The h Bar - 2017-11-12 (page 5 of 6)

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7:00 PM

@Lagranian Ah. No, gamma radiation doesn't work like that. That's because (i) it's neutral and doesn't change either Z or A, and (ii) there's no simple way to predict when it will happen. It's just a way for nuclei to get rid of excess energy, so you just need to check each decay on whether the nuclei are left in an excited state with excess energy they need to radiate away.

No but if they were travelling along straight lines that intersected but weren't antiparallel they could.

my point is relevant to lorentz boosts

@EmilioPisanty Can you show an example?

Anonymous

@Phase Ah, so the confusion is with the definition of head-on collision

I suppose so

@0celo7 Oh god Pewdiepie's newest video is a mindmelter

This is dark man

7:02 PM

@BalarkaSen hey what's up guys it's $PEWDie_{pieeee}$

@Phase thats 2012 pewdiepie

and several more in Wikipedia en.wikipedia.org/wiki/…

christian pewdiepie is an entirely different creature

C... Christian?

I knew he was edgy but

Christian?

7:04 PM

self-proclaimed christian, yes

@EmilioPisanty So, Is it hard to explain?

@Lagranian there isn't any overarching explanation

it comes down to the specific details of each reaction / decay

so can we say that is undefined?

@BalarkaSen Ah I see, was gonna say, would be a bit weird for an actual christian to go around people a stupid [redacted]

@Lagranian physics.stackexchange.com/questions/55745/…

7:06 PM

@Lagranian no. you just say that the emission (or not) of gamma radiation in a given decay depends on the specifics of the decay.

Anonymous

@Phase A head on collision means that the point of impact is on the straight line connecting the center of mass of each of the objects.

@EmilioPisanty So, there's no formula like in alpha decay.

right?

@Blue oh I see.

That's underwhelming.

@Lagranian if you insist on one, then yes

$^n_m A^* \to {{}^{n}_{m}A} + \gamma$

where $A^*$ denotes an excited nuclide

it's the same formula as emitting light in an atom really

Anonymous

7:15 PM

Is the book by Arfken (Mathematical Methods for Physicists) good? I need some reviews

Anonymous

I skimmed through the chapters in the pdf...it looks nice

i like it well enough, though the copy i've got is an older one

(the same one my uncle used in undergrad)

The chapter on functionals is good

Anonymous

Oh, thanks. I'm ordering it then. Also, any idea about Kreysig's functional analysis? It's becoming increasingly difficult for me to read from Reed-Simons (online pdf)...and the actual hard copy of Reed-Simons is too costly. I read the first chapter from Kreysig, it looks good.

Anonymous

Maybe @0celo7 can tell

7:22 PM

He's probably busy melting his computer

overoverclocking to get 60fps in cities

Anonymous

Graduate level books are so effing expensive :/

Guys I found my resource to learn analysis from

Because I feel @0celo7 's list wasn't rigorous enough

Real Analysis

wow I'm already done

Onto Complex analysis

Anonymous

Awesome. Give us a treat when you get your graduate degree next week.

@EmilioPisanty That was what I was looking for ;)

$^n_m A^* \to {{}^{n}_{m}A} + \gamma$

Can i use this formula for every gamma decays?

@Blue Why stop there? It'll be a much shorter course since Relativity is just liberal pish

7:29 PM

@Lagranian yes

if that rocks your boat, then sure

I wouldn't really class it as a formula (it's little more than a tautology), but to each their own

@EmilioPisanty Thanks for all ;)

no worries

Also I wonder a thing

Can I ask my questions here?

@EmilioPisanty really? what about $e^- + e^+ \to 2 \gamma$?

@Lagranian don't ask about asking, just ask

7:31 PM

@EmilioPisanty good.

@Phase that's excited positronium, no? (if you insist on seeing it as a decay process instead of something else)

... point being, yes, there will always be odd edges and corner cases

I just meant beacuse he asked

"can i use this formula for every gamma decay"

@Phase Can't I?

