The h Bar

0celo7

2:01 PM

I have no clue what thermal QFT is about.

Slereah

Thermal states

John Duffield

@0celo7 : they probably cleared it out because it was snarky, and not legitimate criticism at all. I usually give supporting references in my answers, but there's usually nothing similar in any negative comments. This one's a good example.

ACuriousMind

2:20 PM

@DavidZ I'd be interested in seeing mp.mathematical-physics from MO.

David Z

Sure, why not

ACuriousMind

It's a low traffic tag, though

Not sure whether that is good or bad for not clogging up the feed :D

StackExchange

David Z has made a change to the feeds posted into this room

David Z

@ACuriousMind probably good

@JohnDuffield I'm not sure that's accurate - at least, don't take that as an indicator of what sorts of comments we consider to be snarky or not legitimate criticism. But I think it's best if you don't bring it up here. Same goes for you, @0celo7.

3

Q: Why are cooling towers at nuclear power plants shaped the way they are?

The iconic cooling towers at most nuclear power plants are shaped like hyperboloids. Wikipedia mentions that this is because the wide base promotes thin film evaporation and the narrow point accelerates the laminar flow. Out of all the shapes with a wide base and narrow middle, why are hyperboloi...

off topic? I think it might be

0celo7

@ACuriousMind How does one, with full rigor, show that $X\in\mathfrak{sl}(n)$ iff $\operatorname{tr} X=0$?

I'm not convinced of the ol' "take the derivative at the origin".

Or is that just using the "equivalence class of curves" definition of the tangent space?

ACuriousMind

2:36 PM

@0celo7 Not sure what the question is - $\exp(\mathrm{tr}(X)) = \det(\exp(X)) = 1$ gives both directions, doesn't it?

0celo7

@ACuriousMind Using the exponential map is cheating.

ACuriousMind

No, it is not.

0celo7

My solution: let $c(t)\in\mathrm{SL}(n)$. Near the origin, we have the Taylor expansion $c(t)\approx e+tX$, where $X\in T_e\mathrm{SL}(n)=\mathfrak{sl}(n)$. Then $\operatorname{det}c=1+t\operatorname{tr}X=1\implies \operatorname{tr}X=0$.

The Taylor expansion is the definition of the tangent space a la Arnold.

Bass

@0celo7 isn't that the Taylor of $\operatorname{exp}$?

0celo7

@Bass Maybe...

Is the exponential map surjective on the group?

Bass

2:41 PM

@0celo7 I think so, if the group is arcwise connected? But I'm not sure about that

Lorentz group is not connected, so the exponential isn't surjective

0celo7

Well according to Jost there are some elements of $\mathrm{GL}_+(n)$ (positive determinant) that cannot be reached by the exponential map on $\mathfrak{gl}(n)$.

I cannot prove this.

ACuriousMind

@0celo7 You can arrive at this statement through observing that all matrices in $\mathrm{GL}(n,\mathbb{C})$ have logarithms, and then find one of $\mathrm{GL}_+(n,\mathbb{R})$ in it that has a non-real logarithm.

0celo7

@ACuriousMind Sorry, what?

ACuriousMind

@0celo7 The statement "not all matrices in $\mathrm{GL}_+(n,\mathbb{R})$ can be reached by the exponential map on $\mathfrak{gl}(n,\mathbb{R})$ is the same as saying that there are matrices in $\mathrm{GL}_+(n,\mathbb{R})$ that don't have matrix logarithms with real entries.

But, over the complex numbers, all invertible matrices have logarithms, so this is not an existence failure, just a failure of the logarithm to be real.

0celo7

@ACuriousMind I know that, you just said it. I don't see why that's the case.

ACuriousMind

2:49 PM

@0celo7 Because the logarithm is by definition the inverse of the exponential?

0celo7

@ACuriousMind You've lost me.

Ah!

If $\log M\notin\mathbb{R}$ then there can be no $X\in\operatorname{Mat}(n,\mathbb{R})$ for which $M=\exp X$.

So, what real invertible matrix does not have a real logarithm?

$\operatorname{diag}(1,-1,-1)$?

@ACuriousMind Does that work?

ACuriousMind

Now that you can surely check for yourself :P

0celo7

The determinant is $1$ and the logarithm has complex entries.

@ACuriousMind $\mathrm{Id}$ or $\mathrm{id}$?

