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5:00 PM
Less is known about adiabatic computing. We have a theory team investigating it seriously. They published an awesome paper where they benchmark the DWave machine.
@JohnRennie The food's good too.
 
@DanielSank name three of your biggest desires in life, please.
 
@2physics Hahaha ok
 
:D
 
1) Happy family.
 
vzn
ok we are at 1hr, time flies when youre having fun, thx so much DS, that was really awesome, esp enjoyed the Q/A relating string theory & QM computing that will be one for history! everyone is free to stick around. also DS suggested further discussion/ feedback on the AMA fmt/ guests etc in the side room chat.stackexchange.com/rooms/43876/daniel-sank-ama-questions
 
5:02 PM
@vzn string theory?
 
vzn
@DanielSank JDs question etc
 
2) Produce useful pedagogical documentation on the stuff I've learned.
I care about that one a lot.
See github repo :D
3) I dunno, probably total domination in Super Smash Bros. Melee.
Maybe a world record speedrun of Super Metroid...
Actually, I have one secret desire...
It's a software project. I've been slowly, slowly learning what I need to get it done, but it's hard.
Web programming is terrible.
Absolutely terrible.
 
vzn
@DanielSank your secret desire is a prj in web programming? whats terrible about it? @Slereah might be able to help with that (he agrees!) & have dabbled in it myself sometimes ;)
 
@DanielSank ok we wish you happy in life and so much documentation on the related stuffs and ..I dunno :D
 
If we're near the summing up point, I'd like to say how well I think this format works.
i.e. having a separate room to stage questions
and streaming them in to the AMA as appropriate.
 
vzn
5:10 PM
@JohnRennie think its ok/ worth further experimenting but wonder if its really necessary when audience isnt that big. the audience was not very vocal in either room :(
 
@2physics Thanks. Note that the documentation is on github, so contributions are welcome.
@JohnRennie Thank you.
 
The only change I would suggest is maybe we have an interviewer.
 
@JohnRennie lol
8
Q: What format should we use for Physics Stack Exchange Ask Me Anything events?

DanielSankThere's been talk in the hbar of starting an "Ask me Anything" (AMA) series in which featured guests would answer questions from other users. These questions would be about physics, the guest's career, or anything else. What format would work well for a Physics Stack Exchange AMA?

Yes I quite agree.
 
As it is DS had to watch both rooms and pull in the questions himself.
 
@vzn fought me rather hard about this.
Please do vote on that meta post to express your opinion in a way forever recorded!
 
5:12 PM
@JohnRennie I'd rather keep it like this so the AMAer can choose the order &c
 
vzn
@JohnRennie there has been quite a bit of feedback on that either mod or interviewer. think it could well. alas cannot volunteer for it, think its too much prep/ high profile for me, would encourage other volunteers
 
I wore both hats today, but it was a lot of typing and going back and forth. It would have been easier with an interviewer.
...which is exactly why I wrote that meta post.
 
vzn
@DanielSank dont recall that at all can you be more specific? think its fine for guest speaker to make decisions on fmt, do you think the 2room fmt worked well?
 
@JohnRennie oddly enough I thought it was less smooth this way, but what do I know. I wasn't watching too closely.
 
@DavidZ Interesting.
::shrugs::
Vote on meta post?
 
vzn
5:13 PM
@DavidZ less smooth how? we certainly have less extraneous junk in the (main!) transcript
 
It's more difficult to follow the threads of conversation, for me as a reader, but I could imagine it would be the same as the guest.
 
vzn
@DavidZ its less of a "conversation" splitting the rooms!
 
@DavidZ Hmmm, even with the bold question headings?
@vzn I agree with that.
I disliked that aspect today.
Felt like I was writing a memoir...
I was hoping for this:
 
@DanielSank They're orthogonal issues, I think. The bold questions help no matter what other aspects of the format there are.
 
