The h Bar

DHMO

12:02 PM

Is causality defined in physics?

Secret

MAFIA: The + cayley table forms a left zero semigroup, which is why it is trivially associative

Since that is a semigroup, perhaps there exists a semigroup of idempotents for it

rob

Salutations, all

user116211

@rob Welcome, Sir rob.

user116211

@Secret You need to ping me ;P

Secret

It's not interesting enough yet thus I don't want to waste pings

user116211

12:12 PM

@Secret There should be.

Secret

I do not expect there are absorbers (although they are not ruled out when I construct the axioms), therefore if WIP is self consistent, it might be worthwhile to investigate further

Right now I need to check the distributive laws...

Qmechanic

12:28 PM

1

Q: What is the origin of the term 'degeneracy'?

I've grown accustomed to mentally translating 'degenerate' to 'having equivalent energy', but the origin of the term always puzzled me, particularly in light of the more traditional English usage. Etymology of the word suggests that it is formed from Latin prefix 'de-' and Latin root 'genus'. I...

Off-topic, cf. e.g. this meta post?

user116211

@Qmechanic Sounds off-topic.

Secret

it sounds more like a linguistic question (Etymology) than a physics question

user116211

yes.

user228700

@Secret: What is the way to identify exceptions to the octet rule (OK, this might be a really dumb question), lest I intriduce coordinate bonds and ruin everything?

John Rennie

@DHMO Obvious reasons? I won't inquire since it's your decision, but speaking personnally I can't see any benefit to hiding my own identify - though obviously you're not getting my e-mail address or telephone number :-)

DHMO

12:36 PM

@JohnRennie Thanks for not inquiring

@Kaumudi Wrong chatroom?

which grade are you in? the answer depends on your grade sadly

user228700

@DHMO Nah, we discuss everything here :-P

user228700

@DHMO I graduated this spring. Not yet in university.

Secret

Warning, guideline only:
well, to start with, if you have an atom that can form more than 4 bonds, and a lot of halogen atoms surrounding it e.g. $PCl_5$ then it is going to violate octet.

Another example are electron deficient atoms like B, Be. These like to violate octet rule

Metal complexes violate octet like crazy because they obey another rule

DHMO

@Kaumudi ok. in high school you were taught hypervalent molecules, which would not be hypervalent later in your life...

Sugden's hypothesis back in the 20s already explained how those molecules can follow octet

His hypothesis was confirmed in the 50s

user228700

@DHMO I may have been taught this (concept) but I've never before come across the term hypervalent molecules. Googling...

user228700

12:39 PM

@Secret: OK, thanks. I'm stuck with $ClO_4^-$ and I ruined everything by introducing coordinate bonds ugh :/

Secret

Also, noble gas havea full octet, thus noble gas compounds must violate octet to form things like $XeF_4$

Usually, it takes rather electronegative atoms to violate octet, but that is not a hard fixed rule

user228700

@Secret Hm, OK, this makes sense...

user228700

Thanks :-) $ClO_4^-$ is an exception, right..?

user228700

I did this: (Yeah, it's been established that I'm dumb)

user228700

Secret

12:44 PM

well, O is pretty electronegative to start with, and Cl only need one electron to compelte octet, thus you have to violate octet to accomodate the other O as what you drawn there

0celo7

yo what is with these temperatures

we're going from 50 to 80 degrees

if I put on long sleves/pants, I'll be hot later

user228700

The electrons don't add up :/

0celo7

but it's freezing ouside right now

DHMO

@Kaumudi The bottom O and the left O are both charged... only one of them should be charged

user228700

@Secret Yeah :/ When should I introduce coordinate bonds..?

DHMO

12:45 PM

the chlorine should possess 7 electrons

@Kaumudi you shouldn't introduce coordinate bonds when expanding octet

user228700

@DHMO What dyou mean by "when expanding octet"?

DHMO

@Kaumudi you are trying to draw the structure of perchlorate by using expanded octet, right

Secret

@0celo7 don't worry, here our temperature dropped from 30 something C to 11 C at night while it should be spring. The weather is definitely screwed up

0celo7

language

@JohnRennie will ban you

user228700

@0celo7 Are u kidding me? U use the f-word all the time!

DHMO

12:48 PM

@Kaumudi of course you can explain its structure by using 3 coordinate bonds instead of an expanded octet

0celo7

@Kaumudi I have a mental disorder, please don't make fun of it

DHMO

but you are trying to apply the expanded-octet hypothesis, right

user116211

@Kaumudi He has brain tumour; have some sympathy :(

user228700

@DHMO Yeah, that's the thing, I dunno if it'll be an expanded octet beforehand. So I need to ascertain that before starting?