Bass

@ACuriousMind what is a sufficient condition for the exponential map on an arcwise connected Lie group to be surjective?

compactness?

ACuriousMind

@0celo7 Mh, no preference

@Bass I don't know

0celo7

2:58 PM

@ACuriousMind What?

@ACuriousMind Not consistent?

ACuriousMind

@0celo7 Well, of course you should be consistent within one document, but I don't have a general preference which one of these you should choose

0celo7

I should do a Q&A for something.

ACuriousMind

@Bass terrytao.wordpress.com/2011/06/25/…

Indeed, compactness is sufficient

0celo7

@ACuriousMind Lol that proof uses my geodesic ball result :D

> If objects with negative mass could exist in GR, they could repel rather than attract nearby matter.

I'm confused, I thought spin 2 meant attract only?

Certainly Straumann knows his QFT...

ACuriousMind

@0celo7 Conclusion: If objects with negative mass existed, gravity would not be spin-2

0celo7

3:04 PM

@ACuriousMind Interesting...I guess the positive mass theorem is quite important then.

Bass

@ACuriousMind hmm, how is $GL(n,\mathbb C)$ more compact than $GL(n,\mathbb R)$? the logarithm counter-example above does not work in $GL(n,\mathbb C)$

ACuriousMind

I think this is something that's often a bit fuzzy in the presentations: Both negative mass and magnetic charges are "hypothetical charges" that might occur. But while the monopoles' incorporation into the existing EM theory is rather straightforward, the inclusion of negative mass into existing GR (especially the tentatively quantized version) is not.

@Bass Sufficient is not necessary.

0celo7

@ACuriousMind Indeed...I should read up on the positive mass theorem.

I wonder what assumptions one needs for it.

Eww covariant derivatives of spinors...

Bass

@ACuriousMind arrgh. yep.

0celo7

> Theorem 9.2 (Lichnerowicz) A solution of Einstein’s vacuum equations which is regular, globally stationary and asymptotically flat must be flat.'

Dammit why don't you define "regular" and "globally stationary"?

> A general proof of the Penrose inequality is still lacking.

Thesis_ideas ++

@ACuriousMind Apparently one needs to look at Sobolev spaces of spinor valued functions...or something...for positive energy theorem stuff.

0celo7

3:26 PM

@ACuriousMind Is condition (a) here just that $\mathcal{C}$ is diffeomorphic to a contractible compact set in $\mathbb{R}^3$?

All this complement business is really obfuscating the point of this condition for me.

ACuriousMind

@0celo7 No.

0celo7

@ACuriousMind Why not?

I'm seriously confused by what they mean here.

ACuriousMind

What it's saying is this: Compact sets are the "finite" or "small" sets. Conversely, the complement of a compact set is to be thought of as the space "at its edges" or "at infinity". The condition says that the space-like surface looks flat when you go far enough "towards infinity".

@0celo7 Because the two statements are not equivalent, and counterexamples are quite obvious.

0celo7

@ACuriousMind Such as?

ACuriousMind

@0celo7 Which ones have you tried already?

0celo7

3:32 PM

@ACuriousMind None, I'm now trying to decipher your comment.

ACuriousMind

@0celo7 That's your problem. Why do you wonder whether (a) is the same as your statement when you haven't even checked in simple examples whether that even has a chance to be true?

0celo7

Suppose I take $\mathcal{C}$ to be the closure of the "black hole region" of Schwarzschild spacetime.

ACuriousMind

Geez, what kind of "simple" example is that? :D

0celo7

@ACuriousMind One that works.

Since $\mathcal{C}$ is not defined at the origin it's not diffeomorphic to a compact subset of $\mathbb{R}^3$ :)

ACuriousMind

Is that just a convuluted way of stating you are considering a closed 3-ball punctured at the origin?

0celo7

3:35 PM

@ACuriousMind Yep.

ACuriousMind

How do you know that is compact? (I think it isn't)

0celo7

@ACuriousMind Lol, it's not.

Thinking...

Well we know that Schwarzschild spacetime is asymptotically flat, so there has to be some $\mathcal{C}$.

@ACuriousMind I'm stumped! I can't find the $\mathcal{C}$!

ACuriousMind

Hm, I'm not seeing it for the Schwarzschild $\mathbb{R}^3-\{0\}$ either by this definition.

0celo7

And if you add the origin then my (wrong) interpretation matches up with the correct one.

