The h Bar - 2015-08-26 (page 2 of 3)

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2:00 PM

@ACuriousMind :(

2:41 PM

What are they trying to teach kids these days?

Two metal blocks that have slightly different temperatures are placed next to one another. After five minutes, they both have lower but equal temperatures. According to the law of conservation of energy, what most likely happened?

Energy was created inside the blocks.
Energy was destroyed inside the blocks.
Energy was absorbed into the blocks from outside the system.
Energy was transferred from the warmer block to the cooler block

Well energy is not conserved in GR, so...

wait they both have lower temperatures?

ELI5 pls

why doesn't the cooler one warm up a bit

dunno

-2

Q: If space and time are woven into one fabric do I still exist yesterday?

First timer, and not more than an avid layman, so forgive if the question is naive. If space and time are woven into one fabric, and when looking into a telescope at light emanating from the centre of the universe I am looking back in time, do I still exist yesterday? Is it that my organic brai...

@skillpatrol well what is the right answer

I am wondering, if we use relativity, where spacetime is basically a block universe, then for a given event, its past and future at some point in time (defined by the events in the worldline in its future and past light cone) has to exists, right?

it has to be a mix of (3) and (4)

block universe?

2:50 PM

@0celo7 the answer is not given

Eternalism (philosophy of time)

Eternalism is a philosophical approach to the ontological nature of time, which takes the view that all points in time are equally "real", as opposed to the presentist idea that only the present is real and the growing block universe theory of time in which the past and present are real while the future is not. Modern advocates often take inspiration from the way time is modeled as a dimension in the theory of relativity, giving time a similar ontology to that of space (although the basic idea dates back at least to McTaggart's B-Theory of time, first published in The Unreality of Time in 1908...

most peopel tend to refer the spacetime in generla relativiyt works like this, where because there is no objective present, thus all events in the past and future lightcone of an observer is already there as part of the spacetime manifold

@0celo7 I found it on a chemistry help site

the answer is (3) and (4) together

@Secret Well, the thing is...what does it mean for the past or the future to "exist"?

@ACuriousMind 2deep4me

2:53 PM

You could also say that in classical mechanics the data at one instant determines the data at all other instants. The instant you choose is completely arbitrary. I don't think "presentism" vs. "eternalism" is physics in any way.

@0celo7 how do they BOTH have lower but equal temperatures?

@skillpatrol I might have misread

I suppose it means say there's an event C happening in the future lightcone of an observer, the observer will soon realise it will happen soon as measured by his clock even though right at that moment in time, he has not see it happen yet

Yeah, I thing determinism is the word I am trying to say

lol

I read it first the right time

then fucked it up in my head

the problem has no solution, as I originally said

yes

2:55 PM

so a mix of (4) and the inverse of (3)

that should be right

:-/

well if they go into equilibrium and then the environment cools them

environment cooling =: inverse of (3)

yes, it depends on the choice of the room temperature

true

that's a dumb question

why not ask something easy like "which interpretation of QM is correct"

user image

So what I am trying to say is that suppose the observers A,B,C,D all draw a spacetime diagram for their own frame of reference (thus the axes might be skewed differently)
then

@Acurious
what I mean by "exists" is that e.g. in B's diagram, you will still find a point corresponds to D and C in O's diagram

But if the future of some observer has not happen yet, then you won't expect B to have D and C in his diagram, right?

or did I miss something?

the relativity of simultaneity only say the observers don't agree on when events happen and whether they happen together, but they all agree whether it is located in their past or future light cone (thus we have the notion of causality well defined)

@ACuriousMind

that is, their won't be some observers not having e.g. event D somewhere in their spacetime diagram

3:04 PM

@Secret Yes, since relativity has no unique notion of "time", it doesn't make sense to ask "if things have happened yet".

Then if we ask e.g. observer A, then since there's a worldline joining some events that lead to A from the past light cone of A through A to the future light cone of A, then A's past and future has to exists, right?

What does it mean to say they "exist"?

You're talking of them, how could you speak of "A's future" if it didn't exist?

Is it reasonable to define exists as: that all observers agree that a bunch of events S1 S2 S3 etc. are somewhere in their spacetime diagrams and not having some observers have some of these events missing in their diagrams?

ACM is a wise philosopher...

@Secret Um...and who gives you "all observers"? Isn't every event a possible "observer" in the sense I can transform into the frame of an observer that is located at that point?

