« first day (2539 days earlier)      last day (2689 days later) » 

17:01
Later all. Will try to check in in two weeks. My online footprint is very limited right now, just this, really, due to weakness. Treatment is highly effective but takes weeks.
vzn
vzn
@0celo7 lol one might say "he had better things to do with his time..."
Heyy Newton, Vsauce here
@BalarkaSen Uh, really?
@vzn what do you mean, like alchemy and bible prognostications?
Vsauce is the audience
17:07
That is what he mostly did
lmao
@0celo7 If Newton ever stumbled upon a Vsauce video he would give up on calculus
@BalarkaSen Why?
@0celo7 means you can represent elements of $GL(n)$ with spinors the way you can represents elements of $SO(n)$ with spinors, physics.stackexchange.com/a/153849/25851 , mathoverflow.net/q/121620/38721 , physics.stackexchange.com/q/161744/25851
17:13
@BalarkaSen ugh
oh
Wait, what do you mean by spinors
$SO(n)$ isn't made of spinors
It acts on spinors
Reason I'm asking is because it's a really old book so the language is very loose, trying to get both kinds perfect, apologies if it's loose
Lets try the modern language: a spinor is a vector in a spinor representation, where an $SO(n)$ spinor representation is a representation of the double cover of $SO(n)$, or no?
Older language is to use 'projective rep's', which are potentially multi-valued representations, and hence not even real reps (but become single-valued on double covers in modern language), so the goal above is to show if we want reps of $GL(n,\mathbb{C})$ then it implies can use reps of $SU(2)$, but then we'd need multi-valued reps of the simply connected group $SU(2)$, which is impossible
vzn
vzn
@Slereah lol he did spend a lot of time on that which has been "swept under rug" by modern history... hey what are you doing with lasers + SPADs? what kind of laser did you get, whered you buy it? amazon?
he is going to terrorize some ppl
I got it from a shifty chinese manufacturer
Hopefully it will work fine
17:22
(al qaeda)
Al Qaeda isn't chinese
Unfortunately a decent laser is 300-1000€ on most non-shift websites
Chinese laser was 50
vzn
vzn
@Slereah work fine for what... note heather bought one too recently...
Interferometry
vzn
vzn
@Slereah is there a particular experiment you have in mind
17:24
@Slereah are you gonna do LIGO in your basement?
Nah
I might try michelson-morley
The 19th century LIGO
how is the spacetime manifold not the aether
what is this LIGO business anyway
can you explain me that
huh??
Gravitational wave business
@BalarkaSen go learn some GR
17:25
what are thooose
@BalarkaSen basically the metric is flat + waves
When a gravitational wave passes through, the distance along some axis of the interferometer is reduced, which reduces the optical path
And this causes interference patterns
or background + waves
what does waves mean
Like a sine function
17:27
the metric satisfies a wave equation
as a very simple gloss: it's like a giant michelson-morely experiment, except that instead of vibrations in the ether you're looking for vibrations in spacetime.
vzn
vzn
@Semiclassical lol like theres a difference :P
aether = spacetime
Einstein was wrong
does light consist of waves in spacetime structure? if not, then it's not the ether.
vzn
vzn
17:29
@0celo7 wondering... what is the experiment that proves EM waves are different than gravitational waves? o_O
Well for a start an EM wave wouldn't do squat to an interferometer
the fact that you can actually see light and you can't see gravity waves is a pretty clear sign
You can't see radio waves
I don't even know what that question means
also good point @Slereah
17:31
@Semiclassical do you have really broad range optics?
must be annoying seeing wifi everywhere
vzn
vzn
Aug 10 '16 at 16:17, by vzn
@DanielSank found a paper. Tenev/ Horstenmeyer. it gives the vague statements meaning, makes the hunches precise enough to actually be right/ wrong. plz check it out if you actually care about the topic. its full of eqns http://arxiv.org/pdf/1603.07655.pdf
our not being sensitive to the entire range of the EM spectrum doesn't matter here
we're sensitive to some range of it, and strongly so
by contrast, there's no frequency of gravitational waves that we're sensitive to
rob
rob
@vzn There's no such thing as dipole gravitational radiation: lowest-order symmetry is quadrupole. But dipole radiation is the most common angular distribution for EM waves.
vzn
vzn
@Semiclassical lol, you are stuck to the earth. indicates some sensitivity there
@rob not entirely following (not an expert on this), but what is the proof there is no dipole gravitational radiation?
