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12:04 AM
Hi
 
 
2 hours later…
2:26 AM
@DavidZ hi.
Do gravity can be drawn like the other vector field, what will be the components of the field,
?
 
 
1 hour later…
3:33 AM
@YuvrajSingh... Gravitational field? That's 11th grade textbook...
@Mathematica yo
@skullpatrol hi pal!
@skullpatrol XD lamo!
 
 
2 hours later…
5:59 AM
@JohnRennie hi.
 
@YuvrajSingh... hi :-)
 
@JohnRennie have you noticed my question?
 
4 hours ago, by Yuvraj Singh...
Do gravity can be drawn like the other vector field, what will be the components of the field,
This?
 
Yes.
I was referring to electric field.
And magnetic field.
How they oscillate to produce resultant EM field.
So I was looking how gravitational field look like?
@JohnRennie
 
in Newtonian gravity the gravitational field is just a force so it is a vector. In Newtonian gravity we don't get gravitational waves so there is no equivalent of an EM wave.
In GR the gravitational field doesn't really exist. Instead we get a field that describes the curvature of spacetime, and this is a tensor field not a vector field.
In GR we do get gravitational waves, but these are an oscillating tensor not an oscillating vector like an EM wave.
 
6:09 AM
@JohnRennie correct, I am not much known to tensor, tensor :we can transform the vectors using tensor.
Am I right? By the definition I stated above.
 
I'm not sure what you mean by transforming the vectors using a tensor.
Explaining exactly what exactly tensors are can be involved ...
 
There isn't really a good explanation without going into a lot of detail.
 
OK. I will read from wiki, I will let you if I have any kind of trouble.
 
 
1 hour later…
7:33 AM
@AbhasKumarSinha hello my friend
> Though Wuhan has a population of 11 million residents, population estimates for the surrounding province placed the full lockdown at 60 million residents. This made China's action the largest quarantine in history.
India is going to have to match that^
unless a vaccine is found fast
 
8:48 AM
@skullpatrol Thanks for calling me your friend bro :-)
 
9:32 AM
For the coronavirus
 
10:31 AM
Sorry, but can we maybe reduce the unprompted coronavirus posting around here a bit? I'm already bombarded with it by almost every other communication channel I have, it'd be nice if the h bar stayed just the h bar and didn't become the "newest updates on corona" bar.
I don't really mind people discussing how they're doing, but I do mind random news posts that do little more than push it back into my consciousness when I've just managed to escape it for a few minutes. If I'm the only one that feels that way, that's fine and I'll suck it up, but I'd appreciate a bit of restraint.
 
From the graph there: the population of China would start decreasing after 2030! (for India it is 2070)
 
Well, that was kind of the point of China's one child policy
 
Am I allowed to post jokes about coronavirus?
(actually there's a good argument for banning me from attempting jokes at all :-)
 
11:02 AM
morning
 
@JohanLiebert the number of males to females 100+ in China is interesting
 
@JohnRennie Nah, you're like a court jester - occasionally questionably funny but nevertheless necessary ;P One could say your humour is...infectious
 
@JohanLiebert 12,773 to 61,919
 
Mo_
@ACuriousMind populationpyramid.net/germany/2020 Why does the curve for Germany have a cusp at 2020?!
 
@ACuriousMind It's a serious matter. The number of bad jokes about coronavirus is rising exponentially and experts fear it might become a pundemic.
 
11:05 AM
@skullpatrol that indicates a better health care system.
@skullpatrol I too find it interesting that more women live longer than men (and it's not just the case for China only)
 
@JohanLiebert only on average. The oldest person in the UK is currently a man.
 
@JohanLiebert still so many more females?
 
Men have a lower average lifespan because more male children die young.
 
@Mo_ I don't know for certain, but I'd guess it is because the data before the cusp is real and includes immigration, while the data after it is projected from the current demographics and does not include future immigration (which is hard to predict)
 
11:10 AM
@skullpatrol 👆 (the video)
 
@JohanLiebert ok
 
Note the scale - it predicts the population falling by 200.000 between 2020 and 2025, but extrapolating from the past ten years one would assume we get at least that many new immigrants.
 
