The h Bar

Apart from the LUG I haven't seen anything, the students here really lack passion or interest for their majors. It's like everyone just wants a piece of paper with "Engineer" written on it and that's all

John Rennie

Are you cool with hybridisation now?

Bernard Meurer

@JohnRennie Kind of, I don't get why we do it

John Rennie

Do you want to know why we do it i.e. is it worth me ranting on about it?

Bernard Meurer

@JohnRennie The HD caddy got here, using it now

John Rennie

@BernardMeurer Cool :-) You've got the 500GB disk in it?

Bernard Meurer

4:59 PM

@JohnRennie Please rant

@JohnRennie Yep :D

All my music is with me now <3

Except that which I forgot in Brazil

( :( )

John Rennie

A popular approximation for describing molecular bonds is the LCAO method.

Bernard Meurer

@JohnRennie LCAO?

John Rennie

Linear combination of atomic orbitals

A linear combination of atomic orbitals or LCAO is a quantum superposition of atomic orbitals and a technique for calculating molecular orbitals in quantum chemistry. In quantum mechanics, electron configurations of atoms are described as wavefunctions. In mathematical sense, these wave functions are the basis set of functions, the basis functions, which describe the electrons of a given atom. In chemical reactions, orbital wavefunctions are modified, i.e. the electron cloud shape is changed, according to the type of atoms participating in the chemical bond. It was introduced in 1929 by Sir John...

Bernard Meurer

Long Curse About Orientals?

AH

Those MO Diagrams!

I have a hard time drawing them

John Rennie

So if we take two hydrogen atoms then the sigma bond between them can be approximately described by just adding the two atomic 1s orbitals. And actually this works suprisingly well.

4

A: Orbital of Hydrogen molecule

The approximation that we all started out learning is the linear combination of atomic orbitals (LCAO) approach. The molecular wavefunction, $\Psi$, can be expressed as a sum of some set of basis functions: $$ \Psi(\vec{r}) = \sum_n f_n(\vec{r}) $$ and a convenient set of basis functions is the...

Does this all make sense so far?

Bernard Meurer

5:02 PM

Yes, this makes sense

Question: What's a bonding and anti-bonding orbitals?

I know bonding is constructive interference of the electron-waves and anti-bonding is destructive. But what does that mean?

user116211

@BernardMeurer It means the overlap integral for Anti-MO is less than that of MO.

user228700

@JohnRennie: Hybridization again! :-D

Bernard Meurer

@MAFIA36790 Anti-MO?

John Rennie

In the LCAO approximation you start with two 1s orbitals and combine them.

user116211

@BernardMeurer anti bonding orbital.

John Rennie

5:04 PM

You can do this in only two ways, you either add them or subtract them.

Bernard Meurer

Also, why is the anti-bonding more anti-bonding than the bonding is bonding, energy-wise?

God, that sounds horrible in english

Why on the MO Diagram the anti-bonding has more energy

that's what I meant

user228700

@JohnRennie: I'm gonna come back and read all this tomorrow! Thank you from my side as well! :-D

ACuriousMind

Watching this must be how the rest of you feel when I talk about math or QFT all day :)

John Rennie

So you get two molecular orbitals. One of them turns out to have lower energy because you get increased electron density in the region between the nuclei where there is an increased electrostatic attraction.

DanielSank

@ACuriousMind ?

John Rennie

5:06 PM

i.e. the region where the electrons feel the attraction due to both nuclei.

user116211

You know Secular Equations @BernardMeurer?

ACuriousMind

@DanielSank I have no idea what this conversation is about is what I'm trying to say ;)

John Rennie

@BernardMeurer: OK so far? (ignore the interruptions :-)

Bernard Meurer

@MAFIA36790 No

@JohnRennie Why one of the MOs has lower energy? i don't quite get that

John Rennie

@BernardMeurer an electron's energy is lowered if you bring it near a proton. Yes?

user116211

5:08 PM

Read Ortho's post @BernardMeurer

user116211

11

A: Molecular orbital destabilization energy

"The destabilisation of an antibonding MO is equal to the stabilisation of a bonding MO, relative to the constituent AOs." Strictly speaking, the statement above is not true. However, it is usually taught as true in introductory LCAO-MO theory, so let's see where it comes from. It is worth b...

