The h Bar

Solenodon Paradoxus

13:00

Well, if you give a gun to a 1-year-old, it is very likely that you get killed.
1. Killing parents isn't something children can achieve easily.
2. They don't even know what it means to kill somebody and what it requires.
From this I conclude that this argument doesn't back up your point - which is - that little children have an implicit sense of right and wrong somehow. Children don't kill their parents for another reasons.
Morality comes with upbringing, just like the realization of what murder is.

Mew

if you have a human who is kind to others, he will reproduce because others will like him for his kindess and will protect him etc.

ACuriousMind

@Mew [citation desparately needed]

Mew

@ACuriousMind it's my theory

heather

theory $\neq$ citation not needed

Mew

but it is my idea

logic doesn't need citation

I don't like appeal to authority, just to logic :p

ACuriousMind

13:02

@Mew Human nature is empirically accessible (if a certain behaviour was instinctual, you would see it across all times and cultures). I do not see how the evidence supports your claim.

heather

let us start from a different point of view.

Mew

@ACuriousMind I think human behaviour is complicated by many desires

I think some needs outweigh the desire not to killl

e.g. the need for food

heather

let's say that we have instinctual morals that we learn more about as we grow, but also have a desire to break those morals, that is suppressed as we obey them but encouraged as we break them.

Mew

the need to look out for your own tribe

etc.

but one has an instinct to not to kill those in their own tribe

but they will do it if another need trumps it

heather

no, that doesn't seem right. there will always be some psychopath that does it anyway, and where does that guy fit in?

Mew

13:04

yeah there are always people with disease and abnormality

there are people with 2 legs, and people with 1 leg

there is an evolutionary reason to have 2 legs and not 1 leg

similarly there will be variations in the normal

but i think most poeple have the need not to kill and harm others in their group

heather

yeah, but that's scientifically explained (2 vs 1 leg) by genes and all that. how are we explaining psychopaths?

Mew

genes as well

the brain has a structure that is formed by genes

ACuriousMind

@Mew How? Why do you think "killing" is not simply a "neutral" action a priori that humans (or any other animal for that matter) are not instinctually inclined towards or against?

Mew

the brain isn't an empty slate when you're born

Solenodon Paradoxus

@Mew so you claim that the instinct not to kill those who are friendly is internal and isn't connected with upbringing. But I can't see how your argument about children not killing their parents supports your claim. It seems to me that a much easier explanation is that little children don't quite understand what murder is and don't feel the need to do anything at all. They learn this later, about the same time they learn that murder is wrong.

Mew

13:06

the brain has a structure when you're born already that is formed based on genes

and of course abnormalities in the structure can occur

ACuriousMind

@Mew How have you determined that this is an instinct and not a learned trait?

heather

@Mew citation desperately needed

Mew

@heather you think the brain isn't structured at birth?

the brain isn't formed entirely by environment

any neuroanatomy book will show u

heather

oh, sure it is, but i'm not sure that it is completely informed by genes, either, u may want to look at nature vs nuture arguments and twin research.

anyway, i have to head to the bus stop =/

so adios everyone, have a good day/night/24 hour period

Mew

@heather laterz

heather

13:08

@mew, I'd be interested in continuing this conversation at a later date =) quite interesting, gave me some stuff to think about

Mew

@heather it went off topic a bit

I was mainly interested in motivation and why we seek meaning lol

but both interstringt

Solenodon Paradoxus

@ACuriousMind the very definition of "right" and "wrong" can only be given in the context of population/tribe/society/etc.

