The h Bar

4:17 AM

@BernardMeurer I wouldn't bother with the nvidia drivers. The laptop has dual GPUs - the nvidia and the built in HD4000, and the nvidia gpu isn't that great anyway. I would just use te HD4000 for graphics. It's plenty fast enough unless you want to use the laptop for gaming.

user218912

@JohnRennie are you familiar with the book on solid state physics by ashcroft and mermin?

John Rennie

@IceLord No, sorry :-(

user218912

because I need some help for condensed matter and idk if anyone here knows much about it.

user218912

I should learn to be more independent.

user116211

4:42 AM

What is this talking about:

user116211

0

Q: Motion in relation to gravity

Is it possible that gravity could be a byproduct of mass moving through space and if we could stop a masses movement would it still have gravitational influence on other masses within its vicinity. Could it even be possible to slow an object speed to absolute zero everything else is moving we wou...

user116211

?

0celo7

Absolute motion wrt. aether, it seems. Into the trash.

John Rennie

5:00 AM

Morning Kaumudi :-)

user228700

Hello all :-)

user228700

@JohnRennie Can u help me with something..?

John Rennie

@KaumudiHarikumar Yes, of course.

user228700

@JohnRennie I'm trying to solve problems involving forces that depend on both the x and y coordinates of the particle; to find the work done by forces of this kind.

John Rennie

OK, what's the problem?

user228700

5:05 AM

The path is described in sentences such as "The particle is taken from point 1 to point 2" where the coordinates of the two points are given.

user116211

@KaumudiHarikumar You need a line integral along the curve.

John Rennie

Presumably there is extra info e.g. whether it's a conservative force, and if not then what path is taken between the points ...

user116211

If it is conservative, then work with the gradient of the scalar potential.

user228700

@JohnRennie No information about the nature of the force has been provided and regarding the path, well, yes, it has been described in sentences.

John Rennie

and ...

user228700

5:08 AM

@MAFIA36790 Riight. I watched a video by KhanAcademy about this concept but in his video, the path was actually described in terms of a position vector function with time as the independent variable...

user116211

okay...

user116211

Can I see the function of the curve?

John Rennie

Can you post a picture of the problem?

user116211

^

user228700

@JohnRennie Sample sentence: "The particle is moved from the origin to a point (a,0) along the x-axis, after which it is moved to the point (a,a), parallel to the y-axis"

John Rennie

5:11 AM

Well that's easy, because the path is just two straight lines.

Is the force constant, or does it depend on $x$ and $y$?

user228700

@JohnRennie It depends on $x$ and $y$.

John Rennie

Take the first bit, along the $x$ axis. This means $y$ is just a constant - in fact it's zero - so the force is just a function of $x$.

user228700

@JohnRennie No no, see, I did that, and I did arrive at the answer...

John Rennie

We know $$W = \int_{x=0}^{x=a} F(x) dx $$ so it's a straightforward integral

user228700

I did that for the path along the x-axis first and then the one parallel to y-axis after that, taking y and x as constants for those two paths respectively and then I arrived at the correct answer...

John Rennie

5:15 AM

OK, good, so you've done the problem!

user228700

@JohnRennie Well, yeah :P But I looked at the solutions and instead of seperately integrating the function w.r.t $dx$ and $dy$, they integrated wrt $xi+yj$...

user228700

And then they split the integral.

user228700

OK, for u to make better sense of that ^, I must mention that the function is given as $F=-K(yi+xj)$

user228700

So they did the dot product and split the integral.

user228700

How did they do that..? I mean, how can they simply integrate wrt $xi+yj$..?

John Rennie

5:21 AM

When you are moving a particle along a path the work is given by: $$W = \int_a^b \mathbf F(\mathbf r) \cdot d\mathbf r$$ where $\mathbf F$ an $\mathbf r$ are vectors and the $\cdot$ is the dot product.

So $\mathbf F = (F_x, F_y)$ and $\mathbf r = (x, y)$

And the dot product is: $$ \mathbf F(\mathbf r) \cdot d\mathbf r = F_xdx + F_ydy $$

When we're actually doing the integral you usually looks for tricks and shortcuts to help you. For example in this case the trick is to split it into two separate easier integrals, which is exactly what you did and it's what I would have done.

The actual trick used depends on the details of the problem. It's the sort of thing you pick up by doing lots of this type of problem.

