The h Bar

DanielSank

16:02

@yuggib I'm also still waiting to find out if CuriousOne would like to rescind his statement that Google has been "mum" on the issue of what the DWave machine can and cannot do. I found his opinion puzzling given the rather prolific publication history of the Google team over the last few years.

bolbteppa

@0celo7 I just read the derivation of the invariant interval in that book and it's actually unbelievably clever

0celo7

@bolbteppa page

yuggib

@DanielSank :-D

I read some parts of that "querelle"

but I cannot have an informed opinion at all on that subject.

0celo7

why

John Duffield

@yuggib : I'm not making up an interpretation, or spamming, or being intellectually dishonest. I'm telling you about some physics, namely the Breit-Wheeler photon-photon interaction. What's intellectually dishonest is making accusations because you don't know about that physics.

0celo7

16:09

don't you know the Evidence?

bolbteppa

16 - 18, those intervals are starting to make a bit more sense to me now anyway

0celo7

eh, still not convinced

methinks relativity is BS

I'm turning into a classicist

Newton ftw

yuggib

@JohnDuffield We are starting to be a good number to have asked you the same question; you may think about answering it, instead of continuing to change argument. And also, it is not a good practice assuming to know what other people may or may not know/think.

I am not judging you or your knowledge, I was asking a factual explanation of your point of view. You should not judge me, or other people, either.

Oh, yes, I am also stating that you systematically avoid to answer the question that me, and the list of people you can find above had been asking you.

0celo7

16:25

What question is that, for the record

I've asked a multitude

John Duffield

@0celo7 : yes I'm right. I don't make this stuff up.

0celo7

@JohnDuffield what stuff don't you make up

I agree that you don't make up some experimental facts

Others you just pull out of ---

DanielSank

Omg guys, guys....

Can we have a new tag called "Evidence"?

^ This is important.

@0celo7 wat?

0celo7

@DanielSank I don't think Newtons support it

Newton never spoke of this "metric tensor" math nonsense

DanielSank

@0celo7 wat?

@0celo7 OOohhhhh, right, Newton and the Evidence?

Slereah

16:33

@0celo7 Please stop

This is heresy

DanielSank

@Slereah ?

0celo7

I haven't seen spacetime curve, have you?

DanielSank

@0celo7 Uh nope!

0celo7

Just like infinite energy machines

DanielSank

Never!

@0celo7 Wow, you're right. This is popscience woo!

0celo7

16:33

See all of these mathematicians

Einstein, Baez, Shapiro

They deal in cargo cult popscience woo

John Duffield

@DanielSank : I'm insisting on the correct physics, which is that photons interact with photons. I didn't invent that. I'm not thinking about it in some unusual "my-theory" fashion, I'm telling you about things you don't know about, and you can verify what I've told you for yourself.

0celo7

Now I bet if I go tell people the truth on this site, there will be endless carping from those "relativists"

DanielSank

@JohnDuffield I'm puzzled. There are charged particles in the diagram.

Doesn't that mean the electromagnetic excitations interact with charged excitations?

0celo7

@JohnDuffield show me the term in the lagrangian

do you even know what that means?

Slereah

If you do not stop

DanielSank

16:35

@0celo7 Go away for a minute. Don't want troll food right now.

Slereah

I will have to use the Newman Penrose formalism

Newman–Penrose formalism

The Newman–Penrose (NP) formalism is a set of notation developed by Ezra T. Newman and Roger Penrose for general relativity (GR). Their notation is an effort to treat general relativity in terms of spinor notation, which introduces complex forms of the usual variables used in GR. The NP formalism is itself a special case of the tetrad formalism, where the tensors of the theory are projected onto a complete vector basis at each point in spacetime. Usually this vector basis is chosen to reflect some symmetry of the space-time, leading to simplified expressions for physical observables. In the case...

DanielSank

Guys, go away. I would like JD to answer my question. Please stop throwing troll kibble around.

Slereah

He will not.

John Duffield

@DanielSank : what diagram. Mine isn't some alternative viewpoint. It's the correct viewpoint. Now go and check it out for yourself.

