2:12 AM
Slept instead now up feeling much better. The 7cups people seem like cool people but they were not online.
Regailing the patrons at a local coffee pub

1 hour later…
3:33 AM
@dm__ Just had a breakthrough conversation on that site. Excellent stuff. Thank you again

2 hours later…
5:13 AM
remembers the days when chat was more widespread/ bigger deal... ancient dotcom days... wondering does irc still exist? does anyone use it? does it have a web interface? sometimes seems like old internet trends like chat + blogs both drowned out/ fading/ dying somehow...

@vzn real chat rooms are of more fun.

@CaptainBohemian ?!? lol feeling even more FOMO now :P

@vzn what's FOMO?

@CaptainBohemian lol what you said. were you talking about anything in particular or is it a joke? en.wikipedia.org/wiki/Fear_of_missing_out

I have got tired of guessing people's reaction in web communication.

5:19 AM
@CaptainBohemian not following. ps how the heck did you pick your name anyway...?

@vzn during web communication, I can't actually see the person I am interacting with, so I am often guessing their reaction to my message. I am not sure if what I guess is correct for people I actually have seen and known from reality, not to mention to people who I have never seen.

@CaptainBohemian again not really following how that relates to what we were talking about aka non sequitur

@vzn when people don't reply your message, how do you think? You can't see them. Maybe they are annoyed by your message. Maybe they are still thinking how to reply. Maybe they are happy with your message but can't express it through the internet. Maybe they haven't seen your message. This kind of guess can sometimes lead to anxiety in important matters.

@CaptainBohemian ok but lol anxiety about a chat room conversation? ok ok have definitely seen angst in the past... anyway re your name sometimes it seems very incongruous/ counter to your personality expressed on here...

@vzn I do not have much anxiety in chat room because I haven't been engaged with important matter here, but sometimes I just get tred of nonresponse. But I have experienced anxiety with people I know from reality through web communication.

5:36 AM
this reminds me of the old expression to have a friend you have to be a friend. your sentiments also sound something like secrets hatred of ghosting. and re cows recent soliloquy, reminds me of this article / The age of loneliness is killing us theguardian.com/commentisfree/2014/oct/14/…

@vzn when I was in elementary school, I was a very shy person. So whenever I went back to school after a long break, like 2-month summer break, I often had that kind of anxiety whether my classmates still liked me and didn't feel confident to take initiative to talk to them.

@CaptainBohemian "shy" is sometimes mixed up with "introversion" by nonpsychologists.

that seems to be a manifestation that friendship takes persistent meeting to sustain.

@CaptainBohemian re article just posted and related material, somewhat counterintuitively friendship is becoming more elusive in modern world.

@vzn when I was in elementary school, most people thought I was an introvert because I appeared a very silent person in my class. But I think I am an extrovert based on the definition I read about introverts and extroverts afterwards.

5:46 AM
@CaptainBohemian there are standardized/ straightfwd psych tests that you can take that will give you the answer, give it a shot, think they are useful even sometimes valuable diagnostic tools, and now typically easily available on web sites.

@vzn I think I may have taken that kind of test.

yes personality tests are rather widespread and even took one once for a job application right out of college... found it a little jarring at the time for a c++ coding position lol :|

I recall I have found a website which provides various mental tests when I was surfing internet in the library of my graduate school, and did a lot of tests there subsequently, but I afterwards missed the address of that site. The tests there are desinged by doctors and hold high accuracy. They also include various intelligence tests.
@vzn I am particularly into the categorization of 9-type personality.

@CaptainBohemian think have run across that one also aka "enneagram" and found it intriguing. not sure if it is as scientifically based. but many are interrelated via "factor analysis". there is a concept called the "big 5" that probably maps onto different systems.

6:05 AM
@vzn I believe that categorization whether it's 9 or 5 personality because I always get the same personality whichever books I read.
by the way, another reason I prefer real interaction than web interaction is that I seem not follow the general style of web interaction ever since I stated to use messenger.
For example, I don't usually use smilies because I feel they don't actually express what I feel.

gotta run & still dont know why you picked your name but maybe someday right, theres always hope, have a good one

3 hours later…
8:51 AM
morning

kudos

Rep on Physics, Chemistry, Biology and Astronomy SEs. Truly I am a renaissance man! :-)
(and Science Fiction SE but we'll skip lightly over that :-)

All my rep from the sci fi stackexchange is from one post
But it is well earned
11

Alright, before I give a detailed answer, here are some historical details about Games Workshop that are relevant to the issue : Rick Priestley joined GW in 82 with a game he developed called Rogue Trader, which would in the future become Warhammer 40k (due to worrying about it being confused w...

I spent years researching that shit
back in my Warhammer days
Read dozens of weird Warhammer books to piece that together

@Slereah wow, that's a great answer :-)
Sign of a mis-spent youth?