Mew

@ACuriousMind here is how I hypothesize that it is an instinct:

(1) Suppose evolution is true

(2) Suppose individual A has instinct to kill own tribe members

(3) Suppose tribe members have instinct for their own survival

user228700

@Mew: Not to interrupt the flow of this conversation or anything, but did u watch these:

user228700

The Power of Motivation: Crash Course Psychology #17

►

user228700

13:10

Monkeys and Morality: Crash Course Psychology #19

►

Mew

(4) Tribe members will defend against A and thus individual A will be involved in more fights and likely die

(5) Individual A's genes not likely passed on as frequently as other tribe members

(6) Desire to kill other members of tribe slowly is selected away

ACuriousMind

@SolenodonParadoxus I think Bourbaki is a bit old for that, you probably want something a bit more modern especially for the last two points (I can't recommend anything, though)

Mew

(7) Suppose individual B is indiffereent to killing

(8) Individual B will attempt to kill more often over small non-existential threats

(9) Tribe will defend against B and thus B will be involved in more fights and likely die

(10) Individual B's trait gradually becomes less common

Solenodon Paradoxus

@ACuriousMind I'm good, thanks :) I don't really need resource recommendations, we were simply discussing Bourbaki textbooks and I asked if I could benefit from reading them.

Mew

(11) Therefore those who remain are likely to have an inante instinct not to kill other sin their tribe unless to protect their own existence

ACuriousMind

13:14

@Mew That you can tell a just-so story how a given trait evolved is not an argument for it actually being evolved. That people tend to not kill people in their own tribe is equally explained by "meme selection" - societies with a cultural prohibition to kill their own have a competitive advantage over those who don't, so almost all societies that survive will have such a prohibition.

user228700

@Mew: The 1st video is exactly what u were looking for.

Mew

@Kaumudi what does it say motivates humans?

ACuriousMind

@SolenodonParadoxus alrighty then

Solenodon Paradoxus

@Mew do you claim that there is a gene responsible for killing inmates?

user228700

@Mew Why don't u watch it yourself, when u have the time? :-) My synopsis of the video might not be very good. Besides, I haven't watched it completely.

Solenodon Paradoxus

13:17

Because AFAIK natural selection requires mutations in a certain gene to work

Mew

@ACuriousMind but socities have changed dramatically over time, and we didnt' evolve as socities but rather as "tribes". So don't you then think that the tribes will form their "do not kill" rule out of instinct? What else would make them form that rule?

@Kaumudi okayz i will ty :)

Solenodon Paradoxus

@Mew ummm.. common sense?

Mew

@SolenodonParadoxus no Acuriousmind was saying that it was "meme selection" not "common sense"

and I am saying that "meme selection" actually selects on individuals

David Z

I've got a random question, somewhat more related to physics: I'm looking for functions such that $\int_0^R f(r) J_0(kr)r\,\mathrm{d}r$ is symbolically computable for some finite $R>0$ (possibly, but not necessarily, any $R > 0$). The more the merrier. Any suggestions?

ACuriousMind

@DavidZ Ewww. Is $J_0$ a Bessel function?

Solenodon Paradoxus

13:20

@Mew anyways, your natural selection theory requires there to be a gene responsible for the desire to kill. I hardly think it is true.

David Z

@ACuriousMind yep

That integral is, of course, ~~just~~ closely related to, but not quite the same as, the Hankel transform, a.k.a. 2D Fourier transform in polar coordinates

Mew

@SolenodonParadoxus not necessarily a gene, but a collection of genes. And not a gene for "do not kill" but rather a gene for "empathy"

@SolenodonParadoxus have you heard of mirror neurons?

we are genetically wired for empathy

when we see someone performing an action, our mirror neurons fire

as if we are experiencing the same thing

in the same way, when we see another in our likeness being harmed, we may have "mirror neurons" that allow us to feel emapthy

which leads us to experience the negative emotion similar to if the harm was done to ourselves

ACuriousMind

@Mew A "tribe" is a "society", just a primitive one. But it's not instinct (innate unlearned behaviour) that makes them form certain rules but humans delevoping those rules in some form of discourse (even if it is just the elder declaring them) when recognizing they want/need rules for their society to function.

Mew

@ACuriousMind yes but you are saying that once upon a time there were tribes that formed those rules and tribes that didn't. The tribes that didn't died out

and we are left with the tribes that did form the rules

ACuriousMind

@Mew It's two completely different claims to say that the capability for empathy is genetic and that humans' instinctual behaviour is to avoid killing. Please don't move the goalposts.

