3:43 AM
I opened PSE on my phone and it was yellow.

@mithusengupta123 it’s busy now and I don’t have my Jackson handy. Which edition? I’ll try to read this part to plunge myself into this again.

2 hours later…
6:14 AM
Hi All...

6 hours later…
12:42 PM
Could anybody here help me with this- The $r$ coordinate of Schwarzschild coordinates becomes timelike inside the horizon, yet the area of 2 spheres inside the horizon is given by $4\pi r^2$ but with r a timelike coordinate. So does this mean that the area of each 2 spheres centred somewhere inside the horizon decreases. So what I am saying is that can I imagine this
as (mentally imagining) a sphere centred at some position inside the horizon ( with the radial coordinate t as fixed ) whose area sort of decreases as time moves forward.

1:19 PM
Basically so, yes
you just sit in a little sphere that collapses around you
down to the singularity

2:00 PM
@Slereah and this happens for all the spheres inside the horizon, right...also formula for the area of 2 spheres is $4\pi r^2$...this formula makes ANY sense only if $r$ is a spacelike coordinate. You are measuring area so it is obvious that $r$ is spacelike. What sense does the formula make when $r$ is timelike. Is it even the area
of anything

You have to pick your spacelike hypersurface
then you can check its measurements if you so choose

2 hours later…
3:48 PM
Hello Everyone
I need some help
The Paper (Hochreiter 1992) is actually backbone of the paper which I'm reading.
It's a very important paper.
But, It's written in German, I tried reading it but its way too complicated for noobs like me... I don't have any other options than to use Google Translate line by line for this 70-75 page paper
and what I hate most is that there is no single translation either on this whole internet.
Can anyone help me in translating those?
Or is there any option or anything that can ease the pain in my a--.....
How it was even accpeted? It cited some core concepts from non english language....
Or I can happily mail the author and request him for an english translation.
But that seems bit disrespectful thing to do to someone so great that Sepp Hochreiter....
I'm struck! (TT)
I want to go to some corner and cry...
I need a crash course on German.... Can anyone suggest one? Like 4-5 hours should suffice.... then I'll have an hour to read it before I sleep
Sepp's all three papers do have first four sections exact copy paste of each other.... But, different remedies each time.

4:11 PM
I can't help you at all, but think about a research article written in English. Do you think someone studying English for only 4-5 hours would be able to tackle it? Some papers in English are even hard to parse for people who have been speaking English their entire life.

I crawled whole internet
Not a single English version of it

4:24 PM
@RewCie boo hoo
14

First, I apologize if I'm posting this to the wrong place, but it seems correct. My adviser sent me the SGA text of Grothendieck which is in French. Though I can piece together parts of the text, I'm afraid that I'm losing significant parts of the meaning when I just have no idea what a sentence...

48

It seems that knowing French is useful if you're an algebraic geometer. More generally, I've sometimes wished I could read German and Russian so I could read papers by great German and Russian mathematicians, but I don't know how useful this would actually be. What non-English languages are goo...

It's an unfortunate reality that many good things haven't been translated

So, certainly investing some time reading french and German is worth
Maybe, this vacation I should start it.
So, certainly investing some time reading french and German is worth

There is a pdf somewhere full of advice on how to read these papers based on general language principles and the history of language, e.g. certain patterns trace back to yee olde English, old French etc and you can use the sounds to guess the meaning a good bit

Oh okay

@bolbteppa I suspect that advice is highly specific to native English speakers :P

I'd love to find it but I can't so far

4:34 PM
But, still reading a foreign language word by word as a newbie to reach Page 43 seems very time consuming
I'm searching for some sort of AI thing that does the job in seconds.

