/sci/ - Science & Math

>>12619571

>What is the Correspondence principle.

>>12619816
Correspondence principle only works on GR. Limit of low speeds reproduces classical mechanics. Continuum mechanics reproduces continuum mechanics. All is good.

Every instance of the correspondence principle applied with quantum mechanics is an asspull with no analytics.

the standard model is not a discrete model of reality.

>>12619875
Particles are definitely discrete mate. Next you're gonna tell me that group theory is a theory of continuum mechanics?

>>12619891
quantized particles != discrete spacetime and forces

>>12619902
Spacetime is a metric, really nothing to do with your model. It's like the fabric in which you construct your model. The forces are generated by gauge bosons, which are discrete particles. The fields are generated by flickering of anti-particles and particles from the vacuum. It's all discretized mate.

>>12619913
you're clearly a first or second year undergrad. stop trying to talk about things you don't understand.

>>12619917
Ph.D. graduate. Instead of trying to poison the well, address the argument.
>onoes that's a good point
>i can't debunk
>attack credibility

>>12619571
>>standard model of particle physics
>A discrete model of reality
>>Gravitational force
>A continuum model of reality
Both of them treat spacetime as continuous. Continuity of physical quantities in GR could be seen as an approximation to basically infinitely many eigenstates. I mean, there's still the vacuum energy problem, but in principle, I don't see how these are profound contradictions.

>>12619933
>Ph.D. graduate
LMFAO no fucking chance mate. if so I'm incredibly sorry for where you got the degree because it didn't prepare you for your own field
>address the argument
your foundational principles for your argument are incorrect, so there's nothing to argue against.
>forces are generated by gauge bosons
no, they are generated by the gauge fields. you don't need a PhD to know this basic distinction
>the fields are generated by...
there's nothing to say to this because it's a nonsense statement. it is simply not true
>it's all discretized
your argument is still that "particles are quantized" which has nothing to do with discretization. I bet you think the planck length is a fundamental length unit too.

>>12619957
>Both of them treat spacetime as continuous.
This is disingenuous. It's like saying that Economics and Physics both use statistics and falsifiability, therefore Black-Scholes formula and Schrodinger's equation are compatible and should be unifiable. Obviously bullshit. The metric under which you construct a model has nothing to do with the model's ingredients.

Think of it this way: if what you're saying has merit, then Spacetime is the Quantum Gravity we so elusively searched for! Nobel Prize, pls.

>>12619962
>they are generated by the gauge fields.
And what constitutes the field? What generates them in QFT? If you tell me the gauge boson isn't the generator of the gauge field, then you're legitimately retarded. And since the gauge boson (de facto particle) generates the field, even the field is a discrete model. Think about it: the ingredients in your Lagrangian are what? Fields? Yeah, sure. If so, then are you saying the Standard Model of Particle Physics is just bullshit? No particles? Just fields?

>>12619984
not him but
In qft field is more fundamental then a particle. Particles (momentum and spin vawe packets) are eigenvalues of fields. You dont have fields from particle lagrangian, infact quantum relativistic particle lagrangian complicates this picture. There is a reason why we have qft and not relativistic quantum particle lagrangians.

Math aside, this is really a question of chicken and the egg. There is no sufficient information to really determine if fields or particles are more fundamental its just that math works beter when fields are more fundemental.

>>12620002
I always learned you had to promote the particle description to fields. Regardless, if fields are more fundamental, then we've been lying to the public: the standard model of particle physics has nothing to do with particles. It's the standard model of fields!

>>12619973
>This is disingenuous
How?
>It's like saying that Economics and Physics both use statistics and falsifiability
That's not a valid analogy. Especially your conclusion. I never said that both relying on continuous spacetime means they are unifiable, I said your argument doesn't imply that they're not unifiable.

>>12620016
we are lying to the public whenever we speak about theoretical physics. Cant really convey math into natural language and not lose some details.