Mew

13:24

but the composition of the "tribes" changes all the time

@ACuriousMind if you read to the top, the original argument was that humans have an instinct to not harm one another

@ACuriousMind the do not kill was chosen as an example

@ACuriousMind so the posts are being moved back to where they were originall meant to be

@ACuriousMind and if you have genes for "empathy" you likely will have the instinct for "do not kill"

ACuriousMind

@DavidZ I guess you've seen the list of transform examples in Wiki? What exactly do you mean by "symbolically computable"? In terms of elementary functions?

Mew

If ur genes allow u to feel the negative emotion of harming another, why would you harm another?

Solenodon Paradoxus

@Mew what's the status on the theory of genetic markers for empathy? Is it proven experimentally?

Mew

@SolenodonParadoxus I don't know but mirror neurons are genetic

@SolenodonParadoxus I many species of animals have mirror neurons

David Z

@ACuriousMind by "symbolically computable" I mean that it can be expressed in some form that does not involve an integral. Or more precisely, I want something I can numerically evaluate without using numerical integration.

I guess I should check Wikipedia, huh :-P

Mew

13:29

@SolenodonParadoxus I think it is an active area of research

ACuriousMind

@Mew Not at all. An instinct is an specific innate, unlearned behaviour. "Empathy" is the generic capability to put yourself in someone else's shoes, but this only leads to "do not kill" if you have a notion of morality, e.g. that you don't want others to feel negative emotion. It's not an instinct by a chain of reasoning involving concepts such as "I don't want others to feel negative emotion". It's not an instinct if it is derived from empathy.

@DavidZ Well, is the Bessel function itself "symbolically computable" in your sense?

Mew

@ACuriousMind that's not correct. Empathy means you actually feel some negative emotion when you see another experience it. Now assuming people want to avoid negative emotion (which is often assumed in pscyhology), then one with emapthy won't harm another unless for a greater individual need

David Z

@ACuriousMind Yes, it is. I suppose I really should have said "numerically computable without integration", and by that definition the Bessel function definitely qualifies; all good numerical computing libraries including functions to evaluate $J_n$.

Mew

@ACuriousMind the study of mirror neurons show that one's own brain circuitary fires in the nearly same way when we watch someone perform an action as when we are doing it ourselves.

@ACuriousMind if empathy works in a similar way, then it makes sense why we wouldn't want to harm others, as we woudlnt' want our own brains feeling the displeasure

The displeasure wouldnt' be a concious choice, but a hardwiring in the brain

David Z

I'll take a look at the examples on the Wikipedia page, thanks @ACuriousMind

ACuriousMind

13:40

@Mew 1. The function of mirror neurons is much less certain that you make it sound. They are neurons that fire both when we do something and when we observe others do the same. It is not clear at all that they make us experience what we would experience doing the observed act. 2. So...this would make me avoid doing things to other where I see them suffer, because that makes me suffer. However, e.g. beheading or other quick deaths would induce no suffering in me, so why would I avoid that?

Mew

@ACuriousMind Yes mirror neurons may not be exactly how emapthy works but it may work a simlar kind of fashion

I'm not trying to say exactly how it works

but that it is plausible that one can instinctually have emapthy

Solenodon Paradoxus

@Mew You can't possibly deny the effect of upbringing on morality. Children of criminals have a tendency of becoming criminals themselves, it is a simple statistical fact.

Mew

@ACuriousMind sciencedirect.com/science/article/pii/S0163638311000506

@SolenodonParadoxus of course, the mind is a complex thing and people can be trained to behave in ways that oppose their instincts. But that doesn't mean there wasn't an innate instinct at birth that was trained away.;

ACuriousMind

@Mew Huh? I'm not denying the existence of empathy in humans. I'm denying a) that it arises directly from mirror neurons and b) that it inevitably leads to a universal aversion to killing.

Mew

The article is about "Early signs of concern for others"

which implies that concern for others may be instinctive

and thus a result of natural selection

now you must think there is a big leap between "concern for others" and moral codes like do not kill, such that they are totally independent of one another

I believe however that our instinct forms our socitiey's moral code

Solenodon Paradoxus

13:50

@Mew I see, so your theory is that both genes and upbringing are responsible for morality.