Mo_
It apparently means they're shutting the borders in 2020
 
rebuilding The Wall?
 
Dear God no, leave Roger Waters safely in retirement.
 
11:14 AM
Well, sure, with everything going on migration will probably globally be much lower in 2020 than usual, but I doubt that's included in these predictions
 
The data was collected in 2019, so I guess no.
 
@JohnRennie he says his inspiration was spitting on a fan who tried to climb on stage
 
Roger Waters says lots of stuff, and some of it is true.
 
Is there something like optimum population or something?
 
'optimum' in what sense?
 
11:18 AM
optimum for the environment
 
that's easy, it's 0.
 
@ACuriousMind optimum in economics sense. I mean after certain amount the population becomes liability and less than that might not be good for economics of the nation.
 
@ACuriousMind Modern day ecology partly relies on human intervention
Removing all humans would at least for a time have rather drastic consequences
 
@JohanLiebert it's a surprisingly complicated question. We all like having great medical treatments and sophistictaed computers, but these require human productivity to be high enough that we have the resources to spare to develop them.
 
@JohanLiebert That's an ugly road to go down. Letting the poor starve is "economically optimal". Letting the old and sick that can't do any work anymore die is "economically optimal".
 
11:23 AM
The economically optimal solution is to redefine the currency
$1 is now worth $exp(x)
that way we can have arbitrarily high money
 
@Slereah Uh...we can already have arbitrarily high money :P
just print some
 
@ACuriousMind brrr.money
 
that...doesn't look like a trustworthy link
 
@ACuriousMind No! The economics not just only deals with money but also deals with the health and well being of the society (I guess). I say this because my economics text book dealt a lot with the concept of poverty and health as it dear with money and industrialization.
 
freeform TLDs are weird and I'll never get used to it
 
11:25 AM
@ACuriousMind It is trustworthy enough
 
cool tune
 
@JohanLiebert That's not what I assume by default when someone asks about optimality in economics. I fully agree that economy and wealth should not be ends in themselves, but serve a greater good, but that's a particular political opinion not inherent in "economics".
 
I mean just look at the US
Highest GDP!
Including per capita
now look at the distribution and consider suicide
Hilarious
 
@Slereah Yes, I was mostly joking. I'm not an anti-natalist :P
 
Oh I'm not saying anti-natalism is bad
Zero might be pushing it though
 
11:40 AM
I have just received a text from the UK government telling me to stay at home!
Why me? What have I done? :-)
 
@JohnRennie been alive
too long
 
I have started making a lot of money. And the helping hands in doing so are:
Bribe
Black OP
Russian Oligarch
Invade North Korea
I do not know the meaning of (some) of these.
 
what.
 
11:51 AM
shitcoin 😂 😂 😂
 
I'm currently in an online classroom for school.
Let me tell you, it's not fun.
 
@JohanLiebert lamo'
1 new death in China and 30 under testing because of Hantavirus.
 
Does anyone here study online?
 
it's cringe
 
11:53 AM
@NovaliumCompany I do. Physics Wallah!
 
I like that.
 
@NovaliumCompany my brother is having to teach lessons online now.
 
unacademy
@JohnRennie link?
 
He isn't keen on it.
 
He's also a physicist?
 
11:54 AM
@AbhasKumarSinha it's a private network used by the school.
 
general relativity and phd?
 
I'm getting anxiety from school at home. That's great.....................
 
@AbhasKumarSinha biologist.
 
11:55 AM
@JohnRennie mind checking your facebook when you have some spare time?
 
And my niece wants to be an archaeologist. I am the only physicist in the family.
 
@JohnRennie I'm only jobess in my family!
XD
^Unacademy
 
@JohnRennie Aren't you a chemist? :P
 
Physical chemist. That's like a regular chemist but we are manlier.
 
@JohnRennie Sir, how to become a fellow of royal society physics?>
 
12:00 PM
@AbhasKumarSinha politics ...
 
@JohnRennie How to join politics?
 