0celo7

@Slereah

Slereah

16:37

Noooo

DanielSank

@JohnDuffield Is there >0% chance I can get you to directly answer my specific question?

Slereah

Well, I actually dealt with this before

I wrote a little Mathematica program to solve tensor shit for me

0celo7

I am not "troll kibble"

Slereah

because only chumps find the Riemann tensor by hand

0celo7

I am the CEO of Newton, Evidence and Sons Incorporated

DanielSank

16:38

@JohnDuffield Let us briefly (please!) consider this diagram

ific.uv.es/~vos/ilc/ilcFastForward/MachineBackground.html

In it, I see a diagram labeled Breit-Wheeler.

This, I believe, is the process you are talking about.

I will label all my direct questions to you with Q).

Q) Is this the process you are talking about?

0celo7

Our mission: dispel the popsci notions of spacetime, spacetime curvature, black holes, dark energy and most other accepted modern "physics"

DanielSank

@0celo7 Yeah, but you're screwed by experimental data. Wut now?

0celo7

@DanielSank You made that data up.

Slereah

@0celo7 what about electrons

0celo7

Electrons are just charged particles.

That's it.

As we see in this Ampere paper...

DanielSank

16:40

@JohnDuffield ?

John Duffield

@DanielSank : yes, and as you can see in the diagram two photons are converted into an electron and a positron.

DanielSank

@JohnDuffield Excellent.

Slereah

I don't think Ampere knew about particles

0celo7

@Slereah

DanielSank

@JohnDuffield Now, we observe various such processes in Nature. We call the catalog of these known processes the "Evidence".

Slereah

16:41

More probably still charged fluids back then

Hm

What is the most egregious notation I've ever seen

DanielSank

@JohnDuffield Now, one of our duties as physicists is to come up with little stories to help explain the patterns we see in this catalog.

Slereah

Probably still the Penrose notation book

DanielSank

Q) Do you agree that one of our duties is to come up with little stories to help describe what we see in the Evidence?

0celo7

Feynman stories!

Slereah

DanielSank

16:44

@JohnDuffield ?

John Duffield

@DanielSank : not if they're fairy stories. like a 511keV photon spontaneously morphs into a 511kev electron and a 511keV positron to which the other photon couples.

Slereah

I remember a math paper that was full of hearts and losanges and whatnot

DanielSank

@JohnDuffield One thing at a time, please.

Q) Is it our job to come up with stories which reproduce the Evidence in as simple a way as possible?

Slereah

And of course any QFT paper that is entirely treated as a gauge bundle is gonna be egregious looking

monocle popping

basically the two extremes of notation

Not enough abstraction and too much abstraction

John Duffield

@DanielSank : no. It's our job to explain what happened and why, not come up with stories. We know that virtual particles are virtual. We know that the only particles initially present are two gamma photons. And we know that pair production does not occur because pair production occurs.

DanielSank

16:47

@JohnDuffield Dude, please, one thing at a time.

Slereah

Also I suppose that two other extremes are too rigorous and too sloppy

DanielSank

You say "explain what happened and why". Certainly this "explanation" is what I call a "story".

John Duffield

@DanielSank : this gets to the crux of it. The "given" explanation of gamma-gamma pair production is so wrong that even a child can see it's cargo-cult junk.

DanielSank

@JohnDuffield Come on, man, can we please take this one step at a time without all the distracting extraneous editorializing?

It's really discouraging.

I'd like to find common ground with you so we can communicate.

These disparaging remarks from you do not help.

yuggib

@Slereah There is no such thing as too rigorous. Either something is rigorous, or it is not :-P

DanielSank

16:50

@JohnDuffield Wouldn't you say that in the end all of our explanations are some kind of approximate human-readable story to help us understand what's going on?

We invent e.g. "electric field" to help understand the observed push between charges.

ACuriousMind

@yuggib A rarely acknowledged truth ;)

DanielSank

It's a useful concept! So we start forgetting that it's a story, but a story it is.

@JohnDuffield Q) Do you agree with these statements?

Huy

@0celo7: Who did you meet?

