12:00 AM
Therefore in a way it seems that space itself does have potential.

a potential in physics is conservative and connected to a force

Yes

Decrypted: Also, time is money and Hell is other people, so time must be like Hell and money must be like other people. Or perhaps the other way around.

space does not have that property in any physical theory I'm aware of

If Distance = 0 then what does that say about rate and time?

12:02 AM
if a*b = 0 then a=0 or b=0 or a=b=0

Yes

that's all there is to it

Besides which, green is blue plus yellow, whereas 5 is 3 plus 2, so green is very like 5.

in a metaphysical way @WillO

Yes

12:04 AM
O_O
I'm outta this
I'll leave with another linear law: c = K * p, good old Henry

5 was the addition of the two parts, therefore in similarity greens the addition of the blue and yellow.

But M=kPY, so c=Y.
er...cY=M, i mean.

So I have no idea about those representations.
Are they open for expression?
Voltage does need space.
That has a connection.
Speed and velocity have a connection.
Instead of looking at whats different, perhaps look at whats the similar.

yeah, in english physical standard usage, velocity is a vector and speed is its norm

That is a different of type to a classification that is a similar.
If a man doing pushups moves his body in vector 2 feet three times, adding both up and down the total motion was 6 feet.
A person of a similar rate can walk at the same rate that the man was doing push ups and walk 6 feet.
Still either way 6 feet of space was moved through.
Actually 12 sry
Anyways the points still there.
Well 6 from one perspective and 12 from another.
Never mind I thought it would have been fun to talk to someone interested in it. Bye

12:19 AM
O__________________O"""
I will have trouble sleeping tonight

12:33 AM
It is funny to see, how caffe affects the traffic moral, while the week propagates

1:03 AM
@EmilioPisanty yeah, makes sense to me.

1:37 AM
@WillO so, what do

@0celo7 Is there more to that thought?

2:35 AM
Holy crap
This is an inhibitor protein
Sonic hedgehog is a protein that in humans is encoded by the SHH ("sonic hedgehog") gene. Both the gene and the protein may also be found notated alternatively as "Shh". Sonic hedgehog is one of three proteins in the mammalian signaling pathway family called hedgehog, the others being desert hedgehog (DHH) and Indian hedgehog (IHH). SHH is the best studied ligand of the hedgehog signaling pathway. It plays a key role in regulating vertebrate organogenesis, such as in the growth of digits on limbs and organization of the brain. Sonic hedgehog is the best established example of a morphogen as defined...
That's awesome

Question looks good, there is no reaction, but already 2 close votes:
-1

Context I am struggling to get an intuition about Maxwell's equations. I created this silly mental model. I want to know if it is incorrect. How do other people think about these equations in their minds eye? Assumptions: I have an Electric test charge which I can move in the $x$ direction, ...

This is not the way what made the MathSE great.

@WillO What should I do?
The question is so specific I doubt I'll get an answer anywhere

2:51 AM
@knzhou I will post if I see a significant chance that this question won't be closed. Currently I can't see that.

3:27 AM
@ACuriousMind I need you

3:51 AM
@0celo7 Are you still there?

@WillO He's up, just poke him enough
@0celo7 Halp

@0celo7 Hoping you'll see this: MO people get annoyed when you post the same question there and at MSE, especially without announcing that you've done so, because they worry they'll spend time and effort crafting an answer for you without realizing that someone else has already answered you on the other site.
So the usual etiquette is: Wait four or five days after posting on MSE, then post to MO, saying clearly up front that you've already posted on MSE, you've waited a few days, and you haven't got an answer.
But since you're already posted, and since there's already a comment pointing to the cross post, I think you should just ride this one out.
I'm not sure what explains the downvotes. There are no close votes, though.

@WillO yes
@BernardMeurer what
@WillO I see

@0celo7 Can you explain topology to me using only emoticons?

No

4:05 AM
Then you don't understand it well enough

probably
@WillO I got a downvote on that question on MSE, btw

@0celo7 I cannot explain the downvotes. Maybe people think the answer is obvious. Personally, I don't really understand the question, so I have no opinion.
You lost me at the word "soliton".