ACuriousMind

Well, my counterexample was going to be a half-infinite cylinder: Take $[0,\infty)\times S^1$ and remove the compact $[0,a]\times S^1$. The result $(a,\infty)\times S^1$ can be conformally mapped to the plane with the compact disk of radius $a$ removed, but the thing we removed from the cylinder wasn't contractible.

0celo7

3:50 PM

@ACuriousMind Ah, yes.

ACuriousMind

But considering Schwarzschild I think the writer of this definition needs to tell you how to deal with singularities

0celo7

@ACuriousMind Yeah.

ACuriousMind

Perhaps this definition is true for maximally extended Schwarzschild?

Secret

http://physics.stackexchange.com/questions/221432/turbulent-spacetime-from-einstein-equation

This intrigues me

0celo7

@ACuriousMind What, that doesn't have a singularity?

ACuriousMind

3:53 PM

@0celo7 Well, it has, but since I can't remmeber the exact shape of the extended solution, it might be possible to remove compact sets from it such that the definition is satisfied. I doubt it, though, you aren't getting rid of that puncture at the singularity

0celo7

@ACuriousMind So you were just throwing that out ;)

For a second I thought you knew some random GR fact I was unaware of :D

ACuriousMind

@0celo7 Yep, hence the "perhaps" and the "?" ;)

0celo7

4:43 PM

@ACuriousMind What in the next chat session? @JohnRennie might have an idea.

ACuriousMind

@0celo7 ?

0celo7

@ACuriousMind I don't see what the issue is.

ACuriousMind

@0celo7 I'm wondering since when I set the agenda for chat sessions, or what John has to do with it.

0celo7

@ACuriousMind (1) I figure you know because you know such things, (2) That's when he shows up.

ACuriousMind

@0celo7 There, uh, is no agenda for these chat sessions :D

We just talk about whatever the people who show up want to talk about

Judging from the hot meta posts, we seem to have a choice between discussing comment etiquette and discussing downvoting :P

0celo7

4:51 PM

No, I mean when is the next one!

And if JR shows up I can ask him!

ACuriousMind

Oh, you never said when anywhere!

you asked "What in", up there!

0celo7

@ACuriousMind Typo :P

ACuriousMind

The next one is tomorrow

0celo7

That should have been "when is"

ACuriousMind

The schedule is here:

Hmmm

chat is stupid

The schedule is here.

For some reason, it oneboxed the schedule link into a link to the room itself

0celo7

4:53 PM

@ChrisWhite What does this mean? How do you know we annoyed someone?

ACuriousMind

@0celo7 ...Because we're the last site to receive the update? (Also, this is probably a bit tongue-in-cheek, someone's gotta be the last one)

0celo7

@ACuriousMind Oh, we're the last.

John Rennie

@0celo7 I have lots of ideas, most of them obscene. What idea in particular were you thinking of?

0celo7

@JohnRennie I don't see how Schwarzschild spacetime is asymptotically flat according to this definition.

(Note: I get condition (b) which I did not bother including in that image.)

John Rennie

@0celo7 I don't even understand the notation - you're obviously confusing me for someone who isn't making it up as they go :-)

What does the backslash mean?

$\Sigma \\ C$ that is ...

David Z

5:07 PM

@JohnRennie ouch :-P

0celo7

Complement (set theory)

In set theory, a complement of a set A refers to things not in (that is, things outside of) A. The relative complement of A with respect to a set B is the set of elements in B but not in A. When all sets under consideration are considered to be subsets of a given set U, the absolute complement of A is the set of all elements in U but not in A. == Relative complementEdit == If A and B are sets, then the relative complement of A in B, also termed the set-theoretic difference of B and A, is the set of elements in B, but not in A. The relative complement of A in B is denoted B ∖ A according to the...

ACuriousMind

@0celo7 ::pedantic mode on:: Mhhh...the backslash is the set-theoretic difference, not the complement :P

John Rennie

Ah, OK, so $\Sigma \\ C$ is the set of spacetime points that are in $\Sigma$ but not in $C$ - yes?

ACuriousMind

You can't escape a backslash by another one in TeX, a double backslash is a line break

0celo7

@ACuriousMind What is the difference?

ACuriousMind

5:09 PM

\setminus is probably the correct workaround here

@0celo7 You can form $A\setminus B$ when when you are thinking of both $A$ and $B$ as subsets of a larger space, so that $A\setminus B$ is not the complement of $B$ in that context.