Slereah

@yuggib us.metamath.org/mpegif/mmdefinitions.html

0celo7

@Huy Jochen Denzler, one of the analysis profs

he subbed our ODE class for his buddy Freire I guess

(he's a lot better lecturer)

Slereah

16:52

⊢ LMod = {g ∈ Grp ∣ [(Base ‘g) / v][(+g ‘g) / a][(Scalar ‘g) / f][(vsca ‘g) / s][(Base ‘f) / k][(+g ‘f) / p][(.r ‘f) / t](f ∈ Ring ∧ ∀q ∈ k ∀r ∈ k ∀x ∈ v ∀w ∈ v (((rsw) ∈ v ∧ (rs(wax)) = ((rsw)a(rsx)) ∧ ((qpr)sw) = ((qsw)a(rsw))) ∧ (((qtr)sw) = (qs(rsw)) ∧ ((1r ‘f)sw) = w)))}

a bit too rigorous

Huy

@0celo7: I see, don't know him. Seems he just studied at the ETH but never lectured.

funny that he's a better lecturer :P

0celo7

did you look him up?

Huy

@0celo7: just his short CV. did you talk to him in German?

0celo7

yeah, he did not give two fucks

Huy

:D

yuggib

16:53

@Slereah rigorous does not mean you cannot use words. Anyways, that is just rigor

0celo7

I'm gonna stop by his office

Huy

what for?

0celo7

@Huy Lang just about shit his pants

because I need to talk to him about the analysis classes

Huy

wat

Slereah

Words are for the weak meat bags known as hu-mons

0celo7

16:54

it was really strange

John Duffield

@DanielSank : no, our explanation aren't some approximate human-readable story. Our explanations are scientifically accurate descriptions. And I'm sorry to insist on such accuracy, but the electron has an electromagnetic field. Not an electric field. Make sure you read this this "given" explanation of gamma-gamma pair production.

DanielSank

@JohnDuffield Q) Does "scientifically accurate" mean "agrees with the Evidence"?

0celo7

@yuggib wrong

Huy

@0celo7: it seems the ETH hit top 10 for the first time this year in QS World Uni Rankings

I feel so special

John Duffield

@DanielSank : yes, but it's more than that. I tell you a story about angels on the head of a pin that agrees with the evidence.

DanielSank

16:57

@JohnDuffield Ah yes. But the theory (let's just call it "theory" from now on) should also be simple.

and falsifiable.

@JohnDuffield Q) Do you agree?

0celo7

@Huy very strange man btw

totally disheveled

pocket protector

like a Nokia brick phone

Slereah

So your average science professor

Huy

well he is a mathematician

what do you expect

0celo7

the engineering professors are all buff

not even kidding

DanielSank

@0celo7 Yup.

0celo7

17:00

they're actual normal people

DanielSank

@0celo7 Yup.

Slereah

This was my thesis advisor

Not pictured : thick russian accent

0celo7

lol

John Duffield

@DanielSank : I agree. Do you agree that the explanation shouldn't rely upon things that are not explained, that you cannot see? Like angels on the head of a pin?

DanielSank

@JohnDuffield Welllll, that's tricky!

We put all kinds of things we can't really "see" into our theories!

We do it because it's useful, consistent with the Evidence, and falsifiable.

0celo7

17:02

why are we capilatizing evidence

DanielSank

@JohnDuffield I'd usually agree that Angels on a pin shouldn't be in a theory, but that's because I haven't seen a set of experimental Evidence which needed it.

Slereah

evidence and Evidence are not the same thing

John Duffield

@DanielSank : but not invisible angels. They are not useful, or consistent with the evidence, or falsifiable.

DanielSank

@Slereah Oh crap, did I mess that up?

@JohnDuffield Well, ok. But then again, what about "electrons"? Those were invisible to the technology of the time for a long time while they were still incredibly useful in the theory.

@JohnDuffield I can't "see" electric or magnetic fields per se, but they are so incredibly helpful for my understanding of the Evidence that I admit them into my mental constructs.

Of course, I must periodically remind myself that they are just that: helpful notions for remembering how to understand the expermental observations.

@JohnDuffield Do we understand each other?

