The h Bar

DanielSank

5:17 AM

Hi, everybody.

students

Hello.

DanielSank

@students what's up?

students

chillin', you?

DanielSank

Doing my daily Duolingo exercises (Russian and Spanish).

Thinking about coupled oscillators in the back of my mind :-)

students

Wow! learning two languages at once? while thinking about physics?

DanielSank

5:26 AM

Nah I learned Spanish a long time ago. I just use Duolingo to not forget it.

students

(multitasking obviously works for you :-)

DanielSank

Learned Russian in college. Also trying to not forget that one. Fortunately we just hired a guy who speaks both Spanish and Russian better than I do :-)

students

coolio

DanielSank

Heh, actually I'm not so good at multitasking. Take for example this chat conversation... I'm definitely not learning Russian right now :-)

students

:-D

DanielSank

5:29 AM

Not sure I've seen you around here before. New?

students

yup

just asked my first question

wanna see?

DanielSank

Sure. Looks like your user profile doesn't appear yet and I don't feel like trying the SQL interface.

students

5

Q: Did Cambridge change their BSc policy for Ramanujan?

I found this quote at Quora: In March 1916 Ramanujan graduated from Cambridge with a Bachelor of Science by Research (This degree was later renamed as Ph.D. from 1920) for his work on Highly composite numbers. Given how important his paper on Highly composite numbers was it appears that Cam...

DanielSank

Interesting.

students

asked it after watching the movie "the man who knew infinity"

DanielSank

5:33 AM

Are you a student?

@students Good movie?

students

yup

DanielSank

Math student?

students

excellent movie, imho

students

6:00 AM

It appears that ramanujan was at cambridge when russell and whitehead were working on Principia mathematica.

Anonymous

@students skullpatrol? Nah, you're not really new. ;)

Anonymous

6:19 AM

@students FWIW, having socks is fine. But being misleading about it is not. Please avoid this in the future.

Anonymous

6:33 AM

@DanielSank Is Duolingo good?

DanielSank

7:03 AM

@Blue Yes.

Anonymous

8:12 AM

@DanielSank I see. Should probably use it to learn German (gotta decipher a few German lectures). :)

Anonymous

Deciphering spoken German would be slightly harder I guess.

Slereah

8:35 AM

Evening boys

Novalium Company

10:39 AM

I don't understand in a quantum computer you have qubits where a qubit can be any probability between 0 and 1, but when exactly in the process does it's actual value gets determined. If the polarization is random, then the quantum computer is nothing but a machine spitting random probabilities between 0 and 1???

Slereah

10:52 AM

The value gets determined at measurement

Same as all quantum processes

Secret

11:09 AM

The Halo Drive

►

A network of black hole pair highways. must update that into my scifi

user351417

12:27 PM

@Blue I tried using it for spanish a while back and it was pretty terrible.

user351417

It seems like the kind of thing for making yourself not forget the language, but it doesn't quite help you understand how to structure sentences, in my opinion.

user351417

I think I used it for french too, to get a hang of some fancy grammar concepts, and it didn't work for that either.

user351417

However, if you just want to build a vocabulary (e.g. for understanding lectures), I think it may be OK.

Anonymous

@NovaliumCompany Not quite. You'll not understand it (for certain sense of "understand"), no matter how hard you try, until you pick up some linear algebra. :)

user351417

It has decent provisions for learning how to understand what people are speaking.

Anonymous

12:33 PM

@Chair Oh, that's not what I need then. :/ I want to learn a couple of languages from scratch.

Anonymous

From what you're saying, it appears to be more of a brush-up tool. :)

user351417

Yeah, it's pretty much just a brush-up tool, IMO.

user351417

Or maybe that method of teaching is just different from the way I learned french and spanish. But I don't like that way as much

user351417

However, my skill with those two languages doesn't say much for that pedagogy :P

Anonymous

12:51 PM

@NovaliumCompany You'll find some answers here:

Anonymous

11

Q: What is a qubit?

What is a "qubit"? Google tells me that it's another term for a "quantum bit". What is a "quantum bit" physically? How is it "quantum"? What purpose does it serve in quantum computing? Note: I'd prefer an explanation that is easily understood by laypeople; terms specific to quantum computing sho...

physical-qubit

Anonymous

...but I doubt any of them will be satisfactory for you.

Anonymous

Note that some of the answers are pretty misleading too.