Unless you have a specific problem in mind it's hard to say much more.

user228700

@JohnRennie I see. Well, I didn't do the dot product thing. I split it up by assuming one variable to be constant over a given path but OK, I see.

John Rennie

@KaumudiHarikumar actually you did use the dot product but without realising

user228700

@JohnRennie In hindsight, yes.

John Rennie

Along the first part $dy = 0$ so the dot product is just $F_xdx$. Likewise for the second part it's $F_ydy$.

user228700

In the video by Khan Academy, he differentiated the position function wrt $t$ to get the value of $dx$ and $dy$ and then he did the dot product.

John Rennie

5:32 AM

That's a trick called parameterisation.

user228700

@JohnRennie $t$, time, being the parameter in question, yeah..?

John Rennie

Suppose we can write the positions as a function of time i.e. $x(t)$ and $y(t)$

Then we can calculate $dx/dt = f_x(t)$ and $dy/dt = f_y(t)$ for some funcctions $f_x$ and $f_y$. OK so far?

user228700

Yup.

John Rennie

Then we use the physicsts trick of treating the derivatives as fractions to get $dx = f_x(t)dt$ and $dy=f_y(t)dt$

And the dot product becomes $F_x(t)f_x(t)dt + F_y(t)f_ydt$ so it's only a function of $t$. Then the integral is just $\int dt$

user228700

@JohnRennie To do this, $F$ must also be a function of time, no..?

John Rennie

5:37 AM

Remember that $x$ and $y$ are functions of time, so $F(x,y)$ can be written as $F(x(t), y(t))$ where $x(t)$ and $y(t)$ are functions of time.

So we can write $F$ as a function just of time.

user228700

@JohnRennie Ohh, yeah. Stupid me. OK. I understand. Thanks so much! :-)

John Rennie

No, not stupid you, these are tricks we all had to learn along the way :-)

0celo7

Who is stupid?

user228700

@JohnRennie I guess :-) BTW, in ur head, how do u pronounce my name?

John Rennie

You wouldn't normally learn this stuff until first year at university, so you're well ahead of the curve.

0celo7

5:40 AM

@JohnRennie second

John Rennie

@KaumudiHarikumar I've never thought about it. "Cow" "Moody" I suppose ...

0celo7

@JohnRennie do you know about correlation functions?

John Rennie

That's a slightly bad choice of words :-)

0celo7

specifically wrt. the SHO

John Rennie

@0celo7 To be honest I've never really understood correlation functions, though if we're thinking about the same thing they're simple enough aren't they?

0celo7

5:42 AM

Yes. But my answer disagrees with the solution

user228700

@JohnRennie Ah, that sucks :/ You're right about the "cow" part but not "moody" :P It's "Cow"-"moo" (lol)-"thee".

John Rennie

Aha, the "d" is a "th" sound.

user228700

It's a Sanskrit word that means moonlight so at least it's not completely random :P

user228700

@JohnRennie Yes!

John Rennie

Interestingly that was the case in Old English. The letter "d" was called eth and pronounced as a "th".

user228700

5:45 AM

@JohnRennie Oh, that's very interesting!

John Rennie

The Indo-European language theory strikes again! :-)

user228700

@JohnRennie I'm gonna have to look that up :P

0celo7

John Rennie

"John" derives from an ancient Hebrew word meaning "praise be to Jehovah" or something like that.

0celo7

@JohnRennie That last thing should be $0$

but it's not...

I don't see what I could have done wrong.

the $a^\dagger $ takes us to $|1\rangle$, and $a$ back down to $|0\rangle$.

So that's just $i\hbar/2$

John Rennie

5:49 AM

@KaumudiHarikumar कौमुदी - the power of Google!

@KaumudiHarikumar Wikipedia article describing the Indo-European language family.

Though I'm guessing you speak Tamil (as well as Hindi) and that's a Dravidian language that isn't related to the Indo-European lanuages.

Ramanujan

@JohnRennie can I ask one personal question?

0celo7

@JohnRennie enough with languages -- I need QM help

I'm not a physicist, this is confusing me

Ramanujan

Where did you studied?from which university?

John Rennie

Yes of course, though whether i answer depends on how personal it is :-)

@Ramanujan Cambridge University in the UK

Ramanujan

@JohnRennie OMG, are you doing research?

0celo7

5:59 AM

@Ramanujan no, he's too old for that

John Rennie

@Ramanujan Not now. I did a PhD at Cambridge but then went to work as an industrial scientist studying colloid science. Now I'm part retired and work part time as a computer nerd.