Mew

@SolenodonParadoxus of course

Solenodon Paradoxus

With upbringing being more important since it can wash away the effects caused by the genetic markers.

Mew

@SolenodonParadoxus what's "more" important is subjective. But I agree that one can have their innate behaviour modified. E.g. you can train a Lion to be gentle etc.

You can take away the Lion's instinct to hunt

but that doesn't mean the Lion doesn't/didn't have an instinct to hunt

Solenodon Paradoxus

@Mew I think I get your point now.

Mew

yaya

yay*

gtg

laterz all

Solenodon Paradoxus

13:57

But doesn't this eliminate the conditions for natural selection? I mean, suppose that individual (A) tends to be aggressive towards his inmates as a child. But the tribe brings him up to be more compromising by threatening or hurting him. In the end he turns out not a threat to society in almost all cases, effectively eliminating the conditions required for natural selection to work properly?

ACuriousMind

Yeah, once you allow for "instinctual" behaviour to be trained away, it's not clear why any of that behaviour should be expressed in a typical human.

David Z

...oy, we have a chat session today. I totally forgot.

Solenodon Paradoxus

14:13

Hey @ACuriousMind I was wondering what you think about my comment to this answer of yours physics.stackexchange.com/questions/293947/…

Secret

Oscilloscope Music - Pictures from Sound

►

ACuriousMind

@SolenodonParadoxus I don't know anything about string field theory, so I don't really think much about it. To me, the non-perturbative version of string theory is (supposed to be) M-theory, not string field theory.

Solenodon Paradoxus

Well, M-theory is not really a thing yet, right?

I mean there is the matrix conjecture, but I don't think it turned out to be anything more than just a conjecture

ACuriousMind

That's why I said "supposed to be" ;) However, the "low energy" effective version of M-theory in the sense of 11D SUGRA with M2 and M5 branes on it is regularly used. It's at least non-perturbative in the sense that you can take limits that correspond to strong coupling in some of the string theories.

Solenodon Paradoxus

Isn't 11D SUGRA nonrenormalizable?

Or do you mean classical SUGRA

ACuriousMind

14:28

Well, this 11D SUGRA is supposed to relate to "true" M-theory like the 10D SUGRAs relate to the various string theories

I.e. it's only an effective theory, so it doesn't need to be renormalizable

I'm not sure how many people are still looking for "true" M-theory, many seem content looking for interesting physics from compactifying this version of M-theory.

Come to think of it, many papers just write "M-theory" and consider it understood that what is meant is that 11D SUGRA

Solenodon Paradoxus

Yes, exactly!

It really pisses me off because it seems like the authors are trying to show off by using a fashionable term.

ACuriousMind

Well, it will certainly confuse future readers after we have found full M-theory :P

Solenodon Paradoxus

14:44

Yes, about that. I certainly see M-theory become found, but what I don't understand is how people hope to recover standard physics from it.

It seems naive to expect the dynamics of M-theory to just give the desired compactification with all the necessary properties for free.

Of course I am not an expert and my opinion doesn't count :)

So what I'm saying is - M-theory and string theory can just turn out to be interesting mathematical objects, but not physically relevant

ACuriousMind

Entirely possible, yes.

Mike Miller

Can you convince me they're interesting mathematical objects?

ACuriousMind

@SolenodonParadoxus Ah, whether or not the realized compactification has to be uniquely determined by the theory is a point of contention. It depends on whether you want "M-theory/string theory" to be analogous to the Standard Model or to quantum field theory.

If it's analogous to quantum field theory, then it doesn't need to determine that - since QFT also doesn't in any way single out the Standard Model as the QFt to be realized in nature.

@MikeMiller Example: Just yesterday I heard a talk about Stokes matrices and Frobenius manifolds and the speaker said that Cecotti and Vafa already anticipated most of their results in physics language when trying to classify supersymmetric field theories in 2D. Why did they want to do that? Because compactifying string theory on CY 4-folds gives such theories.

