The h Bar

Secret

16:00

ACuriousMind

@Secret I mean this: From the visualization of vector spaces as the arrows in space, it is obvious that lines and planes are interesting things to consider. Their formalization is then the notion of a subvectorspace or affine subspace. The visualization here leads us to the natural mathematical objects to consider. Your ring visualization doesn't do anything like that. It's not evident that ideals should be interesting.

Nothing about it tells me more than the axioms I started with, so it isn't useful

Slereah

@ManishEarth Well generally speaking there isn't a theorem for all classes of CTCs

That's why it's pretty hard

ACuriousMind

In particular, there is no "intuition" about this I could use to reason about true statements, or mathematicially interesting classes of rings like UFDs or Noetherian rings.

Slereah

The definition of a "time machine" is pretty vague

I've seen like three different ones

ManishEarth

@Slereah yep

Slereah

16:02

all with different theorems

ACuriousMind

@ManishEarth You haven't been around in a while, have you? :P

ManishEarth

@ACuriousMind I moderate silently :P

Today I came across a flag on JD. Decided to reply, that was a bad idea

Slereah

Though really the two big theorems which sound the closest to forbidding CTCs are like

Divergence of the vacuum energy at the Cauchy horizon

ManishEarth

yeah

Slereah

And non-unicity of the development of the achronal slice when CTCs are involved

(Although the other type of development is singularities so pick your poison)

Secret

16:04

@ACuriousMind
Actually, how does people discover some interesting subsets of an object such as the ideal of a ring if initially all they have is just the ring axioms?

Slereah

then again singularities probably won't survive quantum gravity

Secret

I mean, as you mentioned, there's Nothing about it tells us more than the axioms we started with. How do they managed to get the idea that these things exists and are interesting?

These properties are not derivable from the ring axioms, then how can people came up with them in the first place when back then all they know are just the ring axioms and ideals?

ACuriousMind

@Secret You start with examples of ring you know well, e.g. $\mathbb{Z}$ or $\mathbb{Z}[x]$. For ideals, you start with thinking about "multiples of numbers" (i.e. principal ideals). And then you have to have that spark of mathematical genius that you should not restrict yourself to just the principal ideals, but arbitrary set where multiplying things just ends up in the set again ("the multiple of a multiple is still a multiple")

Slereah

What's $\mathbb{Z}(x)$?

ACuriousMind

@Slereah That'd be the quotient ring of $\mathbb{Z}[x]$, fixed.

$\mathbb{Z}[x]$ is just the ring of polynomials with integer coefficients in one variable.

Slereah

16:10

oh

ACuriousMind

@Secret: But generally, unless you have a good visualization that tells you why objects should be interesting, the justification for defining them really comes down to "You can prove interesting stuff with them".

Secret

@ACuriousMind I think I know why in my attempt to visualise abstract algebraic objects why I found what you said nonintuitive:

It is that "backward logic" problem again!
http://math.stackexchange.com/questions/1442099/why-in-terms-of-the-structure-of-proofs-and-proof-strategy-is-this-proof-of-mi

My maths professors often said I often run into a cognitive danger of going too meta when trying to visualise something from the top down.

For example in the case of rings, instead of working form knwon special cases and then generalise, I tried to work from the most fundamental axioms that is tr…

That is, in most case of attempt to visualising abstract algebraic objects, I am so greedy that I am trying to construct an illustration that can describe and derive everything we know for that mathematical object (e.g. rings)

0celo7

why do people chat when I'm busy but not when I'm here

@ACuriousMind racist

Slereah

We run away when we see you arrive

0celo7

you're racist against French people

figures, considering you're German (/s in case anyone is confused)

Secret

16:16

Acuriousmind, Slereah and I are currently chatting why and how my visualisation approach is faulty, and we are slwoly identifying some problems in my thinking approaches

0celo7

I see

btw he is knows as ACM

or Bajoran

ACuriousMind

@0celo7 Correlation is not causation. ;)

0celo7

@ACuriousMind you could have struck through "not" and that would have been a good burn

ACuriousMind

@0celo7 Why would I want that?

You think I'm mean :(

0celo7

@ACuriousMind you are!

not as bad as @Danu in any case

obe

16:20

I'm nice though right?

0celo7

(joking, don't get excited if you read that @Danu)

@obe dunno

obe

You know me well enough.

FenderLesPaul

@0celo7 I got roped into a string theory reading group

help

save me

0celo7

lucky fucky

are you assumed to know something about strings

@obe no

obe

D:

0celo7

16:22

see, I've talked to Bajoran

ACuriousMind

@0celo7 What kind of edit is that?

