“Explosions considered fundamental” If you ask for a simple answer to how a car works, you might get an answer like: ”Cars work by having tiny explosions in the engine that push pistons to power the car.”
When I was a kid, this felt like a satisfying explanations. Explosions push things, you can see that happening in movies and games.
But really it is rather lacking. It doesn’t say whyexplosions push, and there does exist a lower explanation for why explosions push — the kinetic theory of gasses.
This is even though “explosions are an ontologically fundamental object that applies force away from the explosion” is a simple hypothesis. You can code an explosion in a video game super easily: you just have a sphere collider (simple!) to detect what is affected and apply a force vector (simple!) to those objects pointing away from the center. It would be much harder to code a game where the air obeys the kinetic theory of gasses.
“Explosions are fundamental” loses out to the Kinetic Theory of Gasses because the Kinetic Theory of Gasses can explain more things — not only explosions, but air conditioners, wind, etc.
And once you know the Kinetic Theory of Gasses, calling every expansion of gas due to increased heat an “explosion” is really weird. Why does the breeze blow? “Sunlight causes an explosion that rises and then air flows to fill the space.”
I don’t have much to say about this, I just thought it was an interesting case.
The “tiny explosions” mental model doesn’t make new predictions in the way that the Carnot model does, but it does encode and compress an enormous amount of useful pre-discovered information. For example, that a car engine is hot like fire and will burn you, that if you mix gasoline and air and light it, it will explode, that a car engine will be made of strong stuff, that a car engine is in something of a delicate engineered balance, and if you make large changes to it, it will typically become extremely loud and catch fire. I think this is enough to distinguish the “tiny explosions” model from typical “guess the teacher’s password” knowledge.
This is a special case of a more general principle: Explanations that are complicated in some language can still be favored on the evidence, you just need more evidence for complicated explanations than simple explanations.
You can in fact live in a complex or arbitrary universes, and just because you have a simplicity prior doesn’t mean your universe has to reflect that simplicity.
Wait though, how does quantum dynamics give rise to the Kinetic Theory of Gasses?
See, this is why I hate quantum physics. It implies that we don’t actually understand anything all the way down.
I console myself by thinking that explanations at different levels can be simultaneously valid. Explosions push stuff and people do things they believe they should are both acceptable explanations for most purposes even without tracking them down to the quantum level.
We understand quantum physics. I mean, I don’t, personally. But I know people who do. And I own books that could explain the whole thing to me if I had the stamina to get all the way through them.
The kinetic theory of gases was developed decades before quantum mechanics. It gives the same results whether its constituent particles are quantum or classical, at least for ordinary phenomena like explosions.
If I understand correctly, we (not me but people) understand what quantum physics predicts but not why the universe works that way. Professionals disagree dramatically on what underlying reality makes the wave equations work as they do.
That would seem to put it on the same epistemic footing as everything else: empirically verifiable but not a base-level explanation.
It’s to the point that there’s articles being written days ago where the trend starting a century ago of there being professional risks in trying to answer the ‘why’ of QM and not just the ‘how’ is still ongoing.
Not exactly a very reassuring context for thinking QM is understood in a base-level way at all.
Dogma isn’t exactly a good bedfellow to truth seeking.
Well, it seems like you have very high standards for “epistemic footing”; indeed standards so high that nothing can meet them. I’m willing to settle for mere empirical verification, mathematical elegance, and logical coherence. All of which are satisfied by our present understanding of quantum field theory.
The controversy over “underlying reality” continues because all theories of underlying reality reproduce identical experimental predictions, so arguments in this area are philosophy rather than physics, and so rather inconclusive.
Of course we don’t know how to reconcile our empirically valid theory of quantum mechanics with our empirically valid theory of gravity, so at least one of the theories is wrong.
