just 'general map that preserves structure of interest'

A bunch of people voted to close that as non-mainstream, which is good, but for the record it also qualifies to be flagged as spam

for self-promotion?

yeah

Hmmm

I never really thought about that aspect of it

I find it to be a very mild case of spam, then

Yeah, it's not the most egregious spam

yeah never occured to me to flag it as spam (I voted non-mainstream)

so I'm not saying there was anything wrong with closing it as non-mainstream, but it is basically an advertisement that doesn't ask a legitimate question.

actually I'm not sure I agree... I put up an answer recently to a question that happens to be the topic of a chapter of my MSc thesis, so I included that as part of it and linked... that's equally self promoting, should it also be flagged spam?

I guess it's an answer rather than a question, but there is a similarity

@Kyle just being self-promotion isn't enough to qualify for the spam flag. It has to be promotional and have no value

i.e. if it's the sort of thing that should be deleted anyway (for not answering the question, or for not being a question), but it also happens to promote the poster's own product/website/etc., then it probably qualifies for the spam flag

Yeah, makes sense

Should we flag it as spam now?

Happy that physics.se is obscure enough for this not to be an issue

I already took care of the linked question

@Danu indeed :-)

Doesn't PhysicsForums allow for non-mainstream "publications" like that?

I just figured I'd mention that as a reminder that we have a spam flag and it can be used for things like this.

Yeah, I really stopped using flags once I got access to the close vote etc queues

@KyleKanos they used to have an Independent Research forum but they closed it a few years ago

but I should start using them again

@DavidZ Guess you can tell how long it's been since I perused their fora

:-P

physicsforum always seems like a crazy sh*tshow when I bump into it

I forgot it existed until Ben started asking/answering questions again

my experience from random googling encounters with physicsforums has been that it's got quite a lot of wrong/gibberish info to wade through before you get to anything that makes sense, and only occasionally do people seem to point out how wrong some of the content is

@KyleKanos why did Ben remind you of it?

@Danu He links to it in some of his Q's & A's

oh, hey, wait! Didn't Ben really quit physics.SE for a while?! I think this happened right around the time I started being active

@Kyle well, it suffers from the problem that affects all traditional forums (fora), which is that you have to follow a potentially long thread of posts to find the answer

@Kyle There is a lot of really terminology-rich discussions which may or may not be complete cr@p

It's good for discussion, not so much for Q&A

And I am incapable of distinguishing them haha

I think if PF had a way of sorting posts based on how well they address the original question, it would look a lot more like Physics SE in terms of quality

(well, maybe if you exclude the homework forums :-P)

@DavidZ do you think this is a good idea of mine, or bad? More generally, do you think it's important to try to get questions out of the 'unanswered' tab if they've been answered in the comments?

Of course, this issue is particularly relevant for highly upvoted questions such as this one

@Danu it's definitely good for the health of the site

So that's certainly something I would encourage people to do if they feel like it

By the way, if you write an answer based on someone else's comments, you're not obligated to make it CW. If they wanted the reputation they should have posted an answer in the first place, not a comment.

You don't have to prominently advertise at the top that the answer was based on someone else's comments, either. I'm not saying it's bad to do so, but all you have to do is satisfy our normal plagiarism policy, which is to mention where your ideas came from. Do consider how it will look when the comments are deleted.

Fair enough, but I didn't want to come across as trying to 'steal' reputation. I just really want it to get an upvote so it'll get out of the tab :(

@ChrisWhite was that the answer that appeared to be random keyboard mashing?

I was thinking that that may just have been someone fallign asleep on the keyboard :)

Does anyone else agree that this guy needs to see that he can't just fit anything to his data to make it fit well?

I feel like the current answer is helping him deceive himself

...shouldn't that be a log plot?

I don't know, but I certainly think adding exponentials would be very strange

that really is quite a strange fitting formula

probably useful somewhere so that it got implemented into his software, but not here (or in physics, afaik)

Hahaha beautiful comment btw

I wish I could star comments

you can vote up shrug

to me it looks like a power law, but I see power laws everywhere, and on linear axes anything that's not linear could be... anything...

Yeah, that's true

I don't know what should be expected in this case

good ol' exponential decay seems a pretty decent choice

yeah that would be my naive guess

I actually don't know what an exponential looks like on log-log off the top of my head, how embarrassing...

Lol

I only know how stuff looks on a linear plot

(I mean... I know a power law is straight on a log-log, too)

but really I don't know anything pretty much

about data in general

ah right

still looks like a curve

guess it's a f(x) = ln(x) tipped on its side

yeah, exactly that, which makes sense of course :/

@Kyle BTW that's the sort of thing that "very low quality" flags are for.

Not that you specifically need to be told... just sayin'

@DavidZ it came up in my VLQ queue, I voted to delete with 'no comment' because I was kind of speechless ;)

Same here

haha yeah, sometimes these things make no sense

I wonder if a meta post showing examples of what to use the different flags for would be useful to some people

It just occurred to me that we probably have some good examples of each type

VLQ examples tend to... not stick around

though maybe they do in mod-land

or 10k+ (20k+?)

10k+... THE DREAM

I think it's 10k you can see deleted posts

@Danu eh, you'll get there, way faster than me too, I need to wait around for decent astro/astrophys/cosmology questions to come around to get any rep, I've been 2 votes away from bronze astrophysics badge for weeks :(

recruit your friends to ask questions so you can answer them ;-)

@Kyle probably because I've been spending ridiculous amounts of time on this website, to the point where I'm bored enough to answer questions that actually don't inspire me ;)

reminds me, question came up when I was talking with some of the other students here, and I thought ooh I should post it... now what was it.....

...this exact thing happens to me so often!!!

ah right, was a damped Lyman-\alpha thing

@ChrisWhite Haha, I was being in a silly mood at the time of writing that