The h Bar - 2018-04-29 (page 1 of 3)

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12:27 AM

Ok so I got back , showered, cooked and now I am eating while deploying my boys to the cloud.

1:18 AM

@vzn yes Bezos is a super human by most standards.

1:34 AM

@Cows nytimes.com/2015/08/16/technology/…

2 hours later…

3:29 AM

Safety working procedures of handling dark energy:

Highly explosive, projectile generation hazard, do not stick anything into the stuff

3:54 AM

hmmm... actually that got me thinking: what happens in a spacetime metric where there's an expanding FRLW metric in a small region and then we launch a particle towards it

my intuition suggest it will effectively slow down as soon it hits the expanding bubble as seen from the observer outside the bubble since an increasing amount of distance the particle has to transverse before it can reach the centre of the expansion (which is also expanding)

The minkowski metric in spherical coordinates is given by:

$$ds^2 = -dt^2 + dr^2 + r^2d\theta^2 + r^2 \sin ^2 \theta d \phi^2$$

and the FLRW metric in hyperspherical coordinates is given by:

$$ds^2 = -dt^2 + a(t)^2 (dr^2 + r^2 \text{sinc} ^2 (r\sqrt{k}) d\theta^2 + r^2 \text{sinc} ^2 (r\sqrt{k}) \sin^2 \theta d\phi^2)$$

So what I need to do is to make this piecewise so that the FLRW metric only took place in a spherical region of some finite radius, while the rest is flat spacetime

But wait, spherical region with center at where? Agh, this is why I said GR screw up the intuition of space so much I cannot create a memory palace for it

Chakrapani N Rao

4:11 AM

Can anyone help me with this physics.stackexchange.com/questions/402639/…

@ChakrapaniNRao I think you've misunderstood what we mean by uncertainty

4:40 AM

@bolbteppa The post I replied to

Chakrapani N Rao

@JohnRennie I am really happy to know where, can you please elaborate, this has been bugging me for the past one month

@ChakrapaniNRao If you consider a stationary electron then the wavefunction will something like a gaussian.

The average position of the electron will be well defined since it will be the peak of the gaussian, and the average momentum will be well defined since it will be zero. OK so far?

Chakrapani N Rao

5:04 AM

@JohnRennie I am not considering stationary electron, but a near stationary electron because I am assuming it's moving

@ChakrapaniNRao An electron always has a rest frame, and in that frame it is stationary.

Chakrapani N Rao

ok

So if we work in the rest frame of the electron and write down its wavefunction then it will look something like a gaussian. Yes?

Chakrapani N Rao

yes

In Heisenberg's uncertainty equation the $\Delta x$ is the standard deviation in $x$ i.e. the quantity usually written as $\sigma_x$. It's defined as $\sigma_x^2 = <x^2> - <x>^2$.

The mean position is zero since a gaussian is symmetrical about $x=0$, however the mean square of x is non-zero.

So even though we are in the rest frame of the electron, which means the average position is perfectly known, the uncertainty in position is non-zero.

It is basically the width of the gaussian.

Are you happy with this? It's important you understand this as this is fundamental to understanding what the uncertainty principle means.

Chakrapani N Rao

5:12 AM

yes I understand this

and I am sorry for my naivete

OK. Now we need to get the momentum, and the simplest way to do this is to Fourier transform the wavefunction of the electron. That gives us the same wavefunction in momentum space.

Chakrapani N Rao

I am agreeing there is uncertainty in position and in velocity

When we do do this we get another gaussian, and the width of the gaussian in momentum space is proportional to $1/\sigma_x$ i.e. the narrower the gaussian in position space the broader it is in momentum space - that's just the way Fourier transforms work.

Chakrapani N Rao

And you explanation seem to assume copenhagen interpretation is true and in probability wave function

No, I am assuming nothing about interpretations. I am purely describing mathematical operations on the wavefunction.

Anyhow, in momentum space we also have a gaussian form for the wavefunction, and as before we know the average momentum precisely $<p>=0$ by definition because that's what it means to be in the rest frame of the electron.

Chakrapani N Rao

5:18 AM

yes

But as before the mean square $<p^2>$ is not zero and therefore $\sigma_p$ is not zero.