Also, what is "their spacetime diagrams" - they all see the same spacetime, just with coordinates transformed by definition, how could points be missing from some of those?

3:14 PM

all observer question: I guess so...

I need a pics for the second question, give me a sec...

user image

So if we consider the coordinates plotted in the rest frame of O and Obar respectively, then we get two different, but related digrams because they are linked by a lorentz transformation

O and Obar will disagree when and where the event A happens (A in O's coordinates and Abar in Obar's coordinates) but they both have this event A in it

user image

3:30 PM

How would you answer a question for a working definition of time? @Secret

Apologies for a super messy diagram

Now say we are in Odouble bar's rest frame. Since the event A (with coordinates Adouble bar in Odouble bar's frame) is in the past light cone of O double bar, then O double bar knew the event A is there

But if we use our usual thinking that the future has not happened yet, then there is no way O and O bar will realise event A is there (since it lies inthe future light cone of both O and O bar) until the light signal from A reaches them

However when we plot spacetime diagrams in the rest frame for each observers, since they are all related by a Lorentz …

that is, if O and Obar use what they know so far based on the infromation from their past light cones, they could not possibly have A or Abar plotted in their diagrams if we try to use our usual sense

But general relativity said, since there's a spacetime manifold where events are plotted, and every event can be an observer by relate them with lorentz transformations, then they are all there in the diagram when the observers plot the events in their rest frame

@Secret I don't see why your "reasoning" would be needed at all. "Spacetime diagrams", no matter from which point of view you draw them all draw the exact same manifold by definition. There's no way a point could be in one of them and not in all others.

yes that's what I am trying to say

Sooo...what's the point of the question "Do future and past events exist" if you just defined existence in a way that they could not possibly not exist?

Since they all draw the exact same manifold, it means the points are there, no matter if they are located in the past or future light cones of two different observers, even if the observers where the event is in their future light cone cannot possibly know they are there because to them it has not happen yet because the light had not reached them yet

Because the spacetime manifold works the way you say, it means the future and past is in some sense "predetermined" thus one will argue that the past and future exists?

I think that's my confusion or thought that I am trying to highlight and I am not sure if otherwise how to view it properly

3:43 PM

The point I was trying to make the entire time is that you don't have a sensible defintion of "existence" of future and past events. Everything you might write down just means they trivially exist. And if it is determinism you're after, classical mechanics is just as deterministic (moreso even, because you can't have the weird geometries of GR)

Ok let me elaborate:
https://en.wikipedia.org/wiki/Growing_block_universe

General relativity as we learnt from textbook is not a growing block, because for any observer, we can plot events anywhere in the spacetime diagram and all observers will agree that the spacetime interval between the same two events are invariant

But if spacetime is actually a growing block, then for some observers, there will be some spacetime intervals become undefined because one of the events is located in their future light cone thus using the growing block view, does not exist

this is where I get the idea of "existence of past and future"

so perhaps what I am trying to say is determinstic vs non determinstic, maybe that's the correct word I am trying to say?

That article doesn't define it, either.

And that "slice of spacetime" doesn't make much sense, it would mean there is a preferred foliation of spacetime into timeslices, contrary to the principle of general covariance.

@Secret They just talk about it, they don't say what it means for an event to exist, and since it is not a physical object, I see no obvious way to define that.

Ok that makes sense, so I guess we first need a definition of existence before it is sensible to talk about the existence of past and future. I will deal with that later

Btw for the "slice of spacetime", Isn't the ADM formalism did a similar thing by foilating spacetime into spacelike slides labelled by their time coordinate? (I know textbook general relativity is not done this way, thus this is a separate question)

Yes, the ADM formalism foliates the spacetime, but it doesn't demand uniqueness of the foliation.

I see...

4:05 PM

@Slereah Just a few more anonymous downvotes from people who don't contribute to the website.

@secret : we don't live in a block universe. We live in a world of space and motion.

@0celo7 : energy is conserved in general relativity. Energy is conserved full stop.

@JohnDuffield for real? I think I'll need an Einstein paper to verify that

@JohnDuffield Acuriousmind and I have previously discuss about something similar (https://en.wikipedia.org/wiki/Growing_block_universe) (you can imagine that time as they mentioned in the link is just a number to label motions, as it always do back in classical mechanics)

But we found that the key to the question of existence of past and future relies on a physical meaning of "existence" and no one as far I know has a sound definition on that

General relativity, if you treat it as a mathematical model (which it is) however is based on a block universe view

@0celo7 There's a bunch of material on viXra about it :P

In fact, the founder of viXra founded it partly because people wouldn't let him publish his "Energy is always conserved!!!" elsewhere.