Bernard Meurer

@JohnRennie Yes, that's what I've been told :)

John Rennie

@BernardMeurer: OK, and if you bring it near two protons the energy is lowered even more. Yes?

DanielSank

@ACuriousMind Ah. I will tell you: Bernardo wants to know why the electron states in e.g. a hydrogen molecule are linear combinations of the electron eigenstates of the individual hydrogen atoms. However, rather than "linear combination", chemists for some reason say "hybridization".

Bernard Meurer

@JohnRennie Yes, that would make sense

John Rennie

5:13 PM

@BernardMeurer Good, then we're nearly there. The bonding orbital has an increased electron density in between the nuclei i.e. where the electrons are near two nuclei. So the electron energy is lowered compared to the energy in the original hydrogen atoms where the electrons are only near one nucleus.

ACuriousMind

@DanielSank I...see, thanks

John Rennie

The antibonding orbital has reduced electron density in th region between the two nuclei, so it has a higher energy than the bonding orbital.

If that makes sense we can get back to hybridisation ...

DanielSank

@ACuriousMind Yes, JohnRennie is explaining why the states in the hydrogen molecule have increased density between the atoms. This is all well and good. However, we're in that all too common situation in which OP (Bernardo), has asked not why the physics is the way it is, but why that physics is expressed in a particular way.

John Rennie

FFS I'm getting to that. Will you stop kibbitzing!

Bernard Meurer

@JohnRennie Got it, but why is it that the anti-bonding is the outer one of the two?

DanielSank

5:15 PM

I like JohnRennie's approach of getting the physics explained first and then getting to the jargon. I heartily endorse that.

@JohnRennie Oh calm down! I'm trying to sort it out for ACuriousMind. I'll stop pinging you though, that was an accident.

John Rennie

What does the outer one of the two mean?

Bernard Meurer

@JohnRennie Well, the further the electron is from the nuclei the more energy it has. So if the anti-bonding orbital has more energy it must be further away from the nuclei than the bonding one, i.e. it is the outermost of the orbitals

John Rennie

Molecular orbitals aren't simple spheroids like a slightly deformed s orbital. The antibonding orbital has a node in between the nuclei so it looks more like a p orbital.

Bernard Meurer

@DanielSank Is it a bad thing that I'm more worried about why are things expressed the way they are then why they are the way they are?

0celo7

@ACuriousMind So basically I'm going blind in one eye, can't see anything past 4 feet. The only time I could get an appointment with an eye doctor was tomorrow after 2, so I'm going to miss the QM midterm review and probably fail the class

DanielSank

5:19 PM

@BernardMeurer No. Not at all.

John Rennie

So I'm not sure it makes sense to describe it as an outer orbital ...

Bernard Meurer

@JohnRennie What do I google for imagery on this?

DanielSank

@0celo7 Wait, what happened?

0celo7

Also I'm in the shitties mood in the world and Rebecca hates me on my birthday and I don't know what to do anymore

Bernard Meurer

@0celo7 Call me

DanielSank

5:20 PM

Did you suddenly lose acuity in one eye?

0celo7

@DanielSank yes

John Rennie

@BernardMeurer google.co.uk/search?q=h2+molecular+orbitals&tbm=isch

DanielSank

@0celo7 Go to the emergency room right now.

0celo7

I can't see anything past reading distance

DanielSank

Now.

3

ACuriousMind

5:20 PM

@0celo7 oO Well, I wouldn't care about the midterm and go get that eye checked out!

DanielSank

You might have a detached retina or something and if you do you could lose vision in that eye for the rest of your life.

Bernard Meurer

John Rennie

Yes, that's a nice picture

But this is taking us away from hybridisation ...

Bernard Meurer

@JohnRennie I see what you mean't now :)

DanielSank

Someone pin my next message...

0celo7

5:22 PM

@DanielSank my family has a history of that and glaucoma

John Rennie

OK, shall we get back to hybridisation?

0celo7

But I don't think the latter one is an issue at my age

DanielSank

@0celo7 Send us a photo of the front door of a hospital. Until then, nobody talks to you about physics.