And in fact if we grind through the maths we'll discover that:

$$ \sigma_x \sigma_p = \hbar/2 $$

Chakrapani N Rao

yes yes

i.e. Heisenberg's uncertainty equation.

So when we talk about uncertainty we are talking about mathematical properties of the wavefunction. The pop science story of you can't know the position and velocity of a particle at the same time is just a pop science story and therefore only an approximation to the truth.

Chakrapani N Rao

yes but what is that experiment or logic that is telling you the difference from the pop science story and your explanation

again which is the experiment that tells that hup is ontological and not epistemological

there seems to be some sort of tautology here, lets roll back to the time before hup and all the quantum weirdness was introduced

and what if I carried out this experiment physics.stackexchange.com/questions/402639/…

if I carried this a billion times over and over again wouldn't I clock even once more than 48 min?

Your experiment is basically considering what happens if we take the stationary electron I described above and let it evolve wth time. Yes?

Chakrapani N Rao

5:34 AM

yes

does it hit the wall?

The electron mean position doesn't change because we know the mean position is exactly zero. But what happens is that the wavefunction spreads out with time i.e. $\sigma_x$ increases with time.

Chakrapani N Rao

let $\sigma_x$ increases with time, when does it hit the wall??

"The electron mean position doesn't change because we know the mean position is exactly zero" not quite exaclty

It doesn't hit the wall

Chakrapani N Rao

@JohnRennie never??

The wavefunction overlaps the wall, and there is some probability of interaction with the wall that depends on the magnitude of the wavefunction at the wall

Chakrapani N Rao

5:44 AM

"probability" this is the word I am trying to avoid

At some point the electron will be detected by the wall, and when this interaction occurs the electron becomes localised at that point.

Chakrapani N Rao

you have assumed in the probabilistic wave function

"At some point the electron will be detected by the wall, and when this interaction occurs the electron becomes localised at that point." this is pure copenhagen

Yes, this is where interpretations come into play

Chakrapani N Rao

"At some point the electron will be detected by the wall", if that some point is more than 48 min then ontological hup collapses, copenhagen collapses, many-worlds collapses

But the Copenhagen interpretation and the HUP are two different and unrelated things

Chakrapani N Rao

5:47 AM

i think ontological hup IS copenhagen

that's how it was built

and i am a physics dummy

so i could be totally wrong

Nope, the HUP is the mathematical treatment I described above.

Chakrapani N Rao

copenhagen is built on that mathematical treatment

No it isn't

Chakrapani N Rao

ok now the conversation is going completely off topic, and yeah I think I over emphasized the relation between hup and copenhagen

@JohnRennie ok, sorry for that

"At some point the electron will be detected by the wall", if that some point is more than 48 min then ontological hup collapses, isn't this true

??\

i sorta doubt it. uncertainty is always statistical.

you can never deduce an uncertainty relation (or its violation) by a single observation.

5:53 AM

@ChakrapaniNRao no. There is some probability per unit time of interaction with the wall. It is entirely possible,, though improbable, that the interaction can take an arbitrarily long time.

One can probably even calculate the probability of it taking at least that long in QM.

Chakrapani N Rao

@Semiclassical "statistical", do you mean that there are counter examples where we know the position and momentum with more certainty than the limit set by hup

No.

I mean that the only way to observe an experimental uncertainty is by making many measurements.

You cannot look at one single measurement and infer uncertainty from that.

Chakrapani N Rao

@Semiclassical Exactly, and that probability is not zero, my whole argument is if even once the elctron takes more than 48min to reach the wall, the "ONTOLOGICAL" HUP BRAKS

False.

The probability of it taking longer than 46 minutes is not zero in QM.

Chakrapani N Rao

5:56 AM

@Semiclassical EXACTLY

Hence, if one makes sufficiently many observations, QM predicts that you are more likely than not to observe it.

This does not break any kind of interpretation of QM.

Chakrapani N Rao

its not zero, that means if you do the experiment a billion times then atleast you would expect the time to be more than 48 min once right??

@Semiclassical I am not talking about interpretation of qm

Yes, and QM predicts this.

I have no idea what you're referring to by ontological HUP then.