John Rennie

Ah, OK, so $\Sigma \setminus C$ is the set of spacetime points that are in $\Sigma$ but not in $C$ - yes?

ACuriousMind

@JohnRennie Yes

0celo7

@ACuriousMind Apparently that's the relative complement, which is also in that article.

Pedant...

ACuriousMind

@0celo7 In that case I reserve the right to take $A\setminus B$ even when $B$ is not a subset of $A$ ;)

0celo7

@ACuriousMind What?

John Rennie

5:13 PM

Isn't the condition jut saying that $\Sigma$ has to be basically the same as $R^3$ if you're allowed to cut out the troublesome bits like singularities?

ACuriousMind

@0celo7 Well, I can take the set of elements of $A$ that aren't elements of $B$ even when $B$ is not a subset of $A$. In that case, "relative complement" doesn't make sense.

0celo7

@ACuriousMind Whatever.

I think we all know what's going on :P

@JohnRennie The problem is that $\mathcal{C}$ is supposed to be compact.

The "area around the singularity" is not compact.

John Rennie

Hmm, yes, ISWYM

0celo7

Maybe that's a typo. What should $\mathcal{C}$ really be?

"Finite"

Something like that...

@ACuriousMind What's a topological notion of something that's not compact but still "finite"?

ACuriousMind

Hmm..."Diffeomorphic to a subset of a compact subset of $\mathbb{R}^n$"?

That'd equivalently be "Diffeomorphic to a subset of $\mathbb{R}^n$ whose closure is compact".

Seems kind of a weird property, though

0celo7

5:20 PM

@ACuriousMind Lol, you need to see the real definition of asymptotic flatness.

::Attempts to take screenshot of PDF in Windows 8::

This is not possible to do.

@ACuriousMind ^ Now that's weird.

Wow, that's a heavy monitor.

ACuriousMind

@0celo7 I don't even...

John Rennie

The dangers of rigour in GR:

math.ucr.edu/home/baez/gr/oz2.html

0celo7

@ACuriousMind Yeah...

ACuriousMind

@JohnRennie Hmm...I do feel a little chilly lately...

0celo7

5:39 PM

@ACuriousMind Wald takes like 6 pages to justify that definition.

0celo7

6:14 PM

@ACuriousMind Currently constructing Ms. Shepard. Does the background affect any dialogue or options in the game?

@ACuriousMind Eww these facial presets suck.

ACuriousMind

@0celo7 Yes, it affects dialogues, though not in a major way.

0celo7

@ACuriousMind Is there a way to import faces? I am terribad at this.

ACuriousMind

@0celo7 Hmmm...I think in ME3 one can import/share faces, but not in ME1 and 2

You'll have to live with the disfigurement you inflict on yourself

0celo7

@ACuriousMind :(

I really like my fallout character

And Skyrim has good presets, too.

This is the best I can do

@ACuriousMind Is "soldier" the best class?

ACuriousMind

@0celo7 I really like the Vanguard in 2 and 3. They're a bit lame in 1, though

Also, I think it's more fun to use biotics/magic than to shoot things

Especially since the shooting is not...terribly well done in 1

Sitting around for things to cool down sucks, though

0celo7

6:30 PM

So what should I do? Can I change my class in later games and keep everything else the same?

ACuriousMind

@0celo7 Ah, yes, you're allowed to change class

You can also remodel your face, if you wish

0celo7

@ACuriousMind I will probably do that. And I'll play as a soldier.

I like guns.

Bah. If I got my squad killed on Torfan they probably deserved it.

@ACuriousMind Can I not skip cutscenes?

ACuriousMind

@0celo7 Uh...I don't know, never tried it, I think

0celo7

I guess I'll rewatch all of this...

@ACuriousMind Is it possible to save Jenkins?

ACuriousMind

@0celo7 Nope

0celo7

6:42 PM

@ACuriousMind How does ammo work in this game?

I don't see an obvious place where my assault rifle ammo is displayed.

ACuriousMind

@0celo7 Pay attention to the tutorial and you'd learn there is no ammo :P

0celo7

@ACuriousMind Crazy

lol Manuel got rekt

0celo7

7:02 PM

@ACuriousMind Squad members can die!?

ACuriousMind

@0celo7 ?