0celo7

I know that he's a mean SoB who would shank me in a heartbeat to gain some quantum knowledge

@ACuriousMind one that makes it rhyme :)

FenderLesPaul

@0celo7 nope

0celo7

@FenderLesPaul ok you're fine then

just learn about strings through the group?

FenderLesPaul

fair point

why am I even doing this

my life has no direction

4

0celo7

16:24

you're rubbing my nose in it

FenderLesPaul

I'm snuggling your nose with it

0celo7

::reads about crystals and finite groups::

Lang!!!

why!

"hey Dr. Lang I know some quantum mechanics"

"oh you can learn all about crystals"

"but I want to do the particle stuff"

"yeah that comes after this 500 page text on crystals"

obe

If you know some quantum mechanics then what do I know?

Crystals are cool though.

0celo7

basic algebra and calculus

obe

I'm ready for HE then.

0celo7

16:27

indeed

FenderLesPaul

@obe haha that was actually pretty funny

0celo7

what was funny

FenderLesPaul

@0celo7 arxiv.org/abs/1509.04875

obe

The fact that HE requires basic algebra and calculus, or that I'm fucked if I read it?

FenderLesPaul

pretty fun paper to work through

0celo7

16:28

@obe btw my working quantum mechanics does not include WKB and some of the stuff you skipped

FenderLesPaul

@obe just the comedic timing

Slereah

Why would you do 500 pages of crystals before basic QM

0celo7

I told you to skip it because I've not needed it in my working memory

@Slereah because the research is about scattering in crystals

obe

@0celo7 I read it anyhow, though I don't remember a thing.

0celo7

@FenderLesPaul whaaaaat

tl;dr?

are they trying to do 3+1 in black hole spacetimes?

Slereah

16:31

@0celo7 snore

obe

@Slereah Dude some people dedicate their entire lives to that.

Slereah

Yes, BORING PEOPLE

0celo7

lol I don't want to

Slereah

Actually that is probably what my great uncle does

0celo7

but it's good experience

Slereah

16:31

He's a mineralogist or whatever

Crystalographist

FenderLesPaul

@0celo7 yeah

0celo7

did I mention that Denzler wants me to double major

Slereah

Rock scientist

0celo7

@FenderLesPaul please put arrows on your stuff or at least include context

FenderLesPaul

@0celo7 no

obe

16:32

It requires interpretations.

0celo7

@Slereah geologist

FenderLesPaul

@0celo7 I love you

0celo7

@obe huh

FenderLesPaul

@0celo7 Hi

0celo7

@FenderLesPaul you're a damn stalker

Slereah

16:33

@0celo7 Nah

FenderLesPaul

@0celo7 it isn't stalking if it's blind love

Slereah

More focused on crystalline structures

than looking at rocks

0celo7

there's a geologist in the group

she's focusing on...crystals?

maybe

Slereah

Tell us all about rocks, geologist

what is the best rock

0celo7

there are big rocks and small rocks

the best rock is

my ~~balls~~ stones

Slereah

16:34

Is it Rock'n'roll

obe

Is re-learning qm with ballentine supposed to offer a lot of insight?

0celo7

dunno

I read it for the rigged hilbert space BS, but I've never needed it

@ACuriousMind will try to argue for it

obe

@ACuriousMind What are rigged hilbert spaces for?

0celo7

but really there's no purpose

Slereah

Rigged Hilbert spaces are what you have been doing your whole life

Because the MAN lied to you

Plane waves aren't wavefunctions

They are not unit rays of the Hilbert space

They belong to the rigged Hilbert space

obe

16:38

Is that important to know?

0celo7

what physical predictions depend on that

obe

yeah

Slereah

It's important if you want to do like

General theorems on QM

0celo7

snore

obe

Why does he talk about rigged hilbert space but not stone-von neuman theorem acm spoke of.

0celo7

16:42

because that's too hard

obe

or does he?

0celo7

only mathematicians understand that one

I don't know

no clue what that theorem is

obe

It's important ACM said it was.

Slereah

Stone-von Neumann is one of those theorem whose wikipedia page does not actually list the theorem

So you have to READ

And reading is for nerds

0celo7

indeed

never read in my life

I go to from equation to equation

Slereah

16:47

2cool4school

I once had to actually only read the equations in a book

Because it was in Latin

0celo7

hah

Slereah

Well, I'm lying

It was a dual version

Latin and ancient Greek

(it was Diophante's Arithmetica)

pretty hard to find an actual translation of it with the original text

0celo7

why on earth would you read that

Slereah

Do you mean why would I read the first book ever to use any extent mathematical notation???