Chakrapani N Rao

my whole point is hup cannot be ontological

that particles do have particular position and momentum at any given time, its just that we can't measure it

That's an interpretation.

There are interpretations in which that claim is made, and interpretations where it is not.

But insofar as they're interpretations, they cannot and do not disagree with what QM experimentally predicts.

Chakrapani N Rao

6:00 AM

@Semiclassical I am not going against qm

The Copenhagen interpretation will agree that a long scattering time can happen. So will the de Broglie Bohm interpretation.

Chakrapani N Rao

I am just trying to prove that hup cannot establish absolute uncertainty

@Semiclassical yes, this is not against the interpretations of qm

@Semiclassical what????

Just because a very rare event can happen doesn't mean said event is inconsistent with the uncertainty bound.

A rare event is a single event. It is not a statistical statement.

The uncertainty bound is, once more, a statistical statement.

Chakrapani N Rao

@Semiclassical I am sorry you are absolutely wrong,

Is it possible for me to flip 100 coins in a row and have them come heads up? Yes. That doesn't make probability theory somehow inapplicable.

Rare events don't tell you much about the statistical uncertainty.

Moreover, even if a rare event can happen, you're not in any position to predict when it will happen.

You can still have a finite uncertainty in momentum and position despite having rare events.

Chakrapani N Rao

6:13 AM

@Semiclassical "The uncertainty bound is, once more, a statistical statement." this is not the prevailing opinion

I am willing to agree its statistical

but that is not what the foremost physicists hold to be true

look up web

Yeah, uh, no.

The uncertainty bound is a statistical statement because that's how you measure uncertainty

this has nothing to do with whether momentum and position have meaning apart from their measured values.

there's nothing strange or unfamiliar about this.

if certain physicists have tended to speak in a way as obscure this point, then so much the worse for that presentation.

Chakrapani N Rao

@Semiclassical I sincerely hope you are right in this, but my learning (which could be wrong) is telling you are wrong

What Heisenberg's Uncertainty Principle *Actually* Means

I should note that the online Stanford Encyclopedia of Philosophy has an entire page on the Uncertainty Principle: plato.stanford.edu/entries/qt-uncertainty/#BohrViewUnceRela

Chakrapani N Rao

Heisenberg's Uncertainty Principle Explained

I really don't care about what random internet videos have to say on it.

Chakrapani N Rao

6:28 AM

Understanding the Uncertainty Principle with Quantum Fourier Series | Space Time

I wonder if there is some confusion about the HUP and the measurement of the HUP.

Chakrapani N Rao

@Semiclassical I have no background in physics, I know only +2(12th grade) high school physics, and therefore I can be easily wrong, I watch youtube and read from websites

The former is a mathematical statement about the wavefunction. The latter necessarily involves interpretations since it's related to measurements.

Chakrapani N Rao

And I think the videos I mentioned especially Veritasium and PBS space time have good reputation and are quite credible

Good reputation on the level of public presentations of physics, perhaps.

6:31 AM

@ChakrapaniNRao yes, but they are aimed at non-physicists and therefore they are only approximations to the truth.

Unless you understand the mathematical desription of QM you don't understand it, or what the hup means.

Chakrapani N Rao

ok then, I really appreciate your time guys

from the Stanford entry I just linked: "The only requirement [on interpretations of quantum mechanics] is that, as an empirical fact, it is not possible to prepare pure ensembles in which all systems have the same values for these quantities, or ensembles in which the spreads are smaller than allowed by quantum theory."

Chakrapani N Rao

this is what britanica says

Uncertainty principle, also called Heisenberg uncertainty principle or indeterminacy principle, statement, articulated (1927) by the German physicist Werner Heisenberg, that the position and the velocity of an object cannot both be measured exactly, at the same time, even in theory. The very concepts of exact position and exact velocity together, in fact, have no meaning in nature

britannica.com/science/uncertainty-principle

I should probably acknowledge some bias here, insofar as I know the prof who wrote said entry

4 mins ago, by John Rennie

@ChakrapaniNRao yes, but they are aimed at non-physicists and therefore they are only approximations to the truth.