DHMO

@Kaumudi yes.

in the expanded-octet hypothesis, period 2 elements cannot expand octet

Secret

12:49 PM

2 mins ago, by 0celo7

language

fixed

user228700

@MAFIA36790 WHAT?! I didn't know this wtf. @0celo7: That wasn't me making fun of u but dude, I'm so sorry!

0celo7

@Secret yay

user228700

@0celo7: Hey, I'm sorry.

user116211

@balarka o/

Balarka Sen

'sup

user228700

12:51 PM

@DHMO Riight. OK, this is new information.

DHMO

@Kaumudi therefore, nitrate is explained by dative bonds instead

user228700

@DHMO Huh? OK, I didn't know that I was supposed to decide whether or not I need to use expanded octet and what not before I start writing the structure!

DHMO

@Kaumudi now you know

user228700

@DHMO Yeah, I do, but I'm still not very clear on the whole coordinate bonds thing. So, for elements that can't expand octet, we introduce coordinate bonds?

DHMO

@Kaumudi yes

this is another failure of the expanded-octet hypothesis

i'm clearly biased by calling it a hypothesis

user228700

12:55 PM

@DHMO Omg I've been struggling with this my whole life! (:-P) Nobody told me this!

DHMO

@Kaumudi so you just met a person who changed your life :-P

did we just use the same emotion

user228700

@DHMO Yeah, the people on this website change my life everyday :-)

user228700

@DHMO Yeah..? :-P

user228700

OK, thanks! Wow.

DHMO

just think of it as a failed hypothesis: you can do anything with it

Secret

12:57 PM

MAFIA: Results on the distributive laws are computed: Due to the presence of the + left zero semigroup, the distributive laws (both right and left) trivially holds.

This is in contrast to my expectationo when I construt the axioms, so I will next check whether any of the previosu formulae have suddenly contradict itself due to me making WIP finite

user228700

@DHMO Yes, but I gotta use it to solve problems so. Anyway, thanks!

DHMO

@Kaumudi you're welcome

Secret

If no contradictions found, then perhaps I can continue on the infinite version of WIP, which will be interesting because we can exploit those zero power theorems

DHMO

@Kaumudi I thought you already finished high school

user228700

@DHMO I did, but entrance exams.

DHMO

1:00 PM

@Kaumudi alright

user228700

I have another quick question, if u don't mind..?

DHMO

ask

Physics Guy

@Ocelo7 Nice profile picture

user228700

When there's a negative charge on a molecule, this negative charge is actually delocalized over the whole molecule, correct?

DHMO

@Kaumudi yes, but in high school it either goes to the most electronegative atom or the center atom

is resonance taught in your high school?

user228700

1:03 PM

@DHMO It's funny how u say "in high school" :-P Okay, how to figure out which atom it goes to? (Since the central atom is supposed to be the least electronegative atom, no?)

Secret

The most electronegative atom tend to have the highest electron density, but at high school level, because we treat electrons classically, it has to be localised at an atom

DHMO

@Kaumudi I thought you said you just finished high school

user228700

@DHMO Wut? No, I mean how u said "in high school it either goes to the most electronegative atom or the center atom"

DHMO

@Kaumudi well, both are essentially different systems

the latter is called "formal charge"

@Kaumudi what is funny about that?

user228700

@Secret And which atom is that..?

DHMO

1:06 PM

@Kaumudi it depends

ultimately it is another failed theory, so you can do whatever you want

user228700

@DHMO Never mind...can you explain that about the latter is formal charge?

DHMO

@Kaumudi the latter system is called formal charge, it assumes that there is no dative bonds

Secret

usually the most electronegative atom, e.g. two of the O in $SO_4^2-$

DHMO

in fact, it is very easy to convert dative bonds to the formal charge system

user228700

@DHMO Which system?

DHMO

1:06 PM

@Kaumudi the formal charge system

user228700

@DHMO Yeah, OK...

DHMO

let's take hydronium as an example

it is positively charged

can you draw/find a diagram according to what you learnt?

I just want to know what you learnt

user228700

@DHMO U mean its Lewis structure?

DHMO

@Kaumudi yes

Ramanujan

@Kaumudi do you know any other structure?!

user228700

1:09 PM

@Ramanujan How about the shape given by VSEPR theory?

DHMO

@Kaumudi I thought VSEPR adds on the Lewis structure

Whatever, just draw anything

user228700

@DHMO Yeah, it does. I was just telling Rananajunan that, oh, never mind. I'll just draw the lewis structure. Drawing...

Ramanujan

@DHMO vsepr shows repulsion of bonds right?

