The h Bar - 2015-02-21 (page 2 of 2)

« first day (1570 days earlier) ← previous day next day → last day (3358 days later) »

6:01 PM

^ truth

I want to listen to the hypersphere. That is my goal. We can hear sums. So if I add up every single point on the sphere I can hear it. Those graphs are the 3d one. The equation to number 5 is shown above. — user1698948 21 mins ago

wat

0

Q: When did the casual definition of the three laws of thermodynamics first appear?

Who is credited as the source, and when were the laws first stated in this form? (1st Law) You can't win. (2nd Law) You can't break even. (3rd Law) You can't get out of the game.

I'm not sure if this can be regarded as a "proper" question.. is this "formulation" of thermodynamics law that popular?

@ACuriousMind Haha

@glance I've never heard it before

and I think it is off-topic

Maybe he took the Fourier transform of a sphere?

And wants to hear it?

6:11 PM

I want to listen to the hypersphere, too

@ACuriousMind that's awesome. We should encourage this people on the site, they contribute enhancing the spirit of the others

@ACuriousMind me neither actually. Off-topic as not-clear or as not-mainstream?

I think we really need a flag reason on the lines of "WTF?"

@glance Yeah, I'm struggling to formulate it

@glance Often, unclear what you're asking fits, but not in this case

@ACuriousMind I know you are a radical. Well, what that fellow wants is as follows: he believes that one and a same wave function may represent a bound state, and a free particle. So, he asks, essentially, why the free particle wave-packet expands during the time, while the bound state doesn't.

@Sofia How is @ACuriousMind a "radical"?

@ACuriousMind besides, I gave him quite a shower (so one says in my country) for the confuse question and big blablabla (wording - bavardage).

@0celo7 Oooo! He is! Yes.

6:16 PM

@Sofia Uh, okay, but that question would have been a lot shorter - "How can the same wavefunction be a bound state in one situation and a free state in another?", right

@ACuriousMind how do the flags reason appear on the queue? Like a short message near the link to the question? what happens if there are different flags with different reasons?

That's actually a valid question (though an easily answered one - the Hamiltonians, and hence the time evolution are different)

@ACuriousMind Ahhh! These "cubs" believe that adding wording and wording, helps.

@glance You see: "The question has been flagged for:" and then a list of all flag reasons that have been cast on the questions.

@Sofia Jan Lalinsky seems to be answering a totally different question, though

Which supports my point that the question is unclear

And reading the current version, I still don't know what is going on when I reach the end.

@ACuriousMind now is clear.

@ACuriousMind but, as I know these children, they begin with a lot of counter-arguments.

6:22 PM

@Sofia @ACuriousMind what question?

2

Q: Does $\lvert\langle p\lvert\psi\rangle\rvert^2$ have any meaning at all?

I used to think $\lvert\langle p\lvert\psi\rangle\rvert^2$ had the meaning of some likelihood of the particle's momentum being $p$ (within some tolerance interval $\Delta p$). Now I'm just confused. I'll use momentum $p$, wavenumber $k$, and velocity $v$ interchangeably here (i.e., I'll use the...

quantum-mechanics oscillators

The answer to the title is just the PDF for momentum, right?

@0celo7 Yes, the body asks something else, though

Nevermind

I don't understand how the title relates to the body, or how velocity distributions relate to the wavefunctions, or how Bohmian mechanics would be relevant, or why we are suddenly talking about a classical limit

I maintain the question is still not clear, @Sofia, and what you said this user "essentially" asks appears in the middle of the post, but I'm not sure if that's their main confusion.

6:26 PM

Okay...what is this ridiculous equation here:

@ACuriousMind Is he asking about the probability current?

-3

Q: Do these graphs represent anything in the real world?