Anonymous

1:08 PM

@Mithrandir: the shortest convincing description of 'a qubit' that I could give to a somewhat mathematically engaged but otherwise typical 15 year old would involve at least a one hour tutorial in physics about the double-slit experiment, the Stern-Gerlach experiment, and/or the Mach-Zehnder experiment. I'd be tempted to introduce vectors at the very least to talk about coordinates on the Bloch sphere. Precisely how I'd go about it would require careful thought and planning, and laying down some physics education to explain what 'quantumness' even consists of. It's no small task IMO. — Niel de Beaudrap Jun 19 '18 at 21:02

Anonymous

Niel's comment is on point. I'd too start with something like "Qubits are elements of two dimensional complex Hilbert spaces (define HS and "complex"). Then cite experiments to answer questions on why physicists really chose that mathematical structure. Then we'd discuss what measurement "does" rather than what measurement "is" (the latter is open to interpretation).

Anonymous

But yeah, there exists no no-math explanation for this. If you want real clarity, you need to resort to math.

Captain Bohemian

2:43 PM

can mathjax be really installed easily?

Anonymous

3:06 PM

@CaptainBohemian Where do you want to install it?

Captain Bohemian

@Blue here.

I mean google chrome. I think Microsoft Edge doesn't work with Mathjax bookmark.

clicking start ChatJax and render MathJax in math.ucla.edu/~robjohn/math/mathjax.html leads to blank webpages.

Anonymous

3:22 PM

@CaptainBohemian Well, you need to drag it to the bookmark bar.

Captain Bohemian

it's like it works now. not sure if it will work forever or just temporarily.

@Blue that can't be dragged.

Anonymous

Anonymous

@CaptainBohemian Do you see "render MathJax" or "start ChatJax" on your Chrome bookmark bar?

Captain Bohemian

I find it needs to click that bookmark every time I go to the chatroom to render all LaTeX commands.

Anonymous

@CaptainBohemian Yes, that's true.

Captain Bohemian

3:33 PM

it's not as easy as I origially imagined. I wonder why people often type so many LaTeX commands here.

Anonymous

An easier option would be to install the Chrome extension or Tampermonkey script.

Anonymous

Any chance of MathJax in chat?

Anonymous

For those, you'll not need to click on a bookmark everytime.

Captain Bohemian

$\gamma^\alpha$

Anonymous

> I wonder why people often type so many LaTeX commands here.

Anonymous

3:35 PM

I use it because MathJax is easier to read than mathematical expressions written using ASCII.

Captain Bohemian

well, I often see physics chat and math chat are full of LaTeX commands. So I considered they are easy to type and read.

Anonymous

Well, they are easy to type and read.

Anonymous

You get used to typing MathJax quickly, over time.

Captain Bohemian

but there is no shortcut keyword. so how do I know how to type $\gamma^\alpha$ if I am not sure how to spell them?

also, I don't know the LaTeX commands of a lot of math symbols.

Anonymous

It's generally assumed that you do know the names and commands corresponding to those symbols. If you don't, you can ask here; someone will probably help you out. There are also some good references like:

Anonymous

3:40 PM

2623

Q: MathJax basic tutorial and quick reference

(Deutsch: MathJax: LaTeX Basic Tutorial und Referenz) To see how any formula was written in any question or answer, including this one, right-click on the expression it and choose "Show Math As > TeX Commands". (When you do this, the '$' will not display. Make sure you add these. See the next p...

discussion faq mathjax reference

Anonymous

Almost every MathJax command you'll ever need is summarized on that page. ^

Anonymous

There's also Detexify.

Captain Bohemian

In the past, physics forum chat room can render LaTeX commands automatically without needing to install anything.

Anonymous

@CaptainBohemian Well, Stack Exchange refused to add it from their end.

Anonymous

(For reasons...which never made much sense to me.)

Anonymous

3:52 PM

2

A: Any chance of MathJax in chat?

This request was discussed by the team on April 9th, 2014. The potential rendering cost would be such that it would need to be a per-room and per-user option; this would then create a situation where users would potentially never be sure how their messages would look to other readers - in other w...

Captain Bohemian

4:09 PM

do I also need to install mathjax and click that bookmark every time when typing LaTeX commands in main sites?

CaptainQuestion

In the chatrooms, yes

Mathjax is enabled on most of the sites that require it.

Captain Bohemian

I mean not chat rooms, but the places to ask questions.

