The h Bar

Cows

12:26 AM

@BalarkaSen yes, I've been told it is mostly seemingly impenetrable

@Secret lol yes those guys eat mathematical structures for fun.

Anonymous

3:38 AM

@dmckee Haha...I remember that picture! :) Perfect Halloween costume ;) You definitely need to frame it

John Rennie

4:07 AM

@Blue Chicken breast pan fried to sear it then cooked in a cream sauce flavoured with a spice paste. It's on a bed of kitchuri rice.

Anonymous

4:48 AM

@JohnRennie Sounds nice :) Were those readymade cream sauce and spice paste?

John Rennie

@Blue It was a ready made spice paste. Life is too short to grind and mix your own spices. I made the cream sauce, but since it was basically just cream it didn't take much making :-)

Usually the meals I make are nice ish, but this one just worked perfectly and it was really delicious! :-)

Anonymous

Nice, nice :D Well cooked rice and chicken can indeed taste great. Something like butter chicken (or the one you made) makes it even better

John Rennie

To be fair it wasn't that different from butter chicken

Cream is just emulsified butter

Anonymous

Here we people rarely use the readymade stuff (one reason being they're usually not good quality/fresh). Everything is made from scratch. Which is why you'll always find Indian moms cooking, throughout the day. :P (However, that tradition is gradually changing)

Anonymous

@JohnRennie True, true :)

John Rennie

4:57 AM

I think it depends on the society. In the UK a large fraction of women work so they don't have time for cooking.

Anonymous

Yeah, nowadays things are quite different and changing with lots of women taking up jobs in the industry (which is good!). But that's the scenario we had while growing up

John Rennie

The good thing is that because in the UK there is a high demand for things like ready made spice pastes the quality of them is good, though they tend to be expensive.

Cows

So much epic code coming together!!! Taking a moment to dance.. such awesome!!

coding hard

ok moving into math mode. First some music for motivation

G-Eazy - 1942 (Official Video) ft. Yo Gotti, YBN Nahmir

►

Slereah

5:33 AM

Secret

5:47 AM

Prefacto

$\neg spell 🙇$

$\exists$Slereah $\implies$ O expt Cryptic

♻

Slereah!! => OoO, ><, QFT

OoO!! => >< (topologies $\neq$ simple)

QFT!! => QM + $\infty$

🤔🤔🤔 ?

? (When Confusion):

Inner sphere

A room where users constructs and speaks in cryptic, a mixed c...

?(h bar): $\exists det(Slereah) = 0$

=>Instability

Instability |- Cryptic

><!! => Albert Einstein -> Hendrik Lorentz -> Poncaire -> .... G => []+---> => ( )

vzn =O (Cryptic) => False

Slereah =O (Cryptic) => False

Secret =O (Cryptic) => Null

QM!! => p,q => $\hat{p},\hat{q}$ , ~ => Schrodinger, . vs ~~~ => O---O

Cryptic (h bar)!! => Incoherence, P(Mess) -| Instability (h bar)

$\forall$ (instability) $\in$ h bar : $\exists$Cryptic ala Instability $\in$ h bar

esc (h bar) => NULL

?(mathematics): $\not\exists A : \det (A) = 0$

=> Stable

( ͡° ͜ʖ ͡°) Slereah $t+\epsilon$

O))) GW 🔥

🤔 <----> GW

LIGO -->O Pr(Aug) > $\epsilon$

Nehal Samee

6:18 AM

@JohnRennie. Available?

Secret

probably not

John Rennie

@NehalSamee I'm working now I'm afraid. Back in a bit.

Nehal Samee

@JohnRennie ok

Secret

6:39 AM

🎮🎮🎮

Trump /\ Kim

t < day => The Plan -> Reality ~ Fantasy

Balarka Sen

@Cows That's not the right conclusion. It is hard, but not impossible, to understand schemes.

John Rennie

@NehalSamee I'm back now for half an hour or so. What did you want to ask?

Secret

I have no idea what Cow's ping is referring to when he pings me earlier

Nehal Samee

@JohnRennie. Problem solving room ?

Secret

My only vague understanding of schemes is it somehow prescribes data, thus I am guessing cauchy surfaces are an example of schemes

Anonymous

6:53 AM

@BalarkaSen Mr. Mathematician, need some help here! Any idea how we can directly say that the spectral norm of a weighting matrix $$W=\frac{1}{Md}[\sum_{m=1}^{M}x^{(m)}(x^{(m)})^{T}] - \Bbb I_d/d$$ i.e. $||W||\leq 1$? Here $\Bbb I_d$ is a $d\times d$ size identity matrix and $x^{(m)}$ is a set of d-elements (which belong to $\{+1,-1\}$). They're treating $x^{(m)}$ as a column matrix. For reference: the claim is made on page 4 here, on the bottom left.