Do these graphs represent anything in the real world? They represent the sum of a sphere over time. I was thinking pressure wave but the 3d version looks too messed up to be one. So throwing that out, what's left? Stuff to do with atoms? Maybe something about plank's constant. I know nothing abou...

waves harmonics

@KyleKanos The sound of the hypersphere, obviously

@0celo7 I have no idea

The probability current appears there

@KyleKanos that's from the guy who listens the hyperspace, so I don't think we can hope to understand his awesomeness

But I don't know why we are suddenty talking about it

6:27 PM

@ACuriousMind Random question: is his definition of the current correct?

I was going to LaTeX it out, but it's like 40 lines when formatted. No thank you.

@0celo7 Yes, I think so

I've always used $\mathfrak{I} (\psi^*\nabla\psi)/m$

Are they equivalent?

@ACuriousMind It's decently clear to me. There's just a lot of elaboration

@0celo7 Yeah, write $\psi = \sqrt{\rho}\mathrm{e}^{iS}$ and work it out, should fit.

6:35 PM

The body is just a bunch of examples where he encounters things that he considers counter-intuitive, following the usual interpretation

@ACuriousMind Derp.

@Danu And what's the question?

The title?

That's not what Sofia said he was asking

I didn't read you guys' discussion

22 mins ago, by Sofia

@ACuriousMind I know you are a radical. Well, what that fellow wants is as follows: he believes that one and a same wave function may represent a bound state, and a free particle. So, he asks, essentially, why the free particle wave-packet expands during the time, while the bound state doesn't.

Meh, I don't think that's the essential question at all

That's just one of his examples

6:37 PM

Exactly why I think this question is unclear!

No, not really

@Danu what is the essential question?

Just Sofia's interpretation is beyond me

@0celo7 Title

the question at the end is "Would there be any way to obtain a position dependent velocity distribution, or even a quantity similar to this, that would agree in the classical limit?"

@Danu PDF for momentum. Done.

6:38 PM

@ACuriousMind Again just an elaboration on his example

Why the page long post?

@ACuriousMind what you believe he was asking? He asked why in the free particle case the evolution of one and the same wave packet differs in the predicted distribution of velocities. If you believe otherwise, then tell us what you believe.

@0celo7 Not good enough

You have to refute his examples

@Danu Hmm. Gotta shovel snow.

@ACuriousMind by the way, he sent me and DavidZ a thank you for clarifying his question.

6:39 PM

He's basically saying: Hey, I know the standard interpretation but, this that and this can surely not be right, can it?

@Sofia I don't know what they're asking, that's what I'm saying here all the time. You say they're asking about time evolution. Danu thinks they're asking about $\psi(p)$

You have to convince him it is right

And the 'this that and this' is very long

But what's the problem with the examples?

I hit the first bit on magnetism in my sophomore E&M semester next week. I suppose the sudden influx of really poor questions about magnetism related to other people being a little ahead of me.

@ACuriousMind Did you read the post?

@dmckee rofl

6:40 PM

@Danu Yes, they say "I have a hard time believing the distribution of velocities in the cases A and B is exactly equal. ", but I don't see why

@ACuriousMind that's the same thing. He asks why in the two cases the velocity distribution evolves differently (he takes m =1 \hbar = 1).

@ACuriousMind Right, he has some suggestion about it depending on $\partial_x \psi$

...but I guess you can't say much more than just: Yeah... nope

@Danu Again, why?! I see a bunch of semi-connected assertions, but no real reasoning

I think this user has a very weird model of QM inside their head, and is communicating it very poorly

@ACuriousMind see my above comment

@ACuriousMind because a free Gaussian is spreading, while a bound state doesn't. His \psi_0 is not a Gaussian but he mentions that it would be better to work with a Gaussian (but he probably wasn't able to calculate the Fourier transform of a Gaussian)

6:44 PM

@Danu But you said we have to refute the examples - how can we refute the examples when it isn't clear why the examples would be problematic at all?

@Sofia So, what? What's the problem with the Gaussian spreading or not?

The upvotes indicate that more people think this question is good, and I really want to understand why

@ACuriousMind : Ayye! The examples were clear, the fellow just talked a lot.