0celo7

what if I can see the electric and magnetic fields

where is your Bacon now?

Slereah

17:07

some fishes can feel them

DanielSank

@Slereah They feel a force, right?

John Duffield

@DanielSank : electrons aren't invisible. And they were discovered when JJ Thomson experimented with cathode ray tubes. The field is the electromagnetic field, so your electromagnetic mental constructs may be wrong, and may result in you misunderstanding the experimental observations.

DanielSank

Abstracting that to a "field" is, IMHO, an abstraction. A really really useful one.

Slereah

@DanielSank : Dunno

John Duffield

@DanielSank : the force is the result of the interaction of two* electromagnetic fields. Do not confuse field and force.

Slereah

17:09

You know, it's weird

John Duffield

* or more

Slereah

There's no biology stackexchange

John Duffield

I have to go I'm afraid. Time for tea.

DanielSank

@JohnDuffield Goodbye.

ArtOfCode

@Slereah Pretty sure there is.

Biology

Slereah

17:09

Oh wait!

ArtOfCode

Definitely is.

0celo7

my ear is still ringing

John Duffield

@DanielSank : nice talking to you. Bye.

Slereah

Time to ask them about fishes boning

0celo7

lol

obe

17:11

My books arrived.

0celo7

time to get reading

Slereah

what book

obe

Cahill, mandl, and panmanabhan.

Slereah

what is it aboot

0celo7

read chap 5 in Cahill now

obe

17:12

They are 3 books. math, qft and gr.

Slereah

never heard of 'em

any good?

0celo7

I really like one of them

obe

Ask 0celo7.

0celo7

I haven't even read two of them!

obe

My bad.

0celo7

17:13

I don't have Cahill with me...

I can get the ebook

obe

The F&F book is really detailed.

0celo7

start cahill

F&F doesn't cover any of HE

HE is just too scary

Slereah

F&F?

0celo7

get with the acronym program

Paddy FF

Slereah

wot

0celo7

17:16

::facepalm:: forget it

the fact that you don't know every GR book is just...sad

even lil obe knows more about GR literature than you

obe

Do I.

Slereah

17:29

Is it

Feynman with an EI and Feynman with a Y

Allan Sherman's "Shake Hands With Your Uncle Max"

►

(terrible musical references)

Merowitz, Berowitz, Handelman, Schandelman
Sperber and Gerber and Steiner and Stone
Boskowitz, Lubowitz, Aaronson, Baronson,
Kleinman and Feinman and Freidman and Cohen

Smallowitz, Wallowitz, Tidelbaum, Mandelbaum
Levin, Levinsky, Levine and Levi
Brumburger, Schlumburger, Minkus and Pinkus
And Stein with an "e-I" and Styne with a "why"

It was actually Stein

nvm

0celo7

@obe seems like it

just think, in a few months you'll know more physics than me

user54412

why are professors allowed to butcher relativity?

user54412

0

Q: Is $X^{\mu\nu} \equiv A^{\mu}+B^{\nu}$ a tensor?

Consider $X^{\mu \nu}$ an "object" with two indices, defined as $X^{\mu\nu} = A^{\mu}+B^{\nu}$. Is $X^{\mu\nu}$ a tensor? Exists some transformation law to carry $X$ to a new coordinate system ? What I need to prove? I have that, if $X^{\mu\nu}$ is a tensor, $$X^{\alpha\beta} = \Lambda^{\alpha}_...

user54412

questions like this should never even be asked

0celo7

EXACTLY

Slereah

17:34

I'm sure mathematicians already say that Einstein notation butchers tensor calculus :p

0celo7

why the hell do people use coordinates

user54412

@Slereah but it doesn't -- the ones who say it are just ignorant

user54412

I think you're all missing the point

Slereah

user54412

any collection of real numbers of the correct size is a tensor, just like any collection of 16 real numbers is a matrix

Slereah

17:35

Well, not exactly

It has to transform correctly

user54412

@Slereah NOOOOOOO

user54412

That's insanity

0celo7

YEEEEEESSSSS

Slereah

It has to be a SECTION OF THE TENSOR BUNDLE

user54412

I specified real numbers. They specify a linear map. Period.

user54412

17:37

If you want to go and prescribe some inconsistent transformation of those numbers, and then point out how it's inconsistent, that's your problem.

