The h Bar

Emilio Pisanty

18:00

@JohnRennie No need to worry, it's on video, he didn't see that one ;).

Hey btw @MarkMitchison have a look at that video

That's part of what we get for posting under our real names, I guess

Not that this one matters that much.

John Duffield

@Sidarth : annihilation takes place because the electron is a 511keV photon in a standing-wave standing-field "knot" configuration, and the positron is the same but with the opposite chirality. Their interaction cancels the knotted-ness, whereafter the two 511keV photons are free to propagate linearly at c.

ACuriousMind

@Sidarth: That's not true, and every time he writes that on the main site, he gets justly downvoted.

Bernard Meurer

@JohnRennie You only get DS status when you let me visit a lab and take me out to lunch :p

John Rennie

I wonder if it's possible to post a non-non-nerd description of why a fermion and anti-fermion annihilate.

I suspect not without doing considerable violence to QFT.

ACuriousMind

@JohnRennie I don't think the quantum field theory justifies any other explanation than "it's not a forbidden process".

Slereah

18:11

My least nerdy way to put it is that it's a rotated radiation diagram :p

ACuriousMind

You can't really explain "how/why" two photons can scatter off each other via the box diagram, either, for instance

Danu

Tonight is a good night

ACM revenge downvoter confirmed, I see

Slereah

Just explaining why antiparticles exist is already complicated

John Duffield

@JohnRennie : sadly the explanation here is cargo-cult nonsense. Virtual particles only exist in the mathematics of the model.

Slereah

Do antiparticles even make sense outside of Fock space?

Bernard Meurer

18:12

@JohnDuffield Did you graduate in CS?

Danu

More of the standard phrases! "cargo-cult nonsense" :D "spinor path" yesss... yessss my child!

ACuriousMind

@Danu We should play bingo with these phrases

John Duffield

@ACuriousMind : yes you can. Light is alternating displacement current, and displacement current does what it says on the tin.

Danu

Yesss "displacement current" another one! :D

Slereah

When will we get to the Dirac belt

Danu

18:14

@ACuriousMind On it!!!

Bernard Meurer

I'm still waiting for my Kuiper Belt

John Duffield

@Danu : light is alternating displacement current. See this. And this.

I have to go, time for tea.

Bernard Meurer

secularcafe.org/showthread.php?t=26985

Slereah

The Dirac belt, to keep up your pant diagram

Danu

@JohnDuffield Yes, yes, yes.

Bernard Meurer

18:15

I think "time for tea" is code for "time to run from actual physics"

ACuriousMind

@Slereah I would not be suprised if some papers actually deal with "pants with belts" :D

Slereah

Physicists are a notoriously punny bunch

My favorite one is the Alpher-Bethe-Gamow paper

Hari Prasad

who is a physicist?

Physicists study a wide range of phenomena in many branches of their field, spanning all length scales: from sub-atomic particles of which all ordinary matter is made (particle physics), to molecular length scales of chemical and biological interest, to cosmological length scales encompassing the Universe as a whole.

Bernard Meurer

Okay?

I was going to answer @ACuriousMind was a physicist, but that works

ACuriousMind

@HariPrasad It is safe to assume that people in this room know what a physicist is :P

Bernard Meurer

18:20

Physics: Some dope magic

John Rennie

I once studied how shampoo makes hair shiny, and actually wrote a paper on it. Does that make me a physicist?

ACuriousMind

@BernardMeurer Just a student, better pick one of the people with finished training

Bernard Meurer

I once made a shitty question about uncertainty and ACM made me feel bad about it, am I a physicist/

Hari Prasad

@BernardMeurer lol

ACuriousMind

@JohnRennie That's dangerously close to chemistry ;)

Bernard Meurer

18:22

@ACuriousMind You're my mental image of a physicist, a guy that looks like a girl (or vice-versa) with a pretty big sword looking menacing

John Rennie

Amazingly I still have the pre-print: International Journal of Cosmetic Science, vol. 19(3) 1997, p131.

HDE 226868

@Slereah I blame Gamow there; I know Alpher was pretty pissed about it.

John Rennie

One of the more prestigious journals :-)

Slereah

@HDE226868 He wanted to have more glory?

HDE 226868

@Slereah It was his first big break; he didn't want Bethe to overshadow him, IIRC.

