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3:01 PM
@BernardMeurer, there's several keyservers offered, which one is best?
 
Doesn't matter :)
Pick the one that's easiest to type
Also, I hadn't exported my privatekey, that was just my key ID
v. good
 
hkp://keys.gnupg.net
 
What's your key ID?
 
@ACuriousMind and reviewers: Could one argue to keep it open because of the physics word space-time in the question formulation, cf. this meta discussion?
 
@heather
 
3:08 PM
@Qmechanic, should i put the word spacetime in all my math questions here then?
or any physics related word?
 
Also, which server is that, idk it
Export to hkp://pool.sks-keyservers.net
 
@BernardMeurer, id: 4D6B346C
that isn't a option
that key server
 
@Qmechanic I guess one could argue that but the physics question would be why do we use a manifold to model spacetime, not what is a manifold. The answers touch on the former but most seem to interpret the question to be mainly about the latter, which is purely mathematical no matter how you look at it.
 
@heather I hate Ubuntu
@heather I find nothing containing that ID
@heather Settings Configure > Key Servers
Add that keyserver
 
okay one moment
there's no settings>configure>key servers, there's settings>configure shortcuts, settings>configure toolbars, and settings>configure kgpg
 
3:15 PM
Configure kgpg > Keyservers
 
okay
 
Let me know once you have exported to hkp://pool.sks-keyservers.net
 
exported
 
Got it!
Do you have a browser on the Linux side?
-----BEGIN PGP MESSAGE-----

hQEMA4rIQuCOXkg5AQf/QDgTD+me3VZ34A3CpjXUXjrzmDENk0evjNwxGgmxCWml
JjZpVS4KDf6tKNB5ByqR47L1FeqWNnvVh0xz+iHMFSXWdXAp9v7uR1dBmVZ+NWpk
xelYtIMSNGj0cvS6adiqUr1A733r+zfCqTzV+ufRz+PP873KeqwsCypxdwUO8uq+
rk3OwSFpNemCcXb7bV0Gc9dCnMxGIRvGxdnHfFXvf5f47hbO+WlZzh39E6rqK1pi
W1fQ9zAu0KKK+wLA89KJ9g95mrBbx2fibm13/ICM0mQDD/HFoTrw51wDUTnnsCBX
l5iIRPFpBY+9x8m92mOx3JZsect+L7eoWwGwAog20tJFAVYxapuA4oX/rbFUzEvP
1EKtgqomo313b5yS/LqIALZ0BPOvh8fHezyNNFW9zGkqo2a/BDyc4i0W3LKUi4uS
IMnieWbb
=YURY
-----END PGP MESSAGE-----
 
a bad browser, but yes
 
3:19 PM
You can get my key by clicking on Key Server Dialog
And searching for my name
"Bernardo Meurer"
@heather Install Firefox?
sudo apt-get install firefox
 
lol, do all your account names contain "nerd", @heather?
 
@ACuriousMind I have that theory too, lol
She'll regret it when she's older and needs a work email :P
 
@ACuriousMind, a lot of them, yeah =P
@BernardMeurer, found you
lemme install firefox
 
do I "import"?
 
3:23 PM
Yeah
 
k
 
Go on File > Editor
Write me a message!
Click encrypt and select me
 
it says no key imported =(
 
Do I show up on your key list?
 
no, i'll try to import again
got it to import
 
3:27 PM
:)
 
now you're not showing up when I click encrypt
=/
 
hey anybody here expert in fluid dynamice
and strong gravity stuff
can he//she kindly share their expertise here:
0
Q: Behaviour of Fluids under strong gravitational field

XaselWe were being given intro to fluid dynamics at our school So the thing that sparked me up is $ g$ in expression of: Static pressure of fluid Bernoulli Principle I am curious how fluids(especially liquids) will behave when they are near or at strong gravitational fields and when they approach...

 
@heather Right click my key
and click sign
 
okay
which sign? "sign key" "sign user ID" "sign and mail user id"
 
User ID
and Key
In any order
 
3:31 PM
@BernardMeurer Don't you want to explain what signing is first? :P
 
@ACuriousMind Nah, you can do it :P
 
okay
I'm chatting from the linux side of my computer now
yay firefox!
 