Some very interesting general points in there even if the goal is French for English speakers

Fortunately not a problem for me

There's a few old French math books that absolutely need to be translated
9

I am trying to find an English translation of Camille Jordan's work "Cours D'analyse". Only the French edition is on Amazon, so since this is a somewhat specialized topic, I thought perhaps someone in this forum might know. TIA, Matt

4:57 PM
Possibly stupid question inc. is $a_p^\dagger a_q^\dagger|0\rangle=a_p^\dagger|0\rangle\otimes a_q^\dagger|0\rangle$?
actually never mind that second bit (which is now deleted in shame)

a state like $|n>$ really means $|n> = |n_1,n_2,...>$ so $|0> = |0,0,...>$ you wouldn't write a vector as a direct product it'd be a direct sum right

But if the Fock space is $\bigoplus_n^\infty \mathcal H^{\otimes n}$, won't a two particle state be in $\mathcal H\otimes \mathcal H$?

yes
but there isn't a $\lvert 0\rangle$ in each $\mathcal{H}$, so what you wrote doesn't really make sense

The state $|n_1,n_2,...>$ is in $\mathcal{H}^{n_1} \oplus \mathcal{H}^{n_2} \oplus ...$, if $p$ and $q$ are different that's like $n_1$ and $n_2$ being different so they're in different subspaces in the direct sum no?

the vacuum is not a single-particle state, it's a zero-particle state

5:12 PM
One interesting point in that French thing is to change a letter in the word to try figure out it's meaning, e.g. verb = verd = word

hmm, but if ladder operators are maps $a^\dagger:\mathcal H^{\otimes n}\rightarrow \mathcal H^{\otimes n+1}$, why doesn't what I've written make sense?
wait but you've changed two letters to go from verd to word >:(

What you have is actually $$a^\dagger_p |1, 0, 0, \ldots \rangle = |0, 1_p, 0, 0, \ldots \rangle$$

@Charlie what is the $\lvert 0\rangle$ supposed to be on the r.h.s. of your equation?

the free vacuum

Where you have the vacuum state being occupied originally
and then changed to a one particle state

5:14 PM
ah, wait, you're right

and i'm almost always talking about bosonic scalar field theory, i don't associate with fermions

That doesn't make sense to say the vacuum is occupied

Since the zero particle Hilbert space is just $\mathbb{C}$ you can even write it down, really
The wavefunction is just $1$

is it always just $|0\rangle=1$?

The wave function is zero

5:16 PM
So the Fock state is $(1, 0, 0, 0, \ldots)$
@Charlie Up to a phase, yes

I guess that makes sense if you're demanding it normalise
yeah fair enough

For the free particle, anyway

You don't have a bunch of $1$'s riding around in the general expansion of a wave function

There are fancier vacuums

@Slereah we don't usually write the vacuum state in the occupation number formalism

5:17 PM
Well not for the states with particles in them, sure

$a^\dagger 1=2$

After that you just have standard wavefunctions

what's the difference between $\lvert 1, 1_p,\dots\rangle$ and $\lvert 0,1_p,\dots\rangle$ if you write it like that?

One particle states are just gonna be $e^{ipx}$

it's enough to have all 0s in the occupation numbers to denote the vacuum

5:19 PM
If there was a $1$ there the rule $a_i^{\dagger}|n_1,n_2,...> = \sqrt{n_i + 1}|n_1,n_2,...,n_i+1,...>$ would fail

Well it's there anyway :p
In the Fock space

@Charlie to answer your actual question, this is not quite right, your l.h.s. is equal to the symmetrized version of the state on the r.h.s.

oh yeah sure

5:37 PM
SE swag:
If the SE think they can buy my loyalty by sending me some old tat they are absolutely correct :-)
7

5:51 PM
I have a function
F(n)=(1/2)f(n-1)+(1/4)f(n-2)
I want to check if i am making mistake
Can anyone use computer code to find f(10)
F(1)=1 and f(2)=3/4

@JohnRennie swag for hitting 300k rep?

1 hour later…
7:24 PM
@ACuriousMind I'm not sure to be honest. It just turned up.