It probably is obvious and I'm just stupid

Have you considered offering a bounty?

I managed to understand the hairy PDE parts of this book in way less time than this
I'm clearly missing some theorem.

4:08 AM
Too soon for that. There is an age requirement.

@BernardMeurer topology is just the study of open sets

It's perfectly possible that it's obvious but you're not stupid.

@dmckee It's been two days

@0celo7 No emoticons

2

I'm confused by a claim made in Brendle's Ricci Flow and the Sphere Theorem on page 37. Let $(S^2,g)$ be a gradient Ricci soliton with soliton function $f:S^2\to\Bbb R$. Since the sphere is $2$-dimensional, we have $$\nabla^2f=(\rho-\tfrac{1}{2}s)g,$$ where $\nabla$ is the LC connection, $s$ i...

@WillO The thing has nothing to do with solitons, really
It's just in the title because people who have studied solitons might have come across this specific thing before

4:09 AM
@0celo7 Of course the downside of that is that people like me who don't know what "soliton" means won't read the question.

I guess
What should the title be then
I basically have a vector field and I want to compute the differential of the associated flow
Do you know what that means?

I can't tell you what the title should be because I don't understand the question. But maybe you should consider stripping it down to the specific point you don't understand, omitting all the context.

The context is necessary to construct the vector field though

Yes, I know what "compute the differential of the flow associated to a vector field" means.

@WillO Ok
The question is basically that
All that mess there is me defining the vector field

4:12 AM
But in a specific case where you're getting a different answer than your book claims?

No, I have no Earthly idea how to get what the book claims
I re-read all of the material in Lee SM on flows, and all of the material in Petersen about Killing fields

And--- there's nobody you can ask face to face?

I had a meeting planned with my advisor to talk about my progress in this book but he didn't show
I won't be able to talk to him until next week, and it's doubtful he will know immediately
I sent him an email with a PDF attached that's basically the MSE post
Don't know if he'll bother
The only other person at my school who might know (besides grad students) is the department head, who is a geometer

Have you thought about emailing the author?

@dmckee said to hold off on that.

4:16 AM
Yah, I can see why.

The author is a big name in Ricci flow, and I could see myself working in that area if I go pure math in grad school
he does reference a paper, which does things differently and never needs that result
I checked the references in that paper -- nothing

Do you feel like you're unable to continue reading until you get this?

Yeah. It's not central to the material or anything but it's really bugging me
I could move on if I knew there was a proof out there, at least
But this seems to be original material (?)
And I'm clearly missing something conceptual!

I think it is commendable to be really bugged by it, but probably wise to try to just move on for the time being.

What does the Hessian of $f$ have to do with the flow of $J\mathrm{grad}\,f$!?

4:20 AM

I don't think I'll keep reading it anyway. School's about to start
I'd be better off reading Bott & Tu and learning about spectral sequences

Well, what you're better off reading depends on what you're most eager to understand.

And I should do more geometric analysis before I continue reading Brendle anyway, perhaps a careful reading of Petersen would be good
Petersen and Jost
Oh shit the time
I've got to be functional at 9:15 tomorrow

And (please don't take this as disparaging; it's meant as friendly advice) if you don't know about mapping cones, then there are probably several other things you should master before tackling spectral sequences.

Bye

4:23 AM
bye bye

@WillO Bott & Tu does spectral sequences
I haven't gotten that far yet
Maybe they call the mapping cone something different

Or maybe they just do things in a different order than I would.

It should be noted that they don't use the fully general result I asked about in the text.
They use a less powerful one where the horizontal cohomologies are exact except for one term
@WillO AND
I'm flipping through it
They have a proof of this result in there using spectral sequences
So we're good

oh.....one more thing!

ok

4:28 AM
I do not know who downvoted you or why ---- but people sometimes downvote to express their displeasure with MSE/MO crossposting. So it might be only that, and not the math.