>>12619571
Either you get used to String theory or fuck off.

>>12620018
I guess I'd phrase it as follows:
Spacetime is the metric of reality. It's of course going to be consistent. Geometrically, it's continuous. Sure. But that doesn't imply Standard Model of Particle Physics can be expressed via continuum mechanics.

>>12620028
This isn't even about math, it's about simple accurate language. Calling a bunch of fields "particles" isn't just losing some details, it's outright false. It'd be like if I described the inverse square law as an inverse square root law.
>Well, you know, we always lie, and some stuff just gets lost in translation, yaknow?

>>12620035
>that doesn't imply Standard Model of Particle Physics can be expressed via continuum mechanics
I don't see how this poses a fundamental challenge for the unification of QFT and GR. I'm not saying there aren't any challenges, I mentioned one myself and the situation looks dire for other reasons, but I just don't understand what exactly you mean. Care to elaborate a bit more?

>>12620016
>I always learned you had to promote the particle description to fields.
then you never learned qft. you start with fields. the "promotion" is by promotion fields to quantum operator fields.
>the standard model of particle physics has nothing to do with particles.
once again you're mixing things up. the standard model is a model of the particles that result from the underlying fields. it is not misrepresented, but if you misunderstand it then that is your own problem. if the nomenclature is the issue then call it whatever you want, but that doesn't change what it is.

>>12620049
The vacuum effect would be a result of trying to generalize a discretized description of nature to large scales. It'd be like saying, if I have 10^(20) particles of sand on a beach, via particle description, I'd get a model with results inconsistent with a fluid description of sand on the beach. If I generalize QFT to large scales, I'll get aberrations that don't exist when I evaluate large scales via a fluid mechanics perspective.

Same problem with stars. We cannot simultaneously describe them via fluid mechanics and with particle mechanics. It's usually just an asspull.
>>12620056
Then how, exactly, do these underlying fields generate particles?

>>12620076
>Then how, exactly, do these underlying fields generate particles?
particles are the excitations of the fields. somebody has already mentioned this to you

>>12620087
See, here's the problem: that doesn't make any sense. If particles are excitations of the field, then what are the fields themselves? You're gonna say with a straight face there exists an electromagnetic field, with positive charge, permeating all of spacetime, from which electrons spontaneously spring into existence? Malarkey. In contrast, if the field has no charge itself, how does the electron acquire its charge? It just magically springs into existence at the same time the electron is generated by the field? Hah!

>>12620076
Ah, now I know what you mean. Sure, I mean, you're applying two different concepts to situations where neither of them are accurate but that's what you always have to do with models first before applying them; check if they are valid in the regime you're describing.
I still don't see how that is an argument against a possible unification. Quantum mechanics becomes Newtonian mechanics when [math]\hbar \rightarrow 0[/math] and GR becomes Newtonian mechanics when v << c. Similarly, a unified theory could yield QM and GR in different limiting cases, where one becomes a discrete description of particles while the other becomes continuous.

>>12620101
>If particles are excitations of the field, then what are the fields themselves?
Find out and claim your Nobel.
>there exists an electromagnetic field, with positive charge
No, it's neutral.
>from which electrons spontaneously spring into existence?
Yes, and their anti-particles.
>how does the electron acquire its charge?
Electroweak symmetry breaking, resulting in C-invariance.

Not that Anon btw.

>>12620104
>Quantum mechanics becomes Newtonian mechanics when h -> 0
I mean, yes, I'm familiar with these. But I've always found this correspondence principle dubious. It always looks like an asspull. Analytically, taking h -> 0 usually gets you something weird, and you need to do a whole lot of massaging and heuristics to make it work.

In GR, the limit is trivial and fundamental. It makes me suspect GR is far more fundamental and correct than is the SM of particle physics.
>>12620118
>Find out and claim your Nobel.
So you have these fields. Well defined. And your claim is they generate particles via excitations, yet we don't even know what these fields are? Give me a break.
>X makes particles.
>We know these particles.
>What's X?
>....