Yes, I used to be active on ServerFault and I got something for being in the top 50 users though that was a lot of years ago.

7:49 PM
Halo, if evolution tends to optimize us towards survival and reproduction, why do vegetarians exist? After all, eating meat should and has always been beneficial and part of the life of the ancient human.
I have a hypothesis: We have a neocortex and it allows us to bypass some evolutionary circuits.

@JingleBells I don't think vegetarianism is genetic :P

That explains is then :P
But having a neocortex is genetic and it allows us to think logically/emotionally and bypass some evolutionary "pushes", such as eating meat (or reproducing)

there are plenty of things humans can decide to do that are definitely detrimental for their personal survival and/or reproduction
but evolution operates on genes, not on individuals, so that tells us nothing

so there will always be outliers, such as LGBT+ or whatever, and vegetarians

if the same gene that kills 1% of the population before they reproduce is extremely beneficial to the other 99%, that gene will be very successful
@JingleBells neither of these traits is established to be genetic, so what's your point?

7:57 PM
@ACuriousMind this is fascinating to me, how the neocortex allows us to "outgrow" evolution in some way

evolution has produced the general human capacity for learning, it does not really produce specific human behaviours

so by making the neocortex, evolution kinda f*cked the 1% up :P

why? humans seem to be very successful
evolution is just a natural process like gravity

ye, like a big gradient ascent algorithm tweaking all genes to increase fitness

it hasn't stopped acting on human genes just because we got smart

8:00 PM
yes, but why don't we see animals that go against evolution? they don't have a neocortex?

Hey all

helo

What do you mean by "go against evolution"?

@JingleBells what does "go against evolution" mean?

not eating meat, not reproducing, being gay, etc.

8:01 PM
I need some help with determining a terminal voltage of a very simple circuit, can someone help me about it?

as I said, evolution operates on genes, not individuals. An individual behaving suboptimally w.r.t. personal reproductive fitness doesn't really mean anything

There are animals that don't eat meat. And I am pretty sure there are animals that engage in "homosexual activity"

a vegetarian pig lol

plenty of apes are herbivores
e.g. gorillas

and how are they not doing what's beneficial for them?
do they choose to be vege? with their neocortex?

8:04 PM

If an organism survives long enough to reproduce then their genes get passed along
Ignoring that there isn't a "vegan gene", vegans can still reproduce, so their genes will still make it to the next generation
Now if there was some gene that caused not eating meat to kill you before you had the chance to reproduce, then that gene would not make it through

Consider that the switch is closed and capacitor is open circuit, what I need to find is $v_0(t)$ terminal voltage in this case. It's 5V and I can find 5V when I transofmr all voltage sources to current sources but when I try to apply node voltage method without source transformation, ı end up with 24V

And since there's no vegan gene, what causes the individual to make the choice of not eating meat?

Or if there was a gene that let you reproduce more efficiently by eating meat then that would make it through

I'm sorry for interrupting your chat, by the way.

8:08 PM
@JingleBells I feel you chose an extremely convoluted way to ask "what is free will" :P

XXDD

Uh oh here we go again

I believe we have no free will and every single spark in every neuron is determined by the enviroment and genetics (and maybe some quantum shysics but no idea how it can be "determined" if it's quantum shysics)
I'm quantum physics.

@M.ÇağlarTUFAN you are likely just making some simple algebra error if your method gives you the wrong result, but what do you want us to help you with here?

Wait a minute, even if quantum mechanics plays a role in our thinking, then isn't it just random will, and not free will lol

8:11 PM
Randomness can still give rise to certainty.

@JingleBells It may we worthwhile to recognize that reductionism may be true but it's useless. No one knows how to go from "here's the genome and a list of environmental factors" to "this guy will stop eating meat at 23"

@ACuriousMind I agree with you, I think I have an error somewhere in my calculations but I couldn't find out. I tried to solve for $v_0(t)$ using node voltage method. How many nodes are there in the above circuit with capacitor as open circuit and swtich is closed?