Mike Miller

You'll also have to convince me the first bit is interesting...

ACuriousMind

@MikeMiller Ufff...well, in this case, it was closely related to a quantum cohomology of the manifold. You like such geometrical invariants, no?

Mike Miller

14:57

OK, you got me.

Secret

Ignoring irrelevant parts of this question, it sounds pretty valid a question. But I guess part of the answer is that we need a model to produce predictable outcomes so we can test them experimentally

ACuriousMind

@MikeMiller Heh :)

Sir Cumference

15:46

Love this proof

ACuriousMind

chat session in 12 minutes? I never adjust to the shifts DST induces...

John Rennie

I was just thinking that.

Sir Cumference

Btw my new telescope just arrived today

fml

John Rennie

@SirCumference you're in the US? In the UK we have clear blue skies at the moment, but of course that means it's freezing :-)

DHMO

Who will be hosting this session?

John Rennie

15:58

David normally does the honours, but there's no sign of him. I guess we get to organise this session ourselves :-)

Secret

rawgit.com/csp256/IsoVis/master/IsoVis.html

John Rennie

I have to say that the chat room doesn't look crowded ...

Secret

some visualiser from some guys

Sir Cumference

@JohnRennie Still envy you :P

I got so eager to try this out

John Rennie

@SirCumference Use it to watch your neighbours

ACuriousMind

16:02

Well, it's chat session time! Welcome everybody, is anyone new to the site, to chat or to the chat session?

I guess not, then :P

Well, I'm not sure if David had an agenda ready, I don't have any topics we would need to discuss. Does anyone have something on their mind?

John Rennie

Tumbleweeds roll across the chat room. In the distance a sign creaks in the wind.

DHMO

How do understand addition reactions?

Kyle Oman

lurk

David Z

Hey guys, I'm here but sorry I couldn't introduce the chat session - I was out doing something and couldn't get back in time

2

Anyway I have no particular agenda for today.

Does anyone have something to discuss?

@KyleOman secretive nod

John Rennie

@DHMO is that physics?

DHMO

16:12

@JohnRennie that just popped up in the feed of this room lol

David Z

If nobody has a topic... we have one featured meta question, which I guess people should be aware of - although you've probably all seen it by now anyway

6

Q: Project Reduplication of Deduplication - Physics

Stack Exchange recently started a collaboration project with the University of Melbourne, in an attempt to improve the automatic detection of duplicate questions. More information on the project and a call for help from the community can be found here: Project Reduplication of Deduplication Has ...

Sir Cumference

@DHMO Don't see it

Strange

David Z

Other than that, let's just do open discussion.

vzn

geez quiet in here can hear a pin drop. heres some actual physics

Is This What Quantum Mechanics Looks Like?

►

DHMO

The pilot wave theory of quantum mechanics.

vzn

16:15

@DHMO not quite but close =D

ACuriousMind

Valter Moretti brought out a paper yesterday giving us another answer (I think) to the frequent question "why does QM need to have complex numbers?"

DHMO

@ACuriousMind because physicists can't deal with quaternions.

ACuriousMind

@DHMO On the contrary, they can. It just turns out trying to base a Hilbert space on them is either inconsistent or reduces to the standard complex case, anyway.

DHMO

@ACuriousMind it was a joke

vzn

(ah sigh that went well!) another random barely-physics topic. saw angels & demons 2nd in Dan Brown movie trilogy wk ago, it has an amusing/ dramatic extended popsci depiction of LHC at beginning.

David Z

16:21

Oh yeah... that was one giant facepalm moment

vzn

16 mins ago, by John Rennie

Tumbleweeds roll across the chat room. In the distance a sign creaks in the wind.

see this is what happens when 0----7 gets snuffed :( :P

David Z

Hmm... did anyone look at the EM drive paper now that it's been published?

vzn

@DavidZ lol EP says emphatically its outrageous/ terrible so it must be false :P

David Z

Sure... though technically one could write a terrible paper that nonetheless describes a true conclusion :-P

ACuriousMind

@DavidZ Which one? There's been a peer-reviewed paper claiming to have seen the effect since 2014 or so at least

vzn

16:26

@DavidZ yeah. so whats your take on it? my feeling is that its been subject to some pretty heavy verification at this point and reputable scientists (NASA!) are risking a lot to publish it. its gone thru years of testing at this point....

