The h Bar

12:02 AM

if $\Psi = \int_{-\infty}^{\infty} dk e^{-L^2(k-k_0)^2}e^{ikx}$ and by stationary phase argument the integral has a chance to be non zero when $\dfrac{d(kx)}{dk} = 0$ => $x = 0$. Given all that, how would I predict the location of the peak of $|\Psi|$?

No calculations, just a prediction

Mohammad Areeb Siddiqui

12:55 AM

rip it is, the location is at x=0 lol

y am i like dis

Mohammad Areeb Siddiqui

2:41 AM

if i have to show that the free schrodinger equation in 1 dimenion is galilean invariant with transformations $x' = x - vt$ and $t' = t$ then should i assume a phase $\psi(k) = kx-\omega t$ and plug in $k', t'$ there and factorise to show that?

vzn

4:02 AM

in theory salon, 2 mins ago, by vzn

US politicians call for a national quantum-computing strategy / physicsworld

Eulb

6:04 AM

@SirCumference \o

Gaurang Tandon

6:41 AM

@EmilioPisanty hey! I saw that you were a bit active around the development of the MathJax buttons userscript. Well, now that it's a bit outdated, I am working on a similar userscript that does that and a lot more. It's almost finished and now I am adding site-specific features. I just wished to ask you if you've new features to ask for in that userscript, or is that "Dirac-ify" feature still sufficient?

Thanks!

Eulb

@Blue who... are you

John Rennie

I woke up in a Soho doorway, a policeman knew my name. He said "You can go sleep at home tonight if you can get up and walk away"

Abcd

7:09 AM

@JohnRennie Why is newton's 3rd law invalidated in case of magnetics?

John Rennie

Newton's third law is essentially conservation of momentum.

What complicates things with magnetic fields is that the field can have momentum and can transfer that momentum to other things. So it can appear that the third law is violated. It isn't of course. You just need to consider the whole system including whatever is generating the magnetic field.

Abcd

@JohnRennie Can you prove to me it is conserved in a numerical question that I have?

Emilio Pisanty

@JohnRennie she said honey, take me dancing, but we ended up a-sleeping in a doorway, by the bodegas and the lights on upper Broadway?

@GaurangTandon frankly, it's been years since I used that script

John Rennie

@EmilioPisanty Paul Simon?

@Abcd if you want to post the question in Problem Solving I'll have a look

Emilio Pisanty

I put unicode ranges and langles in my keyboard and they take the bulk of the friction out

@JohnRennie yep

Gaurang Tandon

7:16 AM

@EmilioPisanty oh, are you interested in using a similar script again? i'm not familiar with Phys.SE so I'm not sure how useful Vector-ify, Dirac-ify are. It would only take me five minutes to implement them, but if no one uses it, it'd be pointless :(

@EmilioPisanty you set up macro codes in your keyboard for those two characters? Now, how about if you type Alt-G, it would automatically insert $|(caret)\rangle$ for you? I wonder why you'd prefer the former to the latter?

John Rennie

@EmilioPisanty the thing about the song Who Are You? is that it encapsulated life as a young man in the UK at the time. Getting so drunk that you woke up in a doorway is something most of us have done - including me. Not that it's anything to be proud of ...

That's why the band remain so important to British men of a certain age.

The Arctic Monkeys achieved the same for the next generation on with their first album.

Emilio Pisanty

8:04 AM

@GaurangTandon it's not a macro

It's part of the software keyboard

Gaurang Tandon

@EmilioPisanty "software" ...you meant you use a virtual keyboard?

Emilio Pisanty

8:37 AM

@GaurangTandon no

I mean the piece of software that translates from physical key presses to symbols

At the OS level

I built it to write comfortably in Spanish on a UK keyboard and I added some science extras

Anonymous

9:04 AM

@Eulb A mean circle.

Anonymous

(with an elongated nose partitioning me into two half-circles)

John Rennie

@EmilioPisanty you wrote your own keyboard driver? What OS?

Gaurang Tandon

9:26 AM

@EmilioPisanty oh, alright

Cows

9:41 AM

Going to attempt to do $\phi^4$ theory literally in my sleep. I am going to be thinking about this for two days. With a little luck i should be able to work out the "gory" details as I lay in bed sleeping.

