Physicists do much more than build models. If all we did was construct models to fit observed data, we wouldn’t expect reliable success when extrapolating far beyond observed regimes. But physical theory has reach beyond modeling: it supports counterfactual claims about how the world would behave were certain details changed. It lets us reason about conditions that had never existed — like sustained nuclear fission — before they were observed anywhere in the universe.
We also see claims established in physics that are not merely less bad models, but stable, theory-independent constraints on reality — e.g. charge conservation, Lorentz invariance within a regime, the existence of atoms, quantization of energy levels, etc. These survived multiple deep theory shifts.
Within philosophy of science, this position is usually called scientific realism, and it’s not fringe among physicists. It’s just often implicit rather than argued out loud. The fact that we phrase results in model language doesn’t commit us to instrumentalism
I think it would be a great help if we spent more time talking about the philosophy of science among ourselves.
I'm being kinda pedantic here, but your first paragraph basically says "physicists don't just build models, they build models." The whole point of applied model theory is to exploit the proof theory of the formal metalanguage that the theory is written in (or more precisely, the soundness and/or completeness of the proof theory, since the metalanguage is usually implicit first-order logic) to derive new theorems that then directly translate to empirical predictions. The counterfactual extrapolation is built-in.
As for the idea that there are stable and theory-independent constraints on reality... maybe, but more data could always make those constraints fall apart, which brings us right back to "less and less bad models" if/when they do. And for what it's worth, science from an instrumentalist approach is procedurally identical to science from a realist approach, so it's not exactly a worthwhile debate in practice.
The way that "model" is used by actual physicists doesn't always seem to map super cleanly on to the way that it's used in model theory. Sometimes its meaning is relatively vague, just to denote some kind of representation of a real kind of physical system which tells you what "stuff" there is in it and how it evolves. These are sometimes referred to as "applications" of the more general principles of a theory. Classic example is a simple harmonic oscillator, where strictly speaking in the language of model theory what we have here is a class of models, as physicists' discussions of simple harmonic oscillators usually abstract away from the particular values of parameters like force constants and masses.
If model is being used in this slightly more vague but possibly more true-to-practice way, then those sorts of constraints on theories do sort of go beyond models. One can reason about the constraints in a way that is entirely independent of any particular representation of a physical system i.e. independently of any particular application of the theory. Even though, yes, you are in effect reasoning about very large collections of models (in the model-theoretic sense) all at the same time.
Also, there are some other examples that u/fox-mcleod didn't raise which are very general principles one could adopt, even more so than conservation and symmetry principles. E.g. "realism" (in the sense of realism about classical observables), "locality" (in the sense of locality that is raised in discussions of the EPR paradox which is stronger than the notion of locality that is strictly speaking required by relativity), and also perhaps "determinism". There might be some others which aren't coming to mind. Perhaps the action-reaction principle, as it is discussed both by Einstein and plays something of a role in contemporary foundational debates.
These are principles which exist at very general level and have often been appealed to in order to justify theory choice and interpretation in physics and it's (genuinely) not clear to me that we can think of the role of these sorts of principles in physics as a matter of merely building less bad models. Yes, empirical evidence may play a role in overturning them (if indeed any of them have been overturned), but the relationship is not one-sided in this way. The same goes for conservation and symmetry principle though perhaps in these cases it is even more true.
So even if we're going with the more precise model-theoretic definition, it does seem like actual reasoning about scientific theories goes beyond building less bad models because physicists look quite closely at what sorts of statements, principles, and laws are actually unifying classes of models together into a theory. They do not just blindly trust a nice model.
That makes sense and that physics progresses though better models rather than final truths. What I’m trying to get at is where the line is, philosophically, between
“this model works extremely well”
and
“this model licenses strong ontological language.”
For example, “X is fundamental” or “Y is physically real,” what—if anything—would justify that step beyond instrumental success? Or is the consensus that such claims are never justified within physics itself, only tolerated pragmatically?
