The h Bar

2:07 AM

Given $R$ is a 2x2 matrix that acts on an input $u$ such that $Ru = u'$ where $u =
\begin{pmatrix}
u_1 \\
u_2 \\
\end{pmatrix}
$ and $|u_1|^2 + |u_2|^2 = 1$

$u_1, u_2 \in \mathbb{C}$

Due to conservation of probability, show that $R$ is unitary

what i tried:

Let $R =
\begin{pmatrix}
w & x \\
y & z \\
\end{pmatrix}
$

$R^\dagger =
\begin{pmatrix}
w^* & y^* \\
x^* & z^* \\
\end{pmatrix}
$

$R^\dagger(Ru) = R^\dagger R(u)$

I evaluated lhs and rhs separatlely and equated the components of the 2x1 matrix

is this the correct approach?

$R^\dagger R = \begin{pmatrix}|w|^2+|y|^2 & w^*x+y^*z \\ x^*w+z^*y & |x|^2+|z|^2\end{pmatrix}$

if $R$ is unitary then $|w|^2+|y|^2 = |x|^2+|z|^2 = 1$. Does this have to do anything with prob. conservation?

I have an approach that is, $Ru = \begin{pmatrix}w & x \\ y & z \\\end{pmatrix}\begin{pmatrix}u_1 \\ u_2 \\\end{pmatrix}$

$=\begin{pmatrix}w \\ y \\\end{pmatrix}u_1 + \begin{pmatrix}x \\ z \\\end{pmatrix}u_2$

John Rennie

4:05 AM

Motl on Duffield:

> Dear JD, it's a matter of terminology whether tirades by a hardcore unhinged crank like you are called a solution. They may be at most a proposal for a solution. At any rate, it's exactly as worthless as if you don't write anything. I "carp" if you write such things because science does. Science is cruel and if you can't live with the fact that according to science, you're just an unhinged crank, you shouldn't try to interact with science and instead, you should stay in your safe spaces.

To give Motl his due, he has a real skill at insulting people :-)

vzn

4:23 AM

...and LuMos blog is definitely not a "safe space"... o_O

Anonymous

6:15 AM

Does locking a question (by a mod) prevent further answers?

John Rennie

6:57 AM

64

A: What is a "locked" post?

Note: The below answer only applies to posts locked for reasons other than "historical significance". The "historical significance" lock reason works differently, and more info can be found here: What is a historical lock, and what is it used for? What does it mean to lock a post? A questio...

Anonymous

@JohnRennie What does "new answers (questions only)" mean though?

John Rennie

@Blue an answer can be locked as well as a question

Mithrandir24601

@Blue Yep

John Rennie

Locking an answer stops comments, etc for that answer but doesn't affect the question or any other answers to the question

Anonymous

@Mithrandir24601 Ugh

Slereah

7:03 AM

hello

Anonymous

7:52 AM

@Mithrandir24601 Montaro's notes look pretty good

Anonymous

I should have read these earlier

Mithrandir24601

@Blue Yeah, I know :P

John Rennie

8:05 AM

Not that I have any objection, but I'm mildly bemused that you two discuss the QCSE moderation issues in the PSE chat ...

I'm tempted to say: get a room you two! :-)

(a chat room :-)

Anonymous

@JohnRennie Lol. We're trying to avoid a certain user from noticing our chats :P

Anonymous

We can make another room here on PSE though

John Rennie

You can create mod only chat rooms. We have one for discussing issues related to the PSE chat. The room has access only for mods and me.

Mithrandir24601

@JohnRennie I've been getting some abuse in the QC chat over several days by a single user (I'm not kidding) and the above conversation involves the user who's been doing that. Things have hopefully calmed down now but I think the above conversation would just take us back to square 1

Anonymous

@Mithrandir24601 Actually JR's idea is good. Can we have our "secret chat room" on QCSE? :P

Mithrandir24601

8:08 AM

@JohnRennie I'm tempted to do that

@Blue OK, now you've asked...