David Z

@ACuriousMind I didn't know that. Although I haven't really been following it. I was referring to the one that was recently published - the Eagleworks paper, I think.

@vzn I don't have much of a take on it because, as mentioned, I haven't been following it very closely.

ACuriousMind

@DavidZ Yeah, Eagleworks have had this one out since 2014, so another one from the same group isn't really much news, imo

vzn

@DavidZ very brave of you merely to cite it! :)

David Z

Ah, I see

@vzn I have no idea what you mean by that

To the extent I have a take, it's that extraordinary claims (such as this one) require extraordinary evidence, and the evidence I'm aware of falls far short of that threshold.

vzn

@DavidZ lets face it, its kind of "untouchable" to borrow a term from indian caste system... could there even be a single question on the site about it? am betting some have been posted & shot down (with no record/ trace left, poof, doncha just luv SE...)

David Z

16:31

@vzn citation needed

vzn

@DavidZ a line/ quote/ scientific philosophy by carl sagan (afaik) that is both highly justifiable and problematic for a lot of reasons.

ACuriousMind

What's needed is independent verification, but so far the only other group claiming to have seen the effect seem to be Chinese researchers (under (ii) in the canonical resource post) where I can't even tell whether their papers are peer-reviewed because there's no "official" translation into English as far as I can tell and I don't speak Chinese.

vzn

@DavidZ exactly. vaporized posts cant be cited. touche

ACuriousMind

@vzn Of course there are questions on the site about it. I just linked the one where we collect all the publications relating to it.

John Rennie

An heretical question possibly, but is it inconceivable that an interacting vacuum could acquire a momentum?

David Z

16:33

@vzn No, I mean if you're going to claim that posts have disappeared, you need to present something justifying that claim. What have you got?

@JohnRennie "interacting" in the QFT sense?

ACuriousMind

@JohnRennie Depends in which framework. The standard definition of a "vacuum" is a Poincaré invariant ground state, which necessarily has zero momentum.

John Rennie

@DavidZ yes, the vacumm of an interacting field theory.

vzn

@DavidZ DZ, we both know SE keeps zero record of deleted posts, its all completely vaporized, plz dont ding me on that. this is expressly declared not to be a site for "nonmainstream physics" by official policy (which here we see can be somewhat problematic to interpret/ apply). anyway thx for the ref Q/A, am a bit shocked to see it incl answer by EP etc, maybe was a tad )( unfair. o_O :P

ACuriousMind

If your vacuum has momentum, you break Poincaré invariance, for which there's no reason at all to believe it happens

John Rennie

@ACuriousMind well the Casimir effect shows that it's possible to locally change the properties of the vacuum ...

David Z

16:36

@vzn Too bad, I am "dinging you" on that. I am not in the mood to tolerate wild accusations without a shred of evidence. So if you're going to claim that posts have been made and deleted without a trace, give us a reason not to dismiss your claim.

Secret

but if Poincaré invariance is broken, then surely lorentz invariance will have to go for that region of vacuum?

what will happen to relativity in that region

vzn

@DavidZ geez DZ, how many posts are deleted from the site per week/ day? its non negligible. my assertion is far from wild, its just basic SE architecture around for years. ps there is nothing unique about Physics wrt that compared to other SE sites :(

John Rennie

@vzn deleted posts remain visible to users with >10k rep

Secret

(NB I knew next to nothing about vacua thus pardon my rush and possibly half baked question)

ACuriousMind

@JohnRennie Well, the energy of the vacuum is a different case because it's a renormalization parameter of the theory. We set it to 0 to have Poincaré invariance, but, well, you can meaningfully compute the "difference" between the theory "in the box" and "outside the box" and that's what the Casimir effect is

John Rennie

16:37

@vzn You appear to be suggesting the SE deliberately delete posts so that even 10k users can't see them.