I would go with looking at which assumptions the model is built from, like lorentzian relativity, conservation of energy, speed of light constraints, Heisenberg's uncertainty principle, the principle of least actions, etc. They are fundamental because they are taken for granted by the theory and essential for the model to work. Break them and you break the model (more or less... Depends upon which convention you are breaking).
Now, in the above, let's make something clear: being fundamental doesn't mean it exists, just that whatever reality is made of followed that principle at least within the valid conditions of the models which depends on it. An example are the combined gas laws. Although at the particles levels, things like pressure, volume and temperature aren't properly defined, the gas laws are fundamental in describing the behavior of gases.
Now, some people don't recognize the gas laws precisely because of that, and hope you can derive them from the quantum theory and/or some unified theory. I'm not sure that's possible due to it's possible that gas laws are an emergent phenomenon. Emergent phenomenon cannot be derived from its components. There are however a lot of different forms of emergence, not only weak or strong, but in how they manifest, but I don't think you can neglect them when talking about what is fundamental or not.
Those claims, in particular the ones about spacetime being fundamental or the quantum wavefunction being real, aren't just discussed in popsci. Those working in the foundations of physics and mathematical physics are often thinking about those sorts of questions.
Edit: They are also discussed in popsci, with varying levels of success...
> We don't often talk philosophy of science among ourselves.
But sometimes I hope you do. Every discipline needs to be philosophically aware of what they are, as a discipline of scholarship. Every discipline, especially disciplines that deal with the core aspects of reality, will benefit from a good understanding of Epistemology particularly about the notions of knowledge, belief, and justified vs. unjustified beliefs.
In any discipline, there are some things that we believe are true and even that our belief is justified. And that justified belief becomes an item of knowledge. But it is also sometimes the case that our justified belief is later shown to be false. We've all had this experience multiple times in life.
> But the main consensus as I see it, is that we don't prove facts about the world, we just build models that are less bad than the previous models.
I might want to agree (because it's a nice conservative statement that clearly is not "over-claiming" stuff). But I don't agree.
FACT /fak(t)/: a thing that is known or proved to be true.
TRUTH /tro͞oTH/: an accurate description of reality.
In order for a fact to be a fact, it has to be essentially undisputed among all parties to the conversation. So if you're arguing about and cannot stipulate to what is a fact and what is not, then those "facts" are not facts. A "fact" is not something that is unknown. Facts are a lot like axioms. I think that pretty much, a "fact" is either an "axiom" or a proven "theorem", or, for physical scientists, proven in observation/experiment. Axioms are not proven, but no one (really) is disputing the reality of the content of the axioms. I do not grant "flerfers" any ground here. They know what the facts are, they just won't admit to them.
The "truth" may be be unknown. There are a lotta truths we don't, yet, know about. Some truths are not facts. But purported facts that are not actually true, represent a false or mistaken conclusion from everyone in the conversation purporting or accepting the "facts". But, if everyone agrees to it, it's still a "fact" in the discussion, but unfortunately, will lead everyone astray until someone disproves it. A disproven fact is no longer a fact.
Even though, some new knowledge might adjust what we know in the Standard Model (which includes Quantum Mechanics), we can pretty well say that the Standard Model is "factual". There may be some focused details that we think are factual and turn out to be disproven in the future, but the theory fundamentals are the most thoroughly tested notions in the history of science.
Remember there is a subtle difference between the notions of "truth" and "fact".
In my opinion, for a physical theory to be considered factual is one that:
Submits itself to be falsified. I.e. the theory has to be about some interaction or some thing about reality that is different if the theory is true than if it's not. There needs to be a meaningful experiment (or multiple experiments) that would differentiate between outcome of the two alternatives. I am quite Popperian about falsifiability.
The theory is confirmed in such experiments, not falsified.
Couple things, Spacetime isn’t “fundamental,” it’s actually an emergent property. This is no longer debated. By “Quantum wave-function is real,” I’m assuming you mean it is a real, ontic, physical object opposed to a mathematical representation encoding probabilities and the observers knowledge. This is still being debated. The Navier Stokes equations objectively describe the motion of fluids, there can be no debate there. The mathematical model matches what we see exactly, what we learn about the evolution of the system by manipulating the mathematical equations that model it will be what happens in the physical system to an insanely accurate degree. The fact that mathematics describes reality is a mysterious fact, but it is a fact. And there is no ambiguity in the math itself. It gives details describing turbulence because physical systems act according to mathematical laws, for whatever reason.