A reasonable desire.

John Rennie

18:25

@HDE226868 Really? The version I heard was that Gamow was a notorious joker and he just thought it was funny.

HDE 226868

@JohnRennie By "he" I meant Alpher. Gamow's absolutely the one to blame.

John Rennie

Alpher–Bethe–Gamow paper

In physical cosmology, the Alpher–Bethe–Gamow paper, or αβγ paper, was created by Ralph Alpher, then a physics PhD student, and his advisor George Gamow. The work, which would become the subject of Alpher's PhD dissertation, argued that the Big Bang would create hydrogen, helium and heavier elements in the correct proportions to explain their abundance in the early universe. While the original theory neglected a number of processes important to the formation of heavy elements, subsequent developments showed that Big Bang nucleosynthesis is consistent with the observed constraints on all primordial...

HDE 226868

Okay, good, I'm not going insane that it was Alpher's first star paper (pun intended).

John Rennie

But yes I can see why Alpher would be annoyed, though in the long term I think it's made the abc paper even more famous. So it has done Alpher no harm.

Danu

Oct 2 '15 at 23:35, by John Duffield

@bolbteppa : yes. Charge is topological. The electromagnetic field is a "twist" field, such that when you move through it you think of it as a "turn" field, hence rot which is short for rotor. It's like the gravitomagnetic field. Go read about it.

What a gem :D

John Rennie

18:30

@BernardMeurer Elric's younger sister?

HDE 226868

I seem to remember an anecdote about Gamow winning a bet by teaching himself to swim only by reading books. Does that ring a bell with anyone?

Bernard Meurer

@JohnRennie What's an Elric?

John Rennie

@BernardMeurer John faints in horror

Danu

@HDE226868 Sounds cool! Never heard of it.

John Rennie

You've never heard of Elric?

Slereah

18:31

You know

Bernard Meurer

@JohnRennie Ehm

John Rennie

Elric of Melniboné

Elric of Melniboné is a fictional character created by Michael Moorcock and the protagonist of a series of sword and sorcery stories taking place on an alternate Earth. The proper name and title of the character is Elric VIII, 428th Emperor of Melniboné. Later novels by Moorcock mark Elric as a facet of the Eternal Champion. Elric first appeared in print in Moorcock's novella, "The Dreaming City" (Science Fantasy No. 47, June 1961); subsequent novellas were reformatted as the novel Stormbringer (1965), but his first appearance in an original novel occurred in 1972 in Elric of Melniboné. Moorcock...

Bernard Meurer

No?

Slereah

I wonder if Duffield is just making up word salads

Concatenating sciency words

Or if it makes sense in his brain

Bernard Meurer

@Slereah I told you already he picked a word list and gets an AI to say this stuff

HDE 226868

18:32

@Danu I read something about it a long time ago, so no guarantee that it's actually real.

Bernard Meurer

He's been trolling teh internetz for years like that

Slereah

A lot of cranks are just engineers trying to make sense of QM with their engineering experience

@BernardMeurer : Is he, though

I mean

If he is trolling

For that long

With that consistency

Bernard Meurer

@JohnRennie That doesn't look like ACM's thingy

Slereah

Has he trolled so long that he became the mask

ACuriousMind

I probably should change my picture again, seems @BernardMeurer has grown a bit...attached to it

John Rennie

18:34

@BernardMeurer google.co.uk/…

Bernard Meurer

@Slereah I think he just thinks he knows what he knows but doesn't really know what he things he knows, like a inverse case of known unknowns

ACuriousMind

@JohnRennie To be fair, many sword and sorcery covers from that time look like that, nothing special to Elric

Bernard Meurer

I'll put an avatar of myself

with sun in my eyes

@Danu LEGEND

ACuriousMind

@Danu lololololol

Bernard Meurer

@Danu Can you get me a wordlist of that? I'll make a python AI

Danu

18:36

It was actually hilarious digging that up.

Hari Prasad

Is there only one type of Higgs boson?

Danu

@HariPrasad The Higgs field as it appears in the Standard Model has only one (complex) physical degree of freedom.

Slereah

No.

There are at least two.

Since the Higgs boson is an SU(2) doublet

But around the vacuum state it only has one degree of freedom yes

ACuriousMind

@Slereah that's like saying there are three up quarks.