They'll live again after combat ends :P

I see you've never played a BioWare game before :D

Danu

I'm proud of my latest tex/tikz achievement:

in TeX, LaTeX and Friends, 2 mins ago, by Danu

ACuriousMind

@Danu Nice!

Danu

@ACuriousMind Thanks.

The lecture was really nice.

ACuriousMind

How long did it take you to get TeX to draw that?

Danu

7:06 PM

Learning how to do the polygons took by far the longest---the top picture took me about 1.5-2 hours.

The middle about 30-50 minutes. The last about 15.

The middle one is the nicest, though :)

Now that I know how to do these things I'll be able to do them much faster though.

Also I'm pretty happy to have good "model torus" and trivial way to extend it to arbitrary genus :)

Pretty sure that'll come in handy at some point ^^

ACuriousMind

Draw me an $\infty$-torus!

user54412

2

user54412

Ok, I can see someone being convinced I don't know relativity. Multiple downvotes on a basic relativity question is a bit weirder. Saying I don't understand astrophysics grad school is more of a stretch, but fine. But then a downvote on a status-completed feature request from 5 months ago?? Someone's seriously becoming incoherent in their rage.

Danu

YOU DONT KNOW JACK SH*T ABOUT IPHONES @SSHOLE!

user54412

LOL

Danu

7:10 PM

@ACuriousMind I have one that looks like $\infty$... ;)

ACuriousMind

@Danu Looks aren't what counts for me!

@ChrisWhite Or you're seeing patterns where there is none and four independent people decided they don't like your specific answers/questions.

user54412

@ACuriousMind I bet you could embed a script in a PDF that recursively does that until it runs out of memory.

user54412

15

Q: Can I embed a game in a Pdf Resume?

I was thinking how it could be cool to have an interactive game on resume. (Obviously the digital version, not paper version.) For the sake of this question and scope of this site, let's ignore whether or not this is a good idea. Is it possible to embed a game or some sort of interactive window...

engine cross-platform languages

0celo7

@ACuriousMind Is that an $\infty$ topos

ACuriousMind

@ChrisWhite Hmmm....a topological variation of a zip bomb? I like it!

user54412

7:15 PM

@ACuriousMind But the ancient feature request? Why?? Also, I know of one or two specific people that have been annoyed by me lately.

user54412

I'm more entertained by believing this is related.

user54412

And of course, as we all know too well, downvotes mean absolutely nothing.

ACuriousMind

@ChrisWhite Ah. This means then that you will be soon demasked as the true sock puppet master here?

0celo7

Wow Kaidan you complete fool

user54412

@ACuriousMind Then I will have failed you, master.

ACuriousMind

7:17 PM

Shhhhh

0celo7

@ACuriousMind who is Saren and why is he mad

ACuriousMind

@0celo7 I won't spoil, oh no.

If you've managed to remain in blissful ignorance of the ME plot, you deserve to experience it in both its high points and its abysmal failures.

(Though the failures are mainly concentrated in the later games)

Ϻ.Λ.Ʀ.

Mhm, what's this chat session physics SE thingy?

Do you guys talk about weird aspects of astrophysics?

ACuriousMind

It's where we chat. In a session.

Ϻ.Λ.Ʀ.

Oooor is it just a sleep over?

ACuriousMind

7:23 PM

It can be if you want.

Danu

Fixed. Sorry, I got called away yesterday. @Danu please do tell me more about "unification". Like how the photon field is unified with the electron field. And the gluon field. Oh hang on a minute: "Gluons can have eight colour charges so there are eight fields". Oh dear. — John Duffield 11 hours ago

lol

Ϻ.Λ.Ʀ.

@Danu please also tell me about physics.

0celo7

@ACuriousMind I know that at one point I have to decide between genocide of one race over the other

but other than that, I don't know anything

Danu

How ironic; he accidentally says something in my favor

ACuriousMind

@0celo7 Well, I didn't genocide anyone. I think the "Everyone lives" outcome is one of the harder outcomes to achieve, though.

Danu

7:27 PM

^errrr? :P

ACuriousMind

@Ϻ.Λ.Ʀ. But seriously, the chat session is just a bi-weekly time where there is a higher-than-average amount of users in this chat. Sometimes we discuss hot meta posts, sometimes physics, sometimes other things

Ϻ.Λ.Ʀ.

Booooooorrrrriiii . . . I meant OK.

Danu

@Ϻ.Λ.Ʀ. What kind of physics are you into?

Ϻ.Λ.Ʀ.