9:05 AM
I prefer to see it as learning bibliographical research
I actually used to manage the biggest background site for Warhammer

9:20 AM
Springer's a pretty weird company
So far I received the bill in the mail for the book I ordered
but not the book itself

10:03 AM
GR makes me so angry
You think it's simpler than QFT but then you get a bit too deep into it and you keep finding fucked up spacetimes

1 hour later…
11:33 AM
Can anybody point me in the direction to an article or book that discusses transforming from a global to local frame in Schwarzschild geometry? So far I have numerically integrated the geodesic equations and got some data. Not really sure how to proceed to local frame though? Any suggestions are greatly appreciated!!

12:14 PM
@Slereah I thought you went looking for crazy spacetimes?

12:30 PM
That's why I am so angry
Bloody Clifton-Pohl torus

1 hour later…
1:38 PM
I wish there was a physics way to see why $\mathrm{SL}(2,\mathbb{C})$ is the double cover of $\mathrm{SO}(1,3)^{\uparrow}$ (without Lie algebras)
Found a physics way to see why it needs a double cover, just not what it should be
The fact the Lie algebra breaks up into to $\mathrm{su}(2)$'s (and)[en.wikipedia.org/wiki/… ] $\mathrm{su}(2) \times \mathrm{su}(2) \approx \mathrm{sl}(2,\mathbb{C})$ seems to be the way to see it :\
Ahh typesetting

2:16 PM
I think Penrose constructs an explicit stereographic projection from $SO(1,3)^{\uparrow}$ to the complex projective line and ends up with $\mathrm{SL}(2,\mathbb{C})$ which seems to be one solution

3:15 PM
Sort[Range[-90 °, 90 °, 30 °]]
{0, -90 °, -60 °, -30 °, 30 °, 60 °, 90 °}
oh, Mathematica
how you drive me crazy sometimes

4:05 PM
I just found I win 200 dollars in my last September-October invoices.

4:32 PM
@CaptainBohemian BOOM! :-)
@Runlikehell hi :-)

@JohnRennie Hi
I'll copy my question here

A black hole merger is much more complicated than my example of an object falling into a black hole because in my example the object falling in is small compared to the black hole i.e. the horizon hardly changes.
In a black hole merger there is a wholesale reorganisation of the two horizons.

ok, so your answer can't be applied at all in the way I was doing it?

I don't think so

But should't the higher peaks correspond to the maximum inspiral velocities?
Like in that moment there should be the max of the emitted waves right? two heavy bodies spiraling as fast as they could

4:42 PM
I guess that seems reasonable, but as I say the merger is a fearsomely complicated process and while I agree with you that's only a guess. I can't say for sure.

Ok, and can you say something about the last part? Where the amplitude decreases. I never really understood what that phase was, applying your answer I thought it could be the spiraling slowing down from our point of view
But they call "inspiral" just the part before the high peaks, so I assume those low amplitude waves can't be considered part of the slow inspiral phase

The amplitude of gravitational waves is determined by the rate of change of the quadrupole moment of whatever is generating the waves.
I forget the exact equation, though it's on the main site somewhere.

Yeah, and a slow inspiral has a lower quadrupole moment than a fast one
a lower rate of change of it

$$P = \frac{32}{5} \frac{G}{c^5} I_{zz}^2 \epsilon^2 \omega^6$$

so proportional to the sixth power of the frequency

4:48 PM
Yes.
As the objects merge the quadrupole moment decreases but conservation of momentum means $\omega$ increases. With such a high power of $\omega$ I'd guess the increase in rotation rate wins.
So the amplitude will only start falling when the merger is so nearly complete that the time dilation starts reducing $\omega$.

So your answer there is not that far from an application here, maybe $\omega$ doesn't go just like the velocity in your graph, but for sure it will grow, peak and then go to zero very fast, that would correspond to the gravitational wave profile we see

Yes

But at this point the nomenclature confuses me, cause i assume they mean exactly what they say with that nomenclature. They call inspiral just the phase before big peaks, this phase is called merger and the latter phase is called ringdown
In the interpretation just given the merger actually happens in the ringdown phase, or after it. While the so called merger phase is still an inspiral phase with the biggest frequency

The peak in my graph is at 3rs. Assuming the same is roughly true for the merging black holes they'll be close enough that their horizons have already started to merge. As I recall the two horizons bulge out to meet each other.
So it seems entirely reasonable to call this the merger phase.
Ringdown is when the merger is so nearly completed that the two black holes are no longer distinguishable as two bodies.
At this point we have a single perturbed horizon.