@ACuriousMind I think a good answer would simply tell him no, no, these things are really ok and not problematic... which Jan's answer does

as far as I know, it's been satisfactorily answered.

@ACuriousMind is it the 1st time you see a quite silly question gets points? Ask me on what I get most points.

@Sofia No, silly questions get points all the time, that doesn't bother me. But I honestly find this one near-incoherent, and I'm starting to wonder if there's some kind of problem with my reading comprehension

Nah, you're fine dude

You get it, but you should just not panic at the ill-formulatedness of this question

6:48 PM

@ACuriousMind you are an aristocrat, you answer only qualitative questions. But I want points, because that gives me privileges, in short, possibility to help.

basically the guy/girl needs some pats on the back and reassurance that it's all fine

@Sofia lol. You're pretty much at the top as far as privileges is concerned

I have found myself too lazy to answer many more questions nowadays, haha

I really want to get the 20 upvotes on this though

17

A: Is it a problem with radiometric dating that carbon 14 is found in materials dated to millions of years old?

There is a lot of discussion about this issue on this internet, so I think this question may be worth addressing seriously. The main point of the debate seems to be the following: Over the past decades, several research groups of self-proclaimed creationist scientists have claimed discoveries of...

@ACuriousMind you, wonder child. Do I have to say in clear words that I am delighted with you? But in experience with people you can't compare with me.

badges are worth it

@Sofia lollollol

@Danu Already gave you mine, sorry

@ACuriousMind I'm not begging :P

6:51 PM

Laaaaaaast Christmas, I gave you my vote...

Once downvoted, twice as shy...

(you posted that answer on Dec 23, btw)

@ACuriousMind you are a physicist. Behind me there are some more titles. What's relevant here is that I am a system analyst. It's in my profession to clarify what the user wishes.

@ACuriousMind right, right. Hat-hunting maybe

I still don't think it answers the question

6:55 PM

@Sofia It's alright, and the OP thinks you did good with your edits, so it seems you did well. I'm just still trying to really parse the question, and I'm failing.

(parse the question = decipher its meaning/intent)

@KyleKanos My answer? :P

@Danu Yes. OP wants to know if carbon dating is okay for such old materials. Your answer is why Miller is a bad scientist

@KyleKanos Heh, perhaps. I do think that, along the way, it should have become clear to the reader that the carbon dating method cannot be used here because of the half-lifetime

"In particular, it is implausible that it would have been considered worthwhile to try to use radiocarbon dating methods on these bones, since the rocks that they were taken from were determined to be 99+ million years old, as shown in this paper by Kowallis et al. Now, it is known that 14C decays at a fast enough rate (half-life ~6000 years) for this dating method to be absolutely useless on such samples."

And that by itself probably could be the answer (with some fluff). Your main point is still that Miller's a bad scientist (cf your entire conclusion)

@ACuriousMind in my connection with customers I was many times in the situation that they even didn't have crystalized in their minds what is their problem. They only knew that they had a problem. It's common for a system analyst to crystalize what is the problem.

7:04 PM

@KyleKanos Yeah, the guy needed some straightening out - it was clear he was coming from a strongly religious background and was unconvinced that dinosaurs actually existed that long ago.

I remember that guy. I think he told me I will burn in hell or something when he visited our chat.

Those kinds of fundamentalists give people like me a bad name :(

(Sorta) unrelated: data.stackexchange.com/physics/query/277067/reversal-candidates

I am (apparently) learning SQL now

If you run that script, it finds how close you are to the reversal

Sorta. It gives you negative-scored questions with your > 10 scored answer

sofia, the reminds me, steve jobs was famous for saying "the customer doesnt know what they want".

Lol, seems I won't get the reversal badge, ever

I don't even have a candidate by that script

on se there is that tension, most want to take questions highly literally but think a less literal interpretation can be more helpful sometimes.