5

Bernard Meurer

It's just that probabilistically the anti-bonding orbital has less chance of being close to the nuclei!

0celo7

@BernardMeurer topology lecture in 3 minutes

HDE 226868

5:22 PM

@0celo7 If you aren't out of this chat in two minutes I'm tempted to kick you.

Medical personnel. Now.

ACuriousMind

@0celo7 So, how are you not already at a doctor?

0celo7

@ACuriousMind class

ACuriousMind

Fuck class

Bernard Meurer

@0celo7 Ignore it dude, go see your eye or I'll pluck it out with a rusty spoon

0celo7

No

ACuriousMind

5:23 PM

You need to take care of yourself first

0celo7

Topology midterm next week too

John Rennie

Speak to the person running the class/exam. They'll be used to students having to leave for medical emergencies.

DanielSank

@0celo7 my dad is right now recovering at home from a detached retina. My brother had this too. It's not that uncommon. Get to a hospital now.

0celo7

@HDE226868 do it but I can't go to the doctor today

Bernard Meurer

@JohnRennie I finally get those pretty drawings on my books!

@JohnRennie Onto hybridization

John Rennie

5:24 PM

OK. Suppose we want to use this idea to describe methane.

DanielSank

If anyone here knows @0celo7 personally please stop what you're doing, call him, and convince him to get to a hospital. This is not a joke.

Bernard Meurer

@0celo7 quit being a pussy, go see a doctor

@DanielSank trying

0celo7

@BernardMeurer don't call me

John Rennie

@BernardMeurer So we'll be approximating the bonding orbitals by adding together the hydrogen and the carbon atomic orbitals, just as we did for our hydrogen molecule. OK so far?

Bernard Meurer

@0celo7 I'll spam your email, it takes me two breaths to write a script

0celo7

5:25 PM

@DanielSank probably not a detached retina because it's been this way for a week

But I really can't see which is weird

Bernard Meurer

@JohnRennie Yes, makes sense

user116211

@BernardMeurer Then you are going back to Valence Bond Theory; but you can use hybridised orbitals in LCAO for approximating MOs; just a note.

ACuriousMind

@0celo7 It's not weird, it's dangerous. Do you want to be blind? Get to a doctor ASAP

0celo7

I have an appointment tomorrow, I couldn't get one today

DanielSank

@0celo7 Speculating about it is foolish.

Bernard Meurer

5:27 PM

@0celo7 Eye patches are not sexy anymore man

DanielSank

@0celo7 Go to the emergency room.

John Rennie

@BernardMeurer the problem is that the methane molecule is tetrahedral but the carbon p_x, p_y and p_z orbits don't point towards the corners of a tetrahedron. They have a cubic symmetry. So it's not easy to see how we can use our LCAO method.

HDE 226868

@0celo7 ER or university med center. Now.

DanielSank

Or for heaven's sake just show up at the eye doctor's office.

If you tell them you suddenly lost vision in one eye they will see you immediately.

0celo7

It's not sudden, happened a week ago

ACuriousMind

5:28 PM

That's...not better.

0celo7

In any case, you're all being unreasonable

John Rennie

Actually any regular optician can do basic checks like seeing a detached retina. If you can't get to a proper opthamologist quickly just go to your nearest optician.

Bernard Meurer

@JohnRennie Hmm, I see

John Rennie

@BernardMeurer OK, we're nearly there I promise :-)

ACuriousMind

@0celo7 No, you're the one that is being unreasonable. You asked for advice, and you got it: Go see a doctor immediately. I don't know what else to say.

Bernard Meurer

5:30 PM

user116211

@0celo7; I'm also having eye problem :(

John Rennie

The s and p orbitals are solutions of the Schrodinger equation. But any sum of solutions of the Schrodinger equation is also a solution. So we can take a combintaion of the s and p orbitals and it will still be a solution to the Schrodinger equation for our atom.

And it turns out that if we take the right combination of s an p orbitals then we get orbitals with a tetrahgedral symmetry - which is exactly what we need to do our LCAO calculation.

And these orbitals made up by combining the s and p orbitals are the hybrid orbitals.