>>12620129
>So you have these fields. Well defined. And your claim is they generate particles via excitations, yet we don't even know what these fields are? Give me a break.
>>X makes particles.
>>We know these particles.
>>What's X?
>>....
Uh, yeah. It's always been this way. What's your problem with that?
>pre-Maxwell
>have light
>it's made of photons
>but what are photons made of?
>...

>>12620136
I'd say it's more like
>photons describe light!
>light is made of photons
>okay so what's a photon?
>ugh?
My point is about circularity, not about fundamental properties. For example:
>fields exist
>particles are excitations of field
>so what's the electric field?
>...?
In other words: if an electron arises from a neutral electromagnetic field, then how does an electron generate its own electomagnetic field that attracts a proton?

>>12620162
>In other words: if an electron arises from a neutral electromagnetic field
Oh, no, it arises from the electron field. That's not an electromagnetic field. So it's not circular, but you're still descending (or shifting questions to other questions) ad infinitum.
E.f. in string hypothesis, they say we have three generations of particles because there are three odd-dimensional holes in the Calabi-Yau manifolds attached at each spacetime point. It explains why we see three particle generations, but shifts the question to the holes. It's a property of physics we have to accept unfortunately.

>>12620180
I guess the disconnect is I don't believe in string theory.

>>12619571
can you break down each word in your post?

>>12619571
>What is statistical mechanics

>>12619891
Are you retarded? Lie groups describe continuous transformations, hence why they have infinite elements.
Also, QFT is a field theory, it is continuous.

this is such a sexy thread <3 pls never die :)!

>>12620180
>>12620180
Also, circularity is still there.
>electron field!
>electrons are excitations of electron field
>okay so what's an electon
>the excitations of the electron field!
>no, I mean, what's the "electron" when you say "electron field"? If electrons don't exist yet, and may never exist, and is just a field, then what's the electron?
>the thing that's excited from the field!

>>12620184
Me neither. That's why I said string hypothesis. Science isn't a matter of belief though.

>>12620234
No. If the word "electron" confuses you, call the field something else. It's not circular. There's a particle field, it gives rise to electrons when excited. Simple as that.

>>12619836
No its not. Go read about Heisenberg.

>>12619891
Particles are not well defined. See hawking and Ellis.

>>12619984
Yes you idiot. How are you not getting this? The standard model is a model of FIELDS. it's quantum Field theory.
>>12620076
Bro this is completely wrong, we can model fliud mechanics using an approximation of small particles because fluids are made from atoms

>>12620184

That's great. It is correct in almost every description of nature (up to what we can measure) and is currently used in almost every area of high energy physics.

Its not really about believing it. Its a description of the work which works. If the underlying principle isn't correct it doesn't matter, at our energy level it is correct.

>>12620251
>There's a particle field, it gives rise to electrons when excited.
So does the same field give rise to tau leptons? The answer is no. Meaning you need an independent field, the "Tau Field". Or should I just call this "particle2 field"? What's unique and different about these two fields by which they generate different particles when excited?

>>12620255
>is currently used in almost every area of high energy physics.
Who's going to tell him?

>>12620264
They behave differently. That's what makes them different.

Its not like we know what things are fundamentally. We don't. That's why we research it. We don't know why the speed of light is constant or why electrons are the way they are. They just are that way and if you can't accept it then fuck off and join a church.

>>12620275
Of course the tripfag is a brainlet. How cliché.

>We don't know why the speed of light is constant
We do. The correct quantity to describe movement in hyperbolic spacetime is rapidity. Velocity is the linearization of rapidity and c a constant that falls out of this.
>why electrons are the way they are
Their properties follow directly from the symmetry groups.

>>12620264
>So does the same field give rise to tau leptons? The answer is no
Well, it's difficult. There's mixing, but the situation is not quite clear yet.