@vzn I mean g waves ARE light waves
everything is light
strings, man
17:33
stare
@vzn They may be part of the same entity if there is a theory that unifies gravity with electromagnetics.
vzn
vzn
@0celo7 strings solitons :P
@0celo7 But light is open strings
While gravitons are closed strings
@Slereah just open the strings
vzn
vzn
@lılostafa exactly... feel we are on the verge of such a theory re tenev/ horstemeyer ref
17:34
open your mind
@vzn strings solitons interuniversal teichmuller theory
for the purpose of present experiments, though, there's not any useful sense in which gravitational waves and EM waves are physically unified
@BalarkaSen gtfo
strings are just $(\infty,2)$-topoi maaaaaan
rob
rob
@vzn General relativity (which predicts gravitational waves) forbids dipole radiation. We haven't observed enough gravitational wave events to experimentally rule that out yet --- but it's discussed in the GW events observed beginning this summer with three interferometers.
vzn
vzn
@BalarkaSen strings solitons interuniversal teichmuller theory number theory :P
56
Q: The enigmatic complexity of number theory

David G. StorkOne of the most salient aspects of the discipline of number theory is that from a very small number of definitions, entities and axioms one is led to an extraordinary wealth and diversity of theorems, relations and problems--some of which can be easily stated yet are so complex that they take cen...

@rob skeptical
17:37
Dipole radiation would imply some kind of vector gravity
which has been ruled out experimentally
vzn
vzn
21
Q: Why there is no dipole gravitational wave?

Arnaldo MaccaroneI have read that "thanks to conservation of momentum" there is no dipole gravitational radiation. I am confused about this, since I cannot see the difference with e.m. radiation. Is this due to the non-existence of positive and negative gravi-charges? Is this due to the non-linearity of Einstein ...

@Slereah ruled out in which experiment(s)?
Alternatives to general relativity are physical theories that attempt to describe the phenomena of gravitation in competition to Einstein's theory of general relativity. There have been many different attempts at constructing an ideal theory of gravity. These attempts can be split into four broad categories: Straightforward alternatives to general relativity (GR), such as the Cartan, Brans–Dicke and Rosen bimetric theories. Those that attempt to construct a quantized gravity theory such as loop quantum gravity. Those that attempt to unify gravity and other forces such as Kaluza–Klein. Those that...
OH MY GOD THERE'S A NEW SEASON OF CURB
rob
rob
@Slereah I thought the constraints on vector "fifth forces" were relatively squashy.
Gravity isn't a fifth force
It's a boring old fourth force
rob
rob
17:44
... but that there's not room for a vector term in one of the Brans-Dicke "extensions" to GR
vzn
vzn
did someone say alternatives? =D
Don't link to some meme article dang it
Give us the real paper
vzn
vzn
spking of QM + gravity + new wrinkles try this one
> Called vacuum birefringence, this bizarre phenomenon was first predicted back in the 1930s, but had only ever been observed on the atomic scale. Now scientists have finally seen it occur in nature, and it goes against everything that Newton and Einstein had mapped out.
@vzn This sentence reads like typical popsci over-exaggeration by some orders of magnitude
vzn
vzn
@Mithrandir24601 lol yeah blame those @#%& poopsci writers :( >:( o_O
17:59
@vzn This is much better: arxiv.org/abs/1610.08323#
@Mithrandir24601 Almost every single news on those websites (phys.org, etc.) looks like an unprecedented breakthrough.
@lılostafa It's maddening
Science = Neil deGrasse Tyson
vzn
vzn
@lılostafa one might say a breakdown in scientiific communication.
18:17
Looking at that article, the Newton/Einstein claim is presented as “space is a vacuum”
In contrast to QM where ‘vacuum’ can be taken as full of virtual particles (I know that’s a gloss)
...and, uh. Well, yeah. That the vacuum state in QED isn’t just ‘empty space’ isn’t a new idea
So in other words nothing new
Also Einstein doesn't claim anything about the vacuum
vzn
vzn
@Semiclassical agreed. its a macroscopic measurement whereas prior measurements of "virtual particles" are mostly in particle colliders, scattering(?) etc...