Danu

It's a complex scalar (in the standard gauge), right.

Hari Prasad

18:38

ok

Slereah

@ACuriousMind Well, isn't there

Hari Prasad

What is the solution to the Schrödinger equation for the hydrogen atom in arbitrary electric and magnetic fields?

Danu

Lol

Slereah

At what point do we say particles are the same?

ACuriousMind

@Slereah No, I would not say so, because the color is not an observable (it's not gauge invariant)

Danu

18:39

@HariPrasad Wanna get famous? ;D

Bernard Meurer

@Danu Word list :p

Slereah

Are electrons the same as neutrinos?

Danu

@BernardMeurer I invited you to a room.

Slereah

Since they are part of the same doublet

Kinnisal Mountain Chicken

@HariPrasad "On 15 December 2015, two teams of physicists, working independently at CERN, reported preliminary hints of a possible new subatomic particle (more specifically, the ATLAS and CMS experiments, using 13 TeV proton collision data, showed a moderate excess around 750 GeV, in the two-photon spectrum): if real, the particle could be either a heavier version of a Higgs boson or a graviton."

Danu

18:39

SUSY STILL ALIVE

IBELIEB

John Rennie

@KinnisalMountainChicken You've been reading New Scientist!

ACuriousMind

@Slereah That's not a gauge symmetry doublet, that's different

Danu

GIVE ME GOD DAMN SUSY NAO

Slereah

Isn't it?

Danu

make my thesis physical pliz.

Slereah

18:40

It's an SU(2) weak doublet

ACuriousMind

@Slereah Hmm, let me check

Kinnisal Mountain Chicken

@JohnRennie I'm guessing that that is not a compliment.

Slereah

Also, are left-handed and right-handed particle different particles or the same?

John Rennie

@KinnisalMountainChicken I like reading the New Scientist as well, and in fact I'm about to read this weeks edition.

Danu

@Slereah Different

Since the right handed neutrino's don't even exist in the SM

John Rennie

18:41

It's a good magazine but you have to remember their prime focus is selling copies of their magazine.

ACuriousMind

@Slereah Ah, yes. Hmm, but the SU(2) is broken. I guess that's the difference to the quarks

Then there are two Higgs, I'd agree

John Rennie

There is certainly an excess at 750GeV but it's a long way from being significant.

Danu

I'm willing to bet on it disappearing.

Kinnisal Mountain Chicken

@JohnRennie Well, then I must disappoint you. I haven't read it for at least 25 years. The quote is from Wikipedia. :)

Danu

lol

John Rennie

18:42

If, and it's a big if, there really is a new particle at 750GeV then there will be huge excitement.

Danu

Like I said, SUSY

Puh-leeaaaase

John Rennie

Good grief, it's on Wikipedia already?

Danu

All the beautiful math will suddenly be physics

ACuriousMind

@JohnRennie Well, according to this paper, the significance is around 3.8 sigma. That's below discovery threshhold, but not "a long way" from being significant, I'd say.

@JohnRennie The initial announcement of this spike was in December, I have no idea why New Scientist acts as if it was news.

John Rennie

@ACuriousMind Ah, OK, I didn't realise the significance was that high.

Danu

18:44

@ACuriousMind Eh, don't forget that 0 to 1 sigma is a lot less special than 4 to 5.

Slereah

@ACuriousMind Well a symmetry being broken only matters in some states, though

Far away enough from the VEV you can have dynamic Higgs

John Rennie

If it's really 3.8 sigma then the next run of the LHC should pin it down.

ACuriousMind

@Slereah Um...if it was an unbroken gauge symmetry, you would have to divide it out, i.e. identify states related by it. Not sure what you're saying.

Danu

@JohnRennie The next report will settle it.

Slereah

@ACuriousMind Isn't symmetry breaking related to the state the field is in?

John Rennie

18:45

I wonder if there is going to be an announcement like the LIGO one. If so we should have another chat event for it.

Danu

Well, it'll just be the yearly report unless they suddenly get very certain!

ACuriousMind

@Slereah Ugh, that depends on whether you're doing the "breaking" by doing perturbation theory around the VEV or by a thermodynamic phase transition

Danu

But even for yearly reports we should have a chat session.