7:10 PM

But I'm a populist, which is nice

@KyleKanos Yeah, it's kinda lame when people do that

@ACuriousMind That Lalinsky didn't answer why the evolution of the free wave-packet is different from the bound packet. Would you answer what you said, i.e. different Hamiltonian? I don't have the right to quote people's saying.

@ACuriousMind Same here :(

@vzn Oooo! Of course! The customer wants the wall be both white and black.

@Sofia Well, it's not that deep an insight, you can just give that answer yourself, I don't have any rights to it (and I don't want to answer a question when I'm not even sure what the question really is, that feels wrong)

7:14 PM

@vzn this is why, in concluding a meeting, one requires the customer to sign. And though, there are a lot of arguings after that.

@ACuriousMind Being tantalizingly close isn't everything either...

@Danu You'll get the badge, eventually. I waited four or five months for the last vote for my populist badge, too. (Though I was waiting for votes on someone else's answer)

user54412

Is anyone here familiar with audio synthesizing software? Can we actually reproduce the sound of the hypersphere from the formula?

@ACuriousMind Heh

19

Q: How to motivate speakers to give less specialized talks at a "colloquium?"

Our applied math department is beginning to have a serious attendance problem at our colloquium. The appropriate level for our colloquium is that any person with an undergraduate degree in a quantitative/theoretical field should be able to follow the talk as long as they are paying close attentio...

graduate-school presentation seminars

In my experience, this is a huge problem in biophysics

Only one biophysics talk have I ever heard (and given that my dept has hired 3 in the last 4 years, that's a lot) made it accessible to not-biophysicists

user54412

7:26 PM

I'm 0 for ~10 in understanding plasma physics talks

I've had 2 and I understood the principles of them

Also:

@KyleKanos Then that's what you had to answer in the first place. Although I believe infinite computing is possible in future. Of course the term infinite itself is subjective as there is nothing in this universe that is infinite, but wouldn't it be possible to build say computers inside of computers(a dimensional hierarchy so to speak of) in order to build an infinite world or computer in this case? P.S thanks for giving me the link to that ternary thread. — Rohit Rockzz 2 mins ago

Computers inside computers? Like Virtual Box?

And then opening another Virtual Box in that Virtual Box?

user54412

Call me an idealist, though, but I feel like it's possible to give an advanced talk followable by a broad audience. Difficult, but not impossible. And as much as I don't like talks where I can't follow anything, I also don't like wasting my time attending dumbed-down talks in my field.

user54412

@KyleKanos Clearly the recipe for infinite computation, right?

@KyleKanos that reminded me of source code. The world inside the world inside the world...

@glance That was a half-decent movie. Terrible "physics" but decent acting & premise

7:31 PM

CW/ KK et al have been meaning to ask you ... have you heard of any grid simulations of solitons? esp 3d solitons?

Lol, that's actually a movie?

@ChrisWhite The one biophysics candidate I mentioned (who was hired) made his talks rather accessible. I talked with people from the different subfields & they all thought highly of it. So I think your idealism is true.

@KyleKanos agreed. If you don't pay too much attention to the non-sense of the thing (which you usually have to do anyway for these films) it's a nice watch

@Danu Yessir. Not just a trailer

@vzn No I have not, sorry.

@KyleKanos That the title sounded too nerdy

7:33 PM

Oh, I see. Yes, it was indeed the name of the movie

@Danu indeed, the title wasn't that much directly related to the movie... I guess they didn't find anything better

user54412

@vzn Nope. I wouldn't be surprised if solitons of some sort existed in simulations in my field, but we don't even use that term, so I don't really know what they are.

Curiously, someone asked about parabolic calculus before the movie was released

(Parabolic Calculus being the means/explanation for the mind-transport in the movie Source Code)

ok thx guys. JamalS is also interested in em.

(source code trailer great! reminds me of that new cruise movie edge of tomorrow, similar "high concept" of re-dying over and over.)