@BioPhysicist wot

since humans are influenced by other humans you would have to simulate every human being in lockstep to make predictions of that kind

I think there is only one and it's the positive terminal of $v_0(t)$

8:12 PM
we can't even simulate a single human

@ACuriousMind ye but my goal is not to make predictions :P

But when I transform all voltage soruces into current sources, node number becomes 2.

@ACuriousMind yet :>
I just saw some guy make a vegan joke on tv and was like "Why are people vegan?" and now I'm here :P

Look up a Galton Board

@JingleBells have you tried asking them? :P

8:14 PM
@BioPhysicist ye but it's still not 100% certain where the ball will fall
nothing is 100% certain actually, except my geography grades
@ACuriousMind I'm looking for a scientific explanation, not "killing pigs is immoral"

@JingleBells Right, but one could make an analogy that the balls are like genes and the overall distribution is like what we actually observe happening. It's a lose analogy, and there are probably some holes, but something to think about. It doesn't make the claim less valid that certainty can still be pulled from randomness.

That's a pretty poor joke

@BioPhysicist How can certainty be pulled from randomness when the final hole of a ball is not certain

@JingleBells Because even though each ball is "random", the distribution is certain (for the most part).
You know what the shape of the distribution will be even if you can't say where an individual ball will end up
That is kind of like how all of thermodynamics works actually

8:23 PM
so on a high level, the binomial distribution pattern can be spotted I get it, but I wouldn't call that certainty (in the sense that I see it) :P

*statistical mechanics
I am certain the distribution will be that shape each time I flip the board

you're certain in that, but not where every ball will land, so it's kinda weird :P
some certainty can be extracted I agree

Right, that was the point I was making lol

So here's the point I take home from our evolutionary discussion above - animals are gay
I honestly didn't know that animals can be gay or vegan lol
if it's not genes, is it environmental factors?
what I'm asking is - why are people vegan when genes do not support it? Is it environmental factors that affect the neocortex to make that decision?

@JingleBells you've already said you understand they often do it for moral reasons
so if you want to understand this in a reductionist way, the correct thing to ask is not "what factors make people vegan" but "what produces our sense of morality"

8:32 PM
why are animals vegan or gay? being gay has nothing to do with morality

why wouldn't some animals be herbivores (we don't call that "vegan" since we usually don't believe they're making a choice)?
there's nothing inherently better about being a carnivore or omnivore

I'm talking about animals that usually eat meat but some of them have become vegan

that...doesn't really happen

although if you put an omnivore in a location where there's no prey for it to catch it will of course "become vegan"

8:34 PM
why does it happen with humans then

regardless of "free will", I think it's clear that humans are capable of decision-making at a level few other animals are

can I use that to distinguish consciousness
if u can choose to be vegan ur consious
if not, ur dumb animal

that's a very odd choice to focus on, but sure

i just defined consciousness, nobel prize now.

the more common way to look at intelligence/consciousness in animals is tool use, ability to reason about mirrors and hidden objects, and ability to use deception/coordination in a social situation

8:39 PM
gotchya, and of course, being vegan
@ACuriousMind hmm, then why most humans eat meat? do they not realize it's immoral, or the evolutionary circuits that want them to eat meat are stronger?

@JingleBells that probably varies a lot, but I think the average meat-eater doesn't think it is immoral, at least not to a degree where they should stop, and/or believes their personal choice is insignificant
if all humans agreed on morality the world would be a very different place :P

sorry it's late
@ACuriousMind so taking all those variations into account, the world at its current state is more inclined to have its people eat meat (either cuz the meat-eating circuits are stronger, people think it's not that immoral, or believe their personal choice is insignificant and other reasons)
@ACuriousMind r u vegan?
alright Imma go to bed, thanks ACM & BioPhysicist