John Rennie

The only downside is that the room locks if it's inactive for seven days, but any mod can unlock it again. The PSE chat mod room regularly locks if our more notorious users are being quiet :-)

Mithrandir24601

(also to clarify I'm going to do this because you're RO and there have been issues in the QC chat room, although having a conversation that arose from flags I believe deserves a private chat room anyway)

Anonymous

@Mithrandir24601 Fair :) "secret chat room" sounds cool though ;)

David Z

8:28 AM

Honestly making a private chat room primarily because of someone you want to exclude sounds like not the intended purpose of private chat rooms.

Mithrandir24601

→ 57 messages moved to The Private Channel

@DavidZ It's the result of mod flags

Anonymous

@DavidZ I think having that conversation publicly will only increase the abuse...

Anonymous

It gets really difficult when an user is being very difficult but yet not suspendable

David Z

Eh, if they're difficult enough, that alone makes them suspendable. (Or more generally, whatever needs to be done to prevent them from continuing to be difficult - sometimes there are other solutions)

Mithrandir24601

i.e. It's a conversation with someone who flagged a post for mod attention specifically about the post they flagged and their reason for flagging. It's also there for conversations about moderation of the QC chat room, which I have been getting abused in (by a single user) over the past few days and I don't want to kick things off again

David Z

8:32 AM

Ah OK that's legit.

Not that it really matters to me, anyway. Whether you use private rooms for their intended purpose or not isn't my business ;-)

Mithrandir24601

@DavidZ Good to know :) (if you do seriously feel it's not legit, do say so - I'm still new to this!)

@DavidZ Yeah, but I bet the CMs would be very unhappy if we didn't use them for their intended purpose :P

David Z

That is true.

Anonymous

What's their intended purpose though?

David Z

"moderation purposes"

Anonymous

Well, this is for moderation purposes :P

David Z

8:35 AM

Discussing a flagged post with the user who flagged it, when you need more information from that user in order to properly handle the flag, is definitely a valid use of a private chat room.

Though I do also note that, if you (@Mithrandir24601) have been taking abuse from someone in the QC chat, call on the rest of your mod team to deal with that. Abuse shouldn't be acceptable, but if that's going to be the case, it's largely up to you to make sure of that.

Mithrandir24601

@DavidZ Oh yeah, I've already done that and we (hopefully) finally got things sorted last night

David Z

Cool, cool

:-)

Anonymous

The problem mainly is that the user involved is quite a prolific poster and knowledgeable about the subject. However, they seem to be quite difficult. So unless they do something that is completely unacceptable we don't want to take the last resort i.e. kicking/suspending. Honestly, it's quite sad to see such behaviour from someone with a PhD and who has been working in the QC industry for 10 years or so (from what they claim)

Mithrandir24601

(maybe 'abuse' was too strong a word but definitely harassment at the least, just to clarify, although I'm not going to be pulling hairs at the distinction here)

David Z

"harassment" makes it sound worse :-P

Mithrandir24601

8:43 AM

@DavidZ Well, it all started last Thursday...

It was quite a stressful weekend to be honest

David Z

@Blue Yeah, I know what you mean. We've had a few of those here. Personally, the lesson I've taken away from those experiences is not to allow someone's expertise to get them a free pass when it comes to the "be nice" rules. It generally doesn't seem to end well.

@Mithrandir24601 Sorry to hear that

Mithrandir24601

@Blue Yes, well, if you go by location etc. in their profile, their location is at Caltech and they link to both quantum corp (whatever that is) and Microsoft. Interestingly, they once wrote a comment mentioning that they wrote a certain paper and none of the authors of that paper are actually at Caltech as far as I could find, so I wouldn't go believing everything you read in someone's profile

Anonymous

@Mithrandir24601 Hmm, well, that issue is there, true. Also no idea what quantum corp is

Mithrandir24601

@DavidZ Ah, that's life as a mod, I suppose. It's sorted now at least. Interestingly enough, said user may also have an issue with my PhD supervisor, going by what they've said in an answer of theirs...

David Z

Yeah, hopefully it's sorted out now

Novalium Company

9:03 AM

How do electromagnetic waves (such as light) travel through vacuum (space)?

Anonymous

Lol, we were having that discussion just a few days back with someone here :)

Novalium Company

:D

Anonymous

First thing to learn is: What is an electromagnetic field?

Novalium Company

Hmm... lemme google

The combination of electric field and magnetic field?