@ACuriousMind I don't want your crackpot theories from arXiv, viXra or any of those other sites. I want Einstein and the evidence.

@JohnDuffield So basically what you said might be true in some form, but we don't have any experimental results to support or refute that as far we knew

Time is still hotly debated in the theretical physics departments, some even potulate spacetime arises form quantum entanglement in a recent thing I read about fom science magazine (which has links to the paper)

4:19 PM

Entaaaaanglement! ::makes spooky noises::

@0celo7 My best memory in the GR course said energy conservation is a nasty topic. because of how non inertia frames makes it hard to define (forgot), and then they talked about red shifted photons as the universe expands

@ACuriousMind
Yeah, those guys came up weird ideas like every single week, and the science magazine love to report them in a watered down fashion

some theorist cannot stand on so muchdeparture from experiemnts and they have recently form a conference that sort of opposite to the string theory conference and how they urge researchers to not to lose touch of the experiment…

I think it is called CONVE something. Let me lok that up later...

always fun to see a discussion involving JD...but only if it does not exceed the 1000 words :-P

Here
https://perimeterinstitute.ca/research/conferences/convergence

then becomes boring

@Secret I was being sarcastic. I just want to see him produce an Einstein source for that statement.

4:28 PM

I know, I just have the habit of play along with the sacarsm by actually pretending to answer the question to dump infroamtion

@Secret Makes sense. Last I heard, there were quite a few folks at Perimeter supporting loop quantum gravity.

@0celo7 He will come up with something...

PS I am referring to your "Entaaaaanglement! ::makes spooky noises::", not the "In fact, the founder of viXra founded it partly because people wouldn't let him publish his "Energy is always conserved!!!" elsewhere."

in case that' the source of the confusion

@yuggib It better not be from a "peer reviewed" journal. They're not very reputable when they endorse the likes of Thorne and Hawking.

@HDE226868 I used to support string theory and many worlds interpretation a lot, but due to so much lack of progress in both fields (and that many worlds seemed "too malleable to be flasifiable" to me) I am now more of the other quanutm graivty and quantum mechanics interpeetation proposals

4:33 PM

@HDE226868 Did you tell them that they are intellectual garbage?

One thing I grew tired of seeing (except as a scifi writer) is the gazillons of dark matter candidate proposals out there. The most recent of these is saying dark matter might be a ball of quarks , as they extrapolate from the idea that spawns from the recent pentaquark findings

@0celo7 I've never met any of them, nor am I likely to try to get onto their list of people who should not have their calls returned.

@0celo7 You should decide whether to channel Lubos or Duffield, both is kinda confusing :P

@0celo7 Dangerous pamphlets full of lies

@Secret What is the most poplar dark matter candidate out there at the moment? I hear WIMPs tossed around a lot in some places, but not in others.

4:35 PM

@ACuriousMind They're both quite entertaining.

@HDE226868 Ah, best Freudian slip I've heard: WIMP - Weakly Interesting Matter Particle

2

@HDE226868 I learn most of these porposals first from newscientist thenin the journals links provided

WIMPS and the cold dark matter candidates are still quite popular. And then there variants like SIMPS, and WIMPZILLAS

another one that pops up alot in the pop science magazines are dark sectors, such as dark photons, dark radiation and whatnot

I would do a "ur mum" joke but she's actually a very interesting lady.

@ACuriousMind Nice.

WIMPZILLAS are basically superheavy WIMPS

One thing I notice they don't give up WIMPS easily

Axions are also quite popular

As for the dark energy side of things, the newest thing mentioned in sciencedaily.com (pop science magazine) is they have built a detector to try to capture chameleons

4:40 PM

@JohnDuffield What is dark matter? I can't find any Einstein sources on it...

@0celo7 Because dark matter (I think) was not discovered yet back in the 1990s when einstein first formulate his general relativity?

Is "Dr. Dydak coughs really loud" a valid comment on a lecture?

My eardrums are really quite fragile.

It's kinda rude, but nothing says you cannot say it

@0celo7 What's he supposed to do about it?

@Secret So if Einstein did not write about it, it must not exist...