Idk, my guess would be no but @EmilioPisanty is far more knowledgeable than I so assume I'm wrong : P

@Phase I wouldn't class the reaction you put up as a decay, because there isn't a nuclide to begin with

it sits at the frilly edges of language and terminology where it's ultimately up to what you take each term to mean

so I'd stick to what I said above

7:40 PM

Oh right

at the simplistic level at which Lagranian wants to understand nuclear decay, yes, you can use that 'formula' for every gamma decay

though also, as I said, I would strongly hesitate to even call that a formula

and, if you decide to use it, please keep at the back of your mind that nuclear physics is more complicated and there's more detailed dynamics that underlie all of this

Like for instance that there are virtual particles that are totally real and exist that fly around pushing things

with their pixie wings

fr tho, are virtual particles just like peturbations?

@Phase virtual particles aren't real

ik but I'm asking about how they're modelled mathematically

there's no useful sense in which they (ontologically) exist

3

Q: Are virtual exchange particles real or just mathematical?

When an electron exchanges a virtual photon with another electron or proton, is the virtual photon a real particle or just a mathematical construct? In string theory, the force carrier particles of the electromagnetic, strong, and weak forces are supposed to be open string bound to their d branes...

string-theory virtual-particles

& links therein

7:43 PM

i dont think they're real tho

I'm just asking about how they actually enter physics

Can we just ban questions with "Is X real" in the title

"Are eyes and mirrors real?"

@Phase yes, they are intermediate steps in perturbation-theory calculations.

they exist in that you'd better use them as you write down all relevant feynman diagrams

but that's not the same as them being observable

even saying "not being observable" seems too charitable, come to think of it

you can also define them as the basis for QFT

In the worldline formalism

7:57 PM

one personal frustration this brings up for me

people go on and on about the weirdness of QM: interpretational issues, measurement problem, etc.

and i agree that's weird. but it seems like if people find undergrad QM to be philosophically confusing, they should find QFT even more so

and yet for the most part most discussions about QM interpretation are limited to few-particle non-relativistic QM.

i imagine the problem is that the barrier to understanding QFT is high enough that, if you're good enough at math/physics to get there, you're probably not interested in the philosophical issues as such.

I am looking at the following exercise:
We have an electromagnetic field. The relation between energy and momentum of a particle with charge $q$ is $$\left (\frac{E-q\phi}{c}\right )^2=m^2c^2+\|p-\frac{q}{c}A\|^2$$ where $c$ is the velocity of light and $\phi=\phi (x,t), A=A(x,t)$ are the scalar and vector potential of the field with values in $\mathbb{R}$ and $\mathbb{R}^3$ respectively.
Find the relation between the velocity and momentum and the equation of motion.

I have done the following:

8:30 PM

@Phase my case is bending from the heat

??????

Rip

@Blue Try Barbara Mac-something’s book

@Phase I took the top off to get better ventilation gyazo.com/e510ccd92c8d459aed3f27b4eb0c0589

holy moly

the efforts for a single game

You like it that much?

The gameplay is fantastic

Story is meh

Anonymous

@0celo7 Rs. 2340. Lol. I'm so broke

@0celo7 you know you recommended those books

Anonymous

amazon.com/Elementary-Functional-Analysis-Graduate-Mathematics/…

8:36 PM

and then one at the end that goes over all the others, as a recap

Could I read the one at the end first, and then start at the beginning of the list?

@Phase what?

the book list you gave me for analysis

Anonymous

I ordered this: springer.com/in/book/9789386279453#otherversion=9788185931890

Anonymous

It's cheap (Rs. 380) and seems to have good reviews

Anonymous

Basically it strains my eyes to read from the pdf of Reed-Simons, otherwise it's a nice book

8:37 PM

does anyone here believe in metatime?

@Phase dunno what you meqn

agh

this is not going well.

@0celo7 ill find the screenshot hang on

Nevermind

@Blue that doesn’t seem to cover Frechet spaces at all

wires were crossed

you recommended Abbott first

8:44 PM

Protip if you play this game. Pressing ANY button skips cutscenes.