Slereah

but in this case, it is not specified that it's just a bunch of numbers

user54412

What else can a bunch of numbers be but a bunch of numbers?

0celo7

I'm confused now

welp

Slereah

Well it could be a

TENSOR FIELD

He doesn't really specify what A and B are

user54412

I'm going to cry now.

user54412

17:38

Pass the drugs.

user54412

I need them.

0celo7

so the transformation rule is irrelevant?

wait

are the Christoffel symbols tensors

that's a collection of numbers

@ChrisWhite what kind would you like

Slereah

"tensor" is kind of a stupid name

Is it because it used to be for material science

0celo7

yup

user54412

@0celo7 The Christoffel symbols, together wither their additional, non-tensorial transformation rules are not. You could take the symbols as components of a tensor though. And then when you go to a different coordinate system, you don't do something stupid like transform them with the wrong transformation.

0celo7

17:40

engineers lern pleb tensors

stress tensors

Slereah

then again, "spinor" is also dumb

0celo7

@ChrisWhite no shit

what is this discussion about again

I agree with everything that @ChrisWhite is saying, but he doesn't agree with me

I'm confused

user54412

Students all over the world think "are these numbers a tensor?" is somehow a valid question. Worse, profs all over the world keep asking it like it's one.

user54412

If you don't hand someone an explicit transformation law, asking them whether the object transforms in a certain way isn't even a wrong question.

Slereah

Well obviously not, because tensors are not arrays of numbers :p

You are confusing them with TENSOR COMPONENTS

0celo7

17:42

good, good

Slereah

(Nitpicking contest)

0celo7

show that Princeton duck who's the boss

are you even Witten

Slereah

Darn ducks

user54412

I saw Dyson today. I wonder if he could take on Witten.

Slereah

Dyson?

Is he still alive

user54412

17:45

he still goes into work and everything

Slereah

Quite amazing

" awesomeness (p<0.001)"

Oh Biology SE

Homosexuality is maladaptive - external stress creates homosexuality

reduce resource stress on family unit, youngest child tend to be gay (E.M. Miller 2000)

*** mitochondrial DNA carries male killing genes, with male being a dead-end (Hurst 1991)

Being straight, in this economy?

0celo7

@ChrisWhite what is the multilinear map defined by $A^\mu+B^\nu$

Slereah

Yeah I find that notation a bit offensive

What happens if you contract it once

0celo7

I'm not even sure what it means

Slereah

Are you adding scalars and vectors???

0celo7

17:52

it's ill-defined notation

Slereah

APPLES AND ORANGES???

0celo7

yes

@Slereah has nailed it

user54412

@0celo7 $f(v,w) = (A^\mu + B^\nu) v_\mu w_\nu$

0celo7

is that a tensor

user54412

what you seem to be hung up on is thinking that writing $A^\mu + B^\nu$ carries some additional information -- an implicit transformation law

user54412

17:55

and that this transformation law is different from the one for $X^{\mu\nu}$

FenderLesPaul

@Slereah if mathematicians say Einstein notation butchers tensor calculus

then that's simply because mathematicians have their heads up in their asses

there's nothing wrong with a notation that far simplifies calculations

if people used mathematician's notations in tensor calculus then physics would be far behind

user54412

that's already akin to equating components with geometrical arguments, but even leaving that aside, if you think $A^\mu + B^\nu$ has an implicit law different from $X^{\mu\nu}$, you must object to even writing the equation $X^{\mu\nu} = A^\mu + B^\nu$, on principle.

obe

@0celo7 How is that possible?

Slereah

Hey, @0celo7

I have an idea for an even worse notation for GR

Huy

@FenderLesPaul mistakes may be overlooked?

Slereah

17:57

Remember how early SR was written in quaternions?

Let's do a quaternion GR

FenderLesPaul

@Huy ?

user54412

So when asked "Is $X^{\mu\nu} = A^\mu + B^\nu$ a tensor?" the only possible responses are "yes, because there is no transformation law given to be violated" or "that's not a valid question." The answer cannot be "no."