Ok, thanks

Good luck and good night.

lost my phone
not good

5:17 AM
Lattice inhibit evolution of cooperation. Now the question is, how

5:35 AM
Hmm. perhaps we can dress atoms with a variety of properties by allowing a small fraction of its amplitude to exhibit states with those properties

For example, suppose I have some atoms all in the ground state $\lvert A\rangle$. Then suppose I want these atoms to have properties similar to chlorine atoms. This means there should be some probability $bb^*$ the atom should have the electronic structure $\lvert B\rangle$ of a chlorine atom. So with carefully tuned lasers to brought the correct electronic transitions I should be able to generate a state $\lvert K\rangle=a\lvert A\rangle + b\lv @JohnRennie I can't see a reason, why a MO-like PSE site couldn't work. Only the beginning would be hard. I don't think that the theoretical physics were killed because of low traffic. I think, it was killed because the CMs aren't really on the top in anything and they simply couldn't understand, why would 2 physics site needed. On the same reason they had closed the MO, if it had been their decision. @JohnRennie I don't understand, why would be the culture of the mathematicians and the physicists so different. Meanwhile the higher space guys are exploring the klein bottle and its twisted generalisations It seems the klein bottle has symmetry wrt double rotations (i.e. rotating in zw and xy plane simutaneously) 5:58 AM @peterh Then you simply don't know the history of the site. The place started slow and never picked up speed. By the time it was shutdown is was roughly a ghost-town. That doesn't mean that there couldn't be successful site of that kind, but the first go didn't work. @peterh I'm afraid you're indulging in wishful thinking. As David says, TP never looked like it was going to achieve critical mass. Psychologists could probably write tomes on why physicists and mathematicians differ - all I can say is that they do. 1 hour later… 7:00 AM @dmckee As I know, the TP people committed some mistakes. And, at the time, the CMs skills were not yet in the current level. I suspect, in a similar case, something would happen from their side which results to save the site. @dmckee They collected a much longer community management experience until now. But, they probably can't or won't understand, why would be multiple sites needed. I suspect, if an area51 initiative would happen, they would close it on the reason, that it would take away visitors from an already existing SE site. @dmckee As I understood their actions: the mods try to hold together a possible largest community in a peaceful way. The CMs try to do the same, but they also control the mods. This whole system tries to minimize the number of the sites and maximize their content. In most cases, it works, but this is an exception. @JohnRennie As I heard, the TP committed some mistakes, for example they also filtered out high level content (and users), too, on some trumped reasoning. But the MO works well. Peter, you seem to have a bee in your bonnet about this. TPSE and Physics Overflow didn't work. If you want to set up a new TP site then please do so, but we both know it will fail. For now please give it a rest. @JohnRennie Next to the contract between the foundation behind the MO and the SE, there are also other correlations. For example, the existence of the MO plays probably an important role to highten the PR of the SE. While the SE gives continous marketing to the MO. A standalone MO had been probably much less successful, because it hadn't get the countless links and ads from the SE network. I think, this could be the reason of the low traffic of the PO, too. @JohnRennie I read a lot about the second quantization. Until I've understood, it is based on Fock space, but in the case of interacting fields the things will be extremely complicated. There is also the Feymann's path integral formalism, maybe it is not Fock-based, but I can't understand it now. 7:33 AM Why do people post this stuff. I just don't understand the mentality... -1 Is Higgs Boson theory a zero constant? There is no relative data to support a Higgs Boson. CERN cannot prove likewise. Maybe it's just some kid who's nicked his parents laptop. Queston one: What is a zero constant Comment one: Read the cern news @JohnRennie Also I not. In my opinion, the close mechanism is for this questions: if they are ready to fix it, they get the option to do so. But, in most cases, they still go away, and the question will be later deleted by the Community bot. Oh you beggar, I was about to post that. We've obviously both just seen it on Facebook :-) > The majority of my callers are the ones who seek advice for an idea they’ve tried to formalise, unsuccessfully, often for a long time. Many of them are retired or near retirement, typically with a background in engineering or a related industry. All of them are men. Twitter, actually, and I've been seeing it for a day or so but more or less, yeah Though despite what one might expect, Hossenfelder says many of the callers genuinely want to learn and will take advice as long as it's well explained. Yeah, I noticed the stark contrast to my experience elsewhere on the internet (e.g. here) What she describes is the sort of thing I had in mind when I posted: 1 I recently took a bit of stick for suggesting that the Minkowski metric was an easy way to understand special relativity, and this morning I suspect I've managed to be more confusing than helpful discussing this with Floris. I wonder if this is the sort of issue that site members would be interes... Though I wasn't going to charge$50 per hour for it :-)

8:30 AM
Oh the AMA is today?