Bernard Meurer

Hmmmm, what about SP1, SP2, and Sp3?

John Rennie

@BernardMeurer OK, does this make sense? You need to be confident about this before we go farther.

user116211

Right eyebrow is swollen and eye is itching; it's red ;/

0celo7

5:33 PM

@ACuriousMind I can't see one immediately

Bernard Meurer

@JohnRennie Yes, this makes sense so far

John Rennie

Good. If we combine the s orbital and all three p orbitals we get the tetrahedral $sp^3$ orbitals.

Or we could combine the s and ony two of the p orbitas to get $sp^2$ orbitals that have a trinagular rather thana tetrahedral symmetry.

Or an s and only one p orbital gives $sp$ which is linear.

But, and this is the key point ...

Bernard Meurer

So with sp3 hybridization I can't have dual bonds?

user116211

But, well, fortunately, I'm not blind.

John Rennie

@BernardMeurer No, because they all point in different directions. Dual bonds would require orbitals that point in the same direction.

Bernard Meurer

5:36 PM

Because I thought how a dual bond + hybridization happened was that Px and Py hybridized with S, and the Pz's formed a $\pi$ bond between them

John Rennie

@BernardMeurer yes, that's a good explanation.

Bernard Meurer

Also, what's the difference between $\sigma$ and $\pi$ bonds?

John Rennie

@BernardMeurer can we get back to that because it isn't relevant to hybridisation?

Bernard Meurer

Absolutely :)

John Rennie

OK, because i still need to explain the key point bout hydbrisiation.

Bernard Meurer

5:40 PM

::eyes wide open::

John Rennie

When we combine the s and three of p orbitals into $sp^3$ orbitals all we are doing is changing the way we describe the orbitals mathematically. Nothng changes in the atom, we aren't moving electrons around.

This can be hard to grasp. Does this make sense?

Bernard Meurer

Good, if we were it would be weird!

I can understand that, it's just a model and we're doing some tango with it to fit reality

John Rennie

So, we're there. Hybridisation is the process of choosing a convenient description of the atomic orbitals so we can then use the LCAO approximation to approximate the bonding orbitals.

Bernard Meurer

@JohnRennie Sweet! Got it!

Ready for the next question I have? :p

John Rennie

Students tend to think of hybridisation as something physical that happens to the atomic orbitals, but it's really just a mathematical trick.

But, there is a complication ...

The s and p orbitals are the solutions to the Schrodinger equation we get when the symmetry is spherical i.e. an isolated atom.

But in a methane molecule the carbon atom isn't isolated - it has four hydrogen atoms near it, and these change the symmetry.

So in fact there aren't distinct s and p orbitals when a carbon atom has four hydrogens near it. The s and p orbitals really do start getting mixed up to make new orbitals.

Bernard Meurer

5:46 PM

Well, in CH4 the carbon has 4 pairs of separable electrons surrounding it, so it has SP3 hybridization, which would imply the geometry being tetrahedral, no?

John Rennie

But you should probably ignore this as an unnecessary complication. Stick to the explanation of hybridisation I gave above.

@BernardMeurer Aha! a standard noob error!

Bernard Meurer

Dangit :p

John Rennie

Remember that the $sp^3$ orbitals are just a mathematical trick - they don't change the atom.

So hybridisation can't make the molecule tetrahedral because, well, hybridisation isn't a real physical process.

To explain why methane is tetrahedral you have to get out your big computer and do a proper molecular orbital calculation.

Bernard Meurer

So I was right!

:p

I do see your point though

user116211

Any reason an outside mod is here?

user116211

5:49 PM

Anyways, welcome @MetaEd.

John Rennie

The is that $sp^3$ hybridisation is a useful description because the geometry is tetrahedral. The geometry isn't tetrhaedral because of $sp^3$ hybridisation.

MetaEd

@MAFIA36790 Thanks!

Bernard Meurer

@MetaEd Who are you going to ban this fine afternoon? :P

MetaEd

@BernardMeurer Me, maybe.

John Rennie

@MetaEd somebody flag? Maybe they didn't like my description of hybridisation :-)

Bernard Meurer

5:50 PM

@JohnRennie Dipolar momentum, what's the deal?