@ACuriousMind He's a very soft spoken guy. I have the volume on max, so the coughs are like nukes.

Fine I'll remove that comment.

4:43 PM

...the volume? Are we at the point where lectures aren't given in person anymore? oO

LA has online lectures.

He's the only prof who does it...

@0celo7 it was discovered some time later

The mainstream view highly embrace dark matter because there are so many evidence to it, darkk energy however is shaky for some camps

I know, that's my bad habit of infromation dumping

I take that back. My MATLAB class also has online lectures.

I tend to have a habit to infromation dump on anything that structure like a question.

The main purpose is obvious
For the more entertainment side of things, it sometimes make a sacarsm more effective because put it in a crude way "nature is joing the fun by demonstrating the sacarsm is actually valid in some sense"

But I do agree, not many people appreciate this side of humour

There's also a more secret usage...

...it helps masks my alligence...

after all I don't chose this name for nothing

@0celo7 Are those additional to the actual lectures, or are there no actual lectures?

4:50 PM

@ACuriousMind The TA clarifies and does problems.

That's a "there are no actual lectures", right?

...pretty much?

wtf, that's weird

Yeah, it's the only class in the dept. that does it.

Not even the other sections of LA do it either.

Although he does "teach" 3 of them.

It's really curious, considering his political views.

He really is the epitome of "lazy professor."

@0celo7 Well non GH spacetimes have a well defined time coordinate, just not Cauchy surfaces

But Carlip's book has a derivation of 2+1 D Schwarzschild using ADM

Even tho it lacks them

4:55 PM

@ACuriousMind For the intro MATLAB class, I can understand it. You watch the videos and read the notes, then come in and ask the TAs questions. I imagine they did that because the sheer number of people rushing in for office hours was unbearable.

But intro linear algebra is not hard...IDK why he does it.

@Slereah It lacks them in 2+1 or in general?

Well it's more Kerr than Schw.

So in general, I suppose

Huh? Schw. has Cauchy surfaces...

Yes, but not Kerr

All Kerr or just extremal?

I know extremal has CTCs.

Regular Kerr also has them, but inside the horizon

Also it is unstable

4:58 PM

Kerr is unstable?

I thought Kerr was the stable state of a BH...

Infalling matter is blueshifted to hell

It's p. unstable

Ok, what do you mean by "unstable" in this context

Test fields are not gonna leave that metric all by its lonesome, if you get my meaning

Infalling matter will do a huge energy influx that's gonna fuck up the metric

And the CTC part of Kerr disappears when that happens

that's why people weren't that bothered by the Kerr CTCs

@0celo7 c.f. Price's theorem

@0celo7 @0celo7 yes, for real. There are no perpetual motion machines. And you don't need an Einstein paper. Because you've got me.

5:07 PM

or work through problem 3 here: astro.cornell.edu/~flanagan/ph6553/hw12.pdf

it's the RN version but the Kerr version is somewhat similar

@Secret : cross my heart and hope to die, GR isn't based on a block universe. I say that as a guy who "roots for relativity" and is forever referring to Einstein.

@Slereah Dammit I told Kerr to stop showing the singularity all the time...that gets the QM guys going

@JohnDuffield Well now do I know you're not perpetuating cargo-cult pop-sci?

I need some references.

@FenderLesPaul Reading list ++

@0celo7 : ask the question about dark matter, and I'll answer it, with references. But not now. I have to go. Wednesday night is roast chicken dinner night, and there's a cool crisp glass of white wine waiting for me.

I'm less interested in that. I want to know how energy is (globally) conserved in GR.

Well you're in some sort of luck I guess

that's exactly my research area at the moment

what exactly do you want to know?

exactly

exactuhley

5:15 PM

I don't want your cargo-cult pop science.

I want Einstein and the evidence.

Einstein didn't know shit about that

So now we have some person on the internet saying he's smarter than Einstein.

@FenderLesPaul I am also interested in this topic. How does the energy loss in redshift due to universe expansion is explained?

Einstein was dum

dummm

because some say they need a notion of global energy conservation to explain that

5:18 PM

@Secret if you had a charge in a time varying electromagnetic field that was losing energy, how would you explain that?

gone into the EM field?

yes

so is it more contentious that it happens with gravity too?

but gravity is basically curvature of spacetime, so are we suggesitng the spectime itself has some kind of energy stored in it even if it is devoid of a stress energy term?

like a rubber surface having some sort of tension?

