The h Bar

Anonymous

12:56 AM

@ManishEarth I remember that article was heavily reformulated and all the math removed by some ip 208. ...

Anonymous

The old article was rather nice ...

Anonymous

...

Anonymous

...

Anonymous

@DavidZ No, not really.

Anonymous

It seems

Anonymous

12:57 AM

that that post

Anonymous

is asking something about whether

Anonymous

Banach-Trashnaski

Anonymous

applies to the physical

Anonymous

world too...

Anonymous

Just like asking "Does F=ma apply in SR, too?"

Anonymous

12:59 AM

@DavidZ I thought it was quite the same...

Anonymous

And

Anonymous

Instead of having a completely unclear question,

Anonymous

it is better to have a question

Anonymous

An unknown error has occured ? ...

Anonymous

which

Anonymous

1:00 AM

is at least useful to people

Anonymous

(slightly)

Anonymous

and

Anonymous

has a rather high chancje of

Anonymous

matching the [OP]'s intention

Anonymous

...

Anonymous

1:01 AM

...

Anonymous

@DavidZ How long is considered "still around" ? .

Anonymous

And, P.S.

Anonymous

If I write @David Zaslavasky,

Anonymous

are you still pinged ? .

Anonymous

Maybe I should try that on myslef .

Anonymous

1:02 AM

@dimension10

Anonymous

@user1403340

Anonymous

@donkey

Anonymous

@monkey

Anonymous

../ .

Anonymous

...

Anonymous

1:04 AM

@ChrisWhite Lubos Motl had an articlee about that...

Anonymous

motls.blogspot.in/2013/08/…

Anonymous

Which I don't really agree with his last paragraph

Anonymous

motls.blogspot.in/2013/08/…

Anonymous

motls.blogspot.in/2013/08/…

Anonymous

motls.blogspot.in/2013/08/…

Anonymous

1:06 AM

Doesn't seem to give the preview...

Anonymous

...

Anonymous

@Bernhard physics.stackexchange.com/review/suggested-edits/20719

Anonymous

I am a donkey...

Anonymous

@Bernhard what's this message i'm replying to? It's automatically here...???

Anonymous

Oh, the same message... : )

ManishEarth

5:48 AM

3

Crazy Buddy

@ManishEarth Cool... ;-)

Did you create it? :D

ManishEarth

Nope

Crazy Buddy

@ManishEarth Ugh... I thought you dug in mathematica again... :P

ManishEarth

Not too hard to make with MMA or TiKZ, but getting the idea in the first place would be hard

Crazy Buddy

I think I can find a lot of comics here (starred) to add to my blog... Thanks to you :P

BTW @ManishEarth: Are there any other (short comic) sites like XKCD (shouldn't be long like SMBC or Abstruse)? o_O

ManishEarth

5:58 AM

Abstruse isn't so long

or smbc ftm

Well, there's Spiked Math

Crazy Buddy

@ManishEarth Sometimes... yeah...

ManishEarth

well so is xkcd sometimes :P

Crazy Buddy

Okay... I'll search for it ;-)

Crazy Buddy

6:25 AM

What about you @DavidZ ? ;-)

Any comics you read? (other than xkcd, abstruse, smbc and spiked math) :P

RhysW

9:29 AM

@ManishEarth nice picture

Physics Meta

10:07 AM

0

Q: What can be done about a tag which is a complete subset of another?

The physics-careers tag contains almost all questions also tagged soft-question. Those which don't are deemed off-topic and closed. Most of the questions ask about the details of working in some specific field. For eg. Current scope of Chaos theory and non-linear dynamics? How can some-one i...

Anonymous

1:30 PM

@Manishearth: meta.physics.stackexchange.com/q/4796/23119

Anonymous

Ihttp://meta.physics.stackexchange.com/q/4796/23119

Anonymous

0

Q: How to write formulas/maths expressions in the forum?

I'm new to this forum, I was wondering how to write neat formulas in the post/question? Do I have to use MathXML and code everithing in XML or is there an editor? thanks, Luther

discussion

Anonymous

I'm pretty sure that's not the right duplicate...

Anonymous

Do we agree with Ron's suspension?

ManishEarth

done

it was a mis click, and then I pasted the correct link to the dupe bar but didn't give it enough time to load

0

Q: Equations of motion for a pendulum and spring system

The question is available here: I've modeled the building as a rod on a torsional spring (with a pendulum hanging from the top). $\phi$ is the angle from the centre for the pendulum and $\theta$ is the angle from the centre for the building. Taking the Lagrangian, $L = T - V$, we have to f...

classical-mechanics lagrangian-formalism harmonic-oscillator

Close?

Physics Meta

1:41 PM

1

Q: How to write formulas/maths expressions in the forum?