Secret

o wait i mixed up schemes with something else that actually prescribes data

Anonymous

"Spectral norm" refers to the largest absolute eigenvalue of a matrix

Secret

Sheaf (mathematics)

In mathematics, a sheaf is a tool for systematically tracking locally defined data attached to the open sets of a topological space. The data can be restricted to smaller open sets, and the data assigned to an open set is equivalent to all collections of compatible data assigned to collections of smaller open sets covering the original one. For example, such data can consist of the rings of continuous or smooth real-valued functions defined on each open set. Sheaves are by design quite general and abstract objects, and their correct definition is rather technical. They are variously defined, for...

It's sheafs i was talking about earlier

Slereah

7:15 AM

Can we ban @Secret for spamming nonsense

Secret

It's only nonsense because you don't understand what it means.

You also have 2 questions outstanding which is why you are the instability of h bar

May 22 at 12:05, by Slereah

"One first cute improvement appears in the list of authors. Aside from Aharonov, Cohen, and Elitzur – who have produced lots of garbage about "weak measurements" over the years – another stellar co-author has been added, the crackpot-in-chief Lee Smolin."

It does not matter how many times you selectively ignore and ghost me. I will ghost bust you every single time to ensure all data in the cauchy surface is traceable

We do not tolerate missing information

May 29 at 11:01, by Secret

and that indifference is a complete waste of efficiency

Secret

7:39 AM

and I still found it extremely strange why vzn is not triggered by a criticism of weak measurement presumably by Slereah

cause if so, it will make our work much easier

[Translation of the above Cryptic]

(This is the final time we will provide an explanation of our actions cause it is clear that Slereah will not comply to our requests)

Perfect
Cannot spell, apologies

Whenever Slereah is present, it is a perfect time to experiment with Cryptic

Let's recap:

John Rennie

@Secret let's not.

Secret

Who is Slereah: Knowledgeable in wormhole physics, general relativity and QFT

John Rennie

No catfights please.

Secret

ugh fine

John Rennie

I'm not going to pick sides here, but this chat is not the ideal place for stream of consciousness posts.

Secret

7:46 AM

Slereah is really annnoying me for selectively ignoring my posts (i.e. he ignores without pressing the ignore button)

John Rennie

When you next feel the urge to make a long post that will be meaningful only to yourself take a moment to think whether there might be a better place to do it.

Secret

And I have no antidote for selective ignorance ghosting behaviour

John Rennie

I selectively ignore your posts too

Secret

You knew which of my posts are just rants and which are genuine, Slereah is not

Slereah has at least 3 known records of ignoring my questions‌, despite polite follow ups

John Rennie

Try not posting rants and see if that helps.

Secret

7:50 AM

I can promise to not put rants from now on, but i seriously doubt Slereah will answer, that's the power of ghosting. There is simply no way to effectly ghostbust anyone in the most general sense

Everytime a ghoster ghosts, the ghoster wins, always, because there is no way to force them to answer, and the only choice is to move on. This is so unfair especially when the person is not a troll

Cows

8:31 AM

@Secret you meant stacks no?

Secret

I don't recall I said anything about stacks, I think I only briefly mentioned about schemes

Cows

oh

Secret

Boteppa said something about stacks though, which is why I am wondering it is actually a mistag

Jun 5 at 21:55, by bolbteppa

Then schemes and stacks are still laughing at you

Cows

lolz

I had no idea other people found it somewhat abstruse

Mithrandir24601

@MohammadAreebSiddiqui For my perspective, I did an undergrad in physics with a year in computer science, then a masters in mathematical physics and am now doing a PhD in quantum engineering. There's no hard rule saying 'this is how to get into the field' but there's a mix of mathematicians, physicists, computer scientists and engineers involved - my advice would be to study what you enjoy (hopefully it's one of those 4 subjects if you're interested in QC down the line)

and if you find you're interested in QC (being interested now does count for that) read about it, aim to do projects in that kind of area, do any QC, quantum information or quantum engineering courses you can. You might also be interested in this or any similar things you might find.

In other words, do things that show you've got an interest and you'll also learn about it, which'll put you in a good place for jobs/PhDs/whatever your final path will end up being

Oh, if you want to build them, a maths degree wouldn't be the ideal way to go, but even that could still work. It sounds like you might be interested in the engineering of them?

Anonymous

10:44 AM

@Mithrandir24601 Chemists are great candidates too! Especially those with experience in computational and quantum chemistry :)

Anonymous

@Secret Why are you obsessed with Slereah? Lol

Secret

Because he selectively ghosts, and only he has the answer to the questions I ask him

Otherwise why would I waste time bothering someone who refuse to answer

putting the whole h bar's existence at stake?

Mithrandir24601

@Blue now that you mention it, I can't really disagree with you there :P

Secret

It will be some learning curve for the quantum optics aspect of stuff, but quantum chemists having already handled far messier equations should not find this a problem

Anonymous

"only he has the answer to the questions I ask him"...really...he's the only person in the whole wide world who can answer your questions? :P If they're related to physics you can ask them on the main site too

Secret

10:55 AM

May 22 at 12:05, by Slereah

"One first cute improvement appears in the list of authors. Aside from Aharonov, Cohen, and Elitzur – who have produced lots of garbage about "weak measurements" over the years – another stellar co-author has been added, the crackpot-in-chief Lee Smolin."