Anonymous

Yeah. Unfortunately I gotta leave now

Anonymous

9:06 AM

Someone here can surely help you

Novalium Company

Meh, I'll ask it later, I have to go too :D

user929304

9:17 AM

@ACuriousMind hi) if you're around later let me know, I have a QM related question :p

Slereah

help I want to murder internet explorer

John Rennie

@Slereah what has it done to you now? :-)

Slereah

Well I have to make a website work on it

and it is all manners of poor

IE doesn't even implement .includes in javascript

So I have to rewrite a big chunk just for that

John Rennie

9:34 AM

Isn't IE ECMAScript compliant? I thought they made a big deal about that.

Slereah

Apparently not!

Edge is

But IE isn't

John Rennie

Ah. Oh well. The joys of supporting legacy apps :-)

Use indexOf I guess ...

Slereah

that is th standard advice, yes

27

Q: .includes() not working in Internet Explorer

This code does not work in internet explorer. Any alternative? "abcde".includes("cd")

javascript

upgrade your browser, general public

I don't want to code for this

Mithrandir24601

@Slereah Solution: Don't use internet explorer

Slereah

I don't

But the clients do

Anonymous

9:48 AM

@Mithrandir24601 It's his job :)

Slereah

So I have to

Anonymous

Attack your clients at midnight

Mithrandir24601

@Slereah Solution: Tell your clients not to use internet explorer :P

Anonymous

And threaten them to change to Chrome

Anonymous

Or else....

Slereah

9:49 AM

if only

Anonymous

We need a replacement for Tor though. A good one which doesn't lag

Anonymous

Gotta protect the privacy

Slereah

Tor goes through a bunch of people

It's gonna lag

Anonymous

I knauw :/

Anonymous

Can't run a drug empire on the dark web without a replacement for that

Slereah

9:53 AM

just sell it via etsy

Anonymous

etsy.com/in-en

Anonymous

lol

Slereah

zelmanov.ptep-online.com/papers/zj-2009-12.pdf

>Newton's constant : $\mathfrak{G}$

What kind of madman is this

Secret

10:10 AM

That is nothing compared to $\mathscr{G}$

businessinsider.com.au/…

nah, still no joy

Are there still alcubierre drive papers pumping out recently?

arxiv.org/abs/1803.08214

hmm, free fall time machine

Birdfight

►

In other news

This is excellant

user929304

10:27 AM

@JohnRennie Hi, are you available for a quick discussion?

John Rennie

@user929304 Yes

user929304

@JohnRennie awesome, for context I am reading this en.wikipedia.org/wiki/Coulomb_blockade and in the part on Tunnel junction

@JohnRennie roughly, let us consider two electrodes separated by a insulator. Then if it is thin enough, single electron tunneling occurs frequently enough that with an applied voltage we can extract current. And often the resistance of the insulator is taken to behave exponentially as a function of thickness, i.e. the conductance between the electrodes decays exponentially with distance. In the article it says we neglect cotunneling.

My question is, would the conductance still be exponentially decaying even in case of cotunneling, say limited to 2 electrons at a time (as opposed to one)? I imagine if the insulator is too thin, then 2 electrons can never tunnel together because of their coulombic repulsion?

Trying to form an idea for how the cotunneling would change the overall picture here.

John Rennie

It isn't an area I know anything about I'm afraid.

Anonymous

Aren't the tunnelling probabilities independent or at least nearly independent? @user929304

John Rennie

Isn't cotunneling an effect in quantum dots?

user929304

10:37 AM

@Blue good question, well I would think if Coulombic blockade is relevant (i.e. thin enough or small enough system sizes) then they cannot be independent

John Rennie

It's when one electron tunnels in and another tunnels out simultaneously so the occupncy of the dot doesn't change.

I don't see how that's applicable here

user929304

@JohnRennie indeed it is also an effect in Q-dots. Here is much simpler, as we re just looking at a tunnel junction, and asking how the conductivity changes if we have more than one electron tunneling at a time

one would expect that it becomes much more involved because presumably the co-tunneling electrons would now interact, but I have no idea

John Rennie

@user929304 why would two electrons tunneling through the barrier be correlated?

user929304

@JohnRennie well I assume the coulombic repulsion between them correlates them, right?

