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12:45 AM
@bolbteppa oh lawd
 
 
5 hours later…
6:12 AM
There are plenty of criticism of math textbooks
Some by none other than Feynmann
 
 
1 hour later…
8:28 AM
Feb 20 '15 at 15:17, by ACuriousMind
A lie-to-children is a simplified explanation of technical or complex subjects as a teaching method for children and laypeople, first described by science writers Jack Cohen and Ian Stewart. The word "children" should not be taken literally, but as encompassing anyone in the process of learning about a given topic regardless of age. It is itself a simplification of certain concepts in the philosophy of science. Because some topics can be extremely difficult to understand without experience, introducing a full level of complexity to a student or child all at once can be overwhelming. Hence elementary...
vs
18 hours ago, by bolbteppa
Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong is a 1995 book by James W. Loewen, a sociologist. It critically examines twelve popular American high school history textbooks and concludes that the textbook authors propagate false, Eurocentric and mythologized views of American history. In addition to his critique of the dominant historical themes presented in high school textbooks, Loewen presents themes that he says are ignored by traditional history textbooks. == Themes == In Lies My Teacher Told Me, Loewen criticizes modern American high school history textbooks...
 
 
1 hour later…
9:41 AM
@EmilioPisanty Haha, thanks. You're the second person to send me that.
 
10:25 AM
@JohnRennie I have a question!
 
10:37 AM
@Akash.B hi :-)
 
11:19 AM
@JohnRennie hi again
I have a doubt regarding newton's law of gravitation and 2nd law of motion
One law says that force experienced by a body is constant while the other is saying that it varies with distance
Which is right?
 
@Akash.B hi
The second law doesn't say that the force is constant. It just relates the force to the acceleration.
In fact you have to combine the two laws to get the gravitational acceleration.
 
@DanielSank well, it does have your name written all over it =)
 
11:41 AM
Hi, everybody.
 
hi pal
welcome
 
12:24 PM
@JohnRennie okay let me say
The force that earth attracts is given as "my"
Srry mg
Right !
Since acceleration due to gravity is a constant can't we say that force is constant as per second law?
Mass is also a constant
 
yes, continue please
 
So can't you find something fishy here?
 
what do you find "fishy"?
 
When we analyze universal law of gravitation
It says that force varies with distance
But when we take a glance at second law
 
between which two masses?
 
12:30 PM
Between earth and an object
Acceleration and mass is constant
So force is constant
@skullpetrol are you understanding? What I meant
 
not really, but continue your line of reasoning please...
 
Okay
Let me start from scratch
What is universal law of gravitation?
The force between an object and the earth is directly proportional to the product of their masses and inversely proportional to their distances
Note the point inversely proportional to the distance
Okay now let's get on to the second law
Let me reduce it to it's equation that is $$f=ma$$
Here acceleration due to gravity is constant which is 9.8m/s and so mass is constant
So what does it mean ?
Force is a constant
As per second law
@skullpetrol so got it right now?
 
not 9.8m/s, but 9.8m/(s^2)
 
Okay sorry about that
 
np
may I suggest you read this
the value of g is equivalent to the ratio of (G•M_earth)/(R_earth)^2
 
12:46 PM
Did you get what I am saying?
 
@Akash.B Acceleration is only approximately constant
 
I think this page will answer your question about the distance @Akash.B
 
1:03 PM
@skullpetrol well if I throw a ball upwards
The r varies right?
Here r really means the distance between the body and object , right?
 
how much is that variation compared to the radius of the earth?
 
1:32 PM
It's not about how small
It's still bound to the fact that force varies
I am looking for an accurate explanation
 
1:52 PM
Hey guys for once i want to post an answer
But its an original answer
I have asked a friend to verify it
Would anyone be willing to be a 2nd checkpoint of this derivation?
I've already tried googling it (can't find it) :(
 
2:22 PM
@Akash.B The accurate explanation is that the acceleration is only approximately the same for small variations of distance from the centre of the earth. If you do the math, you can see that it really doesn't change much based on height, especially for regular people doing things on Earth's surface. It's not exactly the same, but often the change is so small that it can be ignored.
 