I've been on this chapter of manifolds tensors and forms forever and I STILL get the pushforwardģpullback identities mixed up!!

well the problem with gravity is how to quantify the energy-momentum of the gravitational field

since it can't be localized it isn't a easy as with the EM field

but the idea is the same

particles exchange energy with the gravitational field

as far as actually quantifying that energy goes there are the very basic methods of using global quantities at spatial and null infinity

these are the ADM and Bondi energy-momentum

but if the space-time is not asymptotically flat then this won't work

such as with an expanding cosmology

we can instead use quasi-local quantities

which is analogous to your rubber surface analogy

there are multiple ways of going about this

5:23 PM

Interesting

one way is to use the Hamiltonian (ADM) formalism and considering a finite volume of space-time (e.g. a ball) and defining the gravitational energy-momentum of the surface (e.g. a 2-sphere) by the extrinsic curvature

this is called the Brown-York formalism

another way is to consider Noether's theorem in terms of differential forms

integrated over finite spatial regions

this gives a Komar type integral over that finite region

this is done by e.g. Wald and also Abraham Harte

arxiv.org/pdf/0805.4259.pdf

arxiv.org/pdf/gr-qc/9911095v1.pdf

etd.lib.ncsu.edu/publications/bitstream/1840.2/464/1/…

check those out

they're all pretty easy to read

reading list ++

why do you do this to me

Heyyy you're learning coding

@Secret that's a rough overview

I've taken Java classes...

5:27 PM

there are a lot of variations here and there in approaches by different people

cool, that will get me started

dope

5:42 PM

I actually like the surface tension of a bubble analogy

wtf Freire went and retroactively changed the homework assignment

I wonder how far that can be taken

branes mane

manq

it's all branes

5:43 PM

you're all branes

no

I don't see what "find the center of this sphere" has to do with linear algebra

seems like a complete the square exercise tbh

they got some new tenors in the choir

gots me some competition

kill them

with the power of music

aaahhhhhhhhhhh

math.utk.edu/~freire/teaching/m231f08/m231f08autonomous.pdf

I really do not want

5:46 PM

opens mathematica

yeah screw you

I still need to download that

screw me good

is Mathematica better than Maple?

I can get either

or both

not so much for numerically solving ODEs

mathematica is pretty bad at that

mathematica's the cooooleeeeesttttt

5:48 PM

but for other common uses yeah

I think mathematica is better

I use it way more anyways

it can do DimReg pretty well if you write the appropriate "code"

and it has some cool packages for GR index, tetrad, and coordinate calculations

like xAct

idk what condensed matter people prefer for simple numerics

why do they matter

I see what you did there

yes, but it is serious

you randomly brought them up

the German guy in my dept. is CM

he does crystal radiation stuff

Because CM is the most important area of physics

so it only makes sense to consider them

hardly

nuclear, GR and strings

literally the best

oh and whatever @ACuriousMind ends up doing could be cool too

6:08 PM

@0celo7 Get used to that. Some of my lectures had errors in almost every problem set that were gradually corrected as people trying to do them hit stumbling blocks :D

well he did not add much

for one all I had to do was squeeze in that $x\in\mathbb{R}$ for the "top" solution

but now it looks ghetto

6:26 PM

3

Q: Squaring a variable. What happens to the units

What happens to the units of a squared variable? For example, if I squared velocity would the units, metres per second (${\rm m}/{\rm s}$) change as well?

units dimensional-analysis

they get cubed, duh

Why has this question already got four answers and four upvotes?

It's the very opposite of an interesting question.

@ACuriousMind This problem has been bothering me for a while: $A\subset X$ is open iff for each $p\in A$ there is a neighborhood $U_p$ contained in $A$.

This is clear intuitively, but I can't get it from just the definitions.

Which direction bothers you? Both?

Both :/

6:32 PM

Okay: Every point $p$ has an open neighbourhood $U_p$. Since the intersection of two opens is open, $U_p\cap A$ is an open neighbourhood of $p$ contained in $A$ if $A$ is open.

Other direction: $A = \bigcup_{p\in A} U_p$, so it is the union of opens, which is open.

Well that was too easy

Thanks

np

I am curious to know Duffield's opinion on the fact that Einstein is actually the guy who came up with wormhole~

Such conflict

@ACuriousMind Although, I think the $U_p$ I said and the one you used are different, no? The statement "every point $p$ has an open neighborhood" is true regardless of the properties of $A$. I think "your" $U_p\cap A$ is my $U_p$, no? And furthermore, shouldn't your second part be $A=\cup_p (A\cap U_p)$?