Well, signing another user's key means that you have, in some way, verified the user is who they pretend to be.
 
Conventionally, I would only sign the key of someone I have met in person.
 
3:33 PM
@heather What ACM is saying is important
 
The idea here is that of a "web of trust" - if people I trust have signed another user's key, I will be reasonably sure they are who they say they are even if I have never met them.
 
okay...
well, i trust the bernard meurer is bernard meurer
which is kind of sad, because this online stuff is the stuff you're decidedly not supposed to do
but i do trust him
so
 
Well, his key was generated today and doesn't have any signatures. That's suspicious ;)
 
suspicious?
how so?
oh...well. um.
 
Because I could be a russian spy
that killed the real me
 
3:36 PM
I'm kidding. But generally I would be suspicious if the key someone sent me was just generated, unless I just walked them through how to do it
 
a bit late for that. 0_o
 
and created a new keypair pretending to me me
so we can talk and I can steal our valuable info
 
right
so, i've signed you
 
In this case we have, however, witnessed the reason why the key is fresh :D
 
and i've written a message, i've clicked encrypt, clicked you, and now it says "begin pgp message" in the text editor
so now what?
 
3:37 PM
I guess this will be added to list unanswered question of mine:physics.stackexchange.com/questions/298052/…
 
wait a bit @Xasel, if someone wants to/can answer it they will
 
@heather See if you received an email
 
in my gmail (open on the chrome side) i'm not getting an email
 
Wait, then
Open it on the linux side
SO
 
see...well...did i tell you that my chromebook has, um, issues with that?
 
3:39 PM
I have to go have lunch
 
enjoy your lunch!
 
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

- -----BEGIN PGP MESSAGE-----

hQEMA4rIQuCOXkg5AQgAprJ2FhDsP6+G3GSC0SKTuPeVuJNS9LJRp8Vp/cXxrzXa
0ghQxIeHAOg/bG1clsvRHRIuTvkBVr0Z37iJ2cL0FRobMj5bcrhS6kpcALD+mAjH
gyRy78UQtWtQ+Uz1PnlvsKnPLPPa8nQ65fpfyWWC5Q2F/J4Avwfa5dDwEfRFRy5k
QpL9cfpIonOF2wU/vT/Ey59Yv5lS4FQ+y3o9hRGJn/y+oLjuvAUDe5CNH/MuuO1s
KDRy1+V3kW1abaB513j8qrCKGWoV0tZKPiDsjS9/x4C+tSygk5MnRgnyQNXXXwgJ
dUDjM3cRFehByB6YJJQ1qLQL1zLQnYkpF+DMypZ4y9JRAWAmWdZWh9JxnQclg5QZ
Ym+AsM5WEL7WaGY3UbQsiQ52R+xNNAwn19yk5pR101zCUg1RVSeKgy0OMuEdFSuo
Get cracking to decrypt that
There is a signature, telling you I actually wrote that message
and a message, just for you
@ACuriousMind Help her plox
I gotta go
brb
 
bye
I got it decrypted!
=D
-----BEGIN PGP MESSAGE-----
Version: GnuPG v1

hQEMA+bB3Dr9WyBCAQgAo3+htgxKrpuBqn/g/aN+x+UMqHcRdmdsQwyAw5pDzZ4M
IDxLFnRZ7JNuGVi2wgi0gnt5WOIHf0fFy1Mu0IGpNH9MUmiPwRHgk55kTF/iBZ9Q
gkWTRK+VRkAxiy/BqcG0wbwrjwkABEFDhF06vCy/u1n+iQn0yBn9Ey6zm7jhlwxW
kiENN89XyeUEIPoEaXYbx8KXgzv1BXId1BkvcW6avcMEpP38F1At+vLBaFmYnWOF
WzrEZT1Zw68IKwlPGLWbqN2370m7MI8LvsmQ9mQ6XN7K7UcfYYRkyIvLf1Gg0XQB
mUaqtJD0RXGTwkzGtT5Fp3HuS0ktDwqPi+INQKH4etJLAYmEyZG5RA8jV0Hn/X8k
7qVQPgyJop/ewh2K6PzqtFJEnRBpsV2rACAL9jtTmp0q2tW6haxL33TnmS0xR4a6
@BernardMeurer, ^
 
@heather @BernardMeurer all good fun, but why wouldn't you just use gmail?
 