DHMO

@Ramanujan yes

Swapnil Das

@AlfredCentauri Could I ask a SR question to u?

Is time a scalar or a vector?

Alfred Centauri

1:11 PM

@SwapnilDas time is a coordinate

Swapnil Das

Yup, above

Not a quantity?

user228700

@DHMO: Brb, sorry...

Swapnil Das

@AlfredCentauri I visualize time as a component of a 4D vector.

Alfred Centauri

@SwapnilDas that's correct. Proper time, by the way, is a (Lorentz) scalar.

Swapnil Das

@AlfredCentauri Thanks! Idk what a Lorentz scalar is

Alfred Centauri

1:17 PM

@SwapnilDas A Lorentz scalar is invariant under a Lorentz transformation

Swapnil Das

@AlfredCentauri oh, learnt something new. Thanks a lot!

Alfred Centauri

@SwapnilDas you're very welcome - gotta go do some GR now...

Swapnil Das

Best of luck! Bye! @AlfredCentauri

user116211

@SwapnilDas Time-interval is a vector.

Secret

MAFIA: Ok all results are computed. It seems we have divided by zero in this system, although in a sense this system is quite trivial. (Graphic abstract in a few sec...)

user116211

1:24 PM

All trivial?

user228700

I'm back. Sorry about that :/

user228700

@DHMO:

Secret

trivial as in, there are many things that is basically the same blockwise, not that it becomes the trivial structure

user116211

okay.

Secret

You will see it when I present it shortly...

Ramanujan

1:26 PM

@DHMO also 9 elections.

user228700

Hang on, I think I messed up...(Forgive me, I've always sucked at Lewis dot diagrams)

user228700

This better:(?)

user228700

DHMO

and the charge?

user228700

Yeah, I'm not so sure about that :/ Can u help?

DHMO

1:32 PM

@Kaumudi so as I said, there are two systems...

user228700

OK..?

DHMO

so I'm not sure which system you want

user228700

@DHMO What do u mean..?

DHMO

@Kaumudi I think I should mention both systems then.

the "formal charge" should be easier, so I'll start with that.

it's all about which atom you assign which electron to.

In the formal charge system, the electrons in each bond is shared fairly between the atoms.

Swapnil Das

@MAFIA36790 Oh

DHMO

1:35 PM

could you work out how many electrons belong to each of the four atoms respectively then?

user228700

@DHMO Yes. Differences in electronegativity are not taken into account, correct?

DHMO

@Kaumudi correct

user228700

@DHMO Uh, u mean work out the formal charge of each atom?

DHMO

@Kaumudi yes

user228700

Alright...

user228700

1:37 PM

It looks like the F.C of all the H atoms is 0 and that of the O atom is actually +2 :/

DHMO

could you show the step for the O atom?

@Ramanujan very funny

Secret

@MAFIA36790 Let me know if you find anything contradictory

user228700

Well, it has 6 electrons in its isolated state, it's bonded to 4 atoms, all single bonds and it has no lone pairs (going by my diagram, which I don't even know is correct or not), so F.C=6-4-0=+2?

user116211

Subsemigroup to what structure?

DHMO

@Kaumudi hint: it is not bonded to 4 atoms

and your diagram is correct

user116211

1:40 PM

I mean to what set did you restrict the operation?

user228700

@DHMO Wait wait, it does have a lone pair! (According to my diagram) so 6-4-2=0?

Ramanujan

@Kaumudi did you remembered my words (about formal charge?)

DHMO

@Kaumudi hint: it is not bonded to 4 atoms

user228700

@DHMO This. How?

DHMO

@Kaumudi well, for example, it is only bonded to 3 hydrogen atoms

user228700

1:41 PM

@DHMO AAARGH, I'm blind!!!

Secret

@MAFIA36790 The + cayley table is isomorphic to the left zero semigroup of 3 elements, and the distributive law is controlled by it

user116211

okay.

Secret

Null semigroup

In mathematics, a null semigroup (also called a zero semigroup) is a semigroup with an absorbing element, called zero, in which the product of any two elements is zero. If every element of the semigroup is a left zero then the semigroup is called a left zero semigroup; a right zero semigroup is defined analogously. According to Clifford and Preston, "In spite of their triviality, these semigroups arise naturally in a number of investigations." == Null semigroup == Let S be a semigroup with zero element 0. Then S is called a null semigroup if for all x and y in S we have xy = 0. === Cayl...

user228700

I'm so sorry. There's something wrong with me. Hang on. 6-3-2=1?

DHMO

@Kaumudi correct

user116211

1:42 PM

@Secret Yeh, got that.