ACuriousMind

The momentum of the vacuum is not a renormalization parameter, it's just zero, so no Casimir-like effect for that.

David Z

@Secret hmmm... well, translation and Lorentz boosts correspond to different subgroups of the Poincare group, so I dunno, might it be possible to have Lorentz invariance without translation invariance?

vzn

@JohnRennie most users are <10K, the >10K users are a minority one might even say the elite... sorry, have been on SE for >½ decade and still dont have 10K on any site, was not aware of that system, challenge anyone to find it documented openly somewhere, think its probably buried somewhere

David Z

@vzn physics.stackexchange.com/help/privileges/moderator-tools

ACuriousMind

Sure, you can break the Poincaré group to the Lorentz group and retain "local" relativity without having homogeneity. However, interacting QFTs are usually supposed to have Poincaré invariance, that's why I started my reply with "Depends in which framework".

David Z

16:41

-1

Q: At what reputation can an SO user view deleted posts and comments?

I have tried checking privileges but i've not found anything like View Deleted Posts. So thats why I'm asking, At what reputation can a Stack Overflow user view deleted posts and comments Or is it reserved only for moderators?

discussion

John Rennie

@vzn There are a lot of >10k users on this site. It isn't hard to get a rep of more than 10k - you just need to be serious about contributing to the site.

vzn

@DavidZ vzn now slinks away with tail between legs, totally humiliated for all time

@JohnRennie think its a low percentage of total users. that was my point. many thx to everyone for so expertly deflecting/ evading my points.

Danu

Heeeeyo

Secret

Wish I can comment further about that, but currently I was so far behind in physics due to universal algebra experiments that I might need some time to caught up. But from what I have been followed, whatever that EM drive thrust is seemed to be still a bit too small to be practical...?

ACuriousMind

@Danu heyhey

David Z

16:44

@ACuriousMind yeah, for sure. But if we're going to dispense with momentum conservation - I mean, supposing hypothetically that the EM Drive effect is real and is actually an indication of momentum nonconservation - clearly some drastic change in the theory is needed. Dropping the requirement of full Poincare invariance would fit that bill.

Mike Miller

I think I got 10k on MSE after like a year

Danu

Hi Mike

John Rennie

@DavidZ I suspect the problem is finding a way to do that without messing up all of QFT ...

Danu

I'm exhausted after practicing my talk---proving that the Euler class is PD to the generic zero locus is harsh

David Z

@JohnRennie Oh, of course. But theoretical physicists are creative. If we're forced into it, I'm sure we'd find a way. (I say "we" as if I would have anything to do with this :-P)

Danu

16:45

Have to go through some really boring lemmata

I really pray for that stupid EM drive thing being fake. Why did this come up, actually?

vzn

@DavidZ dropping poincare invariance? sounds revolutionary to me... or at least nonmainstream o_O :P

Mike Miller

Why so? Because you don't want pop science types to be happy?

John Rennie

The EM drive effects are actually quite big compared to the sort of precision searches we already do. It's hard to see how such a large effect wouldn't have shown up somewhere else.

David Z

@Danu There was some paper about it published recently. Not really news, but on the other hand there's not much else to talk about.

ACuriousMind

@DavidZ Well, for one, you would break Wigner's classification of particles, meaning the mass need not be a defining property of a fundamental object anymore...

Danu

16:47

Also, NASA scientists publish absolute garbage pretty regularly @vzn

@ACuriousMind Perhaps there'd be some substituting scheme though

David Z

@ACuriousMind Now that would be a reason not to dispense with Poincare invariance lightly

Danu

I mean... there better be

vzn

@Danu lol probably even more after Trump eviscerates the agency... am presuming he will get surely around to it at some pt, or maybe thru negligence etc :o

ACuriousMind

@Danu Well, if only Lorentz invariance is left, you only have spin left as a Casimir to classify the irreducible reps

vzn

@MikeMiller YES! DEATH TO POP SCIENCE! (except for carl sagan!) :P

Danu

16:49

@ACuriousMind Yeah but of ocurse we now know that Poincare invariance is an extremely close approximation

So whatever replaces it will give a substituting scheme

ACuriousMind

Hmm...maybe it's...spontaneously broken? I wonder what term you need to write into the Lagrangian to do SSB for translation invariance.