@KyleKanos haha yes, I recall that as a randomly thrown in complicated word. One would guess that they could at least come up with something loosely related to the actual thing

@vzn in source code there is no time-travel, it's actually "just" a really good simulation with some QM randomly thrown in to back-up the thing. I'd say slightly less commercial and funny than the edge of tomorrow, but both were a nice watch

user54412

7:40 PM

Parabolic Calculus? Isn't that high school physics of projectiles?

you guys might also like existenz said to be partly inspired by salmon rushdie fatwa

(obscure trivia factoid there, just read in video game book)

edge of tomorrow had big budget.

@glance I'm pretty sure it was some sort of parallel universe thing. Gyllenhall's character survives in the end.

$180M. guess cruise still "has it," or at least some of it :)

another recent cruise scifi movie oblivion thought not bad.

sofia do you work with software? you might enjoy jobs / kutcher

@KyleKanos can you have a look at this question. It's typically image processing, one of the domains of computer science.

@Sofia Sadly not my domain though

7:47 PM

@KyleKanos Is there in SE a computer-science site? I would like to flag the question for migration.

@Sofia two, in fact

@Sofia I don't think it should be migrated

That can be a suggestion for OP to repost if they don't get an answer from here

@KyleKanos I learnt image processing by all sort of transforms, in particular Fourier transforms.

@KyleKanos yes, it's image processing.

@ManishEarth what is the procedure for suggesting migration? To flag? Or, to recommend closing?

@Sofia both

VTC, and flag

@ManishEarth what is VTC?

7:56 PM

VTC = Vote To Close

Hmm, the hypersphere user is persistent. They even added a nice colorful sphere

@ManishEarth if I vote to close as belonging to another site, only two sites are indicated, math, and something else that is not computer science.

@ACuriousMind Haha

@Sofia dsp.stackexchange.com is probably best suited for image processing.

What is a "64"

7:58 PM

@Sofia You can put a custom reason, and mention the site you think it should go to in that reason

@0celo7 A number :P

But, in this context, no idea

@Sofia VTC as off topic, flag with the site it belongs to

@ACuriousMind The recent update to the "hearing hypersphere" question

@KyleKanos Argh, I know the context, but I still don't know why what I'm seeing is a 64 :D

Ah

@ManishEarth but what I see there are only two sites, meta.something, and math. No computer science.

8:00 PM

@Sofia Oh, you can't migrate to beta sites

@Sofia Yes, I know

You have to make an actual "Moderator Attention" flag

@KyleKanos Aaaa, O.K.

@Sofia Like I said. VTC as off topic (custom reason, or anything). Flag with a custom reason saying it should be migrated

Sites have had problems with migrations been done by users who don't know the target site's standards

so the list which a regular user can migrate to is short

If only some of those sites would Graduate....

8:03 PM

@ManishEarth Is there some kind of long-term statistic how many migrations we've accepted/rejected from other sites? The 10k tools only show the last few ones, or I haven't found the right button.

Also: what happened the last two weeks???

@KyleKanos :O

Perhaps some users finally started using their votes?

I have noticed more "old" questions being VTC than usual

@ACuriousMind You can use Stack Exchange Data Explorer to find more statistics

but a lot of the migrated posts get autodeleted so that might not work so well

@ManishEarth I feared that would be the answer :P

As I spot them, I tend to VTC old questions that don't match our current policies

8:05 PM

@KyleKanos The autodeletion roomba got to them?

@KyleKanos That query will be skewed for current closevotes no matter what

old, closed posts with downvotes get deleted

<-- Fail

@ManishEarth TY

So I suspect that >150 closes per week is probably normal? And that half of them get deleted due to autodeletion

Interesting

Every time I've used a SEDE graph to prove a point on meta I've had to preface it with a bajillion caveats on various intricacies of the system that skew the results

@ManishEarth , @KyleKanos in the "image processing" domain, all sort of transforms are studied according to which features the transform should stress. Also issues about phases and other things the user asked.