I'd also point out that statements like

"Any attempt to measure precisely the velocity of a subatomic particle, such as an electron, will knock it about in an unpredictable way, so that a simultaneous measurement of its position has no validity."

from Britannica

are really not what a defender of the Copenhagen interpretation would say

that language presupposes that there was a well-defined position or momentum before hand which has been disturbed by the measuring device

in particular, Bohr really took Heisenberg to task for that kind of initial presentation

So I rate that Britannica entry pretty low as far as providing an account that would be credible to a quantum physicist.

but, again, that's not what it's aimed at. it's aimed for a popular, non-specialist audience

Taking it as a starting point is valuable. But it is not authoritative.

Chakrapani N Rao

7:20 AM

@Semiclassical thanks, can I know what are your credentials, so that I can hold the statistical nature of hup to be authoritative

3 hours later…

10:15 AM

@Blue I needed some help regarding stuff, when are you free?

Anonymous

@SwapnilDas Yes?

10:56 AM

@vzn page 9 hitoshi.berkeley.edu/221B-S01/14.pdf section 1.3. 'vacuum polarization', all I can find right now, I don't know how your navier-stokes paper applies or explains this, but more generally, how do you explain any of this

2 hours later…

1:15 PM

@ACuriousMind I forgot how massive TW3 is

They legitimately have 100+ hours of content

1:34 PM

@BalarkaSen @BernardoMeurer Post's new album was streamed 78 million times day 1

1:46 PM

Afternoon, I'm looking for something that explains operator product expansions in d=2 CFTs

There's a lot on say the scaling argument stuff, but say I'd like to know <T(z) phi(w)> for some operator phi, what would be the method for deriving all the terms?

Or <TT> or <phiphi>

I haven't come across anything that doesn't blatantly omit some sort of calculation

David Tong's notes are as close as I can get to something useful but even there it's obscure

2:22 PM

@bolbteppa if youre serious try skimming Sbitnev and finding a single paragraph you think comes closest in whole paper to having some applicability to lamb shift & then lets discuss it further/ at length chat.stackexchange.com/rooms/9446/theory-salon ps got an email from Tenev briefly clarifying their pov re light waves...

@Semiclassical that pov about uncertainty due to measurement disturbance has been explicitly refuted by bell tests/ theory as pointed out by some authorities. "supposedly"... (one of my favorite refs on that is baggott.) global.oup.com/academic/product/…;

2:40 PM

@ChakrapaniNRao there is another intrepretation of HUP related to fluid dynamics but not much unlike what JR sketched out wrt the gaussian wavepacket. suggest looking into solitons. also defn check out veritasiums (viral) video on bohmian mechanics/ fluid dynamics. :)

3:08 PM

A few burgers for lunch - just a few ...

user image

palm sized?

Quarter pounders

I would have bought 8 oz burgers, but I didn't want to do things by halves.

@JohnRennie ...did you eat all of those?

I will probably be full after I ate 2-3 of those

@ACuriousMind I'm afraid so :-)

In my defence ... erm ... OK there is no defence

3:21 PM

Those would have been like three meals for me, probably :P

careful not to turn into an American

@JohnRennie holy fuck

It's important to eat healthy meals. Or so I'm told - I wouldn't know :-)

to be fair my breakfast wasn't better

and I feel bad for eating it

Never feel bad about eating ... well, unless you ate someone's pet.

3:30 PM

or someone...

Humans are a bit tough. They take a lot of boiling.

boiled meat? gross

And to be honest your average human is rather fatty.

@0celo7 A stew is just boiled meat

And a good stew is a thing of pleasure

I always brown the meat first

Humans tend to squeal a lot when you do that :-)

3:34 PM

I wouldn't do it while the human is alive!

The frequency with which this chat returns to the topic of cannibalism is...fascinating

Anonymous

I'm just wondering how many else are laughing just like me silently reading how boiled meat isn't tasty.

Boiled meat is the worst part of Germany

@DivyankaChaudhari To be fair, Ryan is right that if you just boil meat you tend to end up with a grey sludge.

You need to brown it well first to seal it and give extra flavour. Then you can start stewing it.

Anonymous

@JohnRennie Never did that, so don't know. But, this is funny.

