The h Bar

Jake Rose

12:01 AM

The convention is a right hand rule

So there's an ambiguity which depends on the functions @JoeStavitsky

The choice for t is near enough always a positive real number that is increasing so you wouldn't see it there.

vzn

1:06 AM

in theory salon, 59 secs ago, by vzn

Quantum Physics May Be Even Spookier Than You Think / sciam

Secret

3:21 AM

0

Q: Why should heat transfer occur between infinitesimally small temperature difference in a reversible process?

In thermodynamics, a reversible process is quasi static (because every point in the system should be in equilibrium to study the state properties and work done is maximum), but why should heat transfer occur between infinitesimally small temperature difference(why not between finite temperature d...

thermodynamics

Actually, I think that is less spooky if it is confirmed. If it actually takes time for the particle to hop between places in a superposition, it's still quite intuitive and classical sounding. Suppose that is what comes out, I think a follow up experiment will be to decrease the time separation between the post selections and see if this "hopping" can keep up,

it will be interesting if the hopping still occurs and when the time it takes to hop from one place to another will suggest it will take a non quantum signal that is travelling superluminally to made that hop otherwise, because that…

vzn

3:43 AM

@bolbteppa honestly while think this is very interesting, find the popsci writeups on it hard to follow & would like to understand the theory better. strangely they are apparently not making any prediction other than standard QM. think this shows some how difficult it is to pinpoint all the theory in some experiments & dont think it is always entirely done. anyway its by a living legend Aharanov & glad he hasnt given up the fight. en.wikipedia.org/wiki/Aharonov%E2%80%93Bohm_effect

@Secret oops strange somehow the reply # got mixed up meant to reply to your line

Semiclassical

"Elitzur agrees their experiment could have been conceived using the conventional view of quantum mechanics that prevailed decades ago—but it never was. “Isn’t that a good indication of the soundness of the TSVF?” he asks."

my response is basically: No, it's really not.

It's evidence that it's an interesting way of thinking about QM, and maybe a useful one

but an interpretation being useful/productive is a different matter than it being any 'sounder' than other interpretations

vzn

@Semiclassical skimming the nature article, TSVF apparently makes super-QM predictions about reality. ie if measured as predicted it could possibly prove QM is incomplete. finally, a world class theorist making super-QM experimental predictions... o_O nature.com/articles/s41598-017-00274-w

Semiclassical

eh, from the original article:

"It’s generally accepted that the TSVF is mathematically equivalent to standard quantum mechanics,” says David Wallace, a philosopher of science at the University of Southern California who specializes in interpretations of quantum mechanics. “But it does lead to seeing certain things one wouldn’t otherwise have seen.”

that's not definitive, tbf

vzn

> The Two-State-Vector Formalism (TSVF) enables quantum mechanics to reveal hitherto unknown aspects of quantum reality1, 2 [nature]

Semiclassical

That's a pretty ambiguous sentence.

You can read that as either "we hope to see something beyond quantum" or as "we hope to discover new implications of QM"

vzn

3:53 AM

@Semiclassical saw that quote and then was confused. think Wallace (is, or may be) wrong in his characterization and missing some of the subtlety wrt the Nature claims. it is possible for theory B to subsume theory A yet make additional predictions that A cannot ie definition of A incomplete wrt B! ... that seems to be exactly what Aharanov is claiming.

Semiclassical

the latter isn't beyond QM.

What I see in the paper is not: "QM doesn't predict this!!!" but "QM predicts this, and only TSVF makes this prediction obvious"

vzn

they seem to be suggesting, as have conjectured myself (eg around here, heavily scoffed at by others on record), that weak measurements may be tied/ tightly coupled to a super-QM theory.

Semiclassical

I mean, if you actually look at how they compute the predictions, there's nothing super-QM in there

it's just good old unitary time evolution

vzn

@Semiclassical it does not look like strictly standard QM to me but find it difficult to pinpoint the novelty even as they seem to try to point to it... wheres some pro math-physicists around like von neumann when you need him :|

Semiclassical

I'll note the closing paragraph of the original 1991 paper where AV present the 3-box paradox (cited in that Nature paper)

"What we have presented here is a novel approach to standard quantum theory. Our formalism is in complete agreement with the standard approach in all its experimental predictions. It has an advantage that it is symmetrical under time reversal.