Interesting. BTW it's $50 per 20 minutes. @Slereah Yes. IIUC Daniel got summoned to jury service and had to change the date at the last minute. @Bass$150 per hour! Cor, that's more than I get paid for writing code. Sadly I doubt I have the patience required.

@JohnRennie I thought that was basically a good idea (and still do), although I would be a little wary of inviting the average autodidact physicist into chat.
I'm inclined to believe Skype, or video chat in general, is a better medium for that kind of consultation than this site would be.

@JohnRennie Same here :) However, I think you can't compare that to a normal hourly rate. Most likely they won't have three clients per hours.

What she said is very similar to how I use h bar and I am like a client, except with the difference that my primary aim is trying to understand what we know deeply, understand how the maths translate the physics, and make metaphors that does not deviate much from the actual maths so one can communicate the science accurately to layperson and inspired them to learn more while at the same time make them realise that physics requires serious thinking, rather than trying to build a new model or something

8:36 AM
@Bass True. I get paid by the day i.e. in eight hour chunks so the hourly rate is less than if I was contracting for an hour at a time.

@Slereah [Scifi] Since you are the time travel guy (although the CTC type), Temporally postponing the issue of the bottleneck, would you mind helping me to check whether this is at least mathematically and logically self consistent and see what other directions I need to consider to further develop it or watch out for? secretuniverse.wikia.com/wiki/Ripple_dynamics

How can we relate the energy and the radius of a particle in a cyclotron?
Does the radius increases so that frequency remains constant?

Cyclotron or synchrotron?

Cyclotron

The gyroradius (also known as radius of gyration, Larmor radius or cyclotron radius) is the radius of the circular motion of a charged particle in the presence of a uniform magnetic field. In SI units, the gyroradius is given by r g = m v ⊥ | q | ...

8:51 AM
@DavidZ although the real scandal is that someone with 15 years of research experience has to bite through on 3months contracts ... f***ing retarded german underfunded system -_-"
or by offering skype consultation lessons

It's kind of the same everywhere

UK seemed better to me to be honest
when I went there for a year; but maybe it's just because I only saw the surface

@ItachíUchiha The Wikipedia article has a pretty good explaantion of this. Have you looked at that article? If so, are there aspects to it that you find unclear?

but it's a really interesting article btw, thanks for posting - before I forget that @DavidZ :)

I wonder is Hossenfelder can explain what virtual particles are in 20 minutes. Actually I'd pay $50 for that. 8:56 AM It has been going around the internet, I figured it made sense to put it here too. (Anyway, you're welcome.) @JohnRennie for$50 in 20 minutes, I bet she could explain anything :-P

@BernardMeurer For what?

"It is notable that the cyclotron frequency is independent of the radius and velocity and therefore independent of the particle's energy."
@JohnRennie,velocity can be related to the kinetic energy of the particle but how can radius be related to the energy ?

@JohnRennie maybe we should send a PSE excursion team to her office :D

But seriously though, it's not a stretch to explain virtual particles in 20 minutes to someone like you or me who already knows how QFT basically works.
Explaining it to a layperson or a lower-level student is more of a challenge.
@Sanya What we really should do, someday, is to get her in here for an AMA/chat session.