You need to make friends and influence people. Being a brilliant physicist is optional.
 
@JohnRennie seems cringy thing
I've a professor who was once a member of royal society
Yes, he's also hyper active in politics
 
@AbhasKumarSinha humans are like that. Terrible species really.
 
@JohnRennie Why? Is that bad politics?
 
12:03 PM
Completely butchers all of Newton's laws
 
@AaronStevens I think Einstein was only person who did that.
 
Why not just give the advice you want to give? And it's fine if you want to make an analogy, but you have to get the laws right before you make that analogy
 
😂 😂
LMAO
 
@JohanLiebert congratz!
Donald Trump ne bola!
hahahah XD
 
12:08 PM
@AaronStevens like every time a so-called project manager talks about "maintaining the momentum"
 
There is a lot more there. If anyone wishes to see I can upload the screenshots. I am getting stomach ache just looking at those.
 
@AaronStevens I think the problem here is that the author had too much inertia in their blog, couldn't apply enough force to stop, and this was the result.
 
Is there anyone who doesn't get a good laugh by just looking at those comments? (I am in no way trying to make laugh of Mr. Trump, just of those pre designed comments)
 
It's a bit of an overdone joke at this point, really :P
 
@ACuriousMind sorry! :-P
 
12:14 PM
I came up with a new word - mayble, which means I am maybe able to do something...
I'm mayble to study but I have to find my mic
which means I'm probably able to study but...
 
@JMac Is the idea that your advice is meaningless unless you can say "Well science says so"?
 
I unamble to stop laughing!
 
I don't think they realize that all they can make are analogies
They really think Newton's laws are talking about their careers, goals, etc
 
mayblen't
 
At least that's the vibe I'm getting
 
12:18 PM
New word: suren't
I'm suren't if this is going to happen
gimme the bible i'mma bout to rewrite some sh*t
Cyril (born Constantine, 826–869) and Methodius (815–885) were two brothers and Byzantine Christian theologians and missionaries. For their work evangelizing the Slavs, they are known as the "Apostles to the Slavs".They are credited with devising the Glagolitic alphabet, the first alphabet used to transcribe Old Church Slavonic. After their deaths, their pupils continued their missionary work among other Slavs. Both brothers are venerated in the Orthodox Church as saints with the title of "equal-to-apostles". In 1880, Pope Leo XIII introduced their feast into the calendar of the Roman Catholic...
those guys created the bulgarian alphabet
 
@AaronStevens My idea is that if you use really vague analogies you can make them apply pretty much anywhere retroactively to explain things.
 
I'm mayble to surpass them
 
@JMac I think analogies are fine, but don't butcher the base of the analogy
 
12:54 PM
@JMac The entropy of an isolated blog post that is not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium.
 
1:21 PM
Whi do they sign online petition?
Is that helpful?^
 
1:33 PM
0
Q: Please help with alternative wording of question to conform with expectation of site

user1886419https://physics.stackexchange.com/questions/536455/is-there-an-alternative-number-to-the-100-miscommunicated-and-hard-to-comprehen What changes would need to be made to have this not be shut down? Trying to determine: why this is the best number for its purpose given how confusing it is if th...

 
 
4 hours later…
5:11 PM
Good news
the egg is back
by which I mean
My Amstrad CPC works again
 
Did you decide to replay your game collection chronologically out of boredom or something? :P
 
Eeew is that a cassette player? :P
 
No, but it was broken
So I spent some time repairing it
Loaded me some Fantasy World Dizzy to test it
 
neat
 
5:31 PM
Wonder how Ryan is doing?
::crickets::
 
@Slereah Wait, doesn't that TV shoot electrons? I have the same next to me. Please don't remove the front glass, I tried and it didn't end up well.
 
Well I mean
CRTs have a vacuum tube inside
 
By the way, on my CRT TV, when I turn it on and I put my hand to the glass, with my headphones one, weird sounds start to go through the headphones
 
Trying to disassemble it will have many bad effects
like exploding
or imploding, I guess
 
@Slereah Wait, if I throw the TV on the window, it will explode?
 