@Danu Physical physics.

Danu

@Ϻ.Λ.Ʀ. Not my thing, sorry ;-)

Maybe this will interest you, though. It does interest me, and it has a lot to do with physical physics.

0celo7

7:31 PM

@ACuriousMind Does one have to be really nice or something?

I'm bad at this

Ϻ.Λ.Ʀ.

Well, I love all physics that's chemistry. Just please, for God's sake, don't talk about entropy.

0celo7

My character is mean and nice

Danu

@Ϻ.Λ.Ʀ. That may possibly be the only interesting thing about chemistry ;)

0celo7

@Danu nerd

Danu

@0celo7 You jelly of my numerous eclipsing binaries? :)

Ϻ.Λ.Ʀ.

7:32 PM

@Danu (╯°□°）╯︵ ┻━┻

ACuriousMind

@Ϻ.Λ.Ʀ. Why would anyone talk about entropy?

@0celo7 Mhhh...no, I think the outcome is also possible with a mainly renegade character, but it requires a very specific string of decisions across all three games(and granted, most of these do make more sense for a "nice guy/gal")

Ϻ.Λ.Ʀ.

@ACuriousMind The Heisenberg uncertainty principle says that you either can determine what a physicist will say next, or determine what subject he actually was talking about yesterday. You can't find out both.

So!

ACuriousMind

@Ϻ.Λ.Ʀ. That explains why our lectures are so hard to follow :P

Ϻ.Λ.Ʀ.

@ACuriousMind Before Heisenberg no one knew why though. It was a breakthrough.

ACuriousMind

@Danu Whenever you ask "you jelly" I imagine a literal blob of jelly quivering angrily behind a keyboard.

Danu

7:37 PM

@ACuriousMind That's what 0celo7 looks like, no? :D

(at least when I talk to him)

user54412

@Danu I've been meaning to ask - what's your cutoff for eclipsing binary vs planet? At 8%, I think this can be an M-dwarf star with a giant planet.

user54412

Though I guess what really matters is that it gets flagged as something

Danu

@ChrisWhite You mean 80%?

@ChrisWhite Also this.

user54412

@Danu this was 8-10%

Danu

@ChrisWhite Ah, you talk in terms of the drop-off.

I thought you were referencing my latest one (which would be about 20% in your terminology---which is probably the standard one)

user54412

7:39 PM

yeah -- shows I'm not a real member of the community :p

Danu

^I have no idea what the standard convention is

0celo7

@Danu No.

Danu

@ChrisWhite The cutoff is not sharp at all---I don't know and/or care enough to really do any quantitative analysis :P

I've just observed what others call transits and/or eclipsing binaries

and developed some kind of a feeling for it.

@ChrisWhite Actually, looking back at my comment on that particular example, I note that it reads:

> Q1-1 Wow amazing stuff! #transits and/or #eclipsingbinary

Also in the comments, I found some people who say that this system is actually known to be some star emitting debris.

...although someone else provides a link saying it's an eclipsing binary system... oh well :P

0celo7

@ACuriousMind $10 the Citadel gets attacked

why would I be armed if this weren't the case

John Duffield

7:58 PM

@Danu : I didn't say something in your favour. Your answer here isn't in your favour either. Remember you said QED completely incorporates the unification of electricity and magnetism. And yet electron fields and photon fields are not part of the same field in QED.

0celo7

8:12 PM

@JohnDuffield Photons and electrons are completely different. Why would they be a part of the same field?

John Duffield

@ChrisWhite : I downvoted your Interstellar answer here because time doesn't flow, and your answer missed the point that they would have seen multiple waves as they approached, or at least one wave, since it was 4000ft high. I imagine the other downvote wasn't anything to do with your knowledge of relativity, just the quality of your answer. I didn't vote on any of your other answers.

Danu

@JohnDuffield LOL. Hey, @DanielSank, weren't you supposed to give some examples of moving goalposts? :D Trace back this conversation, in that case.

@JohnDuffield The truth is, I have stopped hoping to explain anything to you personally a while back. I don't mind if you don't agree with or don't understand what I'm saying: I'm just putting those comments on your answers to alert people who may not have enough knowledge to see right through them that they are no good, or at least that there are some of us out there who think so. In any case, I'm not interested in discussing this with you in chat.

