tomato tomato

(That's all for the chat session folks - see you in two weeks!)

@ShaVuklia What's the difference?

yea, skip the "or", I was just paraphrasing my first question

@ShaVuklia $p = mv$ so $dp/dt = d/dt(mv) = mdv/dt = ma$

So it's just $F=ma$ in disguise.

lol yea I know that

Oops, sorry. I have misunderstood what you're asking then.

@ShaVuklia Depends on the formalism you use

@ShaVuklia uh, which "or"? Anyway, I'm saying I'm not sure what you see as the difference between being defined and being a placeholder.

Generally though they are not defined the same

So we basically say that whatever it is that is causing a rate of change in momentum, we will call this a force, and it's magnitude and direction will exactly be the rate of change?

$\vec F = \vec \nabla V$, usually

for some potential $V$

you just made Nature unstable

you happy?

I like to define $V$ in terms of $F$ actually. So first define $F$, then define work, then potential

Oh yes, forgot the sign

@ShaVuklia well yes, but the reverse also applies. If we start with a force we know it must be associated with a change in momentum.

but technically they are one and the same thing, right?

I can't see why you would regard one as a placeholder for the other.

the reason why I wouldn't define $F$ as $\dot p$ is that you could create some theory where that is not the case

For instance a theory with higher derivatives

ostrogradski objects

Well he's dead, what is he gonna do

@ShaVuklia isn't that like asking if force and acceleration are one and the same thing because $F=ma$?

so if I'm correct, at this point I should not bother what a force is, and stick to what I know about the effects of a force, which we denote by $\vec F$?

and which we know equal $d\vec p/dt$

actually, physics doesn't bother defining things, does it? it only bothers describing effects?

I don't know what the difference between "a force" and the "effects of a force" are supposed to be.

alright, I think I got it

@ShaVuklia Except that the upwards force my chair is currently exerting on my bottom is not changing my momentum ...

@ShaVuklia In some sense, yeah

@John you could argue it is, but it is also counter-acted

@JohnRennie Not sure I trust you on that

@ShaVuklia but that force is proportional to a four-acceleration.

oh boy

cool, thanks for the conversation, this helped :)

Overall in physics, it may not necessarily be very fertile to ask what something "is" really

what is love?

baby dont hurt me

@slereah true, but i'm so used to everything being defined in mathematics, that I felt a little bit lost for a second when I revised on classical mechanics

What you have in physics is a model of reality , and the important part is what measurements you can get out of it

@AccidentalFourierTransform No love

@AccidentalFourierTransform Who starred that? Have we no taste in music? :-)

@BernardoMeurer dude you obsessed

death grips and free software

thats bernardo

Chris White, come back!, timeloop repeats

oh yeah I forgot that

You promised me so many things

Death Grips and Free Software will be the names of my two kids

@JohnRennie Dude, Rust is hard

Chris White Duffield da Silva

Why "da Silva"?

Dunno

That's racist

lol

@BernardoMeurer from the quick look I had at the language Rust didn't seem especially complicated.

@JohnRennie I'm finding it hard, with the whole ownership stuff

mod probe {
    use std::fs;
    use std::path;
    pub fn files(dir: &path::Path, depth: u16) {
        let mut object_list = fs::read_dir(dir).unwrap();
        for mut object in object_list {
            let metadata = fs::metadata(object.unwrap().path()).unwrap();

            println!("Object: {}", object.unwrap().path().display());
        }
    }
}

This is broken code

what the hell, entire ex-Yugoslavia is about Serbians!

"American wines are better" are more liable to make french people laugh

and I don't understand why

@AccidentalFourierTransform Not up to date - the GEMA recently achieved some sort of settlement with YouTube, unblocking many music videos that were blocked in Germany.

@ShaVuklia I hang out with Yugoslavians most of the time, they are quite competitive :p

@Bernardo haha, I am one

@ShaVuklia Really, where are you from?

so in a couple of years from now you'll think of "This video is not available..." with nostalgia

Bosnia

how cute

I am watching a video that could make a German mad

the old classic

The following is the first "elevator music" I have heard in my life (back in childhood)

@ShaVuklia Ah, my friends are mostly Slovenian and Serbian :)

Jaz sem Bernardo, in sem inžinir računalniški

hahaha you sound like a drunk Bosnian

classic Bernardo

That's pretty much me lol

As you well know I love the serbian culture

I only go to the Balkans bar here in Lisbon. It's nice there

The owner is a 2m tall Serbian named Kikki

Nice guy

all great songs

@Bernardo ah, I wonder if I'll ever see a bar again. I started my first year in maths and physics, and I think I've forgotten what it means to have a life :P

I do love the fashion style of Roki Vulovic

@ShaVuklia Ah, come on, I'm in my first year of Computer Engineering and I have time to go to the bar

When things don't explode in the lab at least :P

hahaha yea i just don't know how to work efficiently i guess

@ShaVuklia Well, code with one hand, drink with the other :)

NSA is watching you

@PhysicsGuy Good, maybe they learn something

Yes.

@PhysicsGuy that explains the recent outbreak of potato related injuries amongst NSA employees.

Is that true?

@JohnRennie @dmckee Talking about potatoes, I managed to run Linux on an FPGA :D

@BernardoMeurer you're quite pleased about this - I can tell :-)

@PhysicsGuy Yes, they tried running Linux on their potatoes, but St. IGNUcius did not bless them

@JohnRennie Yes, I'm super proud

So come on. You didn't port the kernel yourself. That's months of work. Who did the CPU design and the port?