Ramanujan

OK sorry

0celo7

Aha. The solution is wrong, as google shows.

John Rennie

These days I do physics for fun :-)

@0celo7 Link? Your working seemed OK to me ...

0celo7

@JohnRennie The book solution is wrong.

I'm correct.

John Rennie

6:01 AM

Aha! :-)

In colloid science we'd call C(t) an autocorrelation function. We use them in light scattering experiments where you're studying particle motion.

0celo7

the answer is $\frac{\hbar}{2m\omega}e^{-i\omega}$

the book omitted the complex part for some reason

@dmckee you're up...late

John Rennie

Aah and the second part of your answer provides the imaginary component.

0celo7

exactly

but I have the solution manual (thanks Russian servers), and Sakurai says explicitly that $\langle px\rangle=0$.

tfw earned $0.18 interest.

pretty amazing tbh

user228700

@JohnRennie Ah, I see! I didn't know about this.

user228700

@JohnRennie Yes, yes! That's it :-)

user228700

6:22 AM

@JohnRennie No, no, I speak Malayalam, Tamil and Hindi :-)

John Rennie

I only speak English and Physics - two entirely different languages and not to be confused with each other :-)

user228700

@JohnRennie Haha :-) Didn't u ever learn any other languages?

0celo7

@KaumudiHarikumar There's not much use in English-speaking countries.

John Rennie

It makes a big difference living on an island nation. Until the last decade or so there was very little mixing with mainland Europe to we rarely heard other languages.

While most people on the European mainland speak at least two languages in the UK most people only speak English.

The only exception is in Wales where a significant number of people speak Welsh as well as English.

0celo7

Does "sheep" rhyme with "lady" in Welsh?

John Rennie

6:29 AM

I had lessons in French and German at school, but that was forty years ago and I've forgottent what little I ever learned.

@0celo7 :-)

I can see the reputation the Welsh have for unsavoury activities is known even in the US :-)

Wow, while Googling the Welsh word for sheep I found ...

telegraph.co.uk/news/2016/05/25/…

0celo7

@JohnRennie The sheep probably ate her boyfriend's joint.

John Rennie

I bet it makes the meat taste good :-)

0celo7

I should go to sleep.

user228700

@0celo7 What time is it there?

0celo7

2:37am

user228700

6:37 AM

@JohnRennie I see :-) I learned German for a year but like you, have forgotten.

user228700

@0celo7 Holy crap.

0celo7

What?

I'm not sleepy at all, which is the problem.

I had a coffee at 6

user228700

@JohnRennie Whoa.

user228700

@0celo7 Read the newspaper, maybe?

John Rennie

@KaumudiHarikumar I was born in Sudan (my father was working there) and I spent my first nine years there. According to my mum I could speak Arabic quite well as a child, but I've since forgotten all but a few words of it.

user228700

6:41 AM

@JohnRennie Oh! Yes, it's interesting how quickly we pick up languages as children but also, how quickly we can forget them. When I was 5/6, I learned the Hindi alphabet at school and was even able to read small books, but after vacationing with my grandparents for two months, I'd forgotten everything!

0celo7

I used to know chemistry

I can't balance an equation any more.

user228700

@0celo7 Lol. Are ur classes usually not in the morning time? Seeing as u're usually here all night :P

0celo7

classes?

tomorrow is Sunday

user228700

I mean on the weekdays.

0celo7

usually I only get up on weekends up because Rebecca tells me to, but she's not here

@KaumudiHarikumar I'm here until 1 at the latest, I have classes at 9

user228700

6:46 AM

@0celo7 What do u mean "I only get on weekends"?

0celo7

get up

user228700

Right.

user228700

@0celo7 Oh, OK.

user228700

Are u in ur 1st/2nd year of college?

user228700

I'm off to have lunch. Bye!

0celo7

6:49 AM

@KaumudiHarikumar 2nd

@JohnRennie Do I need more books?

John Rennie

@0celo7 silly question, the answer is always "yes"

0celo7

yes.

agreed.

but I will wait until my next paycheck

John Rennie

I have about 20,000 books and that's still too few

0celo7

that way I do not need to move money around

you do not have 20,000 books

John Rennie

e-books

0celo7

6:51 AM

oh, well, sure

I could download a few million

I'm talking about book books

John Rennie

I ony have books that I will in principle read one day, though I'll have to live several thousand years to do it. I don't keep books that are of no interest just so I can say I've got them.