(::shrugs::) because I'm a spy at heart
=P
 
3:50 PM
There is an undeniable entertainment factor in getting these things working, but the novelty has a tendency to wear off after a bit :-)
 
@JohnRennie The paranoid might say that the gmail encryption is symmetric TLS (right?), so using additional asymmetric RSA protects you against a wider variety of attacks?
 
and if you're an international terrorist you may worry about such things.
 
oh, I'm sure @JohnRennie
but still
why not?
 
4:27 PM
Okay, I'm back!
@JohnRennie To teach her about GPG :)
@heather
-----BEGIN PGP MESSAGE-----
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 
@BernardMeurer, okay, decrypted, let me send you a message...
 
Too broad? Too little effort?
0
Q: Specific heat fermi gas bose gas in 2d

Bruno MurinoHow can I find the specific heat of a T = 0K fermi gas and bose gas in 2d?

 
4:42 PM
-----BEGIN PGP MESSAGE-----
Version: GnuPG v1

hQEMA+bB3Dr9WyBCAQf/Re1ZhxupBhOhfCvRIQYNPT1HcF6tZd2bbfMrUWC01XDe
m7NBbaNGB0rUoFimyBBzaR5KRFIphe5DapTWBayb0h6jOE/Q3kQIoFI48GOp4tSc
MG8WUZnkmi/skNNNjPhtXzc/nCyhjNcgDJR/3RK3I5J8DsqsGL28VaEQcly8utsS
fZgDnHvSMb0cMlrhE/rRNFjywEdMCQ/BV1e8wlmI4zmWAyyhiuwAtNzqnTvHoemO
hi2SK6+grijmqm+9RjxslsGGvA4J2Q8B9LbY9YxOfAlcqvpb/31hRS/yYY/kmSxd
Y7IaW0u9h51qAQ2UXkEoZn1Nft5tXGJOnN5GB59UT9LAiQGHztQc3lcFsxTBjU9D
3n1NCRAFPzbp3ihkene0bX8GU4TI4jeKS7KTKY3vi6g60zbFdD/aSTICi8iczWjX
@BernardMeurer, ^
 
Hey you kids know you can send those messages via email, right? :P
 
=P
teenager @ACuriousMind ;)
 
I'm also a bit worried about the "v1" there
 
what about it?
 
The current stable version of GnuPG is 2.0.30
 
4:44 PM
oh...
how do I update?
 
-----BEGIN PGP MESSAGE-----
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Q: Can't upgrade GNUPG?

Joshua Hales SilvaI'm trying to upgrade my 1.4.14 GNUPG to 2.0.26 version and the repository has 1.4.14 version... I tryied removing it and building the lastest version from the official GNUPG website downloading its source code (2.0.26), but I can't do it! it is always 1.4.14! and gpg generates this key: -----B...

meh, GPG 1 is still fine
@ACuriousMind What'd your Key ID
 
@JohnRennie No effort, homework-like.
 
Lemme add you
GPG IS THE NEW FACEBOOK
 
@BernardMeurer, your message isn't decrypting
 
@BernardMeurer 2D700203, but my point was that these messages are rather cluttering the chat and are of no interest to anyone but the two of you.
 
4:47 PM
-----BEGIN PGP MESSAGE-----
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@ACuriousMind Are you on any keyserver
@ACuriousMind Okay, okay, we'll stop :P
Got you
 
@BernardMeurer, nice, Make is the best!
 
gmx.de? REALLY?
 
@BernardMeurer Should be on sks and mit at least
 
Yeah, it's on sks
 
sks?
 