3:40 PM

@vzn sounds right. hence why I view that britannica article very skeptically: no expert on quantum foundations would so blithely equate HUP with 'uncontrollable measurement disturbance'

I don't know the story there in detail, but I know that it's not as simple a matter as that.

(though again I have some bias, seeing as I know the author of the Stanford Encyc. of Phil. entry and have a lot of respect for his opinion)

I mean, if the claim is that various 'popular' presentations of the HUP tends towards incoherence, I don't disagree

But that only means one needs to be more careful/rigorous about how one speaks about HUP

@ACuriousMind I think certain people are drawn to it. I often end up talking to one of my professors about it

@Semiclassical The most important thing when talking about the HUP is actually defining what the uncertainties appearing in it are. Because once you do it becomes clear its standard version is not directly related to actual measurements.

agreed.

it still has empirical consequences, of course. but getting it into that form requires some work

@0celo7 Note to self: Run away from hungry-looking UT professors.

in particular, the notion that the observation of one rare event (in the setting described) is going to invalidate HUP is simply wrong-headed once one appreciates what a test of HUP requires

3:53 PM

@Semiclassical more evidence that n00bz + popscience = the plague o_O :P

2

@vzn I don't understand why one can blindly apply Navier Stokes to the vacuum, and this is all Bohmian quantum potential stuff

@bolbteppa I'm not sure it's Navier Stokes you get in that setting, actually

You get something hydrodynamic, but i'm not sure it's NS

arxiv.org/pdf/1603.03069.pdf

It is some modification in there yeah

hmm

the more important point, though, is that pilot wave business is really not hydrodynamics as such

the way Bush put it in his presentation is that, in their story, pilot wave stuff emerges from hydrodynamics as a sort of averaging over chaos from trajectories in hydro

so I don't think one should collapse those two together.

@bolbteppa why do you ask me about stuff you dont care about? not an expert... ps is there any connection between anomalous magnetic moment of the electron and lamb shift? reading wikipedia, sound related in various ways, but hard to figure out via its typically compartmentalized treatment(s)....

3:59 PM

(my impression is that Bush wants some hydrodynamic interpretation of zitterwebegung)

@vzn just wanted to see what you thought about this crazy phenomenon

@Semiclassical yeah met another guy/ phd recently into zitterbewegung it seems to be already outlined in various papers ie the fluid dynamic interpretation.

The fact that we know how to measure the anomalous magnetic moment of the electron to such precision makes me dubious that one will get some sort of 'subquantum' corrections at the Compton scale, mind

As ever, there's the distinction between being able to interpret a given quantum phenomenon in a certain way and being able to predict corrections to it

I wouldn't be shocked if there's a hydrodynamic interpretation of zitterbewegung. I would, by contrast, be surprised if one could obtain observable differences that way.

@bolbteppa direct manifestation of fluid dynamics phenomena/ properties of the spacetime fabric, currently incorrectly interpreted from widespread/ rampant particle centric pov/ bias (hows that for crazy) :P

This does go to a long-held opinion of mine that treatments of philosophy of quantum theory tend to focus on non-relativisitic QM to the exclusion of QFT

4:05 PM

@Semiclassical lol it takes awhile to translate all the mass epicycles into ellipses so to speak, very timeconsuming/ painstaking work. o_O

which is sorta silly given how precisely QED has been tested.

less philosophy of QM more philosophy of QFT plz

3

@Semiclassical Agreed.

"lots of (measured) decimal places" ≠ "correct theory/ interpretation"

sure. but lots of decimal places do indicate very strong constraints on what sort of observable corrections you can hope to observe

existing theory is both sound/ accurate in its own way and in need of revision. epicycles → ellipses

4:09 PM

you can't invalidate metaphysics by high-precision experiments, but you can invalidate a lot of the physics

← big LHC fan have watched maybe ~3 documentaries luv em all, write reviews in my blog

That said, a hydrodynamic interpretation of QED could still be valuable even if it doesn't lead to experimental predictions. maybe that's a way to make the standard calculations easier to motivate/understand, for instance

@Semiclassical it will lead to predictions, it already has predictions. (maybe even more than mass trendy theories being pursued by the physicist herds like strings etc!)