Ok, so we reach max $\omega$ when the merger is starting to happen. I guess that was the key point to reconcile that interpretation and the nomenclature
Can you see my formulas in LaTeX even if i can't? (I don't have MathJax in this browser)

5:01 PM
Yes. I use these scripts to enable MathJax.
It isn't enabled in the physics chat.

I'll have a look at them, I used to use chrome and had the extension there. Never chatted after I changed so it was a surprise for me to not see anything here
Thank you for your help, that profile is clearer now

5:54 PM
man, moving into a new apartment is a lot of work...

I finished moving into a new place last week, it makes you notice how much stuff you got
mostly useless

I gotta buy a lot of furniture...
and moving it all in and assembling it is gonna be a pain

@Rumplestillskin You make me recall localization of gauge field theories I read somewhere. I wonder why on earth localization of gauge field theories means.
Not long ago I dreamt of moving to a dorm costing over 5000 dollars each month and felt a relief. But I waked up finding it just a dream and felt disappointed.
I think I really like to migrate often. Keeping staying at the same place makes me feel abysmal ennui.

6:39 PM
@CaptainBohemian thanks for the response. I think the best way to do it is to introduce a local tetrad! However, I would like to see it used as an example somewhere as it’s not very clear to me what to do. For example, in the local tetrad, can I propagate a test particle and then transform back to Schwarzschild? I’ve no idea. Any ideas @JohnRennie? @Slereah?

@Slereah Quantum computing and the quantum quacks / JD physicsdetective.com/quantum-computing-and-the-quantum-quacks

@Rumplestillskin sorry for not really replying your question. But I wonder why you want to going from a global frame to a local frame. If there is a global frame to be used, isn't it better?

@enumaris But assembling can be fun too, even if you do it in this way: youtube.com/watch?v=MWuFQGrWda8

if there is a global frame, you can introduce spin structures, at least for some situations.

7:03 PM
@vzn Friendly reminder that name-calling is not cool. We just had a discussion about 'kooks' on Meta, but it applies to chat, too. If there are people who aren't in chat engaging in name-calling offsite, let's not import that bad behavior here.

7:15 PM
(name calling is very cool)

hmmm

@Slereah ?

it's true
all the cool kids are doing it

@rob its a blog post. you guys (mods) have the authority to reject them but dont think its open/ flexible policy.

@vzn Look. The author of that blog post is currently not welcome in our community, in no small part due to his habit of name-calling. We don't need his drama here.

7:28 PM
@rob it depends on how far the ban policy goes. didnt see any drama yet (in this room). the author is of interest to many who write here, eg as in my reply to slereah. hes a controversial writer indeed much like LuMo. thats what many blogs are about. its a physics blog. etc

That includes any unkind discussion of that person, which has apparently started popping up in here after an absence of some months.
I'm not trying to be stern or threatening. I'm just trying to remind folks to be considerate in the things that we write in here.

am aware of some of JDs long history, chatted him him some months myself here. agreed this has a highly volatile side/ element. but maybe we can all be adults in a 2ndary "at a distance" way. weve all been duly warned... many times actually and maybe nobody will respond at all (silence). etc

8:09 PM
You'd think after all these new Office versions Microsoft would finally address the huge bugs

2 hours later…
9:47 PM
@enumaris I moved a couple months ago and still don't have all the furniture I need!

If i wanted to generate a strong magnetic field by applying some DC/voltage on a copper coil, why would i have to use multiple smaller coils, rather than a single large copper coil? If the moving electrons generate the magnetic field, then the large copper coil should fit even more electrons as there is no insulation taking up space

@danielunderwood time to go shopping

I've been doing it slowly
I don't know that that's better than just having a couple really annoying days though

so far I got the bed and sofa
and some rugs
still need chairs, desks, TV's...etc...

9:54 PM
we are a clean family
no drugs

Gotta get some drugs for the living room, for the kitchen, for the bedroom...
The bed and the sofa are probably the worst bits at least. Though I'd imagine it's more of a pain in LA...I can just kind of drive and pick up stuff whenever

I want a big TV
that's gonna be a pain
the rug is also quite heavy...

Just amazon it!
Or get a new car to fit your new TV!

they are shipping my sofa in discrete fedex packages lol
then I gotta assemble everything

That's how mine came, but it ended up being one reasonable box and one ridiculously huge box with the entire frame. I think it depends on where it comes from though

10:01 PM
my sofa is designed to be modular
like you can turn it into a bed
by moving the sections around
and stuff like that
so it's all in sections

Ah that sounds quite nice

yeah, I like it :D

11:04 PM
hi all anyone still interested in making a Physics chat ad? think it would help... heres an example from Computer Science from a volunteer, it works, not fancy. any cs geeks around here plz +1 & plz drop by sometime(s) :) cs.meta.stackexchange.com/a/1594/699

### Computer Science

General discussion for cs.stackexchange.com