The h Bar

enumaris

23:02

So far I've seen all of 1 improved result using the deep speller

dentis -> dentist went from "is a named entity" to "not a named entity" like it should be

lol

Wanting to be anAndroidDevelor

My question got was voted to closed and was told to ask it here

so Im just gonna dump it here

here it comes

I'm very interested by this idea of implementing ideas from computer science to physics. When I say this, I don't necessarily mean writing computer programs that simulate physical phenomena like in computational physics but implementing idea such as entropy and idea of computation-ability into physics. For example idea of entropy is used to model the ideal gas equation. There are many other field in physics that involve idea of computer science as stated here.

Are there research institutes or university research groups that specialize in research that implement theoretical computer science…

oh wait

was this a wrong place?

excuse me if it is

ACuriousMind

In this chat, we unite physics and CS by just being programmers who once did physics :P

@WantingtobeanAndroidDevelor No, you're right - this is the physics.SE main chat

Wanting to be anAndroidDevelor

but that kind of is exactly not what I mean in the question

that would be a computational physics

I don't mean "programming" I mean theoretical computer science like say Turin's machine entropy etc

ACuriousMind

The closest intersection between TCS and physics is probably in the theoretical aspects of quantum information/quantum computing

Wanting to be anAndroidDevelor

but surely there should be more general field like say people are always debating about if this world could be "simulated" or can we say that this physical universe is Turin complete? etc etc

like quantum computing just seems like a practical application of quantum mechanics in computer science

ACuriousMind

23:08

@WantingtobeanAndroidDevelor The name's Turing and in my opinion all the stuff about "simulation" and such is much closer to philosophy than physics.

Wanting to be anAndroidDevelor

sure simulation is a bit off topic

ACuriousMind

Actual physicists mostly aren't interested in whether this world "is" a simulation, they're interested in actually simulating it

Wanting to be anAndroidDevelor

but surely we can show that the universe is Turing complete

or lets say is there a maximum entropy the universe can hold?

etc

so entropy of the universe can never be infinite? so what is the maximum etc

enumaris

o.o

ACuriousMind

@WantingtobeanAndroidDevelor What does that even mean? Turing completeness is a property of abstract machines, not pf physical systems

Wanting to be anAndroidDevelor

23:10

I think there are questions that would be considered a physical question rather than philosopgiacl

But we use Turing machine even if abstract in real logical problems like halting problem

ACuriousMind

@WantingtobeanAndroidDevelor How does that have anything to do with CS? Entropy is a perfectly ordinary physical quantity - while there are interesting analogies to purely informational entropies like Shannon entropy, it is not inherently about computer science

Wanting to be anAndroidDevelor

and no machine can solve problem that Turing complete machine can not

so well if this universe is a bit more than Turing complete then we have a problem

because that would mean it can solve more problems than what we thought could which shouldn't happen

so we should expect the model of universe to be Turing complete, or at least less than Turing complete

ACuriousMind

A Turing machine is an abstract model of a computing device with infinitely many discrete memory cells. It is not clear that there is any way to map our universe to that.

The question "Is the universe Turing complete?" is not well-defined without further assumptions

Wanting to be anAndroidDevelor

it is only abstract because it requires infinite memory

there are many physical machine that is considered basically Turing complete

such as this general computational machine we use

ACuriousMind

Physical models of the universe are not in terms of computing devices, but commonly in terms of differential equations

One does not map to the other straightforwardly.

Wanting to be anAndroidDevelor

23:16

you don't have to map it even

you could just say that this universe is capable of computing a Turing complete machine, ie our computer, therefore the universe must also be Turing complete

and the problem is basically solved

ACuriousMind

Sure, if you are willing to apply ill-defined terms to things, you can say anything :P

Wanting to be anAndroidDevelor

but the definition comes from computer science

a well accepted one and is experimented with

ACuriousMind

@WantingtobeanAndroidDevelor It is not obvious that the universe is a computing device in the sense of computer science!

That's an assumption

Wanting to be anAndroidDevelor

why?

surely by definition of a computational machine I can easily argue that it is

ACuriousMind

@WantingtobeanAndroidDevelor That's not how it works. You claim the universe is Turing complete, you have to explain what that's supposed to mean.

Wanting to be anAndroidDevelor

23:19

If a universe is turing complete then it is capable of computing any problem that we know is able to be computed

that is the useful fact we can extract from saying that the universe is turing complete

ACuriousMind

It is not clear that the universe "computes" anything!

Wanting to be anAndroidDevelor

and so what would your definition of "compute" be?

enumaris

what I'm getting from this conversation is...we are all computer simulations and our lives don't matter... existential crisis intensifies

Wanting to be anAndroidDevelor

I mean that is just your interpretation of what I am saying

all I want to say is that there are so many concepts in computer science that we can implement into our physical understand

ACuriousMind

As an analogy, take a slide rule. I can use the slide rule to get the values of e.g. logarithms by shifting it around in a peculiar fashion. Did the slide rule "compute" the logarithm?