@DavidZ Just need to get the 150$together and keep Lubos away :P 8:58 AM lol @ACuriousMind we could also do the "we are two very interested physics students and we want to come to your office" sketch and see what she replies :D @ACuriousMind Hmm,$150. I might be willing to stump up $150 for Hossenfelder to do an hours AMA ... @DavidZ well, professors for AMA I can see that it would be cool - but I seriously think most of them will not have the time for that :| That's okay, we just invite the ones who do have time. @ItachíUchiha where does it say that? I don't think it's true. The frequency is$f=qB/2\pi\gamma m$and$\gamma$is a function of the particle velocity/energy. 9:03 AM That's a non-relativistic approximation. For the relativistic treatment look at this section in the Wikipedia article on cyclotrons‌​. @ACuriousMind Do you think this might be a good question for the main site? Do you know if it has been asked before? Haven't found anything when googling PSE. @Bass Yes. No. :) What we do have is several questions about why the classical minimum is relevant First-order corrections, yada yada yada, but I don't think any of those answers your question Here you go: 0 Most explanations of Spontaneous Symmetry Breaking (SSB) go like this: They take a scalar field Lagrangian with the "Mexican hat" potential$V(\phi)=−10\phi^2+\phi^4$and argue that since the potential has an infinite number of possible minima, the QFT has an infinite number of vacuum states (see... Unfortunately there's no tag for SSB, so I tagged it with Higgs... 9:18 AM We could make a tag for SSB if it would be useful There's probably enough questions about it, yeah @DavidZ I think it would be useful, but I have no idea if there are enough questions for it.. Of course the only way to actually get the tag on to all the relevant questions is to add it manually, by edits I should make some crepes If you try to add SSB as a tag, the site shows "gauss-bonnet" with just 6 questions. I think SSB has far more than 6 questions, so yes please :-) Of course the actual tag name should be more descriptive than just if possible symmetry-breaking? symmetry-breaking exists, but it has no "ssb" alias.. i.e. when entering "ssb", it doesn't appear. I'd suggest checking the existing questions to see whether they are about spontaneous symmetry breaking specifically 9:46 AM Seems about half of the questions are explicitly about SSB. hmm... fits within 25 characters I'm not the biggest fan of using partial words like that but it's probably better than Oh that might be better 3 hours later… 12:28 PM @JohnRennie Will you be around from ~1-2 EST? I'll perform surgery on the PC in that time >! should be a hidden quote/spoiler, right? Nope @Sanya yes @ACuriousMind strange, doesn't work Well, it doesn't work in chat 12:30 PM in a post I am writing But in answers and questions, it should work I get a quote environment with an exclamation mark in front of the text works fine in the preview when I try it Do you have a space between the > and the !? Or maybe no space between the ! and the text? neither I use >! text @ACuriousMind Morning I've given up Ricci flow for the time being 12:32 PM @0celo7 heyhey On to more algebraic topology @Sanya Yeah, that works fine in my preview. Why do you want to use a spoiler in a physics answer, anyway? @ACuriousMind How would a north-German say "schön" @0celo7 Huh? How would they pronounce it Also...why is the trace basis independent 12:38 PM @ACuriousMind I want to include my old wrong answer for reference but I don't want it to immediately show :D anyway, I got the problem - it was line breaks each line break needs a new >! Oh, it's Trivial @ACuriousMind According to wiki it would be like "Shane" but I don't know @0celo7 Ah yes, you will find some who'll pronounce it like that @ACuriousMind Got my QM textbook It's the linear algebra style @JohnRennie , maybe? @Sanya don't do that unless you're using it to demonstrate something about the correct answer, and in that case I still think a quote block is better. 12:48 PM > A typical problem is that, in the absence of equations, they project literal meanings onto words such as ‘grains’ of space-time or particles ‘popping’ in and out of existence. If you're going to abbreviate, you might as well go for a single full abbreviation @DavidZ maybe wrong answer is - I mainly misunderstood the question so the old answer does not apply I can also just take it out point is, I thought that was unfair In the end you should also set up , , and as synonyms to whatever you choose. Then the autocomplete will do the rest. so I wanted to keep it, but I wanted to keep it out of sight @Sanya it's in the revision history already 12:50 PM @ACuriousMind I am absolutely garbage at linear algebra.$\mathrm{tr}(A^2)\ge0$, right? That's pretty out of sight @0celo7 Not if the matrix is complex @ACuriousMind$\mathfrak{gl}(n,\Bbb R)\$

@DavidZ it seemed very out of sight to me - well, I removed it
thanks :o

12:52 PM
No, it's actually false.
That's highly unfortunate.
@ACuriousMind For antisymmetric matrices things get screwed up

It's one of our principles that when you edit, you shouldn't keep the history of previous versions of the post in the post itself. That's the reason we have a public revision history, so that anything you've already posted will still be accessible no matter what edits you make. (note: exception for the grace period) That leaves you free to completely strip out anything that isn't going to be helpful to someone reading the post for the first time.

ok, yeah, makes sense

1:17 PM

@Bass Correct

1:57 PM
@ACuriousMind halp

@BernardMeurer I'm pretty sure he's gay, sorry

@BernardMeurer With what?