ACuriousMind

Geez, you people need to be less paranoid :P

user116211

He is a mod ACM ;)

user116211

An outside mod.

Bernard Meurer

@ACuriousMind If it has a diamond next to it's name it makes the h-bar shiver :p

John Rennie

@BernardMeurer I've never heard of dipolar momentum ...

ACuriousMind

5:51 PM

@BernardMeurer You do realize I have a diamond next to my name now? :P

Bernard Meurer

@JohnRennie Bad translation on my part

John Rennie

@DanielSank: you can talk now :-)

Bernard Meurer

@ACuriousMind Kinky

user116211

@ACuriousMind You are native to h bar ;)

Bernard Meurer

@JohnRennie Yeah, molecular dipole moment :p

John Rennie

5:52 PM

@BernardMeurer Aha, OK, what about it?

Bernard Meurer

@ACuriousMind Come on, every time that ArtCode guy comes around half the chat get's permabanned :p

John Rennie

@BernardMeurer Untrue and unfair, though a visit from alien mods does bring a certain frisson with it ...

Bernard Meurer

@JohnRennie I don't understand:
1. What does it mean, i.e what *is* the dipole moment
2. What it entices for the molecule
3. How do I find out what dipole moment a molecule has

So basically all of it :p

John Rennie

Do you know what an electric dipole is?

Bernard Meurer

@JohnRennie Not really :/

GPhys

5:54 PM

@dmckee I wonder if I can provide some half decent empirical answers to some of the innumerable old questions about the LIGO detection after I get through this homework

user116211

Poison your prof @bernard.

Bernard Meurer

@MAFIA36790 Am I wrong to find the man a little insane?

John Rennie

@BernardMeurer OK, you need to learn about electric dipoles first.

user116211

@BernardMeurer He is indeed insane.

John Rennie

Electric dipole moment

In physics, the electric dipole moment is a measure of the separation of positive and negative electrical charges within a system, that is, a measure of the system's overall polarity. The electric field strength of the dipole is proportional to the magnitude of dipole moment. The SI units for electric dipole moment are Coulomb-meter (C m), however the most commonly used unit is the Debye (D). Theoretically, an electric dipole is defined by the first-order term of the multipole expansion, and consists of two equal and opposite charges infinitely close together. This is unrealistic, as real dipoles...

Bernard Meurer

5:58 PM

@JohnRennie Reading

user116211

No one is banned \o/

Bernard Meurer

@JohnRennie Okay, I kind of get that

John Rennie

OK, in a molecule that isn't symmetrical, e.g. HF, one atom ends up with more of the bonding electrons near it than the other atom.

Bernard Meurer

The more electronegative of the atoms?

John Rennie

So in effect one atom has a partial negative charge and the other has a partial positive charge. And that charge separation creates a dipole just as the Wikipedia article describes.

Electronegativity is a good guide as to which atom will end up with a slight negative charge, though it isn't 100% reliable.

Bernard Meurer

6:04 PM

Why couldn't nature have made Chemistry easier, nothing ever works in this science :p

John Rennie

Fundamentally chemistry is just quantum mechanics and is in principle very straightforward.

But molecules are many body systems and therefore complicated to do calculations with.

GPhys

Q_Q

I just bombed a graduate QM exam haha

John Rennie

So chemists have ended up with all sorts of rules of thumb that give pretty good predcitions most of the time.

user116211

@JohnRennie Central Field Approximation?

Bernard Meurer

@JohnRennie Don't we have potatoes powerful enough to solve this stuff by now?

John Rennie

6:06 PM

The trouble is that there are lots and lots of these empirical rules - ask @Kaumudi about it some time, but stand well back when you do :-)

GPhys

ogranic chemistry I and II was awful Q_Q

John Rennie

@MAFIA36790 do you mean the self consistent field approximation? As in Hartree-Fock calculations?

user116211

@JohnRennie yes.

Bernard Meurer

Hartree-Fock, hehehehe

John Rennie

I did a final year project on that ...