0celo7

I agree.

I have an immediately available shelf of 34 books that I use fairly regularly

user116211

@JohnRennie Man, you can't get satisfied without turning a page by your hand and enjoy the smell of the old pages of the book (most Dover books do have their signature oldish smell); that's why I prefer actual books to e-books unless the price of the book is beyond my reach.

0celo7

Dover books do have a distinct smell.

user116211

Yes! Yes!!

0celo7

6:54 AM

But these books are AMS Chelsea, which have amazing covers

they're textured, dark red, with gold letters

John Rennie

@MAFIA36790 I completely disagree. The only time I buy paper books is for science textbooks because ebooks are no good for flipping forwards and backwards quickly. For everything else I love reading on my tablet.

0celo7

LOOK AT THAT

user116211

@JohnRennie I'm talking about science textbooks too.

user116211

@0celo7 WoW!!

user116211

@JohnRennie Most of my storybooks and sci-fi novels are in my Kindle reader.

John Rennie

6:56 AM

Even for science textbooks I don't care what they look like. As long as they are printed clearly that's fine by me.

0celo7

@JohnRennie oh come on

user116211

ohh.

0celo7

what's a crappy looking book...

John Rennie

Who flagged 0celo7's comment?

Good grief, have some sense of proportion!

0celo7

I swear if I get banned

John Rennie

6:58 AM

Flag things that are offensive not words you hear every day.

0celo7

^terrible cover

John Rennie

Hi Kaz. Responding to the flag?

Kaz Wolfe

wheeeeee! *crash*

yep

just wanted to pop in and make sure everything was okay

John Rennie

Silly flag IMHO though your mileage may vary

Kaz Wolfe

yeah, it got dismissed pretty fast, so it seems like everything's okay here.

user116211

7:00 AM

@0celo7 Sadly, I still have not encountered any literature of AMS Chelsea; most of the books (e-books) I possess are of Springer, Wiley, Pearson, Addison-Wesley and Dover.

John Rennie

@KazWolfe Thanks for keeping an eye on us naughty physicists :-)

user116211

@0celo7 Kiddish dull cover.

Kaz Wolfe

@JohnRennie It's my job! :D (I honestly don't know why people flag soft-curses, but meh)

have fun, and don't go crazy chasing the higgs boson agian.

Ramanujan

@JohnRennie who is your favorite physicist?

John Rennie

These are the only books I have in paper form (apart from several large boxes of SF paperbacks stored in the loft):

2

user116211

7:05 AM

@JohnRennie Looking nice!

John Rennie

Bottom shelf science and technical, top shelf cultural.

Everything else is in e-book form

user116211

@Ramanujan I think such questions are silly; you can't narrow down to a single physicist; every physicist has his own contribution in different aspects of the field. Choosing one favourite, seems to be comparing them with each other; which I really feel odd.

Ramanujan

@MAFIA36790 hmm

user116211

@Ramanujan Although I love Lumo ;P

John Rennie

My favourite physicists are the ones who try to reach out. Feynmann was probably best at this, though obviously he's no longer around.

Susskind is probably the closest these days. He puts a lot of effort into writing books and giving lectures for young physicists.

user116211

7:10 AM

@JohnRennie BTW, which optics book is that in the bottom shelf?

John Rennie

Though I have to say I find Sussking a difficult lecturer to follow. He seems to spend a long time on simple things then skip quickly through steps in proofs I find hard.

user116211

Hecht?

John Rennie

@MAFIA36790 Hecht and Zajac - an absolute classic! Brilliant book.

user116211

@JohnRennie Ah!

user116211

But I'm really not in agreement with optics ;/

user116211

7:12 AM

I find this a very dull topic ;/

John Rennie

I got temporarily interested in radio astronomy, and a lot of the stuff on Fourier optics discussed in Hecht and Zajac is relevant to that.

user116211

By far, the most interesting physics book for me is Lanczos' The Variational Principles of Mechanics.

user116211

@JohnRennie ohh.

John Rennie

But, like you, I find there are more exciting things in physics than classical optics.

user116211

@JohnRennie yeh, yeh.

user116211

7:14 AM

@JohnRennie, You should read Lanczos, I'm sure you'd find it interesting and worthy to read it.

John Rennie

If/when I find the time to get stuck into a physics book it will be a QFT book. QFT is the last bit of physics I really want to understand before I die.