0celo7

yeah

why bother

you didn't read the first book in French

or English

Slereah

16:53

How do you even know

Hm

What was the first book in English

I think it might have been "The Canterbury Tales"

Dunno about French, though

Rabelais might be one of the first one to write in French?

0celo7

@Slereah fuck. read it.

or at least part of it

Slereah

I have read some of the Canterbury Tales, I think?

It's one of those compilation of baudy stories

Quite ribald

(do not tell the mods I said ribald)

"It is sometimes argued that the greatest contribution The Canterbury Tales made to English literature was in popularising the literary use of the vernacular, English, rather than French or Latin."

Hm, not as ribald as I remember

Might be thinking of another book

"The Golden Ass" was a lot more ribald

And the ass part wasn't even intentional since the original is greek

Satire of greek society and whatnot

John Duffield

@Slereah : the chronology protection conjecture is by Hawking. This little physicsworld article gets across what serious physicists think of him: "There is just one tiny problem with all this – there is currently little experimental evidence to back up M-theory. In other words, a leading scientist is making a sweeping public statement on the existence of God based on his faith in an unsubstantiated theory".

Slereah

This article does not mention the chronology protection conjecture

Nor is the conjecture linked in any way to M theory

0celo7

Remember, Hawking is a punk.

@JohnDuffield Has proved this over and over.

Thus chronology protection is incorrect.

Slereah

17:01

I'm not even sure M theory allows CTCs

Since string theory is on a fixed background

0celo7

I know nothing about it, beside that it's 11d.

Slereah

Any string theorist cares to chime in

0celo7

We don't have any.

Slereah

0celo7

I know @Qmechanic knows some, but he never chimes in.

@Slereah I don't think string theory has interpretations.

At least not in the same sense as QM.

Slereah

17:03

Well string theory is part of QM, as far as I know

0celo7

And any overlap is because strings are QM objects.

Slereah

It probably has the same interpretations as QM

most theories of QG don't really say a lot about QM interpretations

Except very minority ones

0celo7

personally, I think each string is actually piloted by a small being

and they're dumb

Slereah

And usually they just go "Maybe quantum foam?"

0celo7

so while it appears random

really it's just small aliens

Slereah

17:04

gnomes

0celo7

good theory

how big are the gnomes?

where did they come from?

can I start a journal on this

quantum gomology

Slereah

uncyclopedia.wikia.com/wiki/…

0celo7

> Sweden has been the "most progressive" country that has introduced the mandatory pronoun "hen" for everyone. If you've changed your sex and you pretend to be something else than you are, you may feel happy when you're referred to as poultry. And because of this comfort of yours, everyone else has to be poultry, too.

Based Lumo.

motls.blogspot.com/2015/09/harvard-faculty-obliged-to-call.html

> At the University of Tennessee

:O

holy shit

Slereah

What is the Opinion on Motl

I see him mentionned once in a while

But I do not know the buzz

0celo7

based mofo

speaks the truth 99% of the time

John Duffield

17:09

The chronology protection conjecture demonstrates that Hawking doesn't understand time in the slightest. Mind you, that sort of thing doesn't stop people like him writing popscience books. Or telling you about an evil twin universe where time flows backwards. Doubtless @ManishEarth will be telling us that's mainstream too.

0celo7

@JohnDuffield Don't you have a popsci book?

Slereah

He does.

John Duffield

@0celo : yep, I've got loads of 'em.

Slereah

amazon.co.uk/RELATIVITY-Theory-Everything-John-Duffield/dp/…

Most Helpful Customer Reviews
Inaccurate, out-dated

:D

The trolls followed him all the way to Amazon

John Duffield

Hmmmn, £129.30 for a secondhand copy of a £9.99 paperback. Collector's item!

0celo7

17:13

So you are a popsci author?

How can you claim to know anything about physics then?

2

Because Hawking is discredited for his popular books despite having many technical papers and a technical book.

Slereah

I remember a fellow we had on Freenode

Bossbear

0celo7

I don't think you have any academic papers, do you, @JohnDuffield?

Slereah

He had a giant book of his crazy theory

He said he has been working on it for 25 years

It was a little sad

0celo7

So why should we believe you over Hawking? He's more of a bona-fide physicist any day of the week!

Slereah

Baking some potatoes

So taboo, so delicious

John Duffield

17:19

@0celo : I know a lot about physics because I've read a lot. You should believe me over Hawking because I refer to bona-fide physics rather than specialising in hypotheses that have no connection with experimental evidence. Here, have a read of this popscience article explaining why time travel is science fiction. There is no Santa Claus. And no time travel either.