A fact is not a scientific theory. It’s not debatable, and will not update according to new information. A fact is an objective, verifiable observation. “Objects fall” is a fact. The explanation of why they fall (gravity) is a scientific theory. A scientific theory can never be a “fact.” Certain aspects of the theory can be “true” beyond debate due to meeting certain conditions I outline below, but it’s never considered complete and “a fact,” the way “The Earth rotates” is a fact for example. As in, it cannot be updated or replaced with a better model.
A physical theory in physics is a mathematically represented model/framework that explains and describes a natural phenomenon, it makes consistent, verifiable predictions and accurately describes how physical systems behave. The predictions fit within previously rigorously supported frameworks. While information/data/facts about the system come from observation, mathematics, by applying the scientific method, etc. A hypothesis based on that information becomes a theory when it has been extensively tested, is replicated and verified over and over again independently, makes accurate predictions, and is supported by a robust amount of converging evidence. The theory is a model/explanation of the natural phenomena. Not the facts of the natural phenomena. Careful not to mistake the map for the territory.
For example, based on the evidence we had, the mathematical models we had, because it fit our current model, etc. we assumed spacetime was likely fundamental. But new experiments and mathematics show that it’s not, there are geometric structures underlying spacetime and we have a mathematical model of how it arises from these deeper, more basic constituents. This came from empirical data. We never assumed that “spacetime is fundamental” was a fact. The data in the experiments showing it isn’t are factual, but there are no claims as to whether or not the structures underlying Spacetime are fundamental or not.
The interpretation of the scientific data, the mathematics that model physical phenomena, as well as the framework we use to interpret the data within is philosophy. The data is factual (but not proven. It’s a fact that the sun rises each day, but can I prove it’ll rise tomorrow?) but the interpretation of the data is what is being debated, not the data itself. The math and observations regarding the quantum wave function are facts, how to interpret what it means, what it indicates, is philosophy because philosophy is model building. Philosophy doesn’t create empirical facts. The interpretation will become an accepted scientific theory when we have overwhelming scientific empirical evidence for the ontic reality of the wave function, it matches our predictions, etc. We don’t have that yet. And even then, it will be a model subject to updating or even being replaced by a new model that makes better predictions, takes all the evidence into account, etc. not a “fact.” New evidence that doesn’t match our current model leads to new models.
With mathematics that model what physical systems are doing, that can’t be anything but “factual” due to reality itself being a mathematical object (but whether reality is ontologically math or follows mathematical laws is debated in the philosophy of mathematics). However, the explanation as to why the math is what it is and what it means, is a theory and can be debated and updated with new information.
The frameworks and worldviews that we interpret scientific data within that inform our models and our interpretation of the results in studies (and even what we choose to study, what data we think is significant, etc.) are actually metaphysical ones. They contain unproven assumptions. For example “materialism/naturalism”is a metaphysical worldview that existed prior to the information learned through the scientific method, not as a result of it. We interpret data through that framework, the data itself doesn’t necessarily suggest it. And examining those untested and unverified assumptions, examining data that doesn’t fit that framework, etc. relies on the tools of philosophy
We’ve known the standard model/lambda cosmology is incomplete/approximate, or would even be fully replaced from the very beginning. Obviously, quantum mechanics isn’t even compatible with general relativity. We can’t even account for gravity in the standard model. Our current model fails to account for 95% of mass-energy in the universe. 95%. “Spacetime is fundamental” has never been considered a fact, or something that is necessary to be the case according to the math or experimental evidence. There has always been indications that it wasn’t, but empirical and mathematical evidence and theories that can incorporate anything beyond spacetime wasn’t there until recently. The standard model has always been considered “a useful story” and “the best framework we have to make predictions,” not as a “proven” complete theory of reality.