1) Change of topic questions would be staged in the side room.
2) Follow-ups and clarifications would happen in the main room.
 
vzn
5:16 PM
@DanielSank conversations, interviews, AMAs, open forums, (panels!) etc, they all have different flavors, its actually really cool we can support different fmts, would rather not fixate on one fmt myself, maybe try to give guests choice as much as possible... maybe its good to be flexible on it...
 
@vzn Yeah, we're just doing a post-mortem so we know what works.
 
@DanielSank it did feel a bit stream of consciousness, and I think interjections from an interviewer would have helped break it up.
 
vzn
@DanielSank lol thats not nec a bad thing, a mini memoir :)
 
@DanielSank yes, that. I was struggling to come up with the right word, but that was my impression of today's event: it's as if you were writing an article about yourself, or in a way, giving a speech. It lacked the interactive feel that I would associate with a chat event or with an AMA (e.g. on reddit, though of course we're not trying to replicate reddit)
 
vzn
@DanielSank think this basically was achieved and the audience was not too active. think maybe the split room idea works better for a more/ very active audience.
 
5:18 PM
I suspect a part of the reason it was less active is that you pushed questions to a separate room.
 
vzn
@DavidZ speeches are not bad. guests might give speeches. dont have objection to it. think TED and its huge cyber influence etc. but agree speeches are maybe not so in line with the chat room fmt. we should do a live video for speeches maybe. (google hangouts etc)
@DavidZ agreed. was surpised. think we should try to know/ agree on that ahead of time if thats the idea/ intention. dont think it was the wrong decision. think it was a useful experiment (to get response/ data on).
 
Or just make it a blog post, since we are in text format.
 
@DavidZ yes.
 
@vzn you still keep pinging me over and over again :-P
 
I really just wanted to push big change-of-topic questions to the other room.
I should have been more clear about that.
 
vzn
5:21 PM
@DavidZ yes, really am hoping to encourage ppl/ guests to use blogs more, have encouraged DS on that in transcripts, ofc hes a natural but so far holding out :)
@DanielSank np, thats basically how it worked if you asked me. liked it as a channel to add running commentary/ notes etc
 
@vzn I did make a github pages repo...
Just haven't figured out how to use it yet.
 
@DanielSank Honestly, I think it'll be difficult to get that separation the way you want it. Everyone has a different idea of what constitutes big change-of-topic questions, plus people just don't follow directions. Not to say you shouldn't try, but... it will take active moderation to really pull it off.
 
vzn
frankly if you ask me, compared to the other 2 chats, (a small sample) this one was a spectacular success in fulfilling all my expectations (am careful not to have huge expectations! this is cyberspace/ chat etc! only 1hr! all volunteers! little advertising! etc!)
 
@DavidZ good point
@vzn Is that because I didn't stick on one topic the whole time?
 
vzn
@DanielSank to me one big goal of this all is for stuff just to not blow up lol! there are a zillion things that could go wrong & think nothing did, it all went smoothly :) (how about a n00b saying "yay chat flags" at the beginning! hadnt thought of that one before!) lol
 
5:25 PM
@vzn oh, hah
 
I liked the side room, because I felt invited to ask side questions (even if I expected that they would get ignored because time is so short and precious). And I didn't feel like disturbing anyone...
 
@DavidZ Active "moderation" eh?
 
vzn
@ThomasKlimpel agreed, its not so fun to ask questions in main room that are ignored/ skipped :( ... ps thx much for dropping by/ glad to know you havent given up on physics entirely/ have a crazy ref for you/ really wanna discuss with you/ anyone! see Tenev/ Horstemeyer!
 
::gives DavidZ the eyebrows::
 
Well, yeah.
 
5:26 PM
@ThomasKlimpel Did I miss any of your questions?
I'm still here :D
 
in Daniel Sank AMA questions, 38 mins ago, by Thomas Klimpel
Joseph W. Goodman in "Introduction to Fourier optics" uses $\exp[-j 2\pi (f_X x + f_Y y)]$ for the Fourier transform instead of $\exp(-j x \xi)$ as typically used in physics books. This avoids all the hassle with normalization factors, and makes implementation with FFT more direct. Do you have any opinion on this?
 