@Slereah nothing new
i think there’s a difference between a novel manifestation of QED, and a new physical theory
vzn
vzn
@Semiclassical right. and everyone in this chat room will be exactly last to hear/ acknowledge a new theory. :P
18:24
This certainly is a cool experiment. But what it’s testing is QED, and that’s a cornerstone of modern physics
It’s testing something old in a new context
I could have done it myself!
just give me 120 million dollars and I'll do it
In terms of “zomg new physics” this is just not an example
vzn
vzn
@Semiclassical whew, what a relief!
In particular the framing of it as “omg newton and Einstein were wrong” presents it as though there’s some ongoing controversy
And there simply isn’t in this regard
Well I mean, to be fair
Newton was wrong about the QED vacuum
18:29
Insofar as he was in no position to have any opinion re the QED vacuum, sure :P
@lılostafa phys.org isn't that bad. ScienceAlert, on the other hand, is a notorious and repeat offender of extreme overhype.
Everything on ScienceAlert must (unfortunately) be read with a strong cup of the take-it-easies
@vzn yeah, that's erring on the overhype side
but note that Phys.org actually spoke to the scientists in question
the ScienceAlert piece is just re-quotes from other outlets
Even the Science Alert one ultimately acknowledges that they’re testing a prediction of QED
hmmmmm, wait
vzn
vzn
18:35
@EmilioPisanty right, so whered they get the quote about going against newtonian/ einsteinian models...?
no, phys.org is just as bad as science alert in this instance
they're both quoting directly from the press release eso.org/public/usa/news/eso1641
@vzn what quote? the only thing mentioning Einstein on the scientists' mouths is
> "When Einstein came up with the theory of general relativity 100 years ago, he had no idea that it would be used for navigational systems. The consequences of this discovery probably will also have to be realised on a longer timescale," Magnani told New Scientist.
so, again, just re-syndication
vzn
vzn
admit there is apparently some hyperbole introduced by the popsci "translation". but dont think those "translations" are always entirely inaccurate/ baseless. think the insinuation of breaking existing theories/ pointing toward new phenomena/ theory is not entirely unfounded.
The relevant paragraph in the SA article is this one:
“In the classical physics of Newton and Einstein, the vacuum of space is entirely empty, but the theory of quantum mechanics assumes something very different.“
But that’s not a quote, either from the scientists or from the press release
vzn
vzn
ie, the experiment seems to me to be hinting of another interpretation, ie in todays terminology/ ideology, a possible connection between gravitational waves and virtual particles.
Bullshit
18:41
^ that. Or back it up.
help
I have so many papers to sort
@Slereah bubblesort
@vzn So: as a measure of hygiene of this chatroom, can I ask you not to post links to content aggregators like that link? The choice of resource you link to matters. If there's multiple outlets covering the story, and one of them is just quotes lifted from other secondary sources, please choose a link that (i) does not quote from press releases without explicitly noting it, and (ii) does its own research instead of taking it from other secondary sources.
3
Alas it's not a problem of alphabetical sorting
it is a clustering issue
vzn
vzn
@EmilioPisanty shoot the messenger
Just quote my site directly, all my news sources are directly beamed into my brain from my reptilian overlords
18:44
@vzn Can you clarify which 'existing theories' (that we didn't already know have limited domains of applicability) 'break' with this result?
vzn
vzn
lol, physics police alarm/ alert! not einstein!
no, we’re shooting the message. You just insist on standing in the way
4
vzn
vzn
@#%$ bloody msg!
@vzn You're not the messenger, you're actually writing the messages. This is basic internet hygiene. If you want to disregard it in private, that's your choice, but you're repeatedly posting in a public forum.
Gee look at colonel Buzzkill overhere
18:47
@Slereah yeah, I know. funnelling traffic to the pop-sci outlets that actually do things right instead of the content vampires is such a chore =P
I say let all pop science websites die!
vzn
vzn
@EmilioPisanty so pick whatever popsci source you think is legitimate/ superior, if you can find one that meets your rigorous/ stringent criteria, or perhaps you actually effectively reject all such material
Oh hey, what a nice strawman
@JohnRennie The most painful part of cooking is when the food is fully cooked and you're waiting for the extra water to evaporate!