NormalsNotFar

Hi guys, suppose I have some action $S=\int \text{d}V\mathcal{L}$. Furthermore, suppose that $\mathcal{L}$ is constructed, amongst other objects, by a symmetric tensor $g^{ab}$ (like the metric tensor for example).

John Rennie

10:41 AM

@user929304 The coulombic interaction between electrons in a solid is very short range

NormalsNotFar

Now suppose I wish to vary the action w.r.t to $g^{ab}$ and find it to be $\delta[S]=\int\text{d}VT_{ab}\delta g^{ab}$ where $T_{ab}$ is arbitrary. When I impose the variational principle, does only the symmetric part of $T_{ab}$ remain, i.e. is the EoM $T_{(ab)}=0$ and not $T_{ab}=0$?

Anonymous

Even if they're separated by a short period of time, practically, I'd just expect the probabilities to multiply . Oh and also JR's reason is quite valid. Coulumbic interactions are short range.

user929304

@JohnRennie right, and here the usual barrier thicknesses between the electrodes are on the order of a few nanometers, is that already too large for repulsion to be of relevance?

John Rennie

@user929304 The point is that the electrons will tunnel at random locations on the barrier. If the barrier has some significant area, presumably of the order of square microns, then the spacing between the tunneling events will be large compared to the interaction distance. It's not the thickness of the barrier that is relevant but its area.

Anonymous

Yeah, the thickness of barrier isn't very relevant here

user929304

10:46 AM

@JohnRennie ohh, that 's neat! what is the reasoning here that makes the area relevant and not thickness?

Anonymous

He already mentioned it, lol :)

John Rennie

@user929304 I feel like we're missing something here ...

Imagine the barrier as a sheet of paper. The area of the paper will in general be far greater than its thickness.

Anonymous

Tubneling takes place through random locations of the barrier. Those random locations are practically quite far away for coulumbic interactions to take place.

John Rennie

Mark the location of the two tunneling events by putting dots on the sheet of paper.

If you place the two dots on the paper at random they will have an average spacing of around half the size of the sheet.

So they will be too far apart to influence each other.

user929304

Aha! so in this analogy, the area of the paper corresponds in fact to the size of the electrodes and not the thickness of the separating insulator, right?

Anonymous

10:50 AM

Right

user929304

and to have an order of magnitude in mind, roughly, what is the distance at which the repulsion becomes relevant?

John Rennie

I suppose it would be about the size of a Cooper pair

No, actually the Cooper pair interaction is probably too small to be relevant here.

I don't know to be honest, but I would have guessed a few nanometres

Anonymous

It would be interesting though if there exist mathematical models in which the area of tunnelling barrier is of the order of few nanometres too. But I guess it would be ugly :P

Albas

The concept of calling a particle a 'quantum' particle comes from the fact that we do measurements on it and see it doing things according to quantum mechanics. Is that right?

Anonymous

11:05 AM

All particles are quantum particles. Just that in some cases the effects are too prominent.

Anonymous

Fwiw even for reasonably large molecules you can observe quantum effects

Anonymous

Say buckyballs for example

user929304

@JohnRennie Alrighty, thanks for the discussions, it's been great. So I guess we can roughly answer that, as a recap, given the thickness is the same and the area is large enough, the cotunneling wouldn't alter the exponential decay of the conductance between electrodes, as each electron is tunneling independently, thus facing the same barrier as before (with single e-tunneling).

Alternatively, if the area is too small, i.e. the electrodes are very small, then co-tunneling becomes much less probably due to the Coulombic Blockade, i.e. the repulsion between electrons prohibiting them to tunnel simultaneously.

@Blue thanks for the discussions as well!

Anonymous

en.m.wikipedia.org/wiki/Correspondence_principle

Albas

@Blue So what does it mean for something to be a quantum particle, the uncertainty principle?

John Rennie

11:08 AM

@user929304 it's not an area I know much about, but that would be my view.

Albas

@Blue These effects that you talk about, arent they because of the measurement process?

Anonymous

@Albas Particles for which quantum effects are prominent I'd say. Very large molecules can't show tunnelling

Anonymous

@Albas What do you mean by "because of the measurement process" ?

Anonymous

Quantum mechanics is valid regardless of whether any measurement is taking place.

Albas

11:27 AM

@Blue I mean to say that this process of taking a measurement, like using an apparatus to find the energy for instance

Anonymous

I understand that. But those "quantum effects" are not results of you making a measurement. But well, you can say collapse/decoherence is a result of you measuring the system.