Danu

@ACuriousMind $x$? :P

ACuriousMind

@Danu wat

David Z

@ACuriousMind #SCIENCE

@Danu lol

Danu

What wat?

$x$ :D

ACuriousMind

16:51

I thought we were thinking of a field theory, so the Lagrangian must be a function of $\phi,\dot{\phi}$.

dmckee

@Danu If I was going to pray it would be for it to represent something genuinely new. I know with almost perfect certainty that it is nonsense, but there being something real in it would change the possibility landscape around spaceflight options at a minimum and might lead to really big changes.

Secret

Regarding SSB in translation, Not sure if related since this is more of a condensed matter stuff

3

Danu

@ACuriousMind NOTHIGN IS CERTAIN

Mike Miller

There's not exactly much pop math so I feel less spite.

vzn

ok, since nobody said the unspeakable word, now to mimic Bell in his questioning orthodoxy etc, heres why everyone hates it: ANTIGRAVITY

ACuriousMind

16:52

@Danu I think the Euler class thingy has fried your mind :D

Mike Miller

When someone starts making books about how exotic K3 surfaces cause consciousness I'll worry.

Secret

@dmckee Well for one thing, it is said with EM drive, you can reach Mars in 7 weeks

David Z

@Secret Well there are more and more connections between particle physics and condensed matter these days

dmckee

Oh, so Hawking just proved it even more? — World Walker 1 min ago

Danu

@MikeMiller I don't put it past Penrose

Mike Miller

16:54

are you a particle physics person?

dmckee

^ Posted without even reading the wikipedia page. ::sigh::

Danu

K3 surfaces are used a lot in string theory, and Penrose argues we should get consciousness from quantum mechanics (i.e. string theory :D)

Secret

@MikeMiller DavidZ worked with some experimental particle physics phenomenonlogy, and if I recall, dmckee once worked with theory

ACuriousMind

@MikeMiller Careful, don't give the old crazy physicists such good ideas

Mike Miller

It seems to me that the people who talk a lot about how useful string theory is for condensed matter tend to be high-energy people. I'be heard more skepticism on the other end.

vzn

16:55

@MikeMiller CS complexity theory is now flirting with black holes... how about that? close enough?

Secret

I will be extremely careful when reading anything that has the word conciousness = <insert mathematical object>

Danu

@MikeMiller Indeed :)

David Z

@Secret I was actually closer to theory, if I had to pick one. Computational high-energy particle theory/phenomenology

Danu

But, I have a friend who did a MSc. in condensed matter field theory, and he's now asking me how to learn AdS/CFT.

Secret

I see

Yeah, I found that most string theory machinery seemed to end up in the condensed matter domain more than particle physics stuff

Danu

16:57

In the past few weeks there has been a huge spike of famous people (mostly from Princeton/IAS) publishing on a certain condensed matter model (SYK model)

4

Mike Miller

Not that I care very much, other than for my longstanding claim that half this room should stop calling themselves physicists. :P

ACuriousMind

@Secret Ah, interesting, but doesn't work for the QFT case because a non-zero spinor VEV also breaks Lorentz invariance there

Danu

Many big names, including Witten, Maldacena, Klebanov, Gaiotto, etc.

@MikeMiller You want them to be mathematicians instead?

Mike Miller

Well, if they're doing mathematics that offers no significant predictive claims about the real world... :)

vzn

@MikeMiller two words: mathematical physics o_O

Mike Miller

16:58

Call them physical mathematicians and give them all the same funding.

ACuriousMind

@Danu Wait, you mean I might have missed a Witten paper by not subscribing to cond-mat? oO

Danu

Yeah

vzn

@MikeMiller aka String theory? etc! :P

Danu

But you shouldn't have missed it, it was stil cross-listed.

Else I wouldn't have seen it hahaha

Ain't nobody subscribed to cond-mat

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