Even moving the mouse

Anonymous

@0celo7 Oh :/ Anything else it is missing? I'll perhaps study Frechet spaces from some other source if that's the only chapter missing

No, it looks pretty comprehensive

But there’s a value from learning from historical books (Yosida, Rudin, Brezis, RS) because people reference specific things in them

Anonymous

Great. I'll get it by Friday! :D

Anonymous

@0celo7 I know, but those popular books always seem to be "in circulation" in the library. Also, they are quite costly.

Yosida should be cheap

But that’s what I learned from and that was probably a mistake

A lot of it is outdated

OTOH if you want to get into evolution equations it’s a classic

Anonymous

8:50 PM

amazon.in/Functional-Analysis-6e-Kosaku-Yosida/dp/8181281578

Anonymous

Unavailable :P

India has issues, man

Anonymous

I agree XD

$16 here

the combat actually looks quite fun

I'd enjoy it more without the big floating text though

Or with the ability to actually run it satisfactorily without melting my pc

8:59 PM

What kind of physics books do you recommend to me?

Anonymous

@Lagranian At what level?

Anonymous

I mean, at what level are you currently studying...

advanced

@Blue

Anonymous

...

@Lagranian “Cartesian Currents in the Calculus of Variations”

9:03 PM

amazon.com/Gravitation-Charles-W-Misner/dp/0691177791/…

does this seem gd

I dont think you should read that yet

No one actually reads that book.

Wow thats mean

Im gonna tell misner what you said

and Kip

Anonymous

@Lagranian Yeah, that's a gd book for someone who has trouble calculating radial acceleration of objects in the equator.

@Blue lol right

9:06 PM

@Blue that's Not Nice

@Lagranian if you want an advanced topic to look at, try Linear Algebra

it's a foundation thing, so even if you don't get far through it'll still be beneficial in some way later on

but focus on your studies that are relevant at the moment I would say

@Phase tbh I'm interested in quantum mechanics

so love reading books about quantum mechanics

If you're interested in Quantum Mechanics I'd recommend Shankar, but I really don't know what your maths is like

my math is gd

lol

I hope that your issues with radial acceleration today were just a fluke, if they were then try reading what a Linear Operator is and what matrices are like

there are a bunch of pdfs of shankars online.

Anonymous

Shankar has two books on fundamental physics. Do those first for the basics. It's not a good idea to jump directly into QM

Anonymous

9:10 PM

if you have shaky fundamentals

Nah just jump right to reading ViXra papers on Quantum Field Theory

I just realised.

My children are recommending books to people. They’re all grown up :’)

Vixra is ArXiv backwards.

Anonymous

@0celo7 Yes papa

@0celo7 are you a mother or a father

or both

Anonymous

9:11 PM

Our mom's name is bernice

Bernice? I gotta say it suits Xir

Anonymous

Feb 27 at 16:48, by 0celo7

My wife

Indeed

I've some questions

still I didn't get

Don't we all : p just ask

but tryna find a site/forum

9:13 PM

just ask em here if they're relevant to physics

yh but it seems like

a bit diff

?

I don't wanna steal your times

with my questions

Just go for it

If I minded having my time stolen I wouldnt ask : P

yh right

however I don't think everytime I can get an answer from here

9:17 PM

Well no you cant but its worth asking the question at least

This talking about whether or not its ok or advisable to ask is taking far longer than [probably] the question itself

@Blue you're an electronic engineer right?

Could i make a capacitor out of a sandwich

Determine whether the images of the objects placed at the following positions will be upright or inverted. Concave mirror, $s o = 2f $; convex mirror, $f < s o < 2f $; concave lens, $f > s o$ .

here is my question

this is about geometric optics

I currently don't have any idea about the question

what is $so$?

It seems like s o

not so

$s_0$?

is it object distance?

Anonymous

@Phase Yeah, metal coat your sandwich

9:20 PM

@Phase Yes, I think so.