Albas

What I am confused about is that when we say quantum effects, we mean to say things like tunneling. Now when we experimentally see tunneling happening its the interaction of the particle with the apparatus which shows that tunneling is actually happening

So doesnt it all depend on the interaction of the particle with the apparatus

Anonymous

Are you implying that there would be no tunnelling if you didn't "measure" it (whatever you mean by that)?

Albas

Okay I see what you mean

So why does tunneling happen with a quantum particle and not with a classical particle

Anonymous

@Albas You're looking for the proof of the correspondence principle I suppose

Albas

11:37 AM

Hmm I am not quite sure what I am looking for actually. I am just looking for definitions for the term 'classical particle' and a 'quantum particle'. Definitions which will help me differentiate the two

This idea of a classical limit as what I understand of it is how probabilities get affected as you take higher and higher energy levels (like particle in a square infinite well(thats the example I had in mind when I said higher and higher energy levels))@Blue

John Rennie

@Albas classical particle or quantum particle is a false distinction. Everything behaves in a quantum way over short enough timescales, but that timescale falls rapidly with the size of the particle.

The time that quantum behaviour can be maintained is called the decoherence time.

For something like an electron this time is very long. For macroscopic objects the decoherence time is too short for quantum behaviour ever to be observed.

djsmiley2k

hmmm

heh that hurts my head

'quantum stuff is happening to me right now, but I can't ever measure it'

Albas

@JohnRennie So you mean to say that our equations of motion for a large enough particle start changing if I decrease the size of the particle and take short time scales?

John Rennie

I think that's too vague a statement to have much meaning

Anonymous

@djsmiley2k Quantum effects are always affecting you. For example you're not penetrating into the floor because of Pauli's exclusion principle. :)

djsmiley2k

11:46 AM

hehe

I mean some of the effects which I concider 'strange' ;)

I used to often wonder when i was young, if I was lucky, my hand would go through the table or something

Albas

@JohnRennie What I mean to say is how do I write this down properly, this change in timescales and change in sizes

John Rennie

@Albas the theory that describes this is called quantum decoherence

Quantum decoherence

Quantum decoherence is the loss of quantum coherence. In quantum mechanics, particles such as electrons are described by a wavefunction, a mathematical description of the quantum state of a system; the probabilistic nature of the wavefunction gives rise to various quantum effects. As long as there exists a definite phase relation between different states, the system is said to be coherent. This coherence is a fundamental property of quantum mechanics, and is necessary for the functioning of quantum computers. However, when a quantum system is not perfectly isolated, but in contact with its ...

Albas

@JohnRennie Thanks

I do have another question but I will save that until I can formulate it properly

Anonymous

@Albas It's possible to "derive" Newtonian mechanics from QM afaik. I have to revise a few things though

Albas

@Blue Yeah there is that h cross tends to giving you hamilton jacobi

But again that h cross tends to is not a sensible thing to say

Anonymous

11:58 AM

Yeah that is pretty much nonsense

Albas

Yes the way @JohnRennie mentions it (I must be understanding something wrong), it feels more of a 'continuous' process to go from QM to CM

apt45

Hello everybody. Anyone knows the answer? :) physics.stackexchange.com/questions/411392/…

Mohammad Areeb Siddiqui

if $R$ is unitary, then does $R^\dagger(Ru) = R^\dagger R(u)$ hold where $u$ is a 2x1 matrix?

Anonymous

@MohammadAreebSiddiqui Matrix multiplication is associative...

Anonymous

15

Q: Is it possible to recover Classical Mechanics from Schrödinger's equation?