Slereah

"Science Sundays with John Duffield"

I feel this may be biased

John Duffield

@0celo7 : I tried writing a paper but got rejected. I've been invited to write some. I should give it a whirl.

Slereah

Ahahah

John Duffield

@Slereah : a reporter called James Delingpole started a website a couple of years back and I got invited to write for it. I did it for about six months then some unwise changes occurred, hyperlinks got severed, and I jacked it in.

Slereah

Ah yes, science journalism

This bastion of integrity and accuracy

John Duffield

17:28

Just me doing my bit to combat all the cargo-cult woo that's out there.

Secret

Slereah

The splitting real line isn't that complicated to draw, what are you doing :p

Secret

@Slereah I hope this is not a Penrose notation mistake again...

If I have visualise it correctly, then these two exmaples sort of give me how strange non hassdoff space is

As if for the bug eye line, you are in one place until you reached the point 0, which then you are suddenly in points a and b at the same time. After passing through it you are back in just one location again

The branching line is even stranger, you won't be in two place at the same time until you pass 0

what's even strange for the bug eye line is that even if you head to the points a and b (where 0a and 0b are), you …

O crap, I think I made a mistake...

the neighbourhood of 0a and 0b don't overlap in this diagram

but they need to be

Secret

17:49

inperc.com/wiki/index.php?title=Manifolds

I thought points a and b are different points?

Slereah

they are

Secret

Then why do they lie in the same place in the above simple diagram?

Slereah

they do not.

They both lie in "the middle" of the real line, but they are distinct points

(that is part of the problem of relying on drawings)

Secret

(x,a) ~ (x,b) for x=/=0

So how do we plot the point (a,a) and (a,b) since by the equivalence relation they are supposed to be identified, but a=/=b so these points cannot lie in the same spot in the real line?

@Slereah Or more specifically, if I use a and c instead to build the line of two origins, how would it differ from the one build with a and b?

or is it the points a,b have nothing to do with its position on the real line? (that is a is not a units away from the middle of the real line and b is not b units away from the middle of the real line)?

obe

18:13

Physics still doesn't have the new profile.

Slereah

new profile?

0celo7

cf. math

Slereah

it's not very different

Secret

Are a,b actual values on the real line or just symbols similar to the role played by i?

Slereah

they are points in a topological space

Secret

18:31

ah I understand now

Then I guess the branching line is also easily visualized as a line forking out from the point 0

Slereah

Well conventionally it is not represented as a forked line because of Reasons, but kinda yes

(an actual forked line isn't a manifold due to not being locally ~ R)

Secret

It seems that's what Acuriousmind trying to tell me via those two exercise. Non hassdoff spaces can be visualised, but their diagrams are almost always so misleading that they don't help much in learning the nature of the objects

It seems vector spaces are kinda special then, because a lot of them are geoemtric enogh to be drawn without too many misleading things

FenderLesPaul

I wish LQG wasn't so fringe nowadays

it's so much more beautiful and cool than string theory

but I don't want to waste time learning a marginal theory

My Other Head

hi Ladies and Gentlemen, boys and girls. Should I delete my question as having no merit ?

obe

18:49

I don't even like the whole idea of strings, it's so inelegant.

(badly uneducated viewpoint, but nonetheless)

Slereah

LQG is nice and elegant

Although Lorentzian gravity is best

obe

This?

Lorentz ether theory

What is now often called Lorentz ether theory (LET) has its roots in Hendrik Lorentz's "theory of electrons", which was the final point in the development of the classical aether theories at the end of the 19th and at the beginning of the 20th century. Lorentz's initial theory created in 1892 and 1895 was based on a completely motionless aether. It explained the failure of the negative aether drift experiments to first order in v/c by introducing an auxiliary variable called "local time" for connecting systems at rest and in motion in the aether. In addition, the negative result of the Michelson...

Looks like Duffield thinking.

Slereah

"Lorentzian gravity" is fancy talk for "QG from path integrals"

It's called that because there's two big methods of doing it

Using a euclidian metric and using a lorentzian metric

obe

and why is lorentzian metric preferred?

(in a way I can comprehend)

Slereah

Thing is, it isn't.

Lorentzian metrics are not well defined

Euclidian metrics are prefered because it makes sense mathematically to integrate over euclidian metrics

But then there's the problem that not all euclidian metrics can be rotated back to Lorentzian metrics

bolbteppa

19:25

@FenderLesPaul idk I think LQG is really flawed motls.blogspot.ie/2004/10/…

0celo7

@FenderLesPaul heathen

bolbteppa

@Slereah I think he is crazy on literally everything except physics, on physics he is (almost) always good, though I got him to ban me because he could not understand a simple passage from Landau on which he was wrong

0celo7

crazy?

how?