@Lagranian draw ray diagrams

@Blue but that sounds like it'll taste bad

i think instead I'll just wrap each sandwich in tin foil and use that

and then make an ensemble of sandwich capacitors, put a thin sheet of glass on the other end, and hook the capacitors up to a computer

@Phase I drew.

for the largest edible touchscreen

Then your answer should be visible @Lagranian

Anonymous

@Phase That'll do I guess XD

How do you understand if it's visible or not?

9:23 PM

I mean that your answer should be easy to see from your diagram

Draw light rays going from the top of the object and the bottom, if it's still not clear

I might go to bed. @Blue should I get a relatively early night or spend the night learning more maths?

you're my brother support me

since mom and dad aren't here

I couldn't draw the ray diagram

tbh

Anonymous

You're asking that question to a noctural creature, so I'll be biased for sure. Mornings are too noisy. Night is peaceful and best for maths.

What time should i post this?

Anonymous

In fact it is 3 am here and I'm doing maths now. So follow my footsteps, bro @Phase

Anonymous

:P

9:27 PM

then

tomorrow will be better.

right?

Yeah its just i pulled an all nighter in the end last night, and I have lectures tomorrow

anyway

I'll try my chance

tomorrow

idk whether to commit, there is a coffee machine on way to the lectures tho

have a good night everyone!

good luck on the test @Lagranian

9:28 PM

<3<3

@Phase thanks man u are great

<3

Anonymous

See you. All the best for the test. :)

@Lagranian Would you mind explaining to me why your question about alpha decay has appeared on our site?

I find it highly disrespectful that you use this chat room to ask your questions and yet still consistently create new accounts on the site to circumvent the homework policy and your current suspension.

Uh oh

He annoyed the AI

@ACuriousMind initialise calm()

I agree though. Is he question banned on Lagranian or something?

Anonymous

He was banned for impersonating John Rennie

@Phase The Lagranian account is currently suspended on physics.SE

9:33 PM

@Blue thats a joke right?

@Blue No

ACM what's your favourite obsidian game

Im gonna give isometric style RPGs a final Hurrah, and see if I can get back into them

@Phase Probably Planescape, but the combat sucks

Anonymous

user image

Anonymous

Well, I shouldn't speculate

Anonymous

9:34 PM

But...

Anonymous

@Phase

Anonymous

@ACuriousMind Sorry for speculating

@Blue Right, you shouldn't. The suspension was already in place before that Rennie thing happened, fwiw

is planescape: torment equivalent to planescape?

or is it a weird sequel system

@Phase Yeah, it is

Nope, there's only the one :/

9:35 PM

Nice, the deluxe edition is on offer rn

only 10% but still

Torment: Tides of Numenara was supposed to be a spiritual sequel, but imho it sucked :P

aw :(

One last question before I go to bed

What's your expectation for the new cyberpunk CDPR game?

I think/hope it will be glorious, and also that it probably won't come out anytime soon

I hope so too

Idk though

Inb4 they Skyrim it

9:37 PM

I feel like I'll enjoy it less BECAUSE its CDPR

It'll be like trying to resolve the idea of Geralt in futuristic stuff

hope im wrong tho

@Phase Well, certainly, comparison to TW3 is a high bar to clear

Indeed

Everything in that game $_{with\space the\space exception\space of\space roach}$ was masterfully done

Wanna see how my roach often ended up after I called him?

Everything?

Really?

user image

Ok maybe not EVERYTHING

but everything I could look for in a game like that

anyway goodnight chums

Anonymous

Bye. You sleep too early!

9:46 PM

I DIDNT SLEEP LAST NIGHT

Yeesh i get judged for sleeping, and judged for not sleeping in here!

Anonymous

Ouch. Rush to bed then. :P

$_{grrrrrrrrrrrrrrrrrrrrrrr}$

goodnight bro

Anonymous

lol..goodnight

Bernardo Meurer

10:14 PM

Heya

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