>>12620333
Oh yeah sure thing mate, so tell me what hyperbolic ST we live in? Ads? The ESU? How do we know this for certain, and not that our current maps are simply good up to a scale.

>Follows from the symmetry group.

And you think this works perfectly? Read up on spontaneous symmetry breaking. If you're versed in QFT you can look at the Gross Neveu action for a toy example. It shows how symmetries are not always rigid and in some cases can be broken all together. Symmetries provide an excellent framework for describing the fermions, but they are not a perfect representation of these things at all energy levels.

>>12620361
>moving the goalpost
Of course the SM doesn't correctly work anymore when you're going beyond it. Same for relativity. What's even your point? These models are accurate in their respective regime, and the properties they imply are accurate in that regime as well.
>How do we know this for certain
Never. You said so yourself.

>>12620371
He's a string theorist. I wouldn't give him much mind.

>>12620371
You're saying we know why the speed of light is constant, we don't. That's a ridiculous statement and I'd like you to provide a reason for it. You say it's because of hyperbolic space, but we use hyperbolic spaces in phys BECAUSE the speed of light is constant. It's not the REASON the speed of light is constant.

I'm not moving goalposts. I'd find you hard pressed to find any paper or evidence giving a reasoning for light to be constant.

Say for example I asked you why the photoelectric effect exists. You might say 'Because light is perhaps like a particle with discrete energy. You would be right, as far as we know that is a good reason that nature behaves that way. It tells us something about the behaviour of our world. We can even test this and be happy that our theory holds.

The constant nature speed of light is not a product of our understanding of GR, in fact it is an axiom.

>>12620403
Of course we know why the speed of light is constant dude. It follows directly from Maxwell's equations. The only assumptions are the permittivity and permeability of free space are constants.

>>12619571

the universe is analog not digital

>>12620426
But what's the natural frequency??? Is it idiocy?

>>12620403
>You say it's because of hyperbolic space, but we use hyperbolic spaces in phys BECAUSE the speed of light is constant. It's not the REASON the speed of light is constant.
No. We know from experiment that spacetime is hyperbolic. Hence, rapidity describes movement. To build the bridge to Newtonian physics we can linearize for small v, which leads to a constant factor that is the speed of light.
You're right historically, but that's meaningless when arguing from first principles.
>Say for example I asked you why the photoelectric effect exists
I'd argue we know from the standard model that photons are gauge bosons (which are described by symmetric wavefunctions). The rest follows from that.

>in fact it is an axiom
No. You're probably confusing this with the equivalence of inertial and gravitational mass.

>>12620392
Good point.

>>12620483
We knew about the photometric effect first and used it to build quantum theory. Our theory comes from observation and not vice verca. We wouldn't know what gauge bosons even are without the photoelectric effect. Our mathematical MODELS describe reality, they do not define reality.

You mention first principles, one of the proofs of hyperbolic space is the speed of light. Not vice verca. Please for the love of God read a book on the scientific method.

>>12620663
You're confusing historic development with reasoning.

>>12620663
>We knew about the photometric effect first and used it to build quantum theory.
No, that was black body radiation. Photoeffect suggested corpuscles à la Newton. It was only later explained by quantum theory.

mathematician here, when you faggots talk about "fields" you better be talking about either a) vector fields, or b) algebraic fields. If not then I will kindly ask you to cease and desist, thank you.

>>12620880
we are retard. physical fields are just scalar, vector, or tensor fields

>>12619816
well?? what is it?

>>12620972
ok that's fine, carry on then

>>12620101
>If particles are excitations of the field, then what are the fields themselves?
your view is just scientific realism. a field is jut a map and maths are just a tool.

>>12620880
>>12620972
>>12621567
Those are different things. In the most general theories, they're tensor fields.
Scalars like mass aren't fields.

>>12620431
that part is relative

>>12621675
if multiple discrete fields interact and fold then you can get mass

>>12621781
Yes, and mass is emergent in that case, and not a field.