Wanting to be anAndroidDevelor

23:21

and is there like a group who constantly do this?

enumaris

intensifying...

Wanting to be anAndroidDevelor

I don't know what a slide rule is

but if its a physical machine then you could say that the machine computed it yes

ACuriousMind

@WantingtobeanAndroidDevelor An analog device people used before widespread calculators

Wanting to be anAndroidDevelor

then yes a computer doesn't have to be electronic

ACuriousMind

@enumaris Our lives don't matter regardless of whether we're living in a simulation :P

Wanting to be anAndroidDevelor

23:23

I mean

enumaris

@ACuriousMind you computed it, and you are part of the universal simulation, and so ipso facto the universe computed it

Wanting to be anAndroidDevelor

Im not saying we live in a simullation

enumaris

@ACuriousMind existential crisis reaching critical levels...

Wanting to be anAndroidDevelor

all Im saying is we can implement computer science idea in physics

for e.g. energy conservation

we generally just assume that its a law and we don't question it

but maybe there is a more computer science explanation to it

enumaris

It's not a law in GR

Wanting to be anAndroidDevelor

23:24

that is true right

ACuriousMind

@WantingtobeanAndroidDevelor I assure you that no physicist "just assumes that energy conservation is a law"

enumaris

GR says "get rid of it, it ain't cool" and thus it's gotten rid of

Wanting to be anAndroidDevelor

yes

ACuriousMind

For almost a hundred years, we have understood conservation laws as manifestations of deeper symmetries through Noether's theorem.

Wanting to be anAndroidDevelor

so you give theory and back up with experiment that is science

ACuriousMind

23:25

When the symmetry is not there (as in GR), then the conservation law doesn't hold

Wanting to be anAndroidDevelor

so if there is a computer science idea that is backed up by experiment I see no reason why we can'T bring them into physics

ACuriousMind

Maybe you're fixating on CS simply because you haven't seen how rich theoretical physics already is

enumaris

Even when the symmetry is there (as in e.g. the Schwarzschild Solution), the conservation law takes a peculiar form that doesn't really jive with the classical mech conception

Wanting to be anAndroidDevelor

ok so e.g. in ideal gas

danielunderwood

Well CM doesn't strictly require it either

Wanting to be anAndroidDevelor

23:27

we are implementing ideas of computer science to model them even though in practice its the other way around

enumaris

gravitational redshifting for example removes "energy" from light rays...what is conserved is $\xi_a k^a$ with $\xi^a$ the killing vector field corresponding to "stationary" and $k^a$ the wave vector of the light which...I still haven't figured out a great classical mechanics analogy for...

ACuriousMind

@WantingtobeanAndroidDevelor Sorry, what? The thermodynamical conception of entropy far precedes even the tiniest spark of computer science!

Wanting to be anAndroidDevelor

I mean Im not arguing about energy conservation

Im saying that we could explain all these property that energy conservation do not hold from the view point of computer science rather than GR

I mean thats why I said its the other way around

enumaris

Energy in GR is weird is kinda the...thing...

Wanting to be anAndroidDevelor

you could argue that the study of ideal gas lead to development of CS

that is what I mean right we just say its kinda the thing and i know that you don't need an intuitive explanation since it can be backed up by just mathematical logic to be true

ACuriousMind

23:30

@WantingtobeanAndroidDevelor Only if you know nothing of the actual development of either statistical mechanics or CS

Wanting to be anAndroidDevelor

but you could just explain them in terms of computational machine

ACuriousMin I don't really know what you are trying to argue

that computer science have no place in physics or something else i don't even know

I mean your arguments too me just seems to revolve around physics is superior to computer science for some reason

ACuriousMind

I'm trying to say that, even though there are interesting intersections between modern physics and computer science, it is completely ahistorical to claim that one led to the other.

Wanting to be anAndroidDevelor

and what Im trying to ask is what lead to the other

like when we do maths

enumaris

pure math can't lead to physics - physics requires additional inputs (physical postulates)

Wanting to be anAndroidDevelor

they could generally be explained in the field of computer science and like so surely it should interest some people to explain physical properties and laws from the view of computer science

you seems to always think that Im trying to say one is superior to the other and that is not what im trying to say

infact I don't believe that one is superior to other all these subject requires others interconnected like a mesh structure

so as I say my initial question is is there a field who's job is to explain physical phenomena and theory in physics in terms of computer science?