String theory, newer experimental data, and discoveries in mathematics show that Spacetime is emergent. But even in the standard model, we’ve known this. Spacetime literally breaks down at the plank length. It becomes a smooth quantum foam, distance and geometry are invalid at that level. That’s one of the inconsistencies and mathematical incompatibilities between quantum mechanics and general relativity. Unless you want to argue that reality disappears at 1.616x10^-35 plank lengths, spacetime is emergent from something more fundamental. The Ads/Cft correspondence shows that Spacetime geometry emerges from a deeper layer, potentially quantum entanglement.
Recent research gives empirical and further mathematical evidence that spacetime isn’t fundamental:
This is acknowledged, but asking why it’s not incorporated in the standard model is nonsensical, that should be obvious. If we could do that, we could unify GR and GM. We wouldn’t need string theory. There are newer models/frameworks that many physicists are accepting as the new “standard” because they are able to explain newer data the standard model can’t and resolve some of the inconsistencies and things like the information paradox in the standard model. The Holographic universe model and the information universe theory are the two best contenders and fully accepted by a lot of top physicists. In both spacetime is emergent. String theory also proves spacetime is emergent, but we haven’t found any empirical evidence for it what string theory describes. But that doesn’t mean that it doesn’t show anything “true,” for example it’s accepted there are more than 4 dimensions, and our standard model also does not account for that.
This geometric structure was recently discovered to exist beyond Spacetime:
"spacetime is fundamental": No idea what that is supposed to mean. Without an explanation, this is just babble.
"quantum wavefunction is real": Nothing is real, in Kant's sense of the thing in itself. All of the constructs we use in physics are entities that constitute a model.
"Navier-Stokes gives details describing turbulence": Huh? The Navier-Stokes equations say absolutely, positively nothing about turbulence.
Question: Where do you get this stuff? On reddit? 😈
For a theory to be "justified", it would have to provide a model that is at least as accurate, and have the same explanatory power (meaning, describe the same range of phenomena), as a competing theory. In addition, all esle being equal, the simpler theory will be preferred.
That’s fair and I understand that without clear definitions, those claims are sloppy or overstated.
My interest isn’t in defending those formulations, but in understanding whether physics ever licenses any ontological commitment at all, or whether instrumental success is the strongest claim the discipline can make by its own standards.
>whether physics ever licenses any ontological commitment at all
That question actually does have a fairly clean answer: No, it doesn’t, at least not by its own standards.
Physics produces models that organize and predict phenomena. Empirical success constrains those models, but it does not elevate their entities to claims about what exists in itself. As I had commented above, that boundary has been understood at least since Immanuel Kant, and arguably much earlier; Plato’s cave is still a remarkably apt metaphor here. As a matter of fact, I would argue that his metaphor is indeed isomorphous to the situation human cognition is in: Our view of the world should generically be expected to be a low-dimensional projection of the world as it is.
One can of course choose to treat elements of a successful theory as ontologically real, but that move is philosophical, not physical. Physics itself has no internal mechanism for distinguishing “useful structure” from “ultimate reality.”
In that sense, instrumental success isn’t just the strongest claim physics can make; it’s the only kind of claim it is structurally equipped to make. Anything stronger is an extra-theoretical commitment layered on top.
Physix_R_Cool | a day ago
Physicist here. We don't often talk philosophy of science among ourselves.
But the main consensus as I see it, is that we don't prove facts about the world, we just build models that are less bad than the previous models.
Those big claims you are quoting is mostly seen in popsci, and not between academics.
fox-mcleod | a day ago
Physicists do much more than build models. If all we did was construct models to fit observed data, we wouldn’t expect reliable success when extrapolating far beyond observed regimes. But physical theory has reach beyond modeling: it supports counterfactual claims about how the world would behave were certain details changed. It lets us reason about conditions that had never existed — like sustained nuclear fission — before they were observed anywhere in the universe.
We also see claims established in physics that are not merely less bad models, but stable, theory-independent constraints on reality — e.g. charge conservation, Lorentz invariance within a regime, the existence of atoms, quantization of energy levels, etc. These survived multiple deep theory shifts.