5:38 PM
Well not explode explode
But
It is not advised
 
more like what happens to an aerosal canister if it gets punctured
 
Why would a vacuum "explode", I mean, the vacuum will just get filled with air and that's it?
 
The glass tube that makes the CRT screen is a vacuum, since electrons wouldn't go very far in air
@NovaliumCompany hence why I specified implode
 
the problem is how fast said vacuum gets filled with air
and the resulting mechanical pressures etc
 
If I poke a whole in the vacuum thingy and cover it with my hand, my skin would be ripped off?
 
5:40 PM
it probably wouldn't feel too good
 
Probably not
I mean the inside is empty
the outside is normal
the pressure differential is just one bar
 
right
 
coolio, physics
 
I do have a friend who works in the oil industry
 
the bigger issue is that it might fracture in the process
 
5:41 PM
That's why if you go to space without space suit, you don't get ripped off, you just get... bubbly? :D
 
Who told me of an indicent where deep sea divers were in the decompression chamber
And then there was a break
 
oof, yeah
i've heard of that
 
So they went from like 10 bars to 1
It didn't end well
 
@Slereah They found some inner organs a few decks above.
 
@Slereah You mmean, 1 to 10?
 
5:42 PM
@NovaliumCompany No, this was on the way back up
 
I have seen the report. It has pictures. Don't look it up.
 
one incident of of that:
 
@NovaliumCompany Space decompression only happened once
 
So the inside of their chamber was 10 bars, and went to 1?
 
and it was only a glove
 
5:43 PM
Byford Dolphin is a semi-submersible, column-stabilised drilling rig operated by Dolphin Drilling, a Fred. Olsen Energy subsidiary, and in 2009 contracted by BP for drilling in the United Kingdom section of the North Sea for three years. It is registered in Hamilton, Bermuda.The rig has suffered some serious accidents, most notably an explosive decompression in 1983 that killed four divers and one dive tender, and badly injured another dive tender. == Description == Byford Dolphin drilling rig is an Enhanced Aker H-3 design which was built by Aker Group at the Aker Verdal shipyard in 1974. Between...
 
Some astronaut had a break in his glove
His hand ended up super swollen
 
@Slereah I don't understand how this works. How can a person survive a 10 bar thing?
Is it a lot?
 
Gruesome!
 
@NovaliumCompany Why wouldn't they survive it?
 
@NovaliumCompany Humans can withstand a few atmospheres of pressure if they do so gradually
 
5:44 PM
there's been other incidents like that, but i'm failing to find them
 
Emphasis on gradually
 
Sorry I'm not familiar with how many bars a person can survive
 
If the change is abrupt
 
yeah. one big worry is the bends
 
That is when they explode
 
5:45 PM
if it's very slow, you're fine.
 
@Semiclassical Well the bends wasn't an issue there
it was the 'splodes
 
if it's too fast, you get the bends. if it goes really fast, you get the burst
 
4 mins ago, by Loong
I have seen the report. It has pictures. Don't look it up.
 
5:47 PM
even just the abstract is chilling
 
@NovaliumCompany 10 bars is just ten times the pressure the normal atmosphere exerts on you - it's not as if that would crush you or anything. The problem is not in tolerating it, it's in getting there
 
glad i'm not looking at it
 
Another gruesome photo is the Apollo I fire incident
It looks very sci fi horror
 
Stupid question - do airplanes, when in high altitude, to equalize the pressure to 1 bar (so humans are comfortable) is there some type of mechanism that just shoves up air and air until pressure is right?
 
@Slereah ugh
the phrase which always comes to mind with Apollo 1 is "blast kiln"
 
5:48 PM
@ACuriousMind What's the problem with fast switching of pressures?
 
Ever seen a balloon pop?
 
We have air trapped inside of us.
 
@Slereah yes
but humans don't pop
 
your lungs contain lots of little air sacs called alveoli where oxygen enters the blood
 
They do with that large a differential
 
5:50 PM
even if you don't pop, said air sacs certainly can
and then you've got hella internal bleeding
in your lungs
also impacts on the brain. like whiplash but worse
 
I'm learning more now that I did the entire online school day.
Thank you guys.
What's the pressure of the alveoli?
Does it equalize with what you inhale?
 