Anonymous

@CaptainBohemian No

Captain Bohemian

4:28 PM

@Blue does your ASCII mean en.wikipedia.org/wiki/ASCII?

Anonymous

@CaptainBohemian Yes

Captain Bohemian

@Blue I have never learnt this until you tell me just now,

Anonymous

5:28 PM

26

A: How to preserve electronics (computers, iPads and phones) for hundreds of years

TL;DR You cannot. You need purpose-built items, with specially designed components and maybe even ad hoc designs (PSUs without electrolytic capacitors, etc.), capable of withstanding extreme cold. Otherwise, there are several chemo-physical processes that would require to be halted. Batteries...

Anonymous

This was enlightening for me. :)

Captain Bohemian

@Blue where do you have chance to use ASCII now? Aren't these ancient codings?

John Rennie

5:53 PM

@CaptainBohemian ASCII is a subset of UNICODE so it's used in every Windows computer.

Captain Bohemian

6:07 PM

@ZeroTheHero so am I correct in that "an infinite-dimensional representation of a Lie group" means the bundle realizing the representation is infinite-dimensional? Because your example infinite-dimensional Hilbert space is just a bundle over a spacetime manifold.

Anonymous

@CaptainBohemian I was actually referring to the ASCII character set (IIRC it has ~180 characters). In fact, MathJax is far easier to read even if you compare it with mathematical expressions written using Unicode (which has ~137k characters).

Captain Bohemian

@JohnRennie so who use UNICODE now? Windows computer programmers?

John Rennie

@CaptainBohemian all text in Windows is UNICODE. This text I'm writing right now is encoded in UNICODE.

Unicode

Unicode is a computing industry standard for the consistent encoding, representation, and handling of text expressed in most of the world's writing systems. The standard is maintained by the Unicode Consortium, and as of March 2019 the most recent version, Unicode 12.0, contains a repertoire of 137,993 characters covering 150 modern and historic scripts, as well as multiple symbol sets and emoji. The character repertoire of the Unicode Standard is synchronized with ISO/IEC 10646, and both are code-for-code identical. The Unicode Standard consists of a set of code charts for visual reference, an...

Anonymous

@CaptainBohemian For instance, $\gamma^\alpha$ looks much better than 𝛾^α. :)

Captain Bohemian

6:24 PM

@Blue can one write the latter in formal articles like published papers or textbooks? I have never seen published papers or textbooks writing math symbols in that way. That must be very awkward to read when a ton of math formulas and equations are put together. I do have seen someone using Word to type thesis, in which math symbols look very ugly compared to those typed by LaTeX.

Anonymous

> can one write the latter in formal articles like published papers or textbooks?

Anonymous

No, that's pretty much frowned upon these days (even in the 80s or 90s I don't think that would have been acceptable).

Anonymous

I doubt you'd be able to get any physics paper with mathematical expressions written using Unicode characters published in any legitimate journal.

Captain Bohemian

so I asked who use UNICODE nowadays. Are only Window computer programmers using them?

ACuriousMind

what do you think the text you're typing into this chat is encoded in?

Unicode is not specific to Windows, it's the standard for encoding text nowadays

Anonymous

6:29 PM

@CaptainBohemian You probably have a misconception about what "encoding" means...

Anonymous

Character encoding

Character encoding is used to represent a repertoire of characters by some kind of encoding system. Depending on the abstraction level and context, corresponding code points and the resulting code space may be regarded as bit patterns, octets, natural numbers, electrical pulses, etc. A character encoding is used in computation, data storage, and transmission of textual data. "Character set", "character map", "codeset" and "code page" are related, but not identical, terms. Early character codes associated with the optical or electrical telegraph could only represent a subset of the characters used...

Anonymous

It's hard to answer your question "...who use(s) UNICODE nowadays?" unless you define what you mean by "use(s)".

vzn

9:45 PM

Quantum Machine Appears to Defy Universe’s Push for Disorder / quanta mag

> In the 16 months since the result was published in Nature, several groups of physicists have tried to understand the nature of these quantum scars. Some believe that the discovery might herald a new category for how quantum particles interact and behave — one that defies physicists’ assumptions that such a system follows an inexorable march toward thermalization.

> Despite some initial skepticism of Papić’s analysis, Lukin, along with Wen Wei Ho, a physicist at Harvard, and others, then made the link to quantum scarring more explicit in a paper published in January. They identified a classical way to describe the state of the 51-atom system as a point in abstract space. As the system’s state changes, the point moves around.

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