@0celo7 The two parts don't use the same notation :P In "other direction", I use the $U_p$ from the statement. In "Okay", my $U_p \cap A$ is the $U_p$ from the statement

6:39 PM

@ACuriousMind ok

ugh, I ate something that is making me very sick

@Slereah are you still sick?

Somewhat

@ACuriousMind can a first order ODE have a two parameter family of solutions?

I think so?

If it's non-linear

correct

I did not know that

Non linear DEs are kind of shit

6:47 PM

$(y'-y)(y'-2y)=0$ is solved by $(y-c_1\mathrm{e}^x)(y-c_2\mathrm{e}^{2x})=0$

You can look up the lack of unicity of non linear solutions on the mathSE

There's a few threads about it

user54412

7:05 PM

Why is your first ODE course doing nonlinear equations?

user54412

They're hard, there's almost no results pertaining to them, and they pretty much never show up in real life.

they're being mentioned in the text

the text is saying that they won't show up after this chapter

user54412

lol

Hi guys

hello

7:08 PM

I think you mean "They only show up in real life"

@JohnDuffield This is great :D

Everything is nonlinear

We only do linear equations because it's easier

@Slereah lol, no

Or do you mean in the sense that all our theories are only approximations to perhaps nonlinear theories?

user54412

I do the union of GR, fluid mechanics, and plasma physics, and I can't recall ever seeing a nonlinear DE in my work.

>GR >linear

Cool story, bro

Also those other 2 fields

AM I TAKING CRAZY PILLS?

7:11 PM

@Danu Yes.

DE =/= PDE?

user54412

@Danu Well, the GR I do is :P

GR and fluid dynamics are non-linear as hell

0

Q: What are these rank 2 tensors encountered in kappa symmetry?

On page 158 of BBS in the discussion of Kappa Symmetry for the GS Formalism, the definition of the orthogonal projection operators involve these tensors ${{\Gamma _{\mu \nu }}}$. I am pretty sure they are some type of product of gamma matrices but I am not sure where they come from . Projection ...

string-theory supersymmetry

what is the "close because OP did not read" button

@ChrisWhite Sigh

7:14 PM

I can take a course on nonlinear analysis...

You're telling me that's useless?

It is useful but it is not much fun!

Fun pushes up glasses is for losers

Altho there has been big advances in nonlinear analysis recently

Well, recently math-wise

in the 70's

With the inverse scattering method

user54412

What is nonlinear analysis? For that matter, what is linear analysis?

^

7:15 PM

I'm not sure, tbh

Lemme check

@0celo7 Make a custom one.

@Danu ok

Analysis applied to nonlinear systems?

fancy word for "solving non linear differential equations"

Although for nonlinear equations, "solving" is a bit of a lofty goal

"Showing that the solution exists" can be tough already

user image

>for engineers

Not going to be analysis.

7:19 PM

yeah

Just numerical simulation

user54412

I think some people use "nonlinear" for something like "the response isn't Hooke's law" instead of "the highest-order terms in the DE are products of derivatives"

EEs use all sorts of analysis stuff.

@0celo7 Take the course, and I think you'll see what we mean

@Danu I'm not claiming that class is analysis (as in mathematical analysis).

But to say that engineers don't need analysis analysis is wrong.

Most don't, sure.

Maybe, I just meant to say that at least in undergrad you'll get 0 analysis.

7:29 PM

I'm taking analysis next year...

My dept. requires a certain number of math credits, analysis is recommended/required for the other recommended classes.

mmm yoohoo

That guy deleted his post.

@FenderLesPaul One of the physics TAs is holding a Mathematica tutorial on Sunday!

anyone have detailed or at least somewhat detailed sources that talk about this new proposal Hawking has for information paradox?

in terms of supertranslations in the BMS group, somehow giving radiating black holes hair

@0celo7 woo

@FenderLesPaul I have heard about that, is it just from a talk or is there a paper?

It's from a talk apparently

and the paper isn't supposed to be out till September end or something

according to Sabine's blog post

backreaction.blogspot.com/2015/08/…

7:58 PM

@ACuriousMind "theorem of homological perturbation theory" sounds scary

...why are you reading QoGS? :D

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