ACuriousMind

There's a lot of confusion because people use "breaking" both for the thermal phase transition and for the perturbative theory at zero temperature

Danu

I've never heard it about the thermal phase transition---you mean in thermal field theory?

Who does those unappetizing things anyways? (jk it's the same as QFT in de Sitter, which is awesome)

ACuriousMind

18:49

@Danu See this answer I recently saw. It's a bit vague, but it explains why people keep stating confusing things around the "unbroken" symmetry at high energy. The zero-temperature QFT sees only an approximate restoration, while a thermal field theory might see an actual phase transition.

Danu

@dmckee I think the standard "sliding stairs" exercise is significantly easier in the Lagrangian formalism---IIRC.

ACuriousMind

@Danu One prof here even does non-equilibrium thermal field theory :D

Danu

Btw, in Firefox I've stopped seeing most avatars recently. Any ideas what may be causing it?

dmckee

@JohnDuffield This dogged insistence that it matters if something is "real" or not is why I call you a philosopher. Those terms are real enough to describe experiments. We can access those "not real" particles, make them "real" and record them in our detectors. But don't let that interfere with your word games, it's just the on-the-ground truth of how particle physics is done.

3

Danu

@ACuriousMind That's also QFT in de Sitter space (my BSc. thesis was on this) it's pretty awesome.

Let's have some love in chat:

Besame Mucho Cesaria Evora

►

...or something a bit more upbeat:

ACuriousMind

18:51

@Danu I have that too, periodically. It's somehow related to the gravatar servers being inaccessible, there's no fix except waiting that I'd have found

Danu

Amadou & Mariam feat. Manu Chao - Sénégal Fast Food

►

ACuriousMind

Haddaway - What Is Love

►

Danu

@ACuriousMind It's been 3 days or so now. But some have popped back into view in the meanwhile...

@ACuriousMind Every. Time.

ACuriousMind

@Danu Yep :)

Bernard Meurer

Ged demmit my picture isn't changing

ACuriousMind

18:53

Caching. Have patience.

Danu

How does one determine cutoff scales, by the way?

Just check where you start significantly running into trouble by some dimensional analysis handwaving?

ACuriousMind

@Danu What exactly do you mean?

Danu

In QFT, how do I determine up to where to trust my theory?

ACuriousMind

E.g $\Lambda_\text{QCD}$ is where the running coupling blows up

I.e. Landau pole

Danu

RG flow... One of those topics I never learned about :(

I'm so annoyed that the QFT curriculum is such garbage here

ACuriousMind

18:54

The only such scale that's not coming from a running coupling is the quantum gravity/Planck scale, I think

And that's the one scale I'm still not fully convinced of that it is even relevant :D

Danu

@ACuriousMind We don't really need them to blow up though right, order 1 is already killing?

ACuriousMind

@Danu Order 1 kills perturbation theory, but the blow up indicates something worse than non-perturbative-ness is happening

Danu

Dvali always repeats that once this happens, your degrees of freedom are no longer the right ones

Okay, that aligns with what you say.

ACuriousMind

@Danu Indeed, in QCD, that's the scale where stuff "condenses" and all those ugly meson fields start being the proper dynamical variables

dmckee

@Danu By comparing calculation to experiment. How else?

Danu

18:58

@dmckee Ha-ha-ha

(just kidding)

ACuriousMind

I..actually didn't think of that :/

Danu

But that's not a nice situation to have as a theorist ;)

dmckee

Of course I know you guys are always hope to get a little more independent of that whole messy business, and I wish you good luck on the matter. It'll just suggest more and cooler experiment to do.

Danu

For instance in my SM course I learned that there had to be some Higgs-or-something at LHC scales because the electroweak model would run into unitarity trouble if you put in hard masses, below LHC energies.

dmckee

@ACuriousMind ::chuckles::

Danu

19:00

By the way @ACuriousMind the answer by Name YYY you linked confuses me a bit; I'm used to always speaking about temperature and energies as somewhat equivalent---I know the usual QFT is "zero temperature QFT" but can we actually have high energies and zero temperature?!?!

(I'm not confused about the answer, just about my own understanding of the relationship of E and T)

I also posted a comment under the answer (exactly 0 characters left, woohoo!) about this matter :)

@JohnRennie HNQ confirmed, btw!

dmckee

19:16

... and ... protected! Something I should probably have done hours ago, but no harm done.