In all the philosophizing, the wave function is seen as representing probabilities, but relativity throws a hammer at that, e.g. KG equation allows for negative probabilities, so how does the philosophizing modify to account for that

@bolbteppa QM likes Hilbert space, but does QFT?

it again comes to the problem of elevating QM as the philosophical problem while mostly ignoring QFT

My dream would be that a hydrodynamic account of QFT would make it easier to learn/apply QFT.

4:15 PM

I think you can ignore QFT and just work with RQM, they are supposed to be equivalent, particle vs. field perspectives are equivalent etc

But relativity seriously changes things

maybe. I dunno

QFT is pretty firmly in here-be-dragons territory for me

@Semiclassical dream big! a worthwhile dream! think you will see it in your life, gradually. think it is a Big Wave™ coming o_O :)

Dreaming big is a good way to get lost in the clouds.

@bolbteppa is that Relativistic QM? RQM also stands for Relational QM

"The one-particle probability interpretation is limited only to those cases where the positive and negative frequency solutions can be decoupled by the Foldy-Wouthysen procedure" is hardly a qualification they throw into their espousings

4:17 PM

@Semiclassical think globally, act locally™ :)

← Here be dragoons

or rather:

@bolbteppa ugh, FW

$$\Huge{dragon^{dragon^{dragon^{dragon^{dragon^{dragon^{\tiny{dragon}}}}}}}}$$

it's dragons, all the way down

← more interested in slaying dragons than fearing them :P

4:18 PM

For me, I befriend dragons

Relativistic

The hardest thing about the unknown, is how to learn its wisdom without become insane

I see three possibilities

A hydrodynamic interpretation of observed QFT phenomena is 1), not possible, 2) possible but doesn't lead to observable corrections, 3) possible and leads to observable corrections

2 will simply mean that it will become an interpretation of QFT

In either of the latter two cases, it is valuable to study hydrodynamics as a way to gain insight into the known predictions of QFT

that to me seems valuable enough on its own, given how hard it is to break into QFT as a subject

4:25 PM

I wonder what will those divergences in QFT will translate to in a hydrodynamic model (having said that, I literally just jumped into the discussion, thus I know noting about this topic)

So I'd say it's far more pressing to properly formulate said interpretation rather than speculating on being able to observe it

It will always be welcome if we can zoom further into these infinities to see what they actually are

in a conceptual sense, anyways

viewing QFT as the hydrodynamics of a merely possible fluid.

I am new to the philosophy of QFT, what do philosophers interested in that topic?

no idea

i'm pretty ignorant of it myself tbh

5:05 PM

@vzn thanks so much sir

5:21 PM

@Semiclassical sometimes there is too much emphasis on falsifiability of a new theory. but repeatedly in history, new physics theories are devised with superior mathematical elegance. this should not be underestimated. if the "fluid picture" is more coherent than the existing ~~epicycles~~ particle theory, then that is in itself strong evidence... but notice one cannot judge coherence a priori! so in some ways all new theories suffer the ultimate catch22. akin to moth around flame™

@Secret aka spacetime fabric extreme (high) density regions. hossenfelder had a neat blog on that. maybe will try to find it again.

@vzn Falsifiability is what seperates science from astrology. Saying there's "too much emphasis on falsifiability" is basically admitting you have no evidence to support your point.

well, I think that's perhaps a bridge too far. Stuff like string theory is not (yet?) falsifiable but I'd still count it as a scientific endeavor

@ACuriousMind historically many revolutionary theories do not start out as falsifiable. am not against what might be called "eventual falsifiability." construction of falsifiability requires serious work by experts who take the work seriously, which is not done by opponents of the theory...

that said, if a theory has falsifiable predictions which been observed, that's a very strong argument in favor of it

hence why I do take experimental evidence about QM and QFT very seriously

@Secret Singularities in your kitchen / Hossenfelder backreaction.blogspot.com/2009/02/… (so sad, amazing img now 404) :(

5:32 PM

@Semiclassical I'm tired of this adage that string theory is "not falsifiable". That statement is as meaningful as saying that QFT is or is not falsifiable. Which is to say, pretty meaningless because what's falsifiable is specific models within these frameworks, e.g. the Standard Model.