DHMO

therefore, the formal charge is on the oxygen

user228700

@DHMO Which means that...it has one less electron than it should have..?

DHMO

@Kaumudi yes

Ramanujan

@DHMO isn't O have 0 f.c?

DHMO

@Ramanujan not in hydronium cation

user228700

1:43 PM

Alright. So what was ur original point..?

DHMO

@Kaumudi what was your original question..?

Ramanujan

@DHMO this O has 8 e

user228700

@DHMO No, u asked me to draw this at some point...why?

DHMO

@Kaumudi to answer your original question...

@Ramanujan so?

user228700

@DHMO My original question was about how to identify which atom has the charge. U said there are two systems...

DHMO

1:45 PM

@Kaumudi yes. so you already learnt the formal charge system, which does not account for the electronegativity difference

user228700

@DHMO Right.

DHMO

so should we continue to discuss the system which accounts?

Ramanujan

@DHMO so it is stable ( without any extra or less elections)

user228700

@DHMO Uh, yeah, if that's OK..?

DHMO

@Ramanujan yes, but that is not what formal charge means

@Kaumudi now, which atom should the positive charge be at, according to electronegativity?

Ramanujan

1:47 PM

@DHMO then what does it mean ( I still thinks in that way) can you improve me

user228700

@DHMO Definitely not the oxygen atom, so one of the H atoms.

DHMO

@Kaumudi why "definitely not the oxygen atom"?

Ramanujan

DHMO then what does it mean ( I still thinks in that way) can you improve me

DHMO

@Ramanujan well, to calculate the formal charge, first you assign each electron to a certain atom according to some rules

user228700

@DHMO Well, because it's one of the most electronegative atoms in the periodic table and so, it won't be stable, having a positive charge..?

DHMO

1:48 PM

@Kaumudi yes, but except when bonded with fluorine

now, refer back to your photo

user228700

Alright, maybe we need to move this to the CSE chat lest @MAFIA36790 gets pissed again :-P

DHMO

let's say you choose the top hydrogen atom

user228700

@DHMO Hm, yes, which is the only element that is more electronegative than oxygen so that makes sense.

user228700

@DHMO CSE chatroom?

Ramanujan

@DHMO can I know rules

DHMO

1:50 PM

@Kaumudi sure

@Ramanujan the rules is that the electrons in each bond are split equally between the two atoms

ACuriousMind

2:11 PM

0

Q: Why isn't my simple electromagnetic coil working?

For a science fair project I am building a coilgun and so far it has been pretty easy but now I have run into an issue. I have 2 layers of coil wrapped around a straw and when I attach power to the coil and try and put something magnetic inside it it doesn't attract it at all. If you need picture...

electromagnetism

Unclear what you're asking, particularly in light of the comment that OP "somehow fixed it by rewinding the coil"?

ManishEarth

@SwapnilDas yes

Aaron Abraham

Anyone good with optics here? @ACuriousMind @ManishEarth?

user116211

@AaronAbraham You don't have to ping anyone; just ask. If someone is interested, he/she will respond.

Aaron Abraham

Ah well, alright. What about you?

user228700

@0celo7: Just. Cannot. Stop:

0celo7

2:20 PM

Huh?

Aaron Abraham

You were lamenting about optics the other day (at Chem.SE)

@Kaumudi That sounds....*wrong*....

very

;P

ACuriousMind

It sounds only very slightly wrong by the average wrongness in this room :)

user228700

-__- Omg guys. Calm down! ^This is what I meant! @0celo7

Aaron Abraham

By the way, @ACuriousMind do you do optics by any chance?

0celo7

2:22 PM

@ACuriousMind I'm at the rocket factory

ACuriousMind

@AaronAbraham I already read your message the first time. What @MAFIA36790 said - unless you know a specific person is uniquely qualified to answer your question, just ask it without pinging anyone - if someone knows the answer and wants to respond, they will.

Aaron Abraham

@0celo7 Rolling out V2s ;)

0celo7

I'm getting the hang of it

Running out of ammo though

No one has 5.56

Aaron Abraham

@ACuriousMind Will do :)

ACuriousMind

@0celo7 Oh, In FNV. For a moment I thought they would be already letting you construct nuclear rockets :D

0celo7

2:23 PM

That was last semester

Aaron Abraham

Would anyone happen to know what causes foam to appear white? Is it total internal ref. or scattering?

0celo7

I was temped to kill the legionnaires at Novak

I got a fr

Aaron Abraham

I'm tempted to kill you ;)

0celo7

a grenade launcher

It's my secret weapon for such situation

Aaron Abraham

Psst. What game @0celo7 ?