@Slereah having not read any EQG, why is this

bolbteppa

Well the latest thing is him defending Hungary and other places for treating people absolutely viciously because of his fetish for rules, other things are his behaviour on feminism, global warming etc...

0celo7

Rules or principles?

There's a difference.

bolbteppa

19:37

@JohnDuffield I find it hilarious that your book discusses the ideology of belief when you claim to understand spin yet not be able to answer a simple question about it relating to reflections and have absolutely no curiosity on the matter when it's brought to your attention

@0celo7 rules: " "No one can break the EU rules just with the excuse that they haven't prepared for the situation," Hungary correctly says " motls.blogspot.ie/2015/09/…

0celo7

A principle of being in an organization is not breaking the rules :^)

bolbteppa

(So there's no difference after all, huzzah! :P)

0celo7

There is, but in this case one can argue there isn't because of the principles of the organization.

Now if one breaks a rule of an organization that one never swore allegiance to, for example...

bolbteppa

What is this fascination with the fine structure constant? In Heaviside-Lorentz units it's just the thing in Coulomb's law right? Why is it different to being fascinated with the numerical value of say G for example?

0celo7

because $1/137$ :O

it's magiiiiiiic

also it's dimensionless

so magiiiiiiic

bolbteppa

19:51

"I have an even better theory: The constant is a fake number: an outcome of math specifically designed to keep you from looking in the right place. " milesmathis.com/fine.html mind.blown.

Slereah

20:02

@0celo7 Because if you use Euclidian metrics, you are basically path integrating something like $e^S$, which can have a proper measure in integral theory

Named after the delightful Norbert Weiner

The Weiner measure

(heheheh weiner)

@0celo7 Except for the .01 or whatever :p

0celo7

@Slereah .05 I think

@Slereah you can't German

Slereah

mb

0celo7

it's wine-er

Slereah

There's the...

either hypothesis or theorem, I'm not sure

That integrating over all euclidian metrics is equivalent to integrating over all lorentzian metrics

And so the whole can't Wick rotate would not matter

0celo7

:O

proof

Slereah

20:16

Well if it's a hypothesis there won't be much proof!

Let's see

0celo7

well motivation then

Slereah

Hm fuck, where did I read it again

Lemme get my Hawking Gibbons

The motivation may be wishful thinking :p

Though I think it works in 2 dimensions

0celo7

you can use isothermals in 2 dimensions -.-

that makes a big difference

at least one would think so

Slereah

isothermals?

0celo7

isothermal coords

Slereah

20:22

o

0celo7

like all 2d metrics are conformally flat

Slereah

Not truuue

there's three conformal classes in 2D euclidian geometry

tho they depend on the topology

0celo7

explain

Slereah

Well with the uniformization theorem, it's like

Every surface has a metric conformal to either the Riemann sphere, $\mathbb{C}$ or $H^2$

Quite a compact way to write the metrics

0celo7

hmm

what are isothermal coordinates then

Slereah

20:28

$\frac{4dzd\bar{z}}{(1+\vert z \vert^2)^2}$, $dzd\bar{z}$ and $\frac{dzd\bar{z}}{(Im(z))^2}$

Hell if I know

but as said, those are for spaces of a different topology

For the same topology, all metrics will be conformal to only one metric yeah

Also the sphere isn't a Lorentzian manifold so you can ignore it

0celo7

wait what is $H^2$

Slereah

Hyperbolic space

(IIRC it's for surfaces with genus > 1 in the theorem?)

"The first case includes all surfaces with positive Euler characteristic: the sphere and the real projective plane. The second includes all surfaces with vanishing Euler characteristic: the Euclidean plane, cylinder, Möbius strip, torus, and Klein bottle. The third case covers all surfaces with negative Euler characteristic: almost all surfaces are hyperbolic."

Wait tho

Aren't those three metrics conformal with each others

mb you're right

We need a real mathematician

Also I don't know how well this applies to Lorentzian metrics

@ACuriousMind halp

0celo7

@ACuriousMind halp him

dmckee

20:58

@FenderLesPaul is living a scalar life.

5

@bolbteppa Well, the fine-structure constant is dimensionless, so you can compute it in any consistent set of units and get the same answer, which isn't the case for $G$.

ManishEarth

23:10

@JohnDuffield Your ideas seem to not be mainstream. Please note that we only handle mainstream physics on this site, where "mainstream" is defined by this policy. If you have issue with the policy, please bring it up on meta.

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