Let me explain in details. Let $\Psi=\Psi(x,t)$ be the wave function of a particle moving in a unidimensional space. Is there a way of writing $\Psi(x,t)$ so that $|\Psi(x,t)|^2$ represents the probability density of finding a particle in classical mechanics (using a Dirac delta function, perhaps)?

quantum-mechanics classical-mechanics schroedinger-equation faq

Mohammad Areeb Siddiqui

12:07 PM

right, thanks@

!*

Anonymous

They say the derivation given in Sakurai isn't rigorous. Gotta check it out though

Anonymous

I never read Sakurai as such

user929304

@JohnRennie I found something interesting about what we discussed, I quote it for you:

bolbteppa

1:09 PM

@NormalsNotFar you are varying with respect to the $g^{ab}$ component of $g$ so why would you just keep the symmetric part

Albas

@Blue Thats what I follow

Anonymous

@Albas Aren't you a mathematician? You should follow something more rigorous :P

Anonymous

I miss 0celo so much, lol

Albas

@Blue Thats the response I always get

Come on, there exists a mathematician somewhere who likes some hand-waving

:p

@Blue But there's a book by Faddeev which I do like

Anonymous

Never heard of it

Anonymous

1:20 PM

Gotta check

bolbteppa

Faddeev and Takhtajan, two mathematical QM books which are basically just summaries of Landau's QM

Albas

@bolbteppa Takhtajan goes into quite deep topics

bolbteppa

Yeah checking it he does do susy qm and path integrals and that Weyl section

I skimmed through that Hall Mathematical QM book, how can people read such things :p

NormalsNotFar

1:52 PM

@bolbteppa I figured because of the following $\delta[S]=\int\text{d}VT_{ab}\delta g^{ab}=\int\text{d}V\big(T_{(ab)}+T_{[ab]}\big)\delta g^{ab}=\int\text{d}VT_{(ab)}\delta g^{ab}$ and the variational principle says that $T_{(ab)}=0$

Mohammad Areeb Siddiqui

2:20 PM

im trying to find an operator U for a beam splitter such that a photon from that beam splitter in mach zender interferometer has prob. R to be reflected and T to be transmitted through. I ended up with $U = \begin{pmatrix}r & t\\t & r\end{pmatrix}$

where $r = \sqrt{R}, t= \sqrt{T}$

but this doesn't seem to be right because the exercise says the 2,2 element of the matrix is either not real or positive or both

why is that so?

if we act this operator on a 2x1 matrix

the output would be logical

susan J

3:59 PM

Sf6 is chemically inert . My question is when SF6 is in water wouldn't the fluorine form hydrogen bonds with the hydrogen of water molecule releasing enough energy to break the S- F bonds?

Please answer asap , I have a test tomorrow

Nat

@susanJ Dunno what you were asking about, but in general, seems like a question should be asked on the main site.

susan J

brainly.in/question/1005751

refer this for more info on SF6

Nat

4:12 PM

@susanJ Ah, that's really a chemistry question. You should ask on SE.Chemistry.

I mean, if forming HF results in a net lower energy, then it should eventually happen; then it's just a matter of kinetics.

susan J

ok

Nat

But is that reaction energetically favored?

You can look up the enthalpies of formation and do the calculations to figure out if the reaction's favored to have happened at equilibrium. If not, then kinetics aren't really a barrier; but if it is favored at equilibrium while being slow in the lab, then we'd tend to say that steric hindrance is keeping the kinetics slow.

vzn

physics chat session... empty? suggestion this wk: some teamwork action/ cooperation to get Hossenfelder as a chat session guest. (JR once said hed pay her consulting fee... still feeling that way?) physics.meta.stackexchange.com/questions/7783/… backreaction.blogspot.com/2018/06/lost-in-math-out-now.html

enumaris

dun dun dunnnnnn

Yashas

Is there an issue with the site or is it just me?

I get Service Unavailable. HTTP Error 503. The service is unavailable.

John Rennie

4:29 PM

I'm getting it too

rob

@Yashas I'm able to reload physics.se and chat with no trouble. HTTP 503 is sometimes a transient error.

@JohnRennie Ah, I'm in the US and you guys aren't. Obviously SE has shut off the rest of the world to comply with the GDPR.

Terry Bollinger

HELLO Hello hello (hello)... ANYONE HERE Here here (here)?...

Anonymous

@rob lol

Anonymous

It's working fine here though

Anonymous

@TerryBollinger Hello

Yashas

4:31 PM

It's being unpredictable for me here; it works for a second and then it's gone

Anonymous

@BalarkaSen Hey! How're things goin at TIFR?

rob

@Blue Well, now I can't load your profile.

Anonymous

@rob Weird. Maybe some temporary server problems

rob

There's folks discussing the http 503 error in the all-se-mods chat room. So apparently it's network-wide, even though intermittent. I bet it gets fixed "soon."