0celo7

2:25 PM

Fallout Casino

ACuriousMind

@AaronAbraham Scattering mostly, as answered here

Aaron Abraham

But in that case, why isn't soap water white?

THIS was my doubt...

0celo7

Don't doubt. Question.

Aaron Abraham

@0celo7 Oh...sorry, WW2 FPS is my thing...(hence the V2 comment)

ACuriousMind

Because the scattering is at the many surfaces that are in the bubbles. The water has just a single surface where scattering might happen, soapy or not.

Secret

2:27 PM

@MAFIA36790

More results: The nonassociativity has a special form
\begin{align}
(00)0=1 \neq 0(00)=0\\
(0q)0=q \neq 0(q0)=0\\
(00)q=0 \neq 0(0q)=q\\
(q0)q=q \neq q(0q)=1\\
(0q)q=0 \neq 0(qq)=q\\
(qq)q=0 \neq q(qq)=1\\
\end{align}
These can be wrapped up by the following:
\begin{align}
a(bc)=b^{-1}((ab)c)
\end{align}

Aaron Abraham

@ACuriousMind But wouldn't scattering also occur through the bulk of the material?

The same way the sky scatters blue light?

I was under the impression, that scattering was a surface phenomenon.

ACuriousMind

Yes, but much less. The "scattering" here is mostly that the light is partly reflected at every surface, I guess

Aaron Abraham

?

Sorry, kinda lost you there..

0celo7

@ACuriousMind Are there any quests you recommend I get?

Can I join the legion?

I want to play skyrim again

Aaron Abraham

(P.S @0celo7, Sorry, but I'll be borrowing @ACuriousMind for a bit)

._.

0celo7

2:29 PM

She's mine @AaronAbraham

3

ACuriousMind

No surface is 100% translucent. At each surface of the bubbles, a part of the light is reflected, effective scattering it in random directions after many such events.

Aaron Abraham

She?

ACuriousMind

@0celo7 Most are good

@0celo7 Yes

The main quest choice will be between the NCR, the legion and "I'm doing this on my own", essentially

0celo7

Can I be the boss of he legion

@ACuriousMind does loot scale with difficulty?

Aaron Abraham

@0celo7 You can be the boss of my 3rd Panzer unit! ....if you want......

._.

ACuriousMind

2:34 PM

@0celo7 I'll say...yes, but any elaboration might be spoilery

Aaron Abraham

( twirls fingers shyly )

ACuriousMind

@0celo7 I don't think so

0celo7

@ACuriousMind remember when you didn't want to spoil saren

@ACuriousMind Damn. I'm addicted.

How did this happen?

It's like that time I said JUST ONE crack pipe

@ACuriousMind How do I know when there are no more quests?

Aaron Abraham

2:49 PM

@ACuriousMind Follow up question?

ACuriousMind

@0celo7 Uh. I don't think I ever reached that point

John Rennie

Hi docscience :-)

docscience

Hello

Aaron Abraham

@ACuriousMind What causes the scattering at the surfaces?

John Rennie

if anyone's interested i suggested docscience ask here about his question:

1

Q: What actually constitutes a 'rip' in the fabric of spacetime?

Science fiction writers often use the term 'rip' in the fabric of spacetime to provide a means of either time travel or instantaneous travel from one corner of the universe to another. But I've also read and heard bonafide physicists use this term as well, so I suspect there is some credence to i...

spacetime singularities wormholes

docscience

2:53 PM

Thanks John

John Rennie

@docscience: in GR spacetime is a manifold plus a metric.

The manifold dictates the dimensionality and the topology while the metric gives a way of measuring distance.

docscience

... and I think you pointed out the metric is an input, not an output to the field equations

... so how can one go about ripping it?

John Rennie

The manifold topology is an input.

The metric is what you get by solving the Einstein equation.

docscience

so it is an output?

John Rennie

That is we assume a topology, then take the matter/energy distribution and the result is the metric.

docscience

2:56 PM

... or can be?

John Rennie

But a rip would be a change in the topology of the manifold not the metric

docscience

... which is an input

John Rennie

Yes. We assume a manifold right at the start.

And the manifold we normally assume is $\mathcal R^4$ i.e. simply connected 4D spacetime.

docscience

so then 'ripping' would have to consider another set of mathematics, influences OUTSIDE the field equations?

John Rennie

Yes. There is nothing in GR that describes topology change.

You mentioned the quantum foam idea i.e. the idea that at very small distances spacetime is in flux.

And that's a common gee whizz idea on pop sci accounts of cosmology.

docscience

2:59 PM

Yes, one of the physicists that used the term rip was reffering to very small scales

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