GPhys

6:07 PM

it was just empirically true general rules for various reaction types

Bernard Meurer

I hope the name is an indicative oh how hard it is lol

@GPhys I had organic in High School and I hated it

John Rennie

@BernardMeurer Fock that was hard! :-)

GPhys

enough to synthesize a lot of basic organic molecules

Bernard Meurer

It was basically "become an encyclopedia of stuff, none of which we will really be able to understand why happen"

@JohnRennie Figures :P

user116211

@JohnRennie Wow.

John Rennie

6:09 PM

Hartree-Fock is nothing. To get useful accuracy you then need to do a configuration interaction calculation to take into account electron-electron repulsion.

GPhys

the LIGO raw data is interesting

I think I know where most of the major noise is coming from

John Rennie

Configuration interaction

Configuration interaction (CI) is a post-Hartree–Fock linear variational method for solving the nonrelativistic Schrödinger equation within the Born–Oppenheimer approximation for a quantum chemical multi-electron system. Mathematically, configuration simply describes the linear combination of Slater determinants used for the wave function. In terms of a specification of orbital occupation (for instance, (1s)2(2s)2(2p)1...), interaction means the mixing (interaction) of different electronic configurations (states). Due to the long CPU time and large memory required for CI calculations, the method...

GPhys

like the noise at 60 Hz and its harmonics is probably electrical noise

user116211

@JohnRennie Now this is what I have not read yet.

Bernard Meurer

I don't think I could ever do a project on something with "Fock" in it's name without giggling throughout the presentation

GPhys

6:10 PM

and there's this HUGE noise spike at 500 Hz and its harmonics that seemingly must be the vibrating modes of the mirror (??)

user116211

@BernardMeurer They were badass.

John Rennie

@MAFIA36790 you won't do that stuff until post-grad level. I don't think any undergrad course would include it.

user116211

ah!

user116211

okay.

John Rennie

At that point you'll learn that the atomic orbitals, s, p, d, etc, that we've come to know and love don't really exist :-)

user116211

6:12 PM

O.o

John Rennie

Because the symmetry isn't really spherical.

user116211

oh yeh.

Bernard Meurer

@JohnRennie WAIT A SECOND THERE

I'm busting my ass to figure this stuff out

and it's not even true

ACuriousMind

nothing is ever "true"

John Rennie

Suck it up!
But not until you start a postgrad degree :-)

Bernard Meurer

6:14 PM

@ACuriousMind @0celo7 is stupid for not going to the doctor

John Rennie

For now it's true

Bernard Meurer

@ACuriousMind Take that, you kraut

ACuriousMind

@BernardMeurer huh?

Bernard Meurer

@JohnRennie I will finish this semester and never look back hopefully :p

@ACuriousMind You said nothing is ever true

I gave you something categorically true

user116211

@JohnRennie got the point.

John Rennie

6:15 PM

@BernardMeurer I don't yearn for the days of quantum chemistry. It was fun at the time, but GR is much more fun.

DanielSank

@JohnRennie :|

0celo7

@BernardMeurer I agree I am stupid

user116211

@BernardMeurer I still didn't get why you guys are learning chem. How would that help you in being a computer engineer?

0celo7

That's why I can't miss class

Bernard Meurer

@0celo7 Have you told Bob about it?

John Rennie

6:16 PM

@DanielSank was my description worth the wait?

Bernard Meurer

@MAFIA36790 Don't ask me dawg, I have no clue how any of this helps me conquer the world with AI-driven potatoes

John Rennie

@BernardMeurer that's one root to world domination

Bernard Meurer

@JohnRennie Next question: Effective atomic number and shielding effect

0celo7

@BernardMeurer of course

I told him when I first noticed

Bernard Meurer

@0celo7 Have you told Michelle?

0celo7

6:19 PM

No

Bernard Meurer

I'll tell K. she'll bother you until you go lol

0celo7

I'm going tomorrow, chill

Bernard Meurer

@0celo7 Tomorrow comes today

0celo7

That's not going to happen

user116211

@0celo7 Tell them the truth; you are going blind.

0celo7

6:21 PM

@GPhys OMG

I have mine on Friday

I'm so scared

DanielSank

@JohnRennie Yes. It's good to discuss symmetries.