Emilio Pisanty

9:59 AM

@JohnRennie not a driver

just a key mapping

both on ubuntu and on windows

microsoft.com/en-us/download/details.aspx?id=22339

35

Q: What are the steps needed to create new keyboard layout on ubuntu?

The keyboard I am trying to create has a lot of Unicode and looks like this: Being unsuccessful with the following tutorial: https://help.ubuntu.com/community/Howto%3A%20Custom%20keyboard%20layout%20definitions (There are a few errors in the tutorial, and it uses imprecise language such as "C...

keyboard-layout

John Rennie

@EmilioPisanty ah, cool, that's new to me.

Emilio Pisanty

@JohnRennie yeah, it's fairly new

it was pretty shit on windows 7, the windows 10 version is much more usable

John Rennie

I know you can modify keyboard mappings by hacking the registry. I've done that to remap caps lock to shift, because I kept hitting it accidentally. Presumably this app puts a nice user interface on the registry hacks.

J Thomas

11:25 AM

Back to something people were discussing yesterday --

If you want to create radiation with a tremendously long wavelength, you can do it by moving a charge at a tremendously low frequency.

You can get a very very long wavelength if you are willing to move a charge in a sine wave with a frequency of 1 cycle per billion years. You can even do that inside any cavity you want, if you have a way to accelerate your charge the way you want it. In a small cavity it can't go very *fast* in one direction for a billion years, so somebody a billion years and a billion light-years away would need very…

LHC2012

1:55 PM

Hello, can anyone answer questions about rolling resistance? I did an experiment and found results that seems counterintuitive

Specifically, what I did is bend a track at different heights and look at the decay in height of a ball that is on the track, and the results show that for higher heights, the height decay of the ball is faster.

Here's a picture of what I did, and the track is bendable to different heights

How would I make sense of the result of the experiment that the height decays at a higher rate if it is initially placed at a higher height?

bolbteppa

2:54 PM

@vzn when Motl is reviewing Woit's book amazon.com/Not-Even-Wrong-Failure-Physical/product-reviews/… he calls him out for using email messages to bolster his argument, but then in this review of SH's book blogs.sciencemag.org/books/2018/06/04/lost-in-math , which uses a random facebook post to bolster the point of the article, he loves the use of random facebook messages that agree with him motls.blogspot.com/2018/06/…

and even worse, Woit in the comments calls out the author for using random facebook messages even though in his book he apparently uses them to make his argument, hypocrisy much? :p

I'm ready for the string wars :p

vzn

3:27 PM

@bolbteppa there are no rules. blogs are great but its just the "golden rule"-- he who has the gold(blog) makes the rules. would like to see a place thats free of bias. apparently not on planet earth. we all know LuMo is just a iittle )( bit crazy. that craziness can likely only increase... there is a shift/ shear/ tear/ schism now emerging in the foundations of physics... blog conflicts are just the early warning(s)... major scientific paradigm shift in the cyber age... o_O

John Rennie

Physicists have slagged each other off since the dawn of recorded history (and probably before that). I doubt the current outbursts mean a paradigm shift is on the way.

vzn

paradigm shifts are about exactly as regular as earthquakes + volcano eruptions. in a few years, uncertain. in a few decades, certain. btw add "popsci books" to "blogs" as "early warnings".

Eulb

3:46 PM

that book has been getting a lot of hate

Sir Cumference

@Eulb Hey

Anyone know what happened to the real Blue?

Did @Eulb replace him completely?

vzn

@Eulb hatred tends to have an irrational component...

bolbteppa

Deservedly

Albas

Frankly, how is that book ?

Is it just popsci

vzn

@Albas try looking at authors credentials... the book is not dissimilar to 2 that appeared about a decade ago by Woit/ Smolin, also controversial (and with top credentials)... the 3 could be said to be "controversialists"...

bolbteppa

3:56 PM

'Hey we have this huge idea we have no idea what's going on it seems to predict all this stuff and we need to figure out how to test it and develop our understanding' - waste of time, bad, terrible!

Nothing but anti-science tbh

vzn

emperor has no clothes™

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