However, we believe that our approach has more than merely aesthetic value. It simplifies the analysis of the second in a series of three consecutive experiments, i.e. the analysis of the experiment performed on ensembles which are both pre-selected and post-selected. And, most importantly, it suggests new experiments which yield interesting results.…

now, that's obviously not the present paper

but the implication there is definitely not "super-QM" but "QM interpreted correctly"

which is to say, TSVF is not a theory that goes beyond QM but an interpretation which makes understanding certain experiments more natural

vzn

4:07 AM

> It seems to us that it is practically impossible to anticipate these results using the standard approach.

Semiclassical

Anticipate != derive

being able to 'anticipate' results is based off of what one considers intuitive and natural

being able to derive them is based on being able to set up a specific system and extract patterns from it

As far as I can see in either paper, there's never an implication that you could not derive the same results using the standard approach. The implication instead is that you'd never think to look for it if you're working in the standard approach.

I think that's perfectly interesting in its own right. But there's nothing super-QM about it

vzn

ok. cant refute that at moment. have to think about it more, its very subtle. it looks like at least an attempt to step in a super-QM direction... in the general pov/ angle...

Two-state vector formalism

The two-state vector formalism (TSVF) is a description of quantum mechanics in terms of a causal relation in which the present is caused by quantum states of the past and of the future taken in combination. == Theory == The two-state vector formalism is one example of a time-symmetric interpretation of quantum mechanics (see Minority interpretations of quantum mechanics). Time-symmetric interpretations of quantum mechanics were first suggested by Walter Schottky in 1921, and later by several other scientists. The two-state vector formalism was first developed by Satosi Watanabe in 1955, who named...

↑ lol, equivalent to std QM? but also a "minority interpretation"?!?

Semiclassical

4:36 AM

Is that really so strange? Most interpretations are equivalent in predictions to standard QM.

That's why it's an interpretation of QM and not a separate theory.

(e.g. attributing guided trajectories to particles in Bohmian mechanics.)

vzn

to me interpretations are "super QM theory candidates" as soon as any can be squeezed to (finally!) evince a super-QM physical prediction. and think the proliferation of candidates is not merely meaningless. (still awaiting the 21st century einstein...)

Semiclassical

eh. i find it more meaningful just how much QM has resisted that

vzn

lol agreed its a very tough nut to crack :P

← proud badge-carrying member of QUODs along with founder Bell & a host of others...

> absence of evidence ≠ evidence of absence™

Semiclassical

4:53 AM

@vzn no, but it's not something that'll convince someone else to quit their day job either...

vzn

← lol has wanted to quit day job several decades :|

Semiclassical

That line is a reminder to not jump to conclusions against a hypothesis, not an argument for jumping in the other direction.

vzn

feel something building, its in the air. its a very big wave coming. not today. :)

Semiclassical

When I feel something building, that's usually a sign I need to use the bathroom.

vzn

lol & so you fit right in around here... "your mileage may vary" :P

Secret

4:57 AM

Whatever big thing is coming about this timeline, it will come at 2020

Semiclassical

pretty sure they said the same thing back in 2012...

vzn

Semiclassical

A nice picture...and a good reminder that just because a wave looks big, that doesn't mean that the mountain is actually smaller :P

I do have hopes for making progress in understanding QM, mostly because I think learning how to make QC's and improving them further will necessitate such

Secret

Indeed indeed

Semiclassical

i mean, as proof of utility, it'd be hard to beat "I wouldn't be able to make X part of a QC work if I didn't use this interpretation"

vzn

5:04 AM

@Semiclassical not sure what you mean, think waves + mountains go together like yin + yang :P ☯️

Semiclassical

i mean that, while the mountain looks tiny compared with the wave, that's an issue of perspective

vzn

@Semiclassical how about super-QC computers :)

@Semiclassical both are forces of nature so to speak in different ways. sometimes a mountain can be yin & the wave yang. & some waves are bigger than mtns :) o_O

Semiclassical

until we actually know super-QM is a thing (and i'm dubious that it is) I find such speculation to be prodigal

vzn

← admitted full fledged contrarian... just like einstein, t' hooft, etc :P

Secret

5:34 AM

If super QC exists, one promise I want from it is to deliver a physical infinity at my doorstep so I can poke it

Semiclassical

6:01 AM

@Secret someone get this man an ouroboros

Dawood ibn Kareem

6:44 AM

@Secret I'd find it quite inconvenient, to have a physical infinity right by my front door. It would be awkward, having to go round the back to avoid dividing by zero.

Slereah

7:26 AM

morning chaps

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