I'm new to this forum, I was wondering how to write neat formulas in the post/question? Do I have to use MathXML and code everything in XML or is there an editor?

support

0

Q: Only questions with favourite tags

Is there some page that shows only questions that are filtered by my favorite tags? I don't mean favorite tags being highlighted on the main page and other pages. If not, I would like to put forth a proposal for such a page.

discussion feature-request

Crazy Buddy

@ManishEarth Why? Isn't that allowed by us..? o_O

ManishEarth

@CrazyBuddy not sure

Crazy Buddy

@ManishEarth I gone through that again... I don't think it has to be closed. :)

Ohh, it got a vote... ;-)

ManishEarth

I mean, it looks OK, but a bit iffy

Crazy Buddy

@ManishEarth Hey... We've allowed some questions like that....

ManishEarth

1:46 PM

I know :)

Anonymous

3:11 PM

Anonymous

I'm sure

Anonymous

I didn't flag

Anonymous

my own post ...

Anonymous

...

Anonymous

@ManishEarth No...

Anonymous

3:14 PM

That

Anonymous

question

Anonymous

is one of

Anonymous

those questions

Anonymous

which are

Anonymous

homework

Anonymous

3:14 PM

yet

Anonymous

show quite

Anonymous

a

Anonymous

signigficant

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amount of

Anonymous

...

Anonymous

3:15 PM

work ...

Anonymous

Yay, nobody caught my tongue this time!

Anonymous

As I'm just shouting in an empty room . . .

Anonymous

... With 2 ghosts

Anonymous

according to the sidebar.

Anonymous

@ManishEarth Also known as...

Anonymous

3:17 PM

Peturbation .

Anonymous

which is simply sad...

Anonymous

@ManishEarth No, no!!! (Popular Science policing...)

Anonymous

Even in

Anonymous

Type IIA/IIB

Anonymous

/I

Anonymous

3:19 PM

/HE/HO

Anonymous

string theories,

Anonymous

there are D-branes.

Anonymous

In the strongly coupled version.

Anonymous

The difference is that

Anonymous

In Type IIB, IIA, I, HE, HO,

Anonymous

3:20 PM

They' are called D-branes, and in M-theory, they' are called M-branes.

ManishEarth

4:38 PM

@Dimension10 No need to split it over many lines. And I thought it was uncloseable too, but knew it looked closeable so wanted some opinions

@Dimension10 I know that they come in other STs. Didn't know the full list so just mentioned M theory

I didn't say they only come in M theory

Crazy Buddy

@Dimension10: I've already told you once... You're always writing word by word... This isn't competition o_O

Crazy Buddy

5:45 PM

@ManishEarth: Usually, we mean the phase speed of light to be constant... Right?

Ohh.. sorry... group speed (I mixed up the terminology)

So, the phase speed can exceed c... Isn't it?

ManishEarth

Yeah. I think

Crazy Buddy

What about group speed? That always stays the same... Right?

Wiki really confuses me...

> However, in a few special cases (e.g., media designed to amplify the front-most parts of a pulse and then attenuate the back section of the pulse), group velocity can exceed the speed of light in vacuum, while the signal velocity will still be less than or equal to the speed of light in vacuum.

What does this really mean?

Gugg

Can somebody recommend a good, recent book on physics?

Crazy Buddy

6:00 PM

@Gugg Off-topic :D

Gugg

@CrazyBuddy can = not cannot?

Crazy Buddy

o_O

Gugg

Modal logic

Modal logic is a type of formal logic primarily developed in the 1960s that extends classical propositional and predicate logic to include operators expressing modality. Modals—words that express modalities—qualify a statement. For example, the statement "John is happy" might be qualified by saying that John is usually happy, in which case the term "usually" is functioning as a modal. The traditional alethic modalities, or modalities of truth, include possibility ("Possibly, p", "It is possible that p"), necessity ("Necessarily, p", "It is necessary that p"), and impossibil...

Can somebody then perhaps point me to an up to date list/review of great, recent physics books?

Crazy Buddy

@LoganM: So, you've changed the pic? :D

@Gugg I don't think there are much people here (Manish is ~~quite~~ always busy)... They'd reply you tomorrow ;-)

And, no one comes because Gugg is ~~pleading~~ crying :D

Logan M

@CrazyBuddy Yeah, my avatar here is the same as whatever it is on Anime SE because I'm usually in their chatroom. I don't think there's a way to use different pics for different rooms or else I'd use the same one I use on Physics SE here.

Crazy Buddy

6:08 PM

@LoganM I know... It's nice... So, anime user, are you the creator? ;-)

ManishEarth

@LoganM It depends on your chat parent user

Crazy Buddy

14 mins ago, by Crazy Buddy

What does this really mean?

ManishEarth

@CrazyBuddy Has to do with rapidly varying refractive index iirc

But it can't be used for superluminal communication

I forgot

Logan M

@ManishEarth Yes. What I'd like to do is have my chat avatar be the same here as it is on Physics SE, but keep the same one on Anime SE. But that's not possible as long as my accounts are connected. Since I'm over there more than I am here it's more important to be recognizable in that room than in this one.

Crazy Buddy

@ManishEarth Okay then... ;-)

Gugg

6:13 PM

Why are there still schrodinger-equation tags around?