4:49 PM
It's the keyserver you got my keys from
 
@BernardMeurer At the time I made that, the 1 GB storage they offered was really good.
 
oh, okay
 
@ACuriousMind I forget that you're old :P
 
Hmm, I found one person, but I don't know if it's right
 
@BernardMeurer Yeah, I think I have had that address for about 10 years now
 
4:51 PM
well, okay, gmx.de is there, so that makes sense
 
Might be a little less, I don't remember
 
it's weird associating a real name with you
 
@heather If he has a viking name it's ACM
 
yup, viking name
 
4:51 PM
many umlauts
 
my real name is not a secret
 
@ACuriousMind Okay Martin
or should I say...
JOHN DUFFIELD
 
er...that's not a viking name
whoa, that just got weird
gmx.de, i've never heard of that before
 
I literally broke my entire encryption today
 
because you shared your private key earlier?
 
4:55 PM
I hadn't
but I freaked out and thought I had
so I deleted it
and revoked the key
 
Was it the fingerprint?
 
Ye
But then everything was bound to it
 
so you were freaking out and it was your public key all the time?
 
and now I gotta unfuckup everything
Ye
 
lol
 
4:56 PM
I gotta start drinking less
 
(::shakes head in sympathy::)
anyone want to help with a python infinite loop that shouldn't be happening?
 
Now I'm anxious about drinking too much. I'm going to have a beer to relax
 
Purely out of idle curiousity, how do I look up a key id like the one ACM posted? Is there an equivalent of DNS for GPG keys?
 
@JohnRennie Uhum, lemme get you a link
It doesn't work too well
 
@BernardMeurer that doesn' find anything when I enter ACM's key ...
 
5:00 PM
IIRC there are some really good windows GPG clients
Yeah here it's not working either
 
Not that I'm stalking him - I have no other ID to test with :-)
 
but it works on GPG
E421C74191EA186C
Try mine
 
mine's back in the transcript a bit
(my ID)
4D6B346C <-here it is
how do you know how many people have your id?
 
gives "no results"
 
Yeah, idk what's up
 
5:03 PM
eh, I do exist, I reassure you
::shrugs::
 
@JohnRennie get WinGPG
SIGN ME PLZ
 
The website doesn't work for me, either, but Thunderbird's enigmail extracted the keys without problem
 
Same here, kmail works fine
 
OK WinGPG is running, but I see no way to input key ids ...
 
import keys
 
5:08 PM
It appears to offer only import of .asc files
 
Bah, I was sure it was WinGPG the name of the good one
I'm on a roll today
-----BEGIN PGP PUBLIC KEY BLOCK-----
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 that in a text file
and import it :P
 
Too late. It has been uninstalled.
My patience for things that don't work is severely limited these days.
 
Well, there IS a good client for windows
I just seem to have the name wrong :)
 
GPG4Win!
Thanks Google!
 
5:15 PM
@JohnRennie, "that bernard can't remember" =P
 
OK let's try that again ...
It worked :-)
 
The trouble is that having satisfied myself that it works i actually have no reason to use it :-)
 
Lol, let's exchange illegal material
 
I having trouble asking a question on this site without it sounding off topic. I don't want to clutter the site with more attempts to ask off topic questions. Is this a chat room a place to get advice on getting my question ready or at least find out if it's appropriate for this forum?
 
5:21 PM
Sure why not
 
@JordanEvans Hi Jordan, yes here is the ideal place to ask.
 
@JohnRennie exellent
I'm looking the data that will give me a number will tell me how much technology has subsidized the average person's life in modern society compared to hunter gather days or agrarian.
That question was off topic, so I need help with it.
 
I don't really think you can really rephrase it in a way that's relevant to physics
you might want the sociology people or something
 
Yeah @Slereah is right
 
or history
 
5:27 PM
Worldbuilding maybe
 
@JordanEvans What sort of "number" are you looking for? Life expectancy? Child mortality?
 
@JordanEvans I don't understand what that means.
 
I was assuming because one would be measuring energy/work it would make it appropriate for here.
 
What does subsidy mean in this context?
 
@JohnRennie For example, once we had to pick our crops, now we have machines do the picking. Energy and technology has subsidized our lives. I'm guessing the work we once used to do can be quantified. That amount is the subsidization.
 