@ThomasKlimpel Hah! Great question!
There are so many different conventions...
Because angular frequency is so common in physics, normally use this pair:
f(t) = integral (d omega / 2pi) F(omega) exp(i omega t)
F(omega) = integral dt f(t) exp(-i omega t)
 
vzn
@ThomasKlimpel we just had a really fun discussion of fourier sampling a few days ago check out this amazing ref bet youll like it dcs.warwick.ac.uk/~feng/teaching/PowerSpectrum.pdf
 
There are two important things here:
First, there's the choice of sign in the exponents.
You'll see both.
Electrical engineers use the one I use. Physicists sometimes switch it.
The physics switch happens because physicists are often dealing with a wave equation where you have kx - omega t.
You need a Fourier transform for the k/x pair and the omega/t pair.
It's convenient (sort of) to have the signs be opposite.
So, physicists some times switch the sign for the omega transform and leave the k one alone.
At least, I think that's why they do it.
I just always use the same sign everywhere though.
As for omega versus 2 pi f...
 
@0celo7: I'll be around for a bit longer if you want to look at that PC.
 
5:33 PM
They're both fine, but angular frequency is more common in theory calculations, and more convenient because then (d/dt) exp(i omega t) brings out an i omega instead of a i 2 pi f.
 
@JohnRennie was in a meeting
 
vzn
@DavidZ ok youre the 1st person who told me that after literally years in here, maybe you can hit mute while am around, regard it as an SE bug that cant fix myself, trying to remember/ be careful but its part of my SE chat habits built up over yrs :(
 
@vzn It's because you edit so much, dude.
 
^^ that
 
@ACuriousMind: I've only just spotted that you asked people not to flag massages unless they are offensive :-)
 
5:34 PM
Like, 50% of your messages get edited, often multiple times.
 
vzn
@DanielSank you guys have heard of word processors right? :P
 
@ThomasKlimpel is any of this making sense?
 
@JohnRennie I want to explain Ricci flow to her but the mood hasn't been right
 
@JohnRennie Hm, so? A slightly off-topic message was flagged twice, I thought it would be good to clarify the use of flags for those not usually using chat
 
vzn
@DanielSank the style came from my writing (somewhat nonlinearly) on word processors and not thinking thru the entire sentence before writing it, adding clarifying words etc, sorry :(
 
5:35 PM
@ACuriousMind massages
 
And, well, I apparently don't understand it myself
 
Oh, lol
 
No thanks to ACM
 
Have you had any offensive massages recently :-)
 
I guess an offensive massage would also be flagworthy :)
 
5:36 PM
@ACuriousMind Ohhh, it's $\mathrm{tr}(AA^t)\ge0$!
 
I make it a (only roughly obeyed) rule to not edit cat posts where I've pinged another user.
 
@JohnRennie A gentleman never tells ;)
 
s/cat/chat/
 
@ACuriousMind :-)
 
And $\mathrm{tr}(AA^\dagger)\ge0$?
 
vzn
5:37 PM
@dmckee really am not following. is it the dinging noise that happens? it doesnt lead to multiple lines in the inbox right?
 
@JohnRennie What do I do about this computer
 
@0celo7: are you near it now?
 
@dmckee Cat posts?
 
@vzn Yes, every edit triggers the noise anew
 
I don't think I've seen you post cat pictures here
 
5:38 PM
Not that I think that is some kind of general rule, but it is a discipline that I impose upon myself.
 
@ACuriousMind Why not turn off the noise like a normal human
 
vzn
@JohnRennie haha there is an old inspector clouseau scene on that
 
@JohnRennie After my coffee finishes brewing, yeah
 
@DanielSank Yeah, that's exactly why I do it (at least).
 