ManishEarth

@LoganM not possible :p

Crazy Buddy

@LoganM Simple... Kill one of your account. Create another one, post something and vote for yourself, finally come to our chat... Don't forget to use two ~~computers~~ IP addresses at the same time :P

BTW, you can easily bribe Manish by putting a bounty on his answer...

Logan M

@CrazyBuddy I already have plenty of duplicate accounts with chat privileges, so no need to make a separate account (got them fair and square though).

David Z

@Gugg why not?

Crazy Buddy

@LoganM What?? OMG... Manish... Record this & call out the devs...

Logan M

6:17 PM

@CrazyBuddy Pretty sure the devs know. It's not breaking any rules so long as I don't cross-vote or abuse the accounts in any other ways.

Crazy Buddy

Clever way... -_-

@ManishEarth: Do you know that rep. isn't conserved at all... It can be created from nowhere...

Logan M

There are occasionally some questions/answers that I wanted to post, but didn't want rep for, so I made new accounts. I suppose CW would have also worked, but I didn't really want my name on them either in case they were silly or wrong.

I think I have 10 or 20 accounts like that, though I've lost the logins for many of them.

Gugg

@DavidZ Hmm, because of this meta.physics.stackexchange.com/a/4332/17609 perhaps?

Crazy Buddy

@LoganM If I weren't lazy, I'd have done that... (I had a thought like that once) :P

David Z

@Gugg oh, that's what you meant. Sure, we can make that a synonym.

Crazy Buddy

6:20 PM

---
I mean, create an SE account (101 rep.), put a bounty and you lose 100 rep. Now, delete the account by rubbing the shoes of devs (community owns the bounty) and create the account again (you'll see 101 rep. comes for free :D

ManishEarth

I'll merge

Crazy Buddy

I tested this at Stack Apps...

ManishEarth

oh, David already did it

Gugg

Thanks guys.

Crazy Buddy

@Gugg Now, you start crying again... People are around...

Gugg

6:22 PM

@Dilaton You must see this. theguardian.com/science/2013/aug/15/…

Crazy Buddy

@Gugg Why not me?

Hmm... Bears aren't cats. Then, why Dilaton? :)

Gugg

@CrazyBuddy Do you have a cat as a pet? Or a teddy bear? No, I thought so. I bet Dilaton does.

Crazy Buddy

@Gugg I had a cat... It has slightly terribly been misplaced elsewhere (during my relocation) :P

Gugg

@CrazyBuddy Maybe it's time to open some of those boxes you packed when you moved.

Crazy Buddy

@Gugg Okay... It ran away (my terrible kindness maybe responsible for that) :/

Gugg

6:31 PM

@CrazyBuddy Perhaps replace it with something like this? theguardian.com/environment/2009/sep/07/…

Dilaton

7:01 PM

@Gugg aah, they have finally found my brother, cute little being and interesting story ;-)

ManishEarth

7:30 PM

@Crazy wrote a blog post about his SE story

5

> Whenever my ~~easily googleable~~ question gets closed, I get angry. I shout at the people, I shout at the mods. I hate them as if the whole world has burned up.

Crazy Buddy

Ahh... ~~feedback~~ mistakes.. Go on :)

ManishEarth

Not feedback, just that that part made me laugh :P

Crazy Buddy

@ManishEarth Hey... You weren't the mod that time... Ask dmckee... He was my victim :P

ManishEarth

lol

Crazy Buddy

It really really happened... I laugh when I think of it :D

BTW @ManishEarth: Doesn't it look long? I attached a few related comic along the way (to keep people from falling asleep)

ManishEarth

7:34 PM

you're asking me about length? I like long stuff

Crazy Buddy

I know... I've admired at your writing :)

But, what about others? (I don't care anyway) You're the blogger. That's why I ask you...

RhysW

9:49 PM

@CrazyBuddy we have the same blog theme

user54412

10:02 PM

@CrazyBuddy This is a very tricky issue, and thankfully I was taught by one of the few people who doesn't get it wrong

user54412

both phase and group velocities can be arbitrarily high - they have nothing to do with the speed of light

user54412

but most sources think the group velocity is limited by c - I'm surprised wiki got it right

user54412

basically, group velocity is the speed of a wave packet (some disturbance localized in space) moving through a medium

user54412

but that packet doesn't necessarily carry information - it's just the local maximum of some function

user54412

@Gugg popular physics? I recently read a good review of Sean Carroll's The Particle at the End of the Universe

user54412

10:13 PM

haven't read the book myself, but given that the author's GR textbook is one of the best textbooks ever written IMHO, I'm willing to believe this new book is pretty good unless/until evidence points the other way

Physics Meta

11:38 PM

0

Q: Can we have a "newest" rather than "new" page for tags?

Clicking on TAGS at the top of the main page gives three useful ways of browsing through them: popular, name, new. One way of pruning tags would be to get rid of those that fall below a minimum value for number of followers and number of questions they've tagged after a probationary period of sa...

feature-request

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