Kyle Kanos

19:39

Goodbye Peyton :(

0celo7

@KyleKanos Aaaaand my dad has lost all interest in the NFL.

Also only like 3 people here care about football, why post that here?

Kyle Kanos

@0celo7 Would you rather me post RIP Nancy?

Bernard Meurer

There

new picture

user507974

Hey guys

anybody found a published article describing this phys.org/news/…

0celo7

@KyleKanos There are even less conservatives in here.

Kyle Kanos

19:44

And by winning the Superbowl, Peyton Manning finishes his career post-season game above 0.500 (14-13)

@0celo7 Celebratory pre-Easter statements?

0celo7

Probably less Christians still.

Kyle Kanos

Hmm

Bernard Meurer

What's with this peyton dude?

His name sounds like "big boob" in portuguese

2

user507974

what about wireless energy transmission research, but like by JAXA

Kyle Kanos

@BernardMeurer He's an American football player

One of the greatest of all time

And he just retired after 18 seasons

Bernard Meurer

19:47

@KyleKanos Holy crap 18?

Kyle Kanos

Yes. That's a very long time in the NFL

Bernard Meurer

What a legend

Kyle Kanos

He passed for over 70,000 yards in those 18 years, #1 all time

Bernard Meurer

I'd be surprised but I have no idea how much a yard is

Kyle Kanos

1 yard = 3 feet

There are 100 yards on a football field

Bernard Meurer

19:49

I'd be surprised but I have no idea how much a feet is

I'm a metric dude

user507974

10 feet 3 meters

Kyle Kanos

1 yard is slightly less than 1 meter

(91 cm, if I'm not mistaken)

Bernard Meurer

That dude made a total of 64Km of passing?

user507974

@KyleKanos I find the 10:3 gives people a better sense of it since its like a 1.5% deviation from the true value

its more like 10% for the 3:1 comparison isnt it

Kyle Kanos

@BernardMeurer Yes.

Bernard Meurer

19:51

Holy crap

I'm not sure I move that much in a year

Leaving home is always a barrier

0celo7

@KyleKanos did you like the Shawshank Redemtion

Spelled correctly.

Kyle Kanos

Yes, it's a good movie

0celo7

Agreed.

Kinnisal Mountain Chicken

@BernardMeurer He maybe didn't move that much. He just threw (non-spherical) balls that far.

Maybe deflated non-spherical balls.

Bernard Meurer

@KinnisalMountainChicken The point stands, last time I threw something is was my dignity towards the floor

Kyle Kanos

20:00

@KinnisalMountainChicken That's Tom Brady you're thinking of

Kinnisal Mountain Chicken

@KyleKanos You're right, I don't follow the sport.

Kyle Kanos

You're missing out on Life then

Kinnisal Mountain Chicken

@KyleKanos I've been watching some rugby though.

user507974

Hey guys, does anybody have experience contacting Japanese researchers and requesting references and data from their research. Don't want to step on any cultural toes.

Kyle Kanos

Just word it formally

Bernard Meurer

20:10

@user507974 Mention how much you like Naruto

0celo7

20:28

@BernardMeurer huh?

JokelaTurbine

@BernardMeurer Hi.. No we are more like two live crew; "Banned In the USA" youtube.com/watch?v=nEH_ms8d1ws

With the help from fans and all our friends
Freedom of speech will never die
For us to help, our ancestors died
Don't keep thinking that we will quit
We'll always stand and never sit
We're 2 live, 2 black, 2 strong
Doing the right thing, and not the wrong
So listen up, y'all, to what we say
We won't be banned in the U.S.A.!

Bernard Meurer

@JokelaTurbine Good thing I'm not in the USA then

JokelaTurbine

@BernardMeurer I am not either,,, here just seems to be chaged some music videos,,, and I brought my point with this one. no need for "Fuck Martinez";

Qmechanic

@JohnRennie : Hm, yeah, he's apparently not exactly a fan of Phys.SE. Btw, I was the evil moderator that deleted his post (link only visible to 10k+ users) spurred by an anonymous spam flag. This can be seen here. Someone should perhaps write him a comment under his Youtube video and explain him why Phys.SE operates the way it does to ensure quality.

JokelaTurbine