I tried google any subsentence of this quote, and I found nothing

and it does not sounds like a thing that he made up from scratch

Thus only him knew the origin of this quote

John Rennie

That is almost certainly from Lubos Motl, and probably from his blog. It has that Motl quality to it :-)

It's from this post on Motl's blog

Secret

Ah I see. In that case I don't understand why none of the following: "Lee smolin weak measurements", "crackpot Lee Smolin", "Aharonov weak measurements", "<full phrase>" etc. back on 22 May return relevant hits

but anyway, now that it is found, I can investigate deeper on why Motl think Lee Smolin is a crackpot

(Still does not remove the fact Slereah now has a total of 3 questions he selectively ignored, but whatever)

Anonymous

I just copy pasted the whole quote onto Google search

Anonymous

The only link is Motl's blog

Mithrandir24601

@JohnRennie I'll have you know that Eli Cohen is really nice. He's also one of Popescu's postdocs, so knows what he's doing...

Anonymous

11:06 AM

On 22nd May probably it was not picked up by the search engines yet. So those keywords returned no results.

Anonymous

Takes some time

John Rennie

@Mithrandir24601 huh? Do you seriously think I agree with any of Motl's rants?

Mithrandir24601

@JohnRennie of course not. I'm just saying that because I would like to say some stronger statements, but I don't want to have to suspend myself ;)

Anonymous

What's Motl doing nowadays though (other than posting on his blog) ? Does he teach somewhere ?

Rumplestillskin

Hello one and all! I've stumbled across one of those videos where gravity is portrayed as a rubber sheet or a trampoline emulating "spacetime curvature". It got me thinking. How would one explain a polar orbit using such a demonstration? It seems to do the job for equatorial orbits.

John Rennie

11:16 AM

@Rumplestillskin you should not take the rubber sheet model literally. In fact you should not take it at all!

Rumplestillskin

@JohnRennie I know this! :) I was just wondering how do people explain such things using such a demonstration. It's highly misleading!!

John Rennie

However, since you ask, the usual rubber sheet does not imply that the planet's axis of rotation is oriented normal to the sheet. It could be at any angle.

Strictly speaking the rubber sheet model is even less applicable to rotating bodies since whenever we have a rotating body we have frame dragging.

Rumplestillskin

@JohnRennie I am familiar, it was just something that popped in to my head specific to the rubber sheet example.

Do you think a better analogy would be that a ball is placed on a trampoline and then another trampoline is placed on top of this? Then then curvature or the sheet would be stretched to the geometry of the ball?

Slereah

12:57 PM

I think the big book of spacetime requires a section on algebraic topology

there is too much of it

Question is, where

After the chapter on manifold

But is it before or after the chapter on vectors

Slereah

2:43 PM

@ACuriousMind what is $X^{n-1} \sqcup_\alpha D_\alpha^n $

Is that notation supposed to be an adjunction, except with disjoint union instead of union?

Emilio Pisanty

3:18 PM

0

Q: Work done in lifting a object from underwater if it displaces $W'$ of water?

A spherical shot of W gm weight and radius r cm, lies at the bottom of cylindrical bucket of radius R cm. The bucket is filled with water up to a depth of $h\,\mathrm{cm}$ $\left(h > 2r\right).$ Show that the minimum amount of work done in lifting the shot just clear of the water must be$$ [W(...

¬¬ outta closevotes

John Rennie

@EmilioPisanty I have obliged :-)

vzn

@Secret smolin has high physics bkg/ credibility but is critical of string theory with this older popsci book (not unlike the new hossenfelder critique). (from his blog) motl also doesnt like the perimeter institute in canada where smolin works. etc amazon.com/Trouble-Physics-String-Theory-Science/dp/061891868X there is a similar critique by woit amazon.com/Not-Even-Wrong-Failure-Physical/dp/0465092764

Emilio Pisanty

@JohnRennie thx =)

John Rennie

3:34 PM

@vzn Smolin seems to be a bit of mayfly. He flits from subject to subject without ever making a serious dent in anything he works on. I'm not endorsing Motl's criticism of him because it's obviously spiteful and unjustified. But Smolin is not one of the 21st century's great physicists.

vzn

3:50 PM

@JohnRennie smolin has strong credentials/ top degrees. en.wikipedia.org/wiki/Lee_Smolin eg Phd Harvard etc

John Rennie

@vzn so does everyone working in theoretical physics these days. You simply don't get your foot in the door unless you're uber smart. Nevertheless, I stand by my comments.

vzn

we are in agreement about motls over-the-top style/ criticisms of others actively working in the field.

Mohammad Areeb Siddiqui

so the prof. just wrote the following on the board $\int_{-\infty}^{\infty} |\psi (x,t)|^2 \, dx = 1$

Inner sphere

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