I didn't need to port the kernel! I just picked an architecture with a working port

And then I just ran it in nommu mode

Did you actually burn your own FPGA?

The CPU design is what I've been working on for months now :P

Yeah!

It's on my desk

Right now

Fair does, that's cool :-)

@BernardoMeurer And it was easy because MIPS is such a "simple" architecture. Right?

@dmckee Well, I underestimated MIPS :P

These days I find myself boggled by the architecture of microcontrollers.

This project was a major pain in the ass

It was pure masochism

But I now know how a CPU works pretty well :P

And I had the joy of programming directly in binary

"joy"

If you want some fun binary programming story

catb.org/jargon/html/story-of-mel.html

The classic story of Mel

I needed a microcontroller to run some LEDs for a evil jack-o-lantern project and discovered that the easiest thing for we to buy and deal with was a teensy-LC.

48 MHz 32-bit arm processor.

@dmckee Nah, come on, Arduino

16MHz AVR/Atmel stuff

The thing is faster than my first laptop, and about as powerful.

Teensy is OP, even the FP performance is good on it

@BernardoMeurer On the teensy I can more enough current through the IO pin to drive my UV LEDs directly. With an arduino I'd have had to wire each pin through a driver.

" In modern parlance, every single instruction was followed by a GO TO! Put that in Pascal's pipe and smoke it."

"Since Mel knew the numerical value of every operation code, and assigned his own drum addresses, every instruction he wrote could also be considered a numerical constant. He could pick up an earlier “add” instruction, say, and multiply by it, if it had the right numeric value. His code was not easy for someone else to modify."

And yeah. That's overpowered. But it is also awesome.

@dmckee Ah, I see, cool

" Perhaps my greatest shock came when I found an innocent loop that had no test in it. No test. None. Common sense said it had to be a closed loop, where the program would circle, forever, endlessly. Program control passed right through it, however, and safely out the other side. It took me two weeks to figure it out."

heh

@EmilioPisanty Yeah. That. And grading the response after you've figured out how poorly stated the question was is a pain in the neck. /voice of bitter experience

@Slereah Self modifying code is scary hard.

And debugging it approaches impossible.

"He had located the data he was working on near the top of memory — the largest locations the instructions could address — so, after the last datum was handled, incrementing the instruction address would make it overflow. The carry would add one to the operation code, changing it to the next one in the instruction set: a jump instruction."

@dmckee It's also mostly forbidden in most OSs

Which make Core War a game for masochists, because all the best designs are heavily self-modifying.

hello

self modifying code is fairly common in some algorithmic methods

Because some of them don't distinguish code and data

@Slereah That a fairly recent thing. I mean, there have been mainframe system that did a good job of preventing it for as long as I have been programming, but it is only recently that all the desktop OS did a decent job of it.

@Slereah Your comment doesn't make sense, sergeants are not officers.

@Slereah Awesome read, thanks for that

@dmckee yeah, it was a good way to embed viruses into programs :p

We seriously need more LQG researchers

Why?

Jacob Barnett is that one weird kid

from the meme

Oh, I think I know him

Or better, young blood that can move between the gravity candidates and nnot get locked into any

One day he came to the physics chat I used to moderate

the triple integral kid

He's a huge prick

@Slereah I doubt it was him

Who knows

warosu.org/sci/thread/7085201

the media loves gifted children who are the next Einstein

Then one month later you never hear of them again

Sorry guys, but one last time: so I’m reading through the first chapter of some classical mechanics book, and what I see is that they define: $\vec v,\vec p,\vec L,\vec N,W,V$ (and probably even more). All those things are defined. However, for some reason they don’t define $\vec F$. They don’t even care to describe it really, except that “in consequence of interactions with external objects and fields, the particle may experience forces” . But really, what is $\vec F$ then?

If you ask me what is anything in the list I mentioned above, I will simply give you the definition. What could I answer when someone asks what a force is?

$F=ma$

how do you know what $V$ is if you don't know what $F$ is

but that's not what a force is. a force is not defined as $d\vec p/dt$

its "effects" can be described like that, i guess

@ShaVuklia In any physical theory there will be something undefined

ok, I'll ask on the main site then I guess :P

$$\vec F = \frac{\partial \mathcal L }{\partial \vec x}$$

Obviously

One thing people tend to forget is that IQ isn't calculated the same for children and adults

it's points / age, no?

Yeah I think it's something like comparing it to the intelligence of an adult

So a high IQ for a 12 years old might grow up to be just mildly smart

"Barnett was shown reciting a few dozen digits of the decimal expansion of the mathematical constant pi"

what a tool

Who even sits down and learns them?

What's the point?

People who know like 100 are the worst

Go big or go home

I want someone to know 10,000

to pretend you're a genius

"Although Barnett's thoughts on the subject were never shared with the scientific community, the creationist periodical The New American said that Barnett's "expanded theory of relatively has turned heads"."

My sides

$$\Huge\omega^{\pi^{\omega^{\epsilon_0^{\omega^{\cdots}}}}}$$

"On a local news story on ABC affiliate WEWS-TV, Barnett stated a belief that a different theory than conventional relativity must be required because light needs to have nonzero mass in order for conservation of energy and mass-energy equivalence to hold."

wot

wews

sounds like a troll station tbh

He seems like your usual pleb that learned pop science relativity and thinks he has disproved it