Anonymous
2:47 PM
@DanielSank Heyo! I noticed you're a co-author on Google's supremacy paper. Could you answer this if you get time? :D
2
 
woah, you exist!
 
Anonymous
@danielunderwood Hiii!
 
Anonymous
Yeah, I've been a bit busy lately...didn't pop in much :P
 
school/research I suppose?
 
blue? is that really you :-?
welcome back pal
 
2:55 PM
did somebody say blue has returned :P
 
Anonymous
@danielunderwood Yeah, internship and job placement season :)
 
Anonymous
Was preparing for the software internships...didn't manage to get one though. So applying to the research internships for now :P
 
Anonymous
@skullpetrol Hehe, yes. How're you doing? :D
 
I'll trade you a full software job for a research internship hah
 
@SanchayanDutta fine thx
 
2:58 PM
Is this for next summer? Do you guys have the same May-Aug break as we have in the US?
 
Anonymous
This year's summer was mostly spent on doing some Mathematica calculations on the geometry of entanglement stuff (PPT/NPT bound entangled states)
 
Anonymous
@danielunderwood Yup, for summer 2020. However, most people who do well in the internships are offered a full-time job. We had folks from Microsoft, Amazon, and Samsung coming in this year and a few of my classmates managed to get internships there. I did relatively badly as I haven't practised competitive programming in a long while. Brushing up on my C++ skills now (STL!!!!) :P
 
Anonymous
How're you doing? New job or continuing at the previous data science company?
 
3:18 PM
Oh nice! Though "competitive programming" doesn't sound pleasant to me

Well it's the one that I started in January, but more data engineering and security than data science. I do get the occasional day to do data analysis though, so it's decent!
 
@JMac So what if i throw a ball from aeroplane?
Flying at almost 40000 feet
 
1
Q: Can we consider MR Imaging questions as on-topic unless they ask for specific engineering solutions?

Antoni ParelladaContext: This question on basic principles of image formation in medical MRI was asked in May 2014, received an accepted answer at the time, and was left unchallenged until August 2019, at which point I decided to attempt to summarize in some detail the topic in an answer that was well received. ...

 
3:40 PM
@Akash.B It would be slightly different, but less than 1% change in the acceleration
 
4:07 PM
@Akash.B 40k feet is about 12 kilometers. there's a lot more atmosphere to go at that point: nasa.gov/mission_pages/sunearth/science/atmosphere-layers2.html
 
4:19 PM
does anybody know what's the deal with the quantum supremacy paper? It seems it was retracted soon after it appeared, now it's possible to find it on the web but not on official sources
 
I thought the point was that it wasn't officially published yet, just leaked?
 
if I look online I only find sensationalist articles saying that google can now compute the meaning of life or something
@Semiclassical ah, so even the first appearance wasn't official?
 
that was my understanding. should be out officially in a few weeks I think?
 
that would make sense
 
4:45 PM
anyone know how four closed strings moving towards a common point could combine?
 
YMCA
You know what about it?
It's fun to stay there
cuz
 
It's fun to stay at the YMCA
@Ultradark nice egg, mm breakfast
 
 
1 hour later…
6:04 PM
@Slereah what did you want me to get?
I'm in the office today
 
6:52 PM
@Slereah >distance 2 miles
I'm in the same building
@Slereah do you have the princeton library page for it
 
7:09 PM
Isn't that the princeton library page
 
@Slereah I’m looking
 
Thx
 
@Slereah yeah I have it
Go to discord
 
Plz don't destroy it
K
 
7:31 PM
@Slereah the library is in our building
super convenient
 
How serendipitous
I probably don't have any cool library nearby
Even the local physics uni seems fairly light on GR research
 

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