Within philosophy of science, this position is usually called scientific realism, and it’s not fringe among physicists. It’s just often implicit rather than argued out loud. The fact that we phrase results in model language doesn’t commit us to instrumentalism
I think it would be a great help if we spent more time talking about the philosophy of science among ourselves.
Keikira | 20 hours ago
I'm being kinda pedantic here, but your first paragraph basically says "physicists don't just build models, they build models." The whole point of applied model theory is to exploit the proof theory of the formal metalanguage that the theory is written in (or more precisely, the soundness and/or completeness of the proof theory, since the metalanguage is usually implicit first-order logic) to derive new theorems that then directly translate to empirical predictions. The counterfactual extrapolation is built-in.
As for the idea that there are stable and theory-independent constraints on reality... maybe, but more data could always make those constraints fall apart, which brings us right back to "less and less bad models" if/when they do. And for what it's worth, science from an instrumentalist approach is procedurally identical to science from a realist approach, so it's not exactly a worthwhile debate in practice.
Themoopanator123 | 17 hours ago
The way that "model" is used by actual physicists doesn't always seem to map super cleanly on to the way that it's used in model theory. Sometimes its meaning is relatively vague, just to denote some kind of representation of a real kind of physical system which tells you what "stuff" there is in it and how it evolves. These are sometimes referred to as "applications" of the more general principles of a theory. Classic example is a simple harmonic oscillator, where strictly speaking in the language of model theory what we have here is a class of models, as physicists' discussions of simple harmonic oscillators usually abstract away from the particular values of parameters like force constants and masses.
If model is being used in this slightly more vague but possibly more true-to-practice way, then those sorts of constraints on theories do sort of go beyond models. One can reason about the constraints in a way that is entirely independent of any particular representation of a physical system i.e. independently of any particular application of the theory. Even though, yes, you are in effect reasoning about very large collections of models (in the model-theoretic sense) all at the same time.
Also, there are some other examples that u/fox-mcleod didn't raise which are very general principles one could adopt, even more so than conservation and symmetry principles. E.g. "realism" (in the sense of realism about classical observables), "locality" (in the sense of locality that is raised in discussions of the EPR paradox which is stronger than the notion of locality that is strictly speaking required by relativity), and also perhaps "determinism". There might be some others which aren't coming to mind. Perhaps the action-reaction principle, as it is discussed both by Einstein and plays something of a role in contemporary foundational debates.
These are principles which exist at very general level and have often been appealed to in order to justify theory choice and interpretation in physics and it's (genuinely) not clear to me that we can think of the role of these sorts of principles in physics as a matter of merely building less bad models. Yes, empirical evidence may play a role in overturning them (if indeed any of them have been overturned), but the relationship is not one-sided in this way. The same goes for conservation and symmetry principle though perhaps in these cases it is even more true.
So even if we're going with the more precise model-theoretic definition, it does seem like actual reasoning about scientific theories goes beyond building less bad models because physicists look quite closely at what sorts of statements, principles, and laws are actually unifying classes of models together into a theory. They do not just blindly trust a nice model.
- Included some edits to better clarify my point.
[OP] Difficult_Fig7694 | a day ago
That makes sense and that physics progresses though better models rather than final truths. What I’m trying to get at is where the line is, philosophically, between “this model works extremely well” and “this model licenses strong ontological language.” For example, “X is fundamental” or “Y is physically real,” what—if anything—would justify that step beyond instrumental success? Or is the consensus that such claims are never justified within physics itself, only tolerated pragmatically?
ninoles | 16 hours ago
I would go with looking at which assumptions the model is built from, like lorentzian relativity, conservation of energy, speed of light constraints, Heisenberg's uncertainty principle, the principle of least actions, etc. They are fundamental because they are taken for granted by the theory and essential for the model to work. Break them and you break the model (more or less... Depends upon which convention you are breaking).
Now, in the above, let's make something clear: being fundamental doesn't mean it exists, just that whatever reality is made of followed that principle at least within the valid conditions of the models which depends on it. An example are the combined gas laws. Although at the particles levels, things like pressure, volume and temperature aren't properly defined, the gas laws are fundamental in describing the behavior of gases.