Balarka Sen

@Blue Same as it ever was

Anonymous

4:33 PM

Tavern on the Meta

MY GOD, IT'S FULL OF STARS AND BACKLOG! General friendly chit-...

9

7

Anonymous

@BalarkaSen What topics are they covering this time?

Anonymous

Are those like lectures?

Balarka Sen

I was given Bott-Tu (differential forms in algebraic topology) to read. I powered through 3/4 in a week so I have been made to switch to h principles which has been a royal pain in the place where the sun does not shine

Anonymous

"where the sun does not shine" :)

Balarka Sen

No lectures. I attended a few talks

Anonymous

4:36 PM

Algebraic topology sounds interesting. I've been trying to read some Differential Geometry but pretty much stuck up with the QC project stuff (which is quite interesting anyhow :))

Terry Bollinger

Hello @Blue. I'm US too, no errors, just quiet. Hmm. If we are the only ones with a completely clear channel, maybe the US doesn't believe in that physics stuff anymore?... }8^)>

Anonymous

@BalarkaSen I see, nice!

Anonymous

@TerryBollinger Haha :P

Terry Bollinger

Bott-Tu algebraic topology? It sounds genuinely interesting, but I am trying mightily to resist making it a bad pun...

Balarka Sen

I think I can guess the pun

Anonymous

4:46 PM

I'm a poor pun guesser ;_;

CooperCape

So I thought my organic chemistry exam had gone a tad worse for wear. Then I got out the exam and realised the 16% of the exam I'd guessed I'd got all right.

Albas

I don't get jokes ;_;

Terry Bollinger

Argh, I can't stop myself: I know a researcher who devoted himself totally to the study of Bott-Tu, that is, to Bott-Tu-lism, but he found it paralyzing...

5

Balarka Sen

@CooperCape Woo!

Semiclassical

@TerryBollinger ow

CooperCape

4:48 PM

@BalarkaSen Yeah! I surprise myself to say it went well. So did inorganic so I'm feeling oddly pleased about chem.

Anonymous

@CooperCape Congrats! Did happen to me once ;)

Anonymous

But that wasn't in a subjective test

CooperCape

I'd say it was kinda educated but I feel lucky for sure.

40% of the way through now :p Still haven't finished a subject yet urgh

Anonymous

lol...UK A levels are weird

CooperCape

They're just spread out. :p

GCSEs are worse that's like a month+ iirc.

Sid

4:52 PM

@CooperCape GCSEs are O-Level exams, right?

Anonymous

@CooperCape News from your land: thesun.co.uk/news/6498690/…

Albas

@BalarkaSen I am doing Tu's manifolds right now. I thought differential forms went as far as cohomology, seems they go more deeper

CooperCape

@Sid Erm In american form they're taken in 10th grade?

Balarka Sen

Tu's manifolds book is good

Sid

@CooperCape I don't really know. Don't you have O-levels and A-levels?

CooperCape

4:56 PM

@Blue Eh I don't get the stress. I've never been calmer than I am now. (To the point where it's concerning)

Anonymous

GCE Ordinary Level

The O Level (Ordinary Level; official title: General Certificate of Education: Ordinary Level) is a subject-based qualification conferred as part of the General Certificate of Education. It was introduced as part of British educational reform alongside the more in-depth and academically rigorous A-level (official title of qualification: General Certificate of Education – Advanced Level) in England, Wales and Northern Ireland. Those three jurisdictions replaced O Levels gradually with General Certificate of Secondary Education (GCSE) and International General Certificate of Secondary Education ...

CooperCape

Also I feel like 30 exams isn't a new thing considering how long gcses have been running for

Albas

Yea I plan to do it completely. I have heard that the theory of partial differential equations and manifolds are quite related. You know stuff about it ?@BalarkaSen

CooperCape

@Blue That would be it. thanks for the link blue :p

Balarka Sen

@Albas Eh, that's a very broad question.

They are related in multiple ways

Albas

4:59 PM

@BalarkaSen My plan is to analyze the pde's that come up in physics

Balarka Sen

What I am reading right now (h-principles) are a way to "solve partial differential equations over manifolds using topology", broadly speaking

Tavern on the Meta

Transcript for