2

user116211

@JohnRennie I did notice a book of QFT in your shelf, isn't it?

John Rennie

amazon.co.uk/Quantum-Field-Theory-Gifted-Amateur/dp/019969933X

user116211

@JohnRennie ah!

user116211

For the Gifted Amateur...

user116211

7:17 AM

What does that mean?

John Rennie

Allegedly it's a good book for people who are just interested in how QFT works as opposed to wanting to learn it well enough to to do research in it.

user116211

ohh.

user116211

Freeman Dyson also wrote a book on Advanced Quantum Mechanics which is practically a treatise on early QFT.

user116211

amazon.com/Advanced-Quantum-Mechanics-Second-Freeman/dp/…

Physics Meta

7:49 AM

0

Q: publish annual q/a journal

I was thinking of asking the moderators to publish a journal annually, containing the best 100 questions of the year , and their detailed discussion sessions, so that if someone searches for a particular topic 6 years later, it shows up in the journal , along with its detailed discussion.

feature-request

John Rennie

9:20 AM

Doesn't apply to us physicists of course :-)

Danu

:)))

Secret

10:19 AM

0

Q: How do you solve for the minimum kinetic energy given that you have an area of movement of the particle?

How do you solve for the minimum kinetic energy given that you have an area of movement of the particle? It seems kind of random to me. I thought of using the momentum given that you have the position uncertainty and then calculating the lowest possible momentum from the deviation by subtracting ...

quantum-mechanics homework-and-exercises uncertainty-principle

I think he is on the right track, but I should not just wrote an answer and said that "you have done this correctly exactly as you did"?

Bernard Meurer

10:42 AM

@JohnRennie Pff, gaming. I want to use CUDA to speed up my image analysis project!

John Rennie

@BernardMeurer Ah OK it's access to the GPUs number crunching abilities you need.

But can't you install the libre drivers but still use the HD4000 to run the display?

Bernard Meurer

@JohnRennie Yes. I need to run face-recognition on a lot of people from Facebook to find a suitable human to ask on a date

John Rennie

@BernardMeurer if you need a face recognition algorithm to find a girl suitable for you the simple answer is that there are no girls suitable for you :-)

Bernard Meurer

@JohnRennie That's what NVidia Optimus does, but they never released good drivers for Linux. The Libre alternative was breaking my backlight control and there's an OSS third path called Bumblebee which seems to be abandoned

John Rennie

@BernardMeurer to be honest I've never understood how the E6530 manages the dual GPUs. I think under Windows it always uses the HD4000 but you can specify that running certain processes causes a switch to the nvidvia GPU.

Bernard Meurer

10:47 AM

@JohnRennie Well, I'm just trying to use my time more effectively :p If I could make an algo that would detect facial traits which I like and add that to all the shit they make available on their facebooks to create a smaller pool of people to try and talk to it means I have more free time to work on kernels

@JohnRennie So, it has this Nvidia Optimus thing, which is what cause the famous "Fuck you Nvidia" from Torvalds. What it does is that both GPUs share the same framebuffer and, IIRC, Optimus has a specialized chip that will detect load intensity and automatically do load balancing between GPUs or make them shift seamlessly. That however requires drives. The original Nvidia Optimus drivers were shit, and Nvidia's response was basically WONTFIX which pissed everyone off.

At the time the nouveau drivers didn't have a suitable switching mechanics, so Bumblebee came up and implemented that, although from what I've heard it never worked really well. Nowadays nouveau fully supports Optimus technology, but it has a performance drop when compared to the binary-blob based Nvidia drivers

John Rennie

The bumblebee implementation looks ideal if you just want access to the GPU for number crunching. According to Google it doesn't support dynamic switching to the nvidia GPU, but that's fine for your application.

So long as CUDA works.

Bernard Meurer

wiki.archlinux.org/index.php/bumblebee

Let's see what happens

John Rennie

:: John checks the news websites for reports of exploding laptops in Lisbon ::

Secret

11:13 AM

John, how should i wrote an answer to a question where the OP basically have done all the steps correctly thus in effect answered his/her question?

user116211

@Secret Better not answer that.

Secret

ok

user116211

Because such questions are asking basically then to check where they mistook and Phys.SE is not meant for that.