Comparable string-theoretic models make very falsifiable predictions about e.g. observable particle spectra, i.e. there is actually a large set of falsified ST models, just like there's an infinite set of "falsified" QFT models.

yeah we're pretty sure the universe doesn't have the target space $\mathbb R^4 \times T^6$ :p

Eh. By the same token you can say that hydrodynamic models are falsifiable insofar as they predict that there's some scale at which the usual QM behavior no longer holds.

You can falsify that X scale is the correct one, but you can't falsify whether there is one.

But does it predict actual experimental results

Good question.

That's what I really would like to hear an account of, and what I was rather disappointed not to hear from Bush.

@Semiclassical lol "everyone elses conjectures/ hypotheses/ theories are unfalsifiable, except for mine

5:36 PM

Bush does not care about science people

@Semiclassical I haven't seen a coherent exposition of these "hydrodynamic models" but that sounds pretty much like what we're doing with supersymmetry investigations: We can never prove there is no superpartners, only say that there are no superpartners up to whatever scale the LHC has investigated so far.

@Slereah lol! fighting words! he has better credentials and more science than more than >¾ the ppl in this room.

Obviously our belief in the existence of the threshold at all should get progressively lower the farther it has to be pushed out

@ACuriousMind Sure. My point is only that the notion of 'falsifiability' applies to specific parameters in the theory, not to the theory as a general framework. The former is falsifiable, the latter isn't, and I don't think that makes the latter unscientific.

@Semiclassical Well, the general framework is scientific if and only if it produces falsifiable specific models.

5:39 PM

@Semiclassical the concept of falsifiability came from/ originated with popperian scientific criticism/ philosophy and am not sure its entirely taken seriously within scientific circles. ie it has lots of fineprint/ caveats in practice...

Sure, but a theory that's supposed to describe the real world is supposed to have this :p

I mean basically falsifiability is just that it should make some specific predictions

@Semiclassical speaking of LHC...

of course as the Motl says

Falsifiability doesn't mean that it should be falsifiable at reasonable costs

> Popper also wrote extensively against the famous Copenhagen interpretation of quantum mechanics. He strongly disagreed with Niels Bohr's instrumentalism and supported Albert Einstein's realist approach to scientific theories about the universe. en.wikipedia.org/wiki/Karl_Popper#Philosophy_of_science

↑ lol holy cow! o_O

5:58 PM

ps re (work in) falsifiability, recently ran across this work by Quach working with double slit. not fluid pov in particular, but close )(. do think that it might be a 1st area where some discrepancy with QM theory can be isolated but only at high precision measurements, have some similar ideas. sciencealert.com/…

> "[T]here is no fundamental reason why the Born rule should hold. It seems to work in all the situations we’ve tested, but no one knows why."

↑ strongly disagree, the born rule is (apparently) derivable from the fluid pov as analogous to fluid "density"

Anonymous

@vzn I'd be interested in seeing the derivation

@Blue nearly identical formula(s) show up in EM waves and pressure measurement of sound waves (etc) but havent seen anyone really outline it thorougly. googling, try these refs to start arxiv.org/abs/quant-ph/0604178 arxiv.org/abs/1403.0014

Anonymous

@vzn Which formulae exactly?

Anonymous

I will look through those links

Anonymous

But neither of them seem to be related to fluids

6:07 PM

@Blue trying to remember. possibly energy density for EM waves. etc

@vzn Equally true and equally needlessly mystifying would be: "There is no fundamental reason why Newton's second law should hold. It seems to work in all the situations we've tested, but no one knows why"

Anonymous

Okay. Energy density is $\frac{1}{2}\epsilon_o |E|^2$

Of course a physical theory will have some axioms which cannot be derived. That's simply not noteworthy.

Anonymous

The only relation I see is the presence of a squared term. Not sure how that relates to fluids and born's rule

@Blue honestly am struggling to make this connection myself for many years but have seen related material & am in need of helpful cohorts to isolate it more carefully, believe it exists/ is strong but hasnt been coherently presented in 1 place so far. think it might be related to glauber detection theory as outlined here en.wikipedia.org/wiki/…

> The Glauber detection theory differs from the Born probabilistic interpretation,[16] in that it expresses the meaning of physical law in terms of relationships, counting signals in the detection processes, without assuming the particle model of matter.