@ACuriousMind I'm going on a date with a german girl today
What should I know?

Uhhh...you might want to find someone else to give you advice for that case :D

lolwat
@ACuriousMind Come on, you must know something

video tutorials ftw
in general, I find some of those things somewhat true :D

@ACuriousMind You can hide it all you want, I know you get so much P. you have the whole alphabet's worth of hepatitis
Lol this video is just too much for me

@BernardMeurer lol

Even I have a ridiculousness threshold

2:22 PM
@0celo7 Yes, I think 1 p.m. EST is 17:00 UTC and I'll definitely be here because I'm here for Daniel's AMA from 16:00 to 17:00 UTC.

Hello

@BernardMeurer Wait wtf.
How does he know?

@vzn Thanks. I will take a look

2:39 PM
@JohnRennie Ok

Due to the expansion of the universe, the proper distance between us and receding objects is increasing, but not comoving distance, right?

@SirCumference Yes

Awesome, thanks

@DanielSank He's german, he must know something about German women

@BernardMeurer youtube.com/watch?v=S5YmPSbI744 youtube is a real treasure concerning that :D but honestly, I think focusing on her nationality might be a bad idea, given the collective neurosis about being german and thus guilty ... just focus on the person instead

3:05 PM
@BernardMeurer I'm British, and British women remain a mystery to me :-)

3:16 PM
@BernardMeurer why don't you ask me

3:36 PM
@0celo7 because your idea of seduction is explaining Czechoslovakian cohomology?

@JohnRennie I once heard a British woman say she was surprised that American men show interest by being friendly.
Apparently the British system involves directing unpleasantness toward the intended. Weird.
Have you tried that?

Daniel I'm 55. My interest has been targetted at just a single woman for a few decades now, and while I still don't understand her she seems willing to live with that fact :-)

@DanielSank lol sounds like grade or middle school behavior worldwide, ahem uh yes do recall being involved in that long ago :P

@DanielSank I'm not sure the British system involves unpleasantness, but to be honest after 4+ years in London I was left completely in the dark as to how British babies come to be.
Any of our resident TeXperts around, by any chance?

Wow, an abrupt switch from sex to typesetting
Whatever floats your boat I suppose :-)

3:45 PM
@EmilioPisanty I know things...

@JohnRennie You mean SeX to TeX, right?

How do I stop that?

\mbox might work.
\mbox{whatever you want on one line}

@DanielSank Yeah, that worked =)
thx

3:46 PM
@EmilioPisanty Yay!

43

With ~ we can enforce that no line break occures between two words. But this does not seem to work with special characters. I want LaTeX to enforce not to break the line after the - in (re-)creation. In my document the line breaks between (re- and )creation, which looks a bit ugly. How can I a...

@2physics sure

Haha, yes yes we're coming to that.
Four minutes, dude!
@EmilioPisanty I actually got help at TeX SE on how to make section/subsection/subsubsection headers relative in TeX.
That way, if you import a document fragment into a larger document, the headers all adjust appropriately.
Pretty dope.

(hi all not sure how many are present/ in the room but would like to know exactly. right bar shows many icons & many clicked on are in less than 1m "seen" status but not sure if they are present. so my hope is that eveyrone here writes a question or something at least once over the whole hour (possibly at end also ok!) so we can see a large audience in the transcript.)

3:58 PM
Present.
::raises hand::

14

I am Daniel Sank, guest for the Physics Stack Exchange AMA taking place in the hbar chat room on August 12 at 16:00 UTC [a]. I am looking forward to discussing my experience in the USA physics education system from lower education schools up through the PhD program, my research in experimental qu...

Ok let's get this show on the road: