The h Bar

shintuku

03:02

are there any affordable materials that could be used as a filter to measure presence in air of diameter 2.5 μm particles?

Leaky Nun

05:44

@ACuriousMind I feel like this sort of implies (even tho I know it doesn't) that there is some macroscopic properties about light that cannot be derived from each individual photon that makes up the light

ACuriousMind

07:21

@LeakyNun there is a difference between "this property cannot be derived from the notion of individual photons" and "this property is a property of the collective state and not of the state of individual photons"

as an analogy: Temperature is a property of statistical systems, not of the individual particles of which they consist

but that doesn't mean "temperature cannot be derived from each individual particle" - the behaviour of the macroscopic systems is derived from the microscopic dynamics

likewise, definite phases are a property of coherent states, not of individual particle states. That doesn't mean you can't derive the properties of coherent states from the properties of the single-particle states

Ryder Rude

08:14

@PM2Ring yes. I think this experiment shows that mental states are different from what can be described using mathematical systems like physics models

But we shud also note that, as shown in the "responses" section, most physicalists agree with this. Those physicalists just differentiate between "linguistic physicalism" and "physicalism"

Physicalism generally means that everything, including mental states, is "physical stuff". So mental states can still b physical stuff while also not being contained in linguistic structures like information bits or physics models

But then, idk what the definition of "physical stuff" is supposes to b here. I think they're just defining "everything thay exists" as "physical stuff"

In that case, "physicalism vs idealism" is just a matter of semantics imo.

But the real meaningful conclusion here is that mental states are not contained in linguistic structures like mathematics. This is what even most physicalist agree with in their response to "Mary's room"

Jack Rod

09:00

@JohnRennie hi

Sir do we require quantum transistor as well to make quantum computer

How the transmission of such wave work I mean it is quite confusing to understand how a computer will look like

Quantum Computers, Explained With Quantum Physics

►

Jack Rod

09:15

@ACuriousMind hi

Anything to add?

John Rennie

@JackRod I don't know, sorry :-(

I know next to nothing about how quantum computers are built.

Jack Rod

@JohnRennie ok

Slereah

09:49

Looking into Puthoff's polarizable vacuum's theory of gravity for fun

Apparently invalidated by the earth rotation rate experiments

adsabs.harvard.edu/full/1972ApJ...177..775N

Slereah

12:00

fun part is, while crazy people have used his theories to push weird ideas, Puthoff didn't even think it was a serious theory?

He just considered it as a pedagogical tool

PM 2Ring

12:16

@RyderRude IMHO, even if we knew that the qualia of red happens when some particular chunk of brain hardware "runs" some specific chunk of software, that still doesn't help us to explain what the qualia of red feels like to someone who's never experienced it.

We have a similar problem with less abstract stuff, too. Eg, We could describe an apple as a list of different molecules in some geometrical arrangement. But that description is hard for a human to assimilate. It wouldn't be a very helpful way to describe an apple to someone who's never seen or tasted one.

So even though we can reduce stuff to fundamental physics, we generally need to look at stuff at a higher level of abstraction. Similarly, when we want to understand a piece of software we read the source code, not the machine code.

user 85795

If we only knew more about the brain...

Slereah

I'm a brain

you can ask me

PM 2Ring

Speaking of quantum computing, Scott Aaronson recently gave GPT-4 a quantum computing exam. It managed to score a "B", but made some weird mistakes that a human would be very unlikely to make. scottaaronson.blog/?p=7209

2

Slereah

Oh apparently Eric Davies, crazy man, is a friend of Puthoff

So maybe Puthoff is to blame

user 85795

What was so special about Einstein's 🧠

PM 2Ring

12:29

@user85795 Maybe. But my point is that explanations in terms of brain structure and function are of limited usefulness if they're too complicated for a human to understand.

user 85795

We can't even understand the brain of a fruit fly.

Ryder Rude

@PM2Ring so, in ur opinion, the information about qualia has been conveyed in physics. It's just that it's not practically useful for a human to get an idea of qualia. But an extremely intelligent Mary would be able to assemble the information and get an idea of what the qualia is

user 85795

Ryder Rude

I mean a fiction-level intelligent Mary. She wud be able the assemble the information

I personally believe that we can nevr get an idea of what shape something is by the information about the set of points. We can know the shape from the set of points only if we already know what shapes mean becuz we r familiar with shapes

Like, if u have an equation describing a set of points... there is no shape in there. U can only map it to a shape becuz u already know what shapes mean

"Shape" is an inexplicable qualia here

Nihar Karve

12:50

holy smokes

Ryder Rude

Is this bot activity

Nihar Karve

looks legit

Ryder Rude

What are the advantages and disadvantages of being Solipsist in your experience? @ACuriousMind @Slereah

I tried being Solipsist today. One disadvantage is that u can feel alone even in a room full of close people

One advantage is that u r more spontaneous

Solipsists feel alone imo

It can also lead to less empathy but im not sure. I think prolonged belief in solipsism may do that

PM 2Ring

@RyderRude I said "Even if". We can get a rough idea of brain regions associated with sensory experience via functional MRI, but it's still pretty crude. But my main point is that our brains can't understand stuff if its complexity is too high. In particular, we can only understand stuff that's simpler than our mind / brain. And even then the information has to be arranged carefully or we can't assimilate it.

ACuriousMind

@NiharKarve Extremely likely to be LLM output, not only because of the timing, but also because of several characteristic repeated formulations across different answers (e.g. watch out for last paragraphs starting with "In summary,")

Ryder Rude

13:03

@PM2Ring u r again talking about the Godel stuff :P. If the Godel stuff applies, this also means we shud be able to understand the qualia of less complex organisms, in principle. But in practice, it would still b impossible

@PM2Ring I personally believe that mental states are their own thing, and are only correlated to the mathematical models of the universe's ontology. But we shud also note that there may not be any final mathematical model. This would mean that any correlations are always approximate.

PM 2Ring

@RyderRude Kind of, but it's simpler than Gödel's theorem. This is just about the limitations of finite systems, whereas Gödel's theorem involves infinite sets. OTOH, Hofstadter discusses this stuff in Gödel, Eschet, Bach.

Ryder Rude

I mean that it may even be meaningless to talk about an exhaustive mathematical description of the brain

Nihar Karve

@ACuriousMind you're right, on closer reading

Ryder Rude

I mean that there is no reason to expect mathematics or language to exhaustively describe all that exists. Mathematics has its own place in real-world applications, but there has never been an indication that mathematics sits at the root of everything

PM 2Ring

@RyderRude Yeah, shapes is a good topic. I might understand a lot of the geometry of a tesseract (a 4D hypercube), and look at apps & anims illustrating it. chat.stackexchange.com/transcript/71?m=57912812#57912812 But I don't feel that I can understand what the shape of a 4D structure is really like.

ACuriousMind

13:12

@RyderRude I don't know what that means. I don't choose my beliefs about the world based on how they make me feel, I can't "try solipsism": Either I already believe solipsism is true and then I cannot stop believing it any more than I can stop breathing, or I don't believe in it and I can't "try believing" in it any more than I can start breathing water

That you can "try being solipsist today" suggests to me that you have a fundamentally different idea of what believing in something means than I do

Ryder Rude

Ooh yeah. Belief would mean something more permanent :P. Maybe i didnt believe in solipsism today. I just pretended

Becuz ofc, i doubt solipsism. So i dont believe in it

@PM2Ring yeah. That animation looks completely 3D to me

I've seen some mathematicians say that they've trained themselves to visualise 4D. But idk. I think they've bought into their own hype :P

The closest thing I can do to visualise 4D is to imagine four intersecting planes.

Like the corner of a room, but there are four planes

Slereah

@ACuriousMind Well obviously you're not a pragmatist

I don't think there's technically any issue in visualizing 4D in your mind

I'm not sure it's possible but on a formal level there isn't really any objection to it

Your brain just receive discrete informations from your eyes, there's nothing fundamentally three dimensional about how you perceive vision

Ryder Rude

Yeah. Becuz the mind picture is 2D anyway. And still, it gives u an idea of 3D

Slereah

All the 3D reconstruction is done at the processing level

ACuriousMind

@RyderRude ...what do you mean, "the mind picture is 2D anyway"

Slereah

13:22

Although learning to manipulate 4D images, idk how you'd do it

Ryder Rude

This is the idea i use in visualising the room corner with four planes. I just use the trick my brain uses for 3D

ACuriousMind

are you one of these people who can't rotate a cube in your mind's eye

Slereah

@ACuriousMind You're only seeing a cube on the projective plane you fool

Ryder Rude

I mean the picture is still 2D. It's like how you can draw a cuboid on paper

Slereah

of your mind's eye

ACuriousMind

13:23

well, in that sense you could argue we never see 3d anyway

you don't even need to add "in our minds"

Ryder Rude

Yeah, this is y Slereah says there's no fundamental restriction to 4d

Slereah

Different reason

Ryder Rude

What was ur reason? @Slereah

Slereah

see above

Ryder Rude

U said something about discrete information. Do u mean bits?

Like the image converted to binary

Slereah

13:25

no, just how vision is processed

you just have points of lights from the optic nerves being sent to your brain

Your brain doesn't know how those are positioned with respect to each other

ACuriousMind

@RyderRude without getting into details about vision you're just receiving "hey, there's this color here: <color information>" from a more-or-less 2-dimensional surface at the back of your eyes

the "3d" part is entirely constructed in the brain, that's why there's all these funny visual illusions where equally sized 2d objects can appear in different sizes because they trick the part of your brain that does the perspective processing

Slereah

We're lucky enough that most objects in the world are rigid

Ryder Rude

I personally use the trick my brain uses to make me feel the 3D corner of the room. My brain uses 120 degree angles with some depth perception. So i use almost 90 degree angles with some depth stuff to visualise 4D corner of room @ACuriousMind @Slereah

Slereah

Might be hard to reconstruct how space works otherwise

ACuriousMind

what

(to both preceeding messages :P)

Ryder Rude

13:29

Like u can get a feel for 3d co ordinate system on a 2d paper by drawing 3 lines at 120 degrees from a point

So they r never at 90 degrees.

Slereah

If objects constantly deformed you'd have a hard time having a 3D idea of what they look like :p

Ryder Rude

But u gotta pretend they have some depth that makes them 90

Slereah

Imagine trying to make a model of a cube in your mind if it deformed as you rotated it

ACuriousMind

@RyderRude oh, you're talking about an isometric projection

Slereah

@ACuriousMind I know you're familiar with isometric 3D

Ryder Rude

13:31

Yeah. I use this stuff to get a feel for 4d room corner

But i cant manipulate 4d objects. Its just a static image

But perhaps we can have 4D dreams. It would b cool to navigate such a room

ACuriousMind

@Slereah sure, but I think if I think about 3d "abstractly" I actually see the typical projection from drawing 3d diagrams in vector algebra or whatever, i.e. oblique projections

I don't think my mind's eye operates in isometric projection :P

Slereah

@ACuriousMind I just meant from RPGs

Don't you think in little scenes from Disco Elysium

ACuriousMind

the visuals are the least important part of the typical DE scene

Slereah

I dunno

ACuriousMind

the voices in my head just use the textbox without accompanying visuals :P

more limbic system screaming at me, less Kim being supportive

Slereah

13:36

@ACuriousMind Do you hear UPDATED MY JOURNAL in your brain

ACuriousMind

I heard it just now when I read your message

that and "you must gather your party before venturing forth" are seared into my brain

Slereah

Planescape Torment was a tough game for me because I played it in the early 00's and the version that existed back then was sometimes unplayable on modern PCs

It would just flip the fuck out when particle effects appeared

crash the whole PC

Maybe I should give it another playthrough, it's been a while

Game kind of loses steam when you reach Carceri tho

Typical case of game running out of money/idea/time at the end so they just make you kill some monsters

ACuriousMind

13:55

yeah, see also everything Troika did

Slereah

Ahah

I do think about them a lot for that too yes

Boy Vampire did not evolve nicely

ACuriousMind

Bloodlines is so good...for about the first half, and if you use the community patch that fixes a lot of gamebreaking bugs :P

Slereah

it is also very bad because the first and second half are so different that you can really fuck yourself in spending your skills

I bought a bunch of skills for investigating urban mysteries and then I'm stuck in some dungeons fighting ghouls

Those skills do not transfer well

Had similar issues with Arcanum when you go to that big spooky castle

not enough XPs spent on being a big strong man

ACuriousMind

14:12

I don't think I ever played Arcanum more than an hour or so

Slereah

It's an alright game

Did you get troubles at the bridge?

ACuriousMind

I think I just got fed up with the strange combat system

Slereah

My main isometric RPG strategy for combat is "Click attack and wait for it to be over"

It's not the most nuanced

ACuriousMind

the turn-based mode feels very slow and the non-turn-based version feels oddly sped up I think

Slereah

It works better in some games than others

Still have nightmares about Jagged Alliance 2

aka "What if Baldur's Gate happened in Nicaragua"

Ryder Rude

14:34

If possible, pls try solipsism for a day and report ur experiences

Slereah

Finally I can kill anyone I want

Ryder Rude

I wont b responsible for that :P

Try at ur own expense

Slereah

Well you're not even a person so no

Ryder Rude

Tell that to the judge :P

bolbteppa

14:49

@DIRAC1930 Again discussed in that section

Relativisticcucumber

15:45

hi - i want to clarify something about solving the schrodinger equation. so if we solve the equation, say for the hydrogen atom, my understanding is that what we get is basically the atomic orbitals, and that these are the possible states the electron could be in, but we need more techniques to determine which states are most probable, which states an electron is in for a given situation, etc.

[...] but I encountered a case recently where time evolving a hamiltonian showed the population transfer between states. my confusion is how we go from solving the schrodinger equation which defines our possible states to having a case where solving the schrodinger equation actually tells you how something is moving through these levels/states?

ACuriousMind

@Relativisticcucumber are you sure you're talking about the same "Schrödinger equation" in both of these cases

because when we look for the atomic orbitals, we're solving the time-independent Schrödinger equation, which is imo a silly name for "looking for the eigenstates of the Hamiltonian"

when you do time evolution, then you're solving the time-dependent Schrödinger equation, which is what I'd usually just call the Schrödinger equation

Relativisticcucumber

isnt time dep valid for stationary states + time dep term and we just dont see evolution

ACuriousMind

in formulae, the difference is $H\psi = E\psi$ (time-independent, looking for eigenfunctions, acts on a state $\psi\in \mathcal{H}$ in Hilbert spacd) and $\partial_t \psi = H\psi$ (time-dependent, looking for trajectories, acts on a trajectory $\psi : \mathbb{R}\to \mathcal{H}, t\mapsto \psi(t)$

I, too, was often confused about what was going on until I separated these two notions clearly in my head

Relativisticcucumber

yes what i mean is i thought stationary states with time dep term tacked on are solutions to time dep schrod equation

wait maybe im missing the point

ACuriousMind

@Relativisticcucumber they are a basis of solutions

Relativisticcucumber

15:50

right right so my thought is we can consider the time dep schrod equation to be what we are using for both cases i mentioned in my OG question

@ACuriousMind that is my response to this

ACuriousMind

@Relativisticcucumber okay, then the next question is: Was the Hamiltonian there the same in both cases?

because what you describe sounds to me like perturbation theory: You start with some $H_0$ and solve for its eigenstates, and then you look at time evolution of these states under a perturbed Hamiltonian $H_0 + \epsilon H_\text{int}$

Relativisticcucumber

no! in the case with the population transfer there was an interaction term added but i think this is what im misunderstanding. so i thought an interaction term should merely allow more states to be accessed but shouldnt really tell how they are populated?

@ACuriousMind that message was in response to this not the second message

ACuriousMind

@Relativisticcucumber what does "allow more states to be accessed" mean?

the Hilbert space doesn't change if you add an interaction term, both $H_0$ and $H_\text{int}$ are operators on the same Hilbert space and so is their sum

Relativisticcucumber

so the example i am thinking of is if i have a wavefunction for my hydrogen atom and it says im in one stationary state, we see nothing in the time evolution, but if we add a magnetic field i think then i should see something in the evolution, but what i thought is that this new hamiltonian (H0 + Hmag) just shows us that now the electron could be in more states than before, but it doesnt tell us what actually happens to this wavefunction? i think i am missing something though

ACuriousMind

I don't know what you mean by "more states"

the Hilbert space for a spinless single particle is $L^2(\mathbb{R}^3)$

Relativisticcucumber

15:55

i mean if originally it's in s1 maybe it can move to s2 or something like this

ACuriousMind

@Relativisticcucumber So the idea of this kind of perturbation theory is this: We start with the interaction turned off, the Hamiltonian is $H_0$. So the system starts in an eigenstate of $H_0$ (insert some general argument why systems will settle into energy eigenstates here) and time evolution is trivial

Then we turn the interaction on, the new Hamiltonian is $H = H_0 + H_\text{int}$, and in general the eigenstates of $H_0$ will not be eigenstates of $H$

so their time-evolution is no longer trivial, and they start to evolve into superpositions of the eigenstates of $H_0$ (they're no longer eigenstates of the time evolution but they still form a basis of the Hilbert space - the spectral theorem doesn't care whether the operator we're applying it to is the Hamiltonian or not)

Relativisticcucumber

I think what I am confused about is this: "So the system starts in an eigenstate of $H_0$".

i see this conceptually like we can have a system in any linear comb of eigenstates

but hmmmm

ACuriousMind

see physics.stackexchange.com/q/69559/50583 for an explicit discussion of my "insert some general argument" above

Relativisticcucumber

okay okay so is it like we independently solve for these eigenstates then we put our system in some linear combination of these states then the time evolution tells us how it moves from there on? and these are two entirely separate processes?

ACuriousMind

@Relativisticcucumber Yes, the eigenstates still form a basis of the Hilbert space - if you know how each of the eigenstates evolves, you know how any state evolves

Relativisticcucumber

16:03

somehow i am still confused. i feel these two processes have nothing to do with eachother so im not seeing how they follow the same formalism, namely that the time dep schrod equation achieves both, which is defining the eigenstates of the system as well as how things move through these eigenstates

ACuriousMind

there is no "eigenstate of the system"

there are only eigenstates of operators

it's just convenient to use the eigenbasis of the Hamiltonian instead of some other operator, because, as you already said, the eigenstates of $H_0$ evolve under time evolution by $H_0$ as $\mathrm{e}^{\mathrm{i}H_0t}\lvert E_i\rangle = \mathrm{e}^{\mathrm{i}E_i t}\lvert E_i\rangle$, which is very simple

So we usually start by writing the state of our system as $\lvert \psi\rangle = \sum_i c_i\lvert E_i\rangle$

Relativisticcucumber

okay i see so the hamiltonian defines the eigenstates and the wave function does indeed tell us where things will be found in terms of some combination of these eigenstates so the time evolution evolves the wave function across these states because they are built into the hamiltonian -- this is my updated view

that was meant to be stated as a question lol

ACuriousMind

I'm not really sure what you mean by that

maybe we should write down some formula

when we change the Hamiltonian to be $H$, we first figure out what $\mathrm{e}^{\mathrm{i}Ht}\lvert E_i\rangle$ is - it's no longer a stationary state, but we can compute what this is

this, by linearity, then also tells us what the evolution of any state under the new Hamiltonian is: $\mathrm{e}^{\mathrm{i}Ht}\lvert \psi\rangle = \sum_i c_i \mathrm{e}^{\mathrm{i}Ht}\lvert E_i\rangle$

so we don't lose anything by just focusing on the $H_0$ eigenstates and their time evolutions

I don't think there's anything more to this

Relativisticcucumber

okay maybe i should ask for a clarification. i was told today by my professor the exact statement "solving the schrodinger equation for a hydrogen atom tells you nothing about where you will find an electron, it only tells you where you, theoretically, could see an electron". this statement has thrown me into a great deal of confusion so i am wanting to confirm if it is even true.

i guess the issue is not about time evolution since i buy everything you said but is about the conceptual interpretation of this

maybe that quote is not even rigorous enough to discuss

ACuriousMind

I really don't know what that statement is supposed to mean

like, it's not wrong or right, I see they wanted to communicate something there but I have no idea what it was :P

Relativisticcucumber