@ACuriousMind new (better) theories derive what were considered axioms in prior theories.

Anonymous

6:15 PM

The relation would be surely along the lines of energy conservation, which isn't very surprising. You learn that while learning the YDSE experiment itself. That line of thinking doesn't provide any derivation of Born's rule, at all.

Chakrapani N Rao

@vzn I have seen veritasium's crazy video it was just amazing

@Blue its not exactly a "derivation" (yet!) but a strong parallel with other areas.

@ChakrapaniNRao :) you mentioned veritasium so figured youd like it

Anonymous

@vzn Eh. That parallel is way more obvious and well known than you think. Doesn't provide any new insight.

@Blue then who points it out best? [citation needed]

Anonymous

@vzn I guess that's quite well discussed in basic physics textbooks? If you are willing to learn I could dig up some resources for you. See this thread for example

Anonymous

6:21 PM

That's for your EM thing

@Blue right, ok, the analogy is known. it needs a new interpretation. QM probability fluid/ density is real and is refering to spacetime fabric. etc

Anonymous

It doesn't need any new interpretation, unless that provides a new insight.

@Blue lol the new interpretation is a new insight :) :P

Anonymous

Well, if you feel your fluid analogy is deeper than Born's rule itself, you need to substantiate than with the math. Something is only deeper when it takes lesser assumptions than existing theories.

@Blue agreed. am not einstein. still working on it. it seems to relate to fluid dynamics interpretations of schroedinger eqn.

6:28 PM

@vzn I interpret you as a troll, but that doesn't provide any new insight.

It's already well-known.

(gottem)

@BalarkaSen sometimes youre deep, sometimes shallow. :|

i merely provide counterexamples. sometimes the claims are so shallow that they make the counterexamples a tautology, what can i say

Lol aight I'm done trolling here for today

Anonymous

You really don't need to Einstein to learn physics properly. You just need to throw away the attitude of getting overwhelmed by seemingly "deep" things, and instead pursue the math and physics properly. There's a reason why you don't hear of many "college-drop-out" eminent physicists.

Carry on with physics!

@Blue right. no disagreement. you need an einstein to create new theories. real einsteins are very rare. (most are satisfied to work with what is already built, or do not perceive anything larger.)

Chakrapani N Rao

6:37 PM

Guys I need some fact check

HUP right NOW is considered ontological right??

Anonymous

@vzn It's honestly difficult. Being able to learn all the necessary existing work properly and then devoting one's life to developing a "deeper theory" is something that depends a lot on luck, circumstances, perseverance, etc, with there existing a almost certain chance of being wrong. Don't underestimate the number of people who are interested in making a "grand unified theory".

Anonymous

@ChakrapaniNRao No

Anonymous

It's very simple math

Chakrapani N Rao

@Blue thanks

and yes the only motivation is that of curiosity

@Blue no kidding. thx for your concern. am aware of the dangers. einstein himself failed at it and became something of a laughingstock even among other physicists. and some living physicists like 't hooft are not far behind so to speak. in darker moments concede the revolution may not happen in my lifetime. here there be dragons™

Chakrapani N Rao

6:51 PM

But Einstein was a great man and an inspiration that mankind will most probably remember forever

@ChakrapaniNRao What do you mean by it being considered "ontological"?

Chakrapani N Rao

Means that not that we can't measure a particle's velocity and position simultaneous but a particle doesn't have defined values of both simultaneously

the particle's position and velocities are just connected smears

Anonymous

He is asking what you meant by the word "ontological".

Chakrapani N Rao

The Uncertainty Principle | Genius

oh, ontological means the way things are by themselves

Anonymous

Uh...

6:58 PM

@ChakrapaniNRao Yes. Note that in the standard formalism of QM, the uncertainties appearing in the HUP are not about "measurement" at all. The state of the particle defines a way to take expectation values of observables like position and momentum, and the uncertainties are simply the standard deviations of these expectation values, i.e. $ \sqrt{E(X^2) - E(X)^2)$.

Chakrapani N Rao

exactly

and I am trying to "prove" that qm formalism is a wrong

Anonymous

I still didn't understand your question though :P

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