Now, some people don't recognize the gas laws precisely because of that, and hope you can derive them from the quantum theory and/or some unified theory. I'm not sure that's possible due to it's possible that gas laws are an emergent phenomenon. Emergent phenomenon cannot be derived from its components. There are however a lot of different forms of emergence, not only weak or strong, but in how they manifest, but I don't think you can neglect them when talking about what is fundamental or not.
Themoopanator123 | 17 hours ago
Those claims, in particular the ones about spacetime being fundamental or the quantum wavefunction being real, aren't just discussed in popsci. Those working in the foundations of physics and mathematical physics are often thinking about those sorts of questions.
Edit: They are also discussed in popsci, with varying levels of success...
rb-j | a day ago
Electrical Engineer here.
> We don't often talk philosophy of science among ourselves.
But sometimes I hope you do. Every discipline needs to be philosophically aware of what they are, as a discipline of scholarship. Every discipline, especially disciplines that deal with the core aspects of reality, will benefit from a good understanding of Epistemology particularly about the notions of knowledge, belief, and justified vs. unjustified beliefs.
In any discipline, there are some things that we believe are true and even that our belief is justified. And that justified belief becomes an item of knowledge. But it is also sometimes the case that our justified belief is later shown to be false. We've all had this experience multiple times in life.
> But the main consensus as I see it, is that we don't prove facts about the world, we just build models that are less bad than the previous models.
I might want to agree (because it's a nice conservative statement that clearly is not "over-claiming" stuff). But I don't agree.
In order for a fact to be a fact, it has to be essentially undisputed among all parties to the conversation. So if you're arguing about and cannot stipulate to what is a fact and what is not, then those "facts" are not facts. A "fact" is not something that is unknown. Facts are a lot like axioms. I think that pretty much, a "fact" is either an "axiom" or a proven "theorem", or, for physical scientists, proven in observation/experiment. Axioms are not proven, but no one (really) is disputing the reality of the content of the axioms. I do not grant "flerfers" any ground here. They know what the facts are, they just won't admit to them.
The "truth" may be be unknown. There are a lotta truths we don't, yet, know about. Some truths are not facts. But purported facts that are not actually true, represent a false or mistaken conclusion from everyone in the conversation purporting or accepting the "facts". But, if everyone agrees to it, it's still a "fact" in the discussion, but unfortunately, will lead everyone astray until someone disproves it. A disproven fact is no longer a fact.
Even though, some new knowledge might adjust what we know in the Standard Model (which includes Quantum Mechanics), we can pretty well say that the Standard Model is "factual". There may be some focused details that we think are factual and turn out to be disproven in the future, but the theory fundamentals are the most thoroughly tested notions in the history of science.
EdCasaubon | a day ago
Exactly.
OriEri | a day ago
I am troubled by the use of “factual.”
A theory is a tool for making predictions and the more ways it is successfully tested the higher the confidence there is in its other predictions.
If our mind is closed to the possibility that a theories predictions can be incorrect, it is no longer a part of science.
MaleficentJob3080 | a day ago
Within science facts are just statements about what we observe. Theories stand above them and describe the mechanism that makes those facts true.
Themoopanator123 | 16 hours ago
You might find this article interesting.
rb-j | a day ago
Falsifiablilty.
Remember there is a subtle difference between the notions of "truth" and "fact".
In my opinion, for a physical theory to be considered factual is one that:
knockingatthegate | a day ago
You know about spacetime and Navier-Stokes, but don’t know about what makes a theory compatible with our observations of reality?
AdvantageSensitive21 | 21 hours ago
I thought fractual was just a self repeating shape.
Spacetime is not realted to it.
Even though that is me claiming truth from a model based on assumptions.