Secret

12:00 PM

NB: This is a snipplet of a game, hence no point in giving a link

Caption: Sometimes incremental games like these reminds of power series and rates of change of a quantity

Consider a function $f(x)$ and its rate of change $\dot{f}(x)$. Now consider that x is actually a function $x(a(t),b(t),c(t),d(t),e(t),\dots)$. Letting $S=\{a(t),b(t),c(t),d(t),e(t),/dots\}$ and expanding $\dot{f}(x)$ you will obtain the following:
$$\dot{f}(x)=\frac{df}{dx}\sum_{i\in S}\partial_i x \dot{i}$$

user116211

@Secret \ldots

user116211

Hey @loong.

Loong

@MAFIA36790 hi

Secret

Now consider the individual $\dot{i}=\frac{di}{dt}$ terms. Let the values be expressed in terms of scientific notation $k_i\times 10^{n_i}$. Now observe that if one of the $\dot{i}$ terms is larger than another $\dot{j}$ term for some orders of magnitude (where $i,j\in S$) then no matter how much faster the smaller one is changing, the overall change will be dominated by the one with the larger change in the orders of magnitude

user116211

@Secret Use \times ;_;

user116211

12:12 PM

;))

Secret

It might seemed straightforward to illustrate this dominance of the orders of magnitude by taking log both sides and make use of the rule $\ln(xy)=\ln x+\ln y$ and then apply a $\mathcal{O}(n_i)$ like argument to disregard lower or higher order terms. however one cannot simply take log on $\dot{f}(x)$ as $\ln(\text{a bunch of sums})$ have no easy formula.

user116211

@Secret whispers to secret to use \ln ;P

user116211

;))

Secret

I might have to tidy this up a bit and ask the maths chat on how to compare between the relative rates of quantities and the conditions such that no matter how finitely fast the smaller one is rising, its change will be swamped by the change with a large order of magnitude

user116211

@Secret Currently the chat is empty...

Secret

12:19 PM

It is, thus I am just kinda chilling out for now

In case the above maths makes no sense to some later readers: I am trying to investigate and quantify the observation in incremental games that if something gives you points of e.g. 1000/s vs one that gives you points of 10/s, then the former one will drown out the contribution from the latter one

John Duffield

12:44 PM

@JohnRennie : nothing to do with me pal.

Cracks knuckles. OK, I've just finished chapter 10: How does a magnet work? It finishes with Feynman explaining it. I got the wife to time me giving the speil in my best Brooklyn accent, and it took me two minutes twenty. He spent longer than that saying why he couldn't explain it.

user116211

@JohnDuffield me neither past few months ;P

John Duffield

Interviewer: What I want to know is what's going on between these two bits of metal?

Feynman: They repel each other. As to why, well now, the thing you have to know about, is the wave nature of matter. And that the electron is a spinor. [Feynman rolls his finger]. We know this because we have scientific evidence called electron diffraction and the Einstein-de Haas effect. Think of the electron as something like an electromagnetic cyclone. Other particles are like anti-cyclones, and all these particles attract each other or repel each other and go around and around each other.
[Rolls two index fingers around one another]. We have linear and rotational forces. In an ordinary …

And so on!

peterh

1:19 PM

AI with QM computing. Afaik, Daniel Sank tries to make a God.

Secret

2:24 PM

...Uh what?

[Spoilers from that game I just played:]

> Right, check the System Peeker. Let's get this story straight.

Yep! Pretty likely we're on Earth...

So, my plan. This will sound silly,
but try to bear with me.

This idea is based entirely on my total misunderstanding of some Stephen Hawkings book I just picked up in my data thingy...

So, according to this disproven 'Big Crunch' theory, the universe at some point is going to reverse direction and all mush together.

If I've misunderstood correctly, time MIGHT go backwards during the shrinking of spacetime.

Ok fine, it is not time travel, strictly speaking

back to work

John Duffield

2:44 PM

@Secret : time dilation is not time travel. See this answer. It's a reduced rate of local motion. It's living your life in slow motion mode. That's all. There is no magic. And there is no time travel. Sorry.

0celo7

@JohnRennie For the record, I was suspended for 30 minutes last night.

Ridiculous.

What kind of idiot validates that flag?

John Duffield

2:59 PM

Not me. It was Saturday night. I have things to do on a Saturday night.

0celo7

No, it was Sunday morning for you.

It was at 3AM my time

ACuriousMind

@JohnDuffield You can't validate a flag to begin with because you need 10k reputation to see and vote on chat flags.

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