@0celo7 Because the noise tells me when I need to look back at the chat tab. Of course.
 
5:39 PM
@DanielSank That's weeeeiiiird though
 
@DanielSank Yes, it is an opinion, and it is intersting to see how you think about it. It feels mostly like a perspective from a paper and pencil point of view, less so from a software implementation with least amount of surprises point of view.
 
OK I'm around for another half hour or so, then I have an appointment with my armchair and a cold beer
 
@dmckee I look at the little star that appears
 
vzn
@dmckee it doesnt ding every time someone replies in the chat room does it?
 
@JohnRennie IT'S GOING IN THE CUP RIGHT NOW
THEN I HAVE TO WALK 15 STEPS OVER TO IT
chill
 
5:39 PM
I have far too many tabs open all the time to count on being able to see the tab title change. Most of them are surpressed.
 
@dmckee I have 70+ open right now
 
@vzn Just when someone @-tags me.
 
Actually coffee sounds a good idea. Coffee or a beer - damn these hard decisions.
 
Irish coffee, clearly
 
@dmckee oh. Chat posts. I was very confused, you don't seem like a poster of cat pictures.
 
5:40 PM
I think the time of day where the decision between coffee and beer is a hard one is rather narrow
 
vzn
@dmckee the chat replies display @tags, dont know if they are equivalent. maybe only the 1st reply does not ding but later edits do?
 
Not coffee. One of the disadvantages of being old is not drinking coffee too close to bedtime.
 
@ACuriousMind Huh?
 
@ThomasKlimpel Ah, yes.
 
@JohnRennie cat post, right there. (|coffee>+|beer>)/sqrt(2)
 
5:41 PM
Coffee after dinner is normal
 
Software, I forgot to talk about that.
 
So is beer
what is a cat post???
 
In "bongs" even when the tool inserts the @-tag for you.
 
I think in software implementations the right choice is the default one used in numpy.
 
Wrapped spacetime!
-1
Q: how can space time be wrapped?

Sagar TimalsinaEinstein said if space time is wrapped then if we start going forward on time axis from a point on time axis then we can get that point back again,so is it possible to wrap spacetime??

 
5:42 PM
Note that that's a discrete Fourier transform so things are a bit different.
I like this:
 
@JohnRennie ok, bringing up the screensharing thingie
 
X_k = sum_{n=0}^{N-1} x_n exp(-i 2 pi n k / N)
 
@0celo7 Have you looked to see if the parallel port appears in device manager?
 
what do I do @JohnRennie
 
vzn
@DanielSank btw/ fyi also think the session did very well for an off-main-time session, and suspect it might not be replicated for other ("lower profile") misc guests, suspect you would have gotten more audience at main session time
 
5:43 PM
I don't mind if people use a different normalization, but I insist on the sign in the exponent and the use of linear (not angular) frequency.
@vzn Hadn't thought of that.
 
where do I find that
 
Press windows-R and it should pop up a dialog asking you what you want to run. Type devmgmt.msc and click OK.
 
I don't have a windows key
I can't use shortcuts right now
 
Yes, you should absolutely run commands that strangers on the internet tell you to run!
 
I don't know where the Run command is in Windows 10. Can you open a command prompt?
 
5:44 PM
@ACuriousMind heh
 
@ACuriousMind I ran that yesterday when trying to fix it myself
 
What's that fork bomb in /bin/sh, again?
 
@JohnRennie the hell is that
 
@JohnRennie lol, command prompt? What is this 1984?
 
@DanielSank I like that convention you cite from numpy, exactly like I would have expected it.
 
5:45 PM
This isn't going well :-)
 
@JohnRennie that's a joke.
 
@0celo7 The one true way to interact with a computer.
 
btw, ye folks might enjoy this one
 
In the beginning their was the command-line.
 
@dmckee something like :(){::}: I think
 
5:45 PM
I find it incredibly annoying that Windows doesn't encourage shell use.
 