5:31 PM
it is really a question that would be more at home on the history SE, I think
 
I thnk you mean how much has technology improved productivity ...
Hi @Copernic
 
@JohnRennie That is good way to say it.
 
@JohnRennie How can "leichester" be lester?
 
@JordanEvans in that case about 99%, possibly 99.9%, of current productivity levels are due to technological developments since our hunter gatherer days.
@BernardMeurer that's the way it is. Logic doesn't apply to these things.
 
What the hell
 
5:33 PM
@JohnRennie Okay, so what's a good way to ask that for this site or is really not appropriate for this site?
 
@JordanEvans Work, as measured by the physical unit "Joules", is a rather poor measure of "productivity" or progress. How difficult, time-consuming and relevant a task is is almost completely unrelated to how much physical work you have to do to complete it.
 
Not appropriate
 
I don't think it's appropriate here. Sorry.
 
Your question is not about physics, it's about economics and sociology
 
is there an economics/sociology se?
 
5:35 PM
Yes
 
Since @Copernic is here, this is a potentially interesting question:
1
Q: Does earth rotate in a shorter time at 0m than at 5000m?

CopernicWe know rotation period of earth (stellar day) is 86164.098 903 691 seconds of mean solar time. At 0m time is supposed to be more dilated than at 5000m because of gravitational time dilation. Then hypothetically we count less nanoseconds at 0m relative to 5000m of altitude. Then assuming this ...

 
well then, @JordanEvans, try the chat room on economics/sociology/whatever se
 
Does a very rotating rigid body develop internal stresses due to time dilation within it?
 
Thanks, I see.
 
There are no rigid bodies in relativity
 
5:37 PM
@ACuriousMind one where in the steady state the shear is everywhere zero
 
And yes, I'm pretty sure a body will be ripped apart by internal stresses before you will noticably detect "time dilation"
 
The shoulders of giants, the great subsidy.
 
@ACuriousMind I don't mean a Ehrenfest disk type rotation, I mean rotation like the earth is rotating.
 
@JohnRennie Where's the difference, except for the Ehrenfest disk rotating much faster?
 
Since the gravitational time dilation varies from the core to the surface does that effectively mean the angular velocity changes with depth.
 
5:39 PM
1
Q: Does earth rotate in a shorter time at 0m than at 5000m?

CopernicWe know rotation period of earth (stellar day) is 86164.098 903 691 seconds of mean solar time. At 0m time is supposed to be more dilated than at 5000m because of gravitational time dilation. Then hypothetically we count less nanoseconds at 0m relative to 5000m of altitude. Then assuming this ...

 
Assuming the velocity of rotation is small enough for special relativistic effects to be negligable.
 
@JohnRennie Well, that depends in what frame you define "angular velocity", no?
 
You said "Everything (except c of course) is faster in a dilated frame. That's how time dilation works." Twin paradox doesn't work that sense.
 
@Copernic the twin paradox works in exactly that sense:
39
Q: What is the proper way to explain the twin paradox?

John RennieThe paradox in the twin paradox is that the situation appears symmetrical so each twin should think the other has aged less, which is of course impossible. There are a thousand explanations out there for why this doesn't happen, but they all end up saying something vague like it's because one tw...

And see also:
41
Q: What is time dilation really?

John RenniePlease will someone explain what time dilation really is and how it occurs. There are lots of questions and answers going into how to calculate time dilation, but none that give an intuitive feel for how it happens.

 
-2
Q: Can Tachyons at Rest be able to Resist the Gravitation Pull of a Black Hole?

iFloruff391_MewI'm new here, but recently I have been looking around for things on tachyons and black holes. I understand that because, theoretically, tachyons can travel faster than the speed of light, they would be able to escape a black hole due to them possessing a speed faster than a black hole's escape ve...

is this really off-topic? it seems on-topic to me...
 
5:43 PM
@heather It's unclear what it's asking. Tachyons are not expected to have "positive mass" and they can't be "at rest".
 
@heather for that question to make sense you have to define the equations of motion for your hypothetical tachyon.
As it stands the question is unanswerable.
I VTC'd as non-mainstream.
 