GPhys

what happened to me probably won't happen to you

0celo7

Problem 1: compute the path integral for a simple harmonic oscillator

GPhys

I got insanely sick

DanielSank

I would point out that before introducing LCAO, it might be worth making sure the audience has a basic understanding of what the "LC" part of that acronym means.

0celo7

6:22 PM

I'd just die

GPhys

went to exam this morning super drugged so I wouldn't cough and drool and bleed out to death during the exam

0celo7

@GPhys I could be blind in at least one eye

@GPhys I'm sorry :(

GPhys

because of this I missed a lot of what I wanted to study on, but mostly just I missed revising what the last lecture was on

the contnet of the last lecture was one of the two things on the exam

user116211

@0celo7 Will that help you in the exam?

John Rennie

@DanielSank Bernard's course does seem a bit odd. It appears to have introduced advanced ideas without giving students the necessary ground work first.

GPhys

6:23 PM

and I was so tilted and drugged and obscenely sick for the first thing that I didn't get it all the way anyway even though it was easy and i knew it

for the first question*

Bernard Meurer

@JohnRennie That's exactly how it goes

Someone please transfer me away from here. thanks.

DanielSank

A lot (all?) of @BernardMeurer's questions recently will be a lot easier for him to understand once he has a better understanding of linear algebra and the idea of modes.

GPhys

and now I'm home because the drugs started wearing off so I went home and now I'm about to go to bed :)

DanielSank

@JohnRennie Correct.

GPhys

and that was my first graduate school exam :P

Bernard Meurer

6:24 PM

@GPhys You're over at UPenn, right?

GPhys

I feel like death and i can see myself coughing it up (and every other URTI you can think of)

user116211

@GPhys Take some pills.

0celo7

@DanielSank modes?

That's not an LA concept I've heard of

DanielSank

@JohnRennie Hence the creation of our Linear Algebra Happy Fun Time room.

@0celo7 I missed an "and". Fixed.

0celo7

Oh ok

@MAFIA36790 ???

John Rennie

6:26 PM

And now I'm going to sneak off quietly ...

GPhys

@0celo7 so

it can't possibly go that bad for you :)

0celo7

According to @DanielSank I have a detached retina

user116211

@0celo7 Is it dangerous?

0celo7

Pretty sure my gf hates me. My parents think I'm a failure. Not doing too hot either

@MAFIA36790 blindness in one eye

So maybe

I wasn't planning on being a jet pilot

user116211

At least I'm not blind; only too much itching ;/

0celo7

6:30 PM

Probably a fungus

user116211

:(

user116211

Eyebrow is swollen.

0celo7

Maybe a worm

GPhys

the dumb part about QM is it's really easy if I can just abstract myself past this silly vectorspace notation

user116211

Corner of the Eye-ball is too much red.

Obliv

6:31 PM

wow the h-bar really is a bar

where people come and talk about their problems over some non-alcoholic drinks

0celo7

@GPhys what vector space notation

GPhys

bra ket?

0celo7

Why is that silly

How else are you going to do QM?

GPhys

by refusing to internalize it for 2 years and writing all my notes in matrix algebra :D

0celo7

Wtf

heather

6:34 PM

@GPhys, I'm glad someone else feels that way. It drives me nuts. It's just harder to read.

GPhys

to be fair that's mostly on my old QM instructors

0celo7

How do you even do that

@heather I thought it was really intuitive when I first learned it

user116211

@GPhys Hardly heard of such practice ;/

GPhys

is Griffiths really all that different from such a thing? @MAFIA36790

heather

@0celo7, I understand the vectors and everything (sort of) - it is intuitive and makes sense. But the bra ket notation is just confusing. For me, anyway. In fact, I asked a question about the point of bra ket notation. Let me find it...

0celo7

6:35 PM

Griffiths is terrible, or so I've heard.

heather

27

Q: Why ket and bra notation?

So, I've been trying to teach myself about quantum computing, and I found a great YouTube series called Quantum Computing for the Determined. However. Why do we use ket/bra notation? Normal vector notation is much clearer (okay, clearer because I've spent a couple of weeks versus two days with it...

^aforementioned question

DanielSank

@0celo7 I said you might.

Emilio Pisanty

@heather Thanks

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