All real computer nerds use a command prompt!!
 
@JohnRennie Yes.
 
I'm a geometer, not a computerer
 
185
Q: Why did the command ":(){ :|: & };:" make my system lag so badly I had to reboot?

blade19899 DANGER! Do not run this command to 'test' it unless you are prepared for a crash and/or force-rebooting your system. I was in my Virtualbox running 12.04 trying to compile an app, and while waiting I happened to chance upon a forum where a comment said: Try :(){ :|: & };: Fun, too...

 
OK click the start button thingy at the bottom left. Scroll down to find (I think) system accessories and the command prompt should be there.
 
5:46 PM
bottom left
 
You've got the bar set to autohide. Hover the cursor at the bottom of the screen and it should rise up.
 
nope
 
@JohnRennie Can people move the bar in Windows? I don't use the fool thing enough to know.
 
@dmckee sure - apparently, even without knowing how to do it, from some of the stories I've heard
 
@dmckee yes.
 
5:48 PM
this isn't working!
I can't use the actual computer right now
 
@0celo7 OK I gave up and asked Microsoft how to open the device manager:
 
But if they've moved it it becomes their problem to recall where they put it.
 
My toolbar is at the top, usually. Less distance from where the mouse usually is.
 
Seen recently in my office hallway.
 
Now what
 
5:49 PM
Right where the Guys at PARC meant it to be and where the Steve's put it. But Bill just had to be different.
 
@0celo7 Aha! On your PC it's at the top right. That Windows flag icon.
 
I found it
 
@EmilioPisanty nice
 
I use Windows 8 on my machine
And OSX
Windows 10 is strange
@ACuriousMind What is your honest opinion on what I should do about the flow thing?
I'm asking you as a human
I know you don't know how to derive it
But what should I do
 
@0celo7 Let me boot up the human emulation routine to answer that :P
 
5:52 PM
Anyhow, once you get the Start menu open I think you can scroll down, find the System accessories heading, click on that heading and you should see the command prompt.
 
@ACuriousMind I mean as opposed to a rubber duck
 
> As long as you have funding, quantum gravity is basic research at its finest. If not, it’s pretty much useless knowledge.
 
@JohnRennie I have the device manager open
waiting for instructions
 
@EmilioPisanty By Dad always kept a adage posted in his office.
 
Find the heading: Ports (COM & LPT) and click the plus sign to expand it
 
5:53 PM
> Basic research is what I'm doing when I have no idea what I am doing.
 
I think it was attributed to Werner von Braun (sp?)
 
Aha! It's got the wrong port number! It should be LPT1.
 
@dmckee It's in David's link over from the stars sidebar
 
Life Pro Tip?
 
5:54 PM
Pretty interesting reading
 
Right click that LPT3 item and choose Properties.
 
vzn
@dmckee lol tell it to ACM
 
@dmckee Wernher
 
ok
select that then hit OK?
 
5:55 PM
Change the port number to LPT1
 
Yeah. I read that. Nice bit. I've had the notion for a long time of wriing an (anonymous) document "What do I do if they called me a crackpot" trying to lay out the steps to getting up to speed and taken seriously.
 
Then click OK
 
But I think that may be better.
 
yes
now what
 
vzn
5:55 PM
similar quote wonder if someone famous said it
Aug 6 at 22:58, by CuriousOne
I remember somebody else claiming that one can't produce original research by publishing things one understands. ;-)
 
Shove my dongle in and see what happens?
 
It should now look like:
 
Yep
 
Right, try the dongle
 
Ok, have to remove it from the other PC
And I need to locate the disk
Not on my desk
uh-oh
 
5:57 PM
@dmckee There's a few good ones around. I believe I have solved a famous open problem. How do I convince people in the field that I am not a crank? over on Academia has some really good ones.
 
@0celo7 the words every IT support person hates to hear!
 
@JohnRennie Will report back in ~15 minutes.
 
OK, I'll go open the beer
 

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