6

John Duffield

@0celo7 : because of pair production and annihilation. See [the QED given explanation](en.wikipedia.org/wiki/Two-photon_physics#Processes ), it's dire. Then look at the Poynting vector here. IMHO it's pretty obvious from classical electromagnetism that the electron field is just a configuration of the photon field.

0celo7

@ACuriousMind I took Garrus in my squad and let Ashley go. Good decision? Where is she if I want her back?

John Duffield

@Danu : then don't come out with things like "How ironic; he accidentally says something in my favour" when I didn't.

0celo7

8:22 PM

@JohnDuffield Obvious besides the fact that it contradicts almost everything we know about quantum mechanics...sure.

Danu

@JohnDuffield I wasn't talking to you (and I guess I will once again stop doing so now).

John Duffield

@0celo7 : it doesn't contradict anything. What does is this: "A photon can, within the bounds of the uncertainty principle, fluctuate into a charged fermion–antifermion pair, to either of which the other photon can couple". That says pair production occurs because pair production occurs.

ACuriousMind

@0celo7 You can choose the composition of your squad everytime you leave the Normandy

ACuriousMind

I wish we could ban Einstein profile pictures :P

0celo7

@ACuriousMind Wtf?

Danu

8:31 PM

lol

0celo7

What's wrong with me

ACuriousMind

@0celo7 Give me some time to compile a list ;)

0celo7

@ACuriousMind I mean my profile pic

ACuriousMind

@0celo7 Oh, lol, not that Einstein :D

That comment was not directed at you at all

John Duffield

@Danu : the moot point is that QED does not "completely incorporate the unification of electricity and magnetism" because it separates the classical-electromagnetism electromagnetic field into the photon field and the electron field.

But if you prefer not talk about it, no problem.

ACuriousMind

8:34 PM

It's just that choosing Einstein (or Feynman, for that matter) as your profile picture on a physics site strikes me as the most unoriginal thing one could do

0celo7

@JohnDuffield What is your formalism for unifying the two?

Danu

@DanielSank ^^^ more see above :D

ACuriousMind

And a bit presumptuous at that, too.

Danu

@ACuriousMind That's the feeling I get, too.

ACuriousMind

Although I am currently sporting the image of the most capable scientist of an alien race renowned for their scientists...that might be even more presumptuous :P

Sadly, you'll have to wait for the second game before you meet him, @0celo7

Danu

8:40 PM

@ACuriousMind We all knew that already ;)

0celo7

I'm a cat.

Danu

@ACuriousMind You guys' talk makes me consider picking ME2 back up again too :P

ACuriousMind

@0celo7 So that's why you get along so well with @Slereah

Nov 6 at 15:50, by Slereah

I am a cat

John Duffield

@0celo7 : I don't have one, this is just a matter of interpretation, and taking on board the hard scientific evidence and the input from classical electromagnetism / relativity / TQFT etc. See for example what I said about How to explain what an electron is to someone new to physics?

Sure there may be things you don't like in there, but it would be wrong to ignore all that classical electromagnetism etc stuff.

0celo7

Maybe you wouldn't have an answer at -10 if you quoted a respectable HEP researcher saying the same things.

I've already given some counterpoints, but that question was sadly deleted.

user54412

8:49 PM

@ACuriousMind I vote myself as contender for unoriginality.

user54412

3 and a half years later, and I'm still looking for inspiration for a profile picture.

ACuriousMind

@ChrisWhite I generally assume people using the default gravatar just don't care.

user54412

I actually want something else. But I really can't think of anything.

user54412

I don't want a normal picture of myself. I don't have any simulation results that look good at that size. And I don't have a cat.

0celo7

@ChrisWhite Do the Princeton seal.

Or find Witten, pants him, take a picture, and use his undies.

John Duffield

8:56 PM

@0celo7 : Don't appeal to authority. I referred to the evidence. That's more important than what some "respectable HEP researcher" says. And do note that there were no counterpoints to that evidence.

0celo7

@JohnDuffield I'm not appealing to authority. I've given many counterpoints.

ACuriousMind

Geez, are we back to not ignoring him?

Time is indeed cyclic, it appears.

0celo7

Maybe you're just bad at articulating your point. If you quoted someone who is better at that, we might come to some agreement.

Or maybe you can't find anyone.

Don't know what that would mean.

@ACuriousMind Depends on my mood tbh.

John Duffield

@0celo : you appealed to authority with your "respectable HEP researcher". As for your many counterpoints, give me a link to one.