"Everything (except c of course) is faster in a dilated frame. That's how time dilation works."


Even human cell life cycle, right? Then you are telling me that both twins have the same apparence, but one is older than the other one.
 
@Copernic I'm telling you that you need to read the articles I linked to understand what time dilation is and how it works.
 
@ACuriousMind, @JohnRennie, that makes sense, thank you.
 
I read it! Thx
 
5:45 PM
The twin paradox is probably the single worst understood physical situation in all of science.
 
@JohnRennie The twin paradox is probably the single worst understood explained physical situation in all of science.
 
@heather If you're intrested I can recommend an excellent book on tachyons, FTL travel, etc. I know, I know, yet more interestign books :-)
@ACuriousMind not now it isn't (John says smugly :-)
 
@JohnRennie, I'd be glad to read it =) I love exploring breaking the laws of physics
 
"Everything (except c of course) is faster in a dilated frame. That's how time dilation works." I am sorry, but I disagree.
 
@JohnRennie I'm rather sure the professionals understand it perfectly fine. They're just, for some unfathomable reason, fond of acting as if it's all a big mystery.
Same as with the virtual particles/quantum fluctuations schtick - they know better, they just act as if they didn't for reasons I don't understand :P
 
5:49 PM
It's a really well written book. Enough maths to be interesting without so much maths it's impenetrable.
@Copernic An observer chooses a coordinate set, and one of the coordinates is $t$. All observers do this. Everything is then measured using the coordinate time $t$.
 
ooh...what level of maths are in there? @JohnRennie
 
Time dilation happens becauise a different observer will in general be using a different set of coordinates, and the two $t$ axes will not match up.
That means different observers assign apcetime events to different values of $t$.
But with a single observer's cooordinates $t$ is just a time axis as we (think) we all understand.
@heather You would have no problems with it.
The level of maths is around A level as taught in the UK, i.e. ages 17 to 18, but you're easily up to that level already.
 
@JohnRennie, okay, I will most certainly add that to my list, it looks incredibly interesting!
 
If you wanted an ebook then erm, cough, a friend of a friend might have a copy.
Just to decide if you want the hardback of course :-)
 
gotcha...i think i'll just purchase it; i prefer physical books =) thanks for the offer though!
 
5:55 PM
@Copernic the point is that an observer at some distance $r$ from the centre of the Earth chooses a time coordinate and in that coordinate system the angular velocity of the Earth has some constant (i.e. independent of depth) value.
An observer at a different height $r'$ does the same and because their $t'$ axis doesn't match the other observer's $t$ axis they measure a different, but still constant, angular velocity.
But I think there is some interest in calculating the four acceleration for corotating points inside the Earth to see what the value of $a^\phi$ is and whether it varies with depth.
 
@JohnRennie I found this today, it feels strangely relevant
Bullshit (also bullcrap in the US) is a common English expletive which may be shortened to the euphemism bull or the initialism BS. In British English, "bollocks" is a comparable expletive. It is mostly a slang profanity term meaning "nonsense", especially as a rebuke in response to communication or actions viewed as deceptive, misleading, disingenuous, unfair or false. As with many expletives, the term can be used as an interjection, or as many other parts of speech, and can carry a wide variety of meanings. A person who communicates nonsense on a given subject may be referred to as a "bullshit...
i.e. specifically the last section:
 
@EmilioPisanty relevant to what? Our resident GR expert? :-)
 
> Bullshit asymmetry principle
> Publicly formulated the first time on January 2013 by Alberto Brandolini, an Italian programmer, the Bullshit Asymmetry Principle (also known as Brandolini's law) states that:
> > The amount of energy needed to refute bullshit is an order of magnitude bigger than to produce it.
5
 
@Copernic NB Emilio doesn't mean you, he's referring to someone else :-)
 
And you are saying me that the observer in a dilated frame wil measure a quicker velocity than the other one. That is absolutely nonsense.
 
5:59 PM
@Copernic It isn't nonsense, it's what happens.
 
@EmilioPisanty, so true.
 

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