So yeah claims and truth and all that stuff.
quantum-fitness | 9 hours ago
We cannot say if the wave function is real or just a tool, since you cannot directly measure it. Both are equally valid.
hologram137 | a day ago
Couple things, Spacetime isn’t “fundamental,” it’s actually an emergent property. This is no longer debated. By “Quantum wave-function is real,” I’m assuming you mean it is a real, ontic, physical object opposed to a mathematical representation encoding probabilities and the observers knowledge. This is still being debated. The Navier Stokes equations objectively describe the motion of fluids, there can be no debate there. The mathematical model matches what we see exactly, what we learn about the evolution of the system by manipulating the mathematical equations that model it will be what happens in the physical system to an insanely accurate degree. The fact that mathematics describes reality is a mysterious fact, but it is a fact. And there is no ambiguity in the math itself. It gives details describing turbulence because physical systems act according to mathematical laws, for whatever reason.
A fact is not a scientific theory. It’s not debatable, and will not update according to new information. A fact is an objective, verifiable observation. “Objects fall” is a fact. The explanation of why they fall (gravity) is a scientific theory. A scientific theory can never be a “fact.” Certain aspects of the theory can be “true” beyond debate due to meeting certain conditions I outline below, but it’s never considered complete and “a fact,” the way “The Earth rotates” is a fact for example. As in, it cannot be updated or replaced with a better model.
A physical theory in physics is a mathematically represented model/framework that explains and describes a natural phenomenon, it makes consistent, verifiable predictions and accurately describes how physical systems behave. The predictions fit within previously rigorously supported frameworks. While information/data/facts about the system come from observation, mathematics, by applying the scientific method, etc. A hypothesis based on that information becomes a theory when it has been extensively tested, is replicated and verified over and over again independently, makes accurate predictions, and is supported by a robust amount of converging evidence. The theory is a model/explanation of the natural phenomena. Not the facts of the natural phenomena. Careful not to mistake the map for the territory.
For example, based on the evidence we had, the mathematical models we had, because it fit our current model, etc. we assumed spacetime was likely fundamental. But new experiments and mathematics show that it’s not, there are geometric structures underlying spacetime and we have a mathematical model of how it arises from these deeper, more basic constituents. This came from empirical data. We never assumed that “spacetime is fundamental” was a fact. The data in the experiments showing it isn’t are factual, but there are no claims as to whether or not the structures underlying Spacetime are fundamental or not.
The interpretation of the scientific data, the mathematics that model physical phenomena, as well as the framework we use to interpret the data within is philosophy. The data is factual (but not proven. It’s a fact that the sun rises each day, but can I prove it’ll rise tomorrow?) but the interpretation of the data is what is being debated, not the data itself. The math and observations regarding the quantum wave function are facts, how to interpret what it means, what it indicates, is philosophy because philosophy is model building. Philosophy doesn’t create empirical facts. The interpretation will become an accepted scientific theory when we have overwhelming scientific empirical evidence for the ontic reality of the wave function, it matches our predictions, etc. We don’t have that yet. And even then, it will be a model subject to updating or even being replaced by a new model that makes better predictions, takes all the evidence into account, etc. not a “fact.” New evidence that doesn’t match our current model leads to new models.
With mathematics that model what physical systems are doing, that can’t be anything but “factual” due to reality itself being a mathematical object (but whether reality is ontologically math or follows mathematical laws is debated in the philosophy of mathematics). However, the explanation as to why the math is what it is and what it means, is a theory and can be debated and updated with new information.
The frameworks and worldviews that we interpret scientific data within that inform our models and our interpretation of the results in studies (and even what we choose to study, what data we think is significant, etc.) are actually metaphysical ones. They contain unproven assumptions. For example “materialism/naturalism”is a metaphysical worldview that existed prior to the information learned through the scientific method, not as a result of it. We interpret data through that framework, the data itself doesn’t necessarily suggest it. And examining those untested and unverified assumptions, examining data that doesn’t fit that framework, etc. relies on the tools of philosophy
quantum-fitness | 9 hours ago
Please tell me where in the standard model or lambda cosmology (or whatever is accepted now) does space-time emerge.
hologram137 | 7 hours ago
We’ve known the standard model/lambda cosmology is incomplete/approximate, or would even be fully replaced from the very beginning. Obviously, quantum mechanics isn’t even compatible with general relativity. We can’t even account for gravity in the standard model. Our current model fails to account for 95% of mass-energy in the universe. 95%. “Spacetime is fundamental” has never been considered a fact, or something that is necessary to be the case according to the math or experimental evidence. There has always been indications that it wasn’t, but empirical and mathematical evidence and theories that can incorporate anything beyond spacetime wasn’t there until recently. The standard model has always been considered “a useful story” and “the best framework we have to make predictions,” not as a “proven” complete theory of reality.