Try Wikipedia pal.
 
:-)
 
Is that penguin the one being celebrate there or is it just a coincidence? (👇)
 
5:55 PM
1 min ago, by skullpatrol
Try Wikipedia pal.
 
I thought wikipedia had a list of decompression chamber failure incidents but I'm only finding the Byford Dolphin incident
 
Okay that was a bit messy. I have to dig a little bit more.
 
digging is good practice
 
I was just searching for some treasure below some random X sign!
 
like a reporter/gold miner
aka Google-fu
 
6:00 PM
Today I learned the pronunciation of google
It's goo.gl
Not : goo.gal
 
10^100
 
In the process of diffusion, I understand that it's "random motion of particles" that causes them to go from high to low concentration but I'm still a bit confused. Do the particles push off each other and that's how they expand into low concentration or is it simply that with their random motion, they can't go to where there are already particles of their kind, so they go to where there are not simply because that's the only place they can go and they need to move cuz random motion?
nvm I watched a khan academy video
 
dsm
6:28 PM
Has anyone seen the work of Anthony James? One of the most visually stunning things I've ever seen. Watch in 4K if possible:
 
6:44 PM
Are ions not atoms? I can't find anything official suggesting otherwise, but someone well educated is very convinced that they aren't considered atoms... but I don't see much else supporting that.
 
given that "neutral atom" is a phrase, i doubt it
that said, not all ions are atoms according to Wikipedia: "An ion is an atom or molecule that has a net electrical charge."
so allowing for charged molecules as well.
 
@Semiclassical But molecules are also defined as made up of atoms, so they are still comprised of atoms by any definition I can find.
 
sure, but
a brick house is not a brick :/
 
Oh, I forgot the specific wording. "Plasma isn't atoms" was the specific way they were wording that. They seem very convinced that it's true, but when I asked for references the first time it was "well maybe it's just me"; the second time they mentioned that they don't know any physicists who would disagree with them... then disengaged again when I asked for any good reference.
 
i mean
plasma is made up of atoms
 
6:56 PM
Would you say the sun doesn't have atoms because it's a plasma? That just seems strange to me.
 
I mean
This sounds like a semantic issue
I think they're taking the stance that an atom is natural (i.e. has electrons)
 
if I have a house made of bricks, I'm fine with saying "the house contains bricks"
but I wouldn't say "the house is a brick"
 
How come the panda module in python doesn't need to be called?
 
or, more simply: "my house is brick" is fine, "my house is a brick isn't"
 
for example, if I do something like print(date.index) I dont need to add ()?
 
6:58 PM
@Semiclassical But you wouldn't say "I can't count the number of bricks in my house because my house isn't a brick", would you?
The argument was that you can't estimate the number of atoms in the universe based on stars because stars are plasma which isn't atoms...
 
sure I would. an implication is vacously true if the premise is false.
 
@Semiclassical If your house isn't a brick, but made of bricks, it would be weird to say "I can't count the number of bricks in my house because my house isn't a brick"
 
"If my house isn't a brick, then I can't count the number of bricks in my house."
= "If I can count the number of bricks in my house, then my house is a brick."
okay, yeah, wouldn't say that
 
@Semiclassical That makes no sense... "If the world isn't a tree, I can't count the number of trees in the world"
 
"B because A" is logically equivalent to "If A then B" is logically equivalent to "If not B, then not A"
and the last statement indeed doesn't make sense
so yes, I wouldn't say it
but "plasma isn't atoms" seems like a distraction to me. plasma is composed of atoms
and that's all you need to justify counting them
 
7:14 PM
@JakeRose Why would you need to add ()? Index is likely an attribute, not a method
 
ahhh
HAven't struck up against attributes vs methods a whole lot
didn't realise
 
7:42 PM
@Semiclassical could you not also have 'B because A' but also 'C because A'?
I don't know much formal logic
 

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