ACuriousMind

23:36

No, I'm saying that they are disjoint fields that investigate structures that a priori are incommensurable, i.e. you cannot directly compare an arbitrary physical system to a computing device because they simply are not the same thing

Wanting to be anAndroidDevelor

surely you can't compare arbitrary physical system because they are arbitary

they need to be defined to be compared to anything

enumaris

@WantingtobeanAndroidDevelor not that I know

Wanting to be anAndroidDevelor

like we use maths in physics all the time

enumaris

I know of no field which tries to explicitly use results from computer science to describe the physical world (apart form computers)

Wanting to be anAndroidDevelor

we have physical interpretation of what things in maths means

enumaris

23:39

using math in physics is kinda like using computers to simulate physical situations

but you said that's not what you're looking for

Wanting to be anAndroidDevelor

like with your argument its like saying we can never use complex number in physics because they are arbitary and physics and maths is a different subject

I mean using a computer to simulate physical situation is very different from theoretical computer science

thats just programming basically

which is a field of computer science but its not theoretical

ACuriousMind

@WantingtobeanAndroidDevelor No. Many things in math have no physical interpretation whatsoever. In fact, no structure in math has a unique physical interpretation. You need to take a physical system - or a class of physical systems - and define a mathematical representation that corresponds in some well-defined way to what we can actually observe.

Wanting to be anAndroidDevelor

like you say you can just do the same thing with computer science but really the other way around

enumaris

uhhhh

ACuriousMind

The natural numbers do not mean anything. Only when we decide that they count a particular quantity (like a number of atoms) we assign a physical meaning to them. What I've been trying to say all this time is that you haven't exhibited any such assignment between things in computer science and physics.

Wanting to be anAndroidDevelor

23:43

we can define a computational model that represents the physical universe in some well defined way to what we can actually observe

but you can kind of do a bit more with computer science

because you can look at them in terms of information rather than some arbitrary units

enumaris

wat

Wanting to be anAndroidDevelor

like let me ask you this, if there is a particle with 0 mass and 0 charge have absolutely neutral property in everything that doesn't interact with anything we observe

do we say that the particle exist?

and the answer Im expecting is no, physically it doesn't exist

and maybe since we never observed this particle it might have contradicting property to particles we have observed

so maybe this particle just move around the universe at a constant speed just passing through everything, we could say it physically doesn't exist but from the point of information science, if the information exists, then it does exist

ACuriousMind

I'd say you have lost me, but I'm not sure I was ever following you.

Wanting to be anAndroidDevelor

so what do you say

?

would you say if there were a particle with no mass no momentum no property that make it interact with what we observe. Would you say it physically exist?

because I would say no.

ACuriousMind

I don't know what it means to say that there is a particle we cannot observe even indirectly.

enumaris

23:50

a sterile neutrino that doesn't mix with the active flavors? Those have mass tho...

hmmm

Wanting to be anAndroidDevelor

you don't know what it means because its hypothetical perhaps but you could say its a bit like neutrino except it isn't

so what would you say?

I think physically speaking you can just say it doesn't exist

user1732

Define: exist

ACuriousMind

@WantingtobeanAndroidDevelor No, I don't know what it means because I don't know what "there is a particle with property X" means if we cannot actually do any experiments to ascertain it has property X (even if property X is "has no mass, etc.")

You seem to be making some sort of difference between "the particle exists" and "the particle physically speaking exists". I don't know what that difference is.

Wanting to be anAndroidDevelor

I mean just take it as a fundamental fact, so I guess you are saying that we can not say it exists or it doesn'T exist because you can never run an experiment to back it up physically

enumaris

Maybe it's semantics but saying there is a particle with XYZ properties implies existence already...

Wanting to be anAndroidDevelor

23:54

exactly right?

I mean not everything can be physically proven

especially things that we can't observe

enumaris

Sure...

Wanting to be anAndroidDevelor

and also phenomena that can'T be repeated

also things that you can't define

those are some fundamental stuff thats required to scientifically prove anything

enumaris

But then you're heading in the direction of spirituality and philosophy which physicists tend to not discuss very much lol

Especially not within the purview of physics

Wanting to be anAndroidDevelor

just wait a sec what I stated about provable is a very scientific stuff it doesn't require philosophy

its like junior school science question

user1732

-_-

enumaris

23:56

I don't follow

Wanting to be anAndroidDevelor

but maybe we can theories or theoretically show, using theory that is experimentally backed up, that something exists but just not be able to show it with experiment like a particle that doesn't interact

danielunderwood

If it doesn't interact, I don't know that there's any way to view it as physics

enumaris

Not be able to show experimentally even in theory?

Wanting to be anAndroidDevelor

exactly

being able to show it in theory is not experimental proof

enumaris

Or not able to show experimentally in practice? E.g. gravitational waves before LIGO

Wanting to be anAndroidDevelor

23:59

kind of like neutrino, neutrino was theorized then experimentally observed

what if there was a very credible theory that predict existence of particle that we can not observe physically

ACuriousMind

It was observed because the theory made predictions of how it could be observed! That is completely different from a "particle that we cannot observe".

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