FenderLesPaul

@Rigor youtube.com/watch?v=xyWHRC8A_uU&feature=youtu.be

@Rigor youtube.com/watch?v=Bo24u42nsz0

Slereah

"Metrics and Quaternion Products"

Oh god

It exists

FenderLesPaul

@Rigor some new ambient/psych albums and songs I found

@Rigor also are you into sitar stuff?

I don't play but I listen to it a lot because it has a very psychedelic feel

so I can recommend stuff there too if you want

Slereah

18:03

"On factorization of Einstein's formalism into a pair of quaternion field equations"

Help

I'm sorry I ever brought it up

I don't want to unleash this evil in the world

FenderLesPaul

@Slereah does that have utility?

or is it for fun?

Slereah

It is not for fun

It is punishment

For our sins

FenderLesPaul

y'all need Einstein

Slereah

This paper is written in old timey 60's style

Typewriter + pen equations

It truly is a punishment

FenderLesPaul

who is it by?

Slereah

18:08

streaming.ictp.it/preprints/P/66/081.pdf

How many formalisms are there for GR

There's basic GR

Teleparallelism

ADM

First order formalism

quaternions

Hm, what else

Spinor GR

Gauge GR

Spin-2 field GR

Self-dual GR

That's about all I can think of

FenderLesPaul

you're all I can think of

Slereah

Shut up you fool and kiss me

FenderLesPaul

#smooth

obe

@FenderLesPaul I'm curious to know what QM book did you use?

Slereah

0

Q: Communication back in time?

On the wikipedia page for time travel, it mentions that Robert Forward said (theoretically, unknown since we don't have a working theory of quantum gravity) that if a heavy nucleus was subjected to an intense magnetic field, it would elongate into a Tipler cylinder and allow gamma rays to be sent...

electromagnetism general-relativity time quantum-gravity time-travel

Perfect

user54412

18:30

"Several experiments have been carried out to try to entice future humans, who might invent time travel technology, to come back and demonstrate it to people of the present time. [...] no time travelers are known to have attended either event."

user54412

Sometimes I wonder if Wikipedia is being written with a careful, unbiased tone, or with sarcastic understatement.

Slereah

free cookies for time travelers

vzn

hi all have been attempting to follow this JD vs Everyone debate & hitting some of the links. not an expert in QFT but neither side seems to be all that clear about what exactly is "wrong"... and am surprised to see so much debate over "interpretation"... dont like to see the harsh tone in here... JD writes in a rather harsh way, but a tiny )( pt in JDs favor, he seems to have zoomed in on an area of frontier physics that is leading to new experiments & predictions.

Slereah

Well mostly because most of what he says is a word salad

0celo7

@FenderLesPaul ::looks on in horror::

You slut

Now I know what you've been doing behind my back!!

::cracks @Slereah over the head with MTW::

Get out!

Slereah

18:42

Nicolas Cage Losing His Shit

►

Such a master thespian

FenderLesPaul

@0celo7 it's not what it looks like!

@obe Sakurai

0celo7

@obe remember that @FenderLesPaul is smart

Don't trust him

FenderLesPaul

:(

@0celo7 I wrote you a song

0celo7

Fuck. I just added another book to my list.

FenderLesPaul

it's called "0celo7 come he will"

0celo7

18:46

Lang is sending me a book on neutron scattering. I don't even really want to work with him

He German'd me

FenderLesPaul

nicee

0celo7

@ACuriousMind I got another German rant today

Two in one day!

skill patrol

About?

0celo7

I'm about as German as a bullet to the back of the head now.

Grad students leaving possibly radioactive samples all over the lab

skill patrol

Not good.

0celo7

18:52

Indeed.

They're not labeling stuff, so while nothing may be radioactive, there's no way to know

Unless you get out the Geiger counter

user54412

Sometimes heavy metals are more hazardous chemically than the radioactively.

0celo7

I don't know what exactly they're doing.

Might be some of those in there

skill patrol

@FenderLesPaul groovy

@vzn you should come join the fun.

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