@vzn I'm not forcing you to do anything. I'm trying to get you to take responsibility for the messages you post in public forums.
vzn
vzn
18:49
@Semiclassical ?!? EP himself said physorg was better occasionally until after the physorg link was posted.... moving the goalposts
@vzn sure, I'll own up to that
I will sustain, though, that on average, phys.org tends to be rather better at keeping the hype to reasonable levels than ScienceAlert
vzn
vzn
admittedly sometimes not able to measure up to/ falling short of the extremely high stds of chat room "hygiene" around here
(one particularly egregious example being physics.stackexchange.com/questions/266308/…, where the phys.org piece does measure up)
@vzn I seriously don't see what's so hard about this
you see the difference between content aggregators and independent research, right?
if going back to the source material is wrong then I don’t want to be right
@Semiclassical come again?
18:53
Wasn’t intending that as a reply, oops
@Semiclassical I still didn't get it, though =P
My point being that, regardless of whether the popsci sources are reputable, one can still go back to the source and check how it was presented there
If saying “let’s go back to the source material” counts as moving the goalposts, then I’m okay with that accusations
@Semiclassical yeah, but that can be a lot harder, and it requires domain-specific knowledge
@Semiclassical ah, gotcha
True. And I’m counting the press release as source material, which is a bit questionable
@Semiclassical ooooof. Super questionable.
18:57
Though in this case it’s definitely clarifying in that it reveals what has been added onto the article
Jim
Jim
@0celo7 you summoned me?
But in any case we're preaching to the choir here, since @vzn has yet again vanished halfway through a discussion as soon as people started asking them to do a teeeny tiny bit of work before posting links in a public channel.
Lol
I’m on my phone so I can’t see who is here now
@Jim we were wondering about the core of a neutron star
Jim
Jim
what about it?
18:59
@Slereah what was your question
we were wondering if there's a consensus
Jim
Jim
neutrons
And I’ll say that there are certainly cases where being speculative about physics isn’t offensive
(which, for the record, is: (i) check whether a source is just parroting a press release before posting here, (ii) check whether it's just a content aggregator that's pulling bits and pieces from other secondary sources, and if either then (iii) choose another link that doesn't do those before posting on this chatroom.)
@0celo7 what?
None of which requires domain-specific knowledge, none of which is particularly hard, and none of which is even specific to science.
19:01
@Jim good deal
is that it?
Jim
Jim
yup
neutrons all the way down
For instance, I don’t mind QM interpretations stuff—at least, I don’t mind being speculative about questions which can’t be resolved experimentally
Jim
Jim
the size of the star is maintained because of the pauli exclusion principle
Isn't the core of the neutron star speculated to be possibly weirder things?
Like quark matter or weird mesons
(Appealing to the spookiness of QM as a way to justify pseudoscientific BS, by contrast, gets me irritated quick)
Jim
Jim
19:03
@Slereah well, we can't actually measure the core. So it could be weirder stuff. But the observations that I know of all match the math if it's just neutrons
(I’m looking at you, homeopathy)
Would we expect the deep core to affect our current observations, though?
@Semiclassical well, where I'm in they spell that homöopathie if it makes you feel better
@Jim I remember reading somewhere that under extreme conditions and huge gravitational pressure, this force may overcome the Pauli exclusion principle and cause the star to collapse.
But I wonder, isn't the Pauli exclusion principle a fundamental mechanical feature of any QM system, no matter how strong the forces are?
Jim
Jim
19:08
@lılostafa yeah, a black hole
The question ^
Jim
Jim
@lılostafa black holes are a trump card. Nothing prevents them from winning
But the Pauli exclusion principle holds under any circumstances. It follows from basic symmetry properties of the neutrons. It doesn't seem to have anything to do with the forces involved and their magnitude
@lılostafa But then when you add a strong gravitational field into the mix, what happens to this?
(as in gravity+QM)
@ACuriousMind halp
19:12
Plus, the point isn’t “the exclusion principle goes away”. It’s that Pauli exclusion ceases to be relevant compared to gravity
@Semiclassical This is exactly what doesn't make sense to me. If we could say it simply doesn't hold in extreme gravitational fields it would be ok.
I’m not making a claim one way or the other about whether it in some sense remains
I’m claiming that we shouldn’t expect it to matter
Why is physics so awful
Everytime we have a theory with some awful math in it
it turns out to be wrong
and the better theory is even worse
Oh this question is asked here before physics.stackexchange.com/questions/93988
@BernardoMeurer Pinging is not a good, fast way to summon ACM. Try posting some sensitive materials. He'll be here in a jiffy ;)
19:30
too many papers
rob
rob
@lılostafa Please don't post mischief to summon another user who happens to be a moderator; there will be unintended and undesired side effects.