String theory, newer experimental data, and discoveries in mathematics show that Spacetime is emergent. But even in the standard model, we’ve known this. Spacetime literally breaks down at the plank length. It becomes a smooth quantum foam, distance and geometry are invalid at that level. That’s one of the inconsistencies and mathematical incompatibilities between quantum mechanics and general relativity. Unless you want to argue that reality disappears at 1.616x10^-35 plank lengths, spacetime is emergent from something more fundamental. The Ads/Cft correspondence shows that Spacetime geometry emerges from a deeper layer, potentially quantum entanglement.
Recent research gives empirical and further mathematical evidence that spacetime isn’t fundamental:
https://www.scientificamerican.com/article/what-is-spacetime-really-made-of/
https://www.quantamagazine.org/can-space-time-be-saved-20240925/#:~:text=Well%2C%20the%20traditional%20view%20is,should%20eventually%20take%20its%20place.
This is acknowledged, but asking why it’s not incorporated in the standard model is nonsensical, that should be obvious. If we could do that, we could unify GR and GM. We wouldn’t need string theory. There are newer models/frameworks that many physicists are accepting as the new “standard” because they are able to explain newer data the standard model can’t and resolve some of the inconsistencies and things like the information paradox in the standard model. The Holographic universe model and the information universe theory are the two best contenders and fully accepted by a lot of top physicists. In both spacetime is emergent. String theory also proves spacetime is emergent, but we haven’t found any empirical evidence for it what string theory describes. But that doesn’t mean that it doesn’t show anything “true,” for example it’s accepted there are more than 4 dimensions, and our standard model also does not account for that.
This geometric structure was recently discovered to exist beyond Spacetime:
https://www.quantamagazine.org/physicists-discover-geometry-underlying-particle-physics-20130917/
https://scgp.stonybrook.edu/wp-content/uploads/2020/11/Tessler.pdf#:~:text=In%202013%20Arkani%2DHamed%20and%20Trnka%20have%20discovered,its%20discovery%2C%20the%20amplituhedron%20was%20extensively%20studied.
EdCasaubon | a day ago
Question: Where do you get this stuff? On reddit? 😈
For a theory to be "justified", it would have to provide a model that is at least as accurate, and have the same explanatory power (meaning, describe the same range of phenomena), as a competing theory. In addition, all esle being equal, the simpler theory will be preferred.
RedJamie | 21 hours ago
NS is absolutely related to turbulence
[OP] Difficult_Fig7694 | 15 hours ago
That’s fair and I understand that without clear definitions, those claims are sloppy or overstated. My interest isn’t in defending those formulations, but in understanding whether physics ever licenses any ontological commitment at all, or whether instrumental success is the strongest claim the discipline can make by its own standards.
EdCasaubon | 13 hours ago
>whether physics ever licenses any ontological commitment at all
That question actually does have a fairly clean answer: No, it doesn’t, at least not by its own standards.
Physics produces models that organize and predict phenomena. Empirical success constrains those models, but it does not elevate their entities to claims about what exists in itself. As I had commented above, that boundary has been understood at least since Immanuel Kant, and arguably much earlier; Plato’s cave is still a remarkably apt metaphor here. As a matter of fact, I would argue that his metaphor is indeed isomorphous to the situation human cognition is in: Our view of the world should generically be expected to be a low-dimensional projection of the world as it is.
One can of course choose to treat elements of a successful theory as ontologically real, but that move is philosophical, not physical. Physics itself has no internal mechanism for distinguishing “useful structure” from “ultimate reality.”
In that sense, instrumental success isn’t just the strongest claim physics can make; it’s the only kind of claim it is structurally equipped to make. Anything stronger is an extra-theoretical commitment layered on top.