12

A: What can be done about the (current) ongoing flood of homework and very basic questions overwhelming our site?

Firstly, you're asking two separate questions that need to be dealt with differently. One question has to do with HW posts, and another has to do with basic posts. The Data Now for the data: Unfortunately I can't cook up a query that reliably separates basic and non-basic questions. Analy...

eg there

It's really a sine-wave ish thing with a rate of increase proportional to the net rate of increase, however the roomba makes it look like there's a spike

Hello, I am looking for some space-time, where can I find it, and on what days of the week is it available?

8:10 PM

No one gets any of my space-time!

@ManishEarth Ugh, I remember that post now. Is it really necessary to have that egregious list he put there?

@ACuriousMind I'm confused by the definition of the index of a vector field. Zeidler defines the index of a saddle as $-1$. What's the saddle of a vector field?

@KyleKanos meh. old meta post

don't care

@ACuriousMind : Well, there is this mathematician. No expansion, but there are a group and an alternative named after him :)

@0celo7 Uh, the higher-dimensional equivalent of a saddle point? It's a point that looks similar to a source or sink, but there are no vectors coming in or out, the field just "avoids" it.

@Qmechanic Haha, forgot about good old Tits. He even has his own building.

8:30 PM

@ACuriousMind The Poincare-Hopf theorem blew my mind. It's pretty deep.

bad news for you guys, I was unharmed in the cyclone

@SabreTooth How is that bad news

Glad to hear it @SabreTooth

@0celo7 It's always beautiful when some ugly analytic construction suddenly is solely topological :)

@SabreTooth Did it look cool?

8:36 PM

it was a sheet of rain - 2 main centres to the north were hammered badly

@ACuriousMind Any idea of a book with the proof? It's not in any of Lee's books. I'm Googling right now, but it'd be nice if you knew one.

@0celo7 I don't know books, remember?^^

That's why I said "if"

I wasn't hopeful.

@KyleKanos I am still around

@SabreTooth I think the survival of anyone in hazardous weather such as that is actually a good thing.

8:38 PM

my lab was damaged though

How badly?

air vent of fume hood on roof partly collapsed - water damage in the lab, 2 windows busted

part of the roof peeled off (iron sheets)

nowhere near as bad as elsewhere

Is there insurance on the building?

yup, so all good

Is this your work lab or your home lab?

8:46 PM

work lab; home lab was dismantle and stored - so unharmed

That's convenient that it can do that

an Experimental Physicist trick - it is made out of a fold out outdoor chair

9:39 PM

@Qmechanic Not to forget that theorem about the inability combing the hair on a spherical object flat without a part...

/ Yeah, my inner thirteen year-old lives on.

On another subject entirely: some users just can't even be arsed to do some division on their own. ::sigh::

@dmckee That one is Der Satz vom Igel in German - "The theorem of the hedgehog"

@ACuriousMind Not so much fun as the English name for it, but still pretty evocative.

10:06 PM

Every once in a while someone comes here and asks how the error of measurements gives the error of derived quantites. I was taught error propagation before they let me take any measurements or do any experiments. Is it common in other countries to set people "loose" on experiments without teaching them experimental and evaluation techniques first?

(If yes, why?!)

Yes. ::grumble::

As to why, well, because ... er, I mean ... uhm, that is ...

Well, apparently the standard propagation formulas are too hard for introductory classes.

@dmckee What? But they know what a derivative is, right? That's the "hardest" part I could see there.

More seriously, a lot of my students are rather under-prepared and taking the time to get the conversant with the ideas of uncertainty and with classifying the different kinds chews up a lot of time.

Additionally, one might like a little motivation for learning a set of pretty boring mathematical facts by actually playing around in the lab first

@ACuriousMind well you are assuming that the fact that they teach them the techniques implies that they actually heard/understood it

10:12 PM

@ACuriousMind Recently I've been teaching our algebra/trig-based "for non-majors" sequence, and most of them don't know what a derivative is.