@Bernardo Is this going to be the iconic cover of No Love Deep Web
@BalarkaSen You caught me
rob
rob
5 messages moved to Trashcan
@rob Oh come on
19:38
@rob lmao they blocked me from requesting access to that room
Sigh, what a stark reminder of why I stopped hanging out here
@BernardoMeurer what did you do?
@0celo7 I made a joke that in order to get help with induction proofs I needed to post pictures of my genitalia here
Apparently that is somehow not ok to say
@rob This is preventing ACM from being summoned.
rob
rob
Sorry, multitasking and can't debate policy this afternoon. I was much more interested in the discussion about the Pauli principle and black holes above.
19:44
@rob Apparently there is not a satisfactory answer for that question (on this site, the question I linked to)
vzn
vzn
20:09
@Semiclassical lol and who worked out that property/ phenomena/ math
In the context of the World Wide Web, a content farm (or content mill) is a company that employs large numbers of freelance writers to generate large amounts of textual content which is specifically designed to satisfy algorithms for maximal retrieval by automated search engines. Their main goal is to generate advertising revenue through attracting reader page views, as first exposed in the context of social spam. Articles in content farms have been found to contain identical passages across several media sources, leading to questions about the sites placing search engine optimization goals over...
ScienceAlert is an non-obvious example. It took me 3 years and pointed out by a chinese physics group that it is actually a content farm
Having said that, my way to deal with content farms is to trace the original source and not post the content farm's link
rob
rob
@Secret That's the way. And if the content farm makes it hard to trace the original source, that's a good clue to quit using them to find things.
Well, most of the english ones tend to do their referencing well. The chinese ones are the worst because you will not find any original attribution
20:34
@BernardoMeurer huh
yeah, china is really investing in research
vzn
vzn
@Semiclassical mod DZ used to work there, blogged on it
i'm not sure how China's total research investment compares with the US, but
they're definitely making a go of it
vzn
vzn
@Semiclassical the govt there is more serious about science & here its years of softness bordering on decline
it's weird to think that there are so few Einstein papers on GR
I think I have like 3 in my collection
21:10
sigh - y'all know by now I can't grant you access to Trashcan
@ArtOfCode Please go
what happened
oh some people are requesting access to Trash
i guess
Why can't we go to the trash anymore@?
I used to love being invited to the trash
the trash and the trashcan are inequivalent objects
Trashcan is a private room
the latter is for super sensitive garbage moved to elsewhere unseen by mods, the former is for normie garbage written by edgy kids that room owners remove from rooms because it's of no value
or such is my impression
"Two formalisms, one renormalized stress-energy tensor"
Why do I have a paper named after a gross porn
rob
rob
@BernardoMeurer I used the bear-proof trash can
@Slereah ahaha
21:18
@ArtOfCode Yeah, people here do know all the rules, they just like playing this game with the mods.
What is the relation between the renormalization fixed point and the critical point? It’s like a critical phase transition doesn’t necessarily occur at a renormalization fixed point.
@rob How did you discover I am a bear?
@rob Note that, as stated in that WP article, grizzly bears can sometimes break into those cans ;)
 
1 hour later…
22:48
@Semiclassical An example due to Nelson: There exist differential operators $A,B$ on a certain $L^2$ space such that $A$ and $B$ are both self-adjoint with the same core, they commute on the core, but their exponentials do not globally commute
23:21
@Semiclassical The strange part is that it seems to have to do with the underlying manifold (Riemann surface of $\sqrt{z}$)
ooook
yeah, that's kinda goofy
What does core refer to?
@Semiclassical A core $C$ of a closed operator $T$ on a Banach space $X$ is a linear manifold in $X$ such that $\overline{T\upharpoonright C}=T$
Basically, it's a subspace that carries all the information of $T$
but doesn't have to be all of $X$ or even all of the domain of $T$
hmm
looking at Wikipedia, I see the synonym "essential domain"
and I feel like I may have seen that one before
23:51
@Semiclassical entirely likely
worrying about these things is what a lot of basic math QM is about
torsion is really an intriguing thing
it seems to carry a lot of mystery
there are spin torsion besides spacetime torsion; there may still torsion of other things

« first day (2539 days earlier)      last day (2689 days later) »