When I get the calculus based students using the formulas is going to be mandatory even if I don't expect them to "get it" right away.

@dmckee can I ask you which country are you referring to?

That said, when I took the for-physics-majors intro sequence (at quite a good school), we were not shown a convincing motivation for those formulas for the first year or so: it was just rote work.

@glance I'm at a second tier state school in the US of A.

@dmckee : Hm, it seems we are going low today. We might have to impose "no underage in the h bar" :)

The thing is that the algebra/trig class is for pre-med, biochemists,pre-nursing, pre-dental and so on.

These students aren't going to do physics and need it mostly as background and to motivate things they learn in their major fields.

@glance Well, if they hadn't understood it, I would expect that they tell us what they didn't understand about it.

But it seems I'm expecting too much today, anyway

10:19 PM

@ACuriousMind doesn't frequenting, e.g., this site, answer your own question? I'm tempted to flag this as insufficient research effort on your side :P

@ACuriousMind Let's put it this way, students come to my school rather than a more prestigious one for a reason. With the "best" of them that reason is that they were able to skate through high-school and haven't learned to apply themselves yet nor accumulated much knowledge.

Those are the best, because ignorance can be cured.

And some of them eventually turn into pretty good students who am I not embarrassed to recommend for grad school if that is what they want.

@glance I was trying to understand where these questions come from, if these were just incredibly lazy people who did not bother to open their lecture notes, or if it could be that they actually were never taught this.

(Because, in the lab courses I had, it would have been impossible to have done any measurement and not seen error propagation - that was literally the first page of the instruction manuals)

"literally the first page of the instruction manuals" As it should be.

at my university error propagation is tought before going into the lab, too (it is thought in a lot of school several years before going to university for that matter). Still, I can think of a handful of people who didn't really know how to do the calculations even after after the experiences in the lab, for the usual reasons like not bothering reading the notes or listening to lectures ecc.

10:54 PM

@ACuriousMind Regarding this (physics.stackexchange.com/questions/567/…) - Is "Shapiro time delay" an actual concept, or is it more nonsense?

The Shapiro time delay effect, or gravitational time delay effect, is one of the four classic solar system tests of general relativity. Radar signals passing near a massive object take slightly longer to travel to a target and longer to return than they would if the mass of the object were not present. The time delay is caused by the slowing passage of light as it moves over a finite distance through a change in gravitational potential. In an article entitled Fourth Test of General Relativity, Shapiro wrote Because, according to the general theory, the speed of a light wave depends on the strength...

I'm not actually sure how much of that post is nonsense, it's just wholly unclear what the user wants to tell us (I suspect it doesn't answer the question, though)

@ACuriousMind Weird. It didn't show up on my search. I must have mistyped it.

It happens

I wonder why they chose to type e.g. it,s instead of it's

It doesn't answer the question at all, it just tries to explain why neutron stars live longer than stars on the main sequence. So I suppose "nonsense" is a bit harsh. "Misguided" might be better.

11:23 PM

@ACuriousMind That looks suspiciously like GR...Why are you meddling in such affairs

@0celo7 Have I ever said anything about staying away from GR? :P

@ACuriousMind I guess not. BTW, Gauss-Bonnet-Chern is eerily awesome.

These theorems are pretty cool.

A lot better than the non-theorems of geometry.

Although, is Gauss-Bonnet-Chern technically differential topology? It uses curvature.

@0celo7 Curvature stuff is technically differential geometry, I think, but the borders are quite fluid in these areas

« first day (1570 days earlier) ← previous day next day → last day (3358 days later) »

Transcript for

Feb '1521

The h Bar

General chat for Physics SE (physics.stackexchange.com). For M...

join this room
about this room

00:00

06:00

12:00

18:00

all times are UTC

site design / logo © 2024 Stack Exchange Inc; legal

mobile