I think my standards for epistemic footing are exactly what you mention. What Ii’m saying is that, without an explanation of why quantum mechanics works as it does, it’s not really a privileged level of explanation. Explanations at higher levels of analysis—chemical, psychological, etc—can all have those properties and be adequate in themselves. Coherence across levels is of course valuable as it’s more logical coherence.
I guess maybe it is just an abstraction like any other. I can’t put my finger on it but it seems weird in a way that abstracting fingers into a “hand” does not. Maybe something to do with the connotation of “explosion” as “uncontrolled and destructive” when internal combustion is neither.
“Explosions considered fundamental”
If you ask for a simple answer to how a car works, you might get an answer like:
”Cars work by having tiny explosions in the engine that push pistons to power the car.”
When I was a kid, this felt like a satisfying explanations. Explosions push things, you can see that happening in movies and games.
But really it is rather lacking. It doesn’t say why explosions push, and there does exist a lower explanation for why explosions push — the kinetic theory of gasses.
This is even though “explosions are an ontologically fundamental object that applies force away from the explosion” is a simple hypothesis. You can code an explosion in a video game super easily: you just have a sphere collider (simple!) to detect what is affected and apply a force vector (simple!) to those objects pointing away from the center. It would be much harder to code a game where the air obeys the kinetic theory of gasses.
“Explosions are fundamental” loses out to the Kinetic Theory of Gasses because the Kinetic Theory of Gasses can explain more things — not only explosions, but air conditioners, wind, etc.
And once you know the Kinetic Theory of Gasses, calling every expansion of gas due to increased heat an “explosion” is really weird. Why does the breeze blow? “Sunlight causes an explosion that rises and then air flows to fill the space.”
I don’t have much to say about this, I just thought it was an interesting case.
The “tiny explosions” mental model doesn’t make new predictions in the way that the Carnot model does, but it does encode and compress an enormous amount of useful pre-discovered information. For example, that a car engine is hot like fire and will burn you, that if you mix gasoline and air and light it, it will explode, that a car engine will be made of strong stuff, that a car engine is in something of a delicate engineered balance, and if you make large changes to it, it will typically become extremely loud and catch fire. I think this is enough to distinguish the “tiny explosions” model from typical “guess the teacher’s password” knowledge.
This is a special case of a more general principle: Explanations that are complicated in some language can still be favored on the evidence, you just need more evidence for complicated explanations than simple explanations.
You can in fact live in a complex or arbitrary universes, and just because you have a simplicity prior doesn’t mean your universe has to reflect that simplicity.
Wait though, how does quantum dynamics give rise to the Kinetic Theory of Gasses?
See, this is why I hate quantum physics. It implies that we don’t actually understand anything all the way down.
I console myself by thinking that explanations at different levels can be simultaneously valid. Explosions push stuff and people do things they believe they should are both acceptable explanations for most purposes even without tracking them down to the quantum level.
Two comments:
We understand quantum physics. I mean, I don’t, personally. But I know people who do. And I own books that could explain the whole thing to me if I had the stamina to get all the way through them.
The kinetic theory of gases was developed decades before quantum mechanics. It gives the same results whether its constituent particles are quantum or classical, at least for ordinary phenomena like explosions.
If I understand correctly, we (not me but people) understand what quantum physics predicts but not why the universe works that way. Professionals disagree dramatically on what underlying reality makes the wave equations work as they do.
That would seem to put it on the same epistemic footing as everything else: empirically verifiable but not a base-level explanation.
It’s to the point that there’s articles being written days ago where the trend starting a century ago of there being professional risks in trying to answer the ‘why’ of QM and not just the ‘how’ is still ongoing.
Not exactly a very reassuring context for thinking QM is understood in a base-level way at all.
Dogma isn’t exactly a good bedfellow to truth seeking.
Well, it seems like you have very high standards for “epistemic footing”; indeed standards so high that nothing can meet them. I’m willing to settle for mere empirical verification, mathematical elegance, and logical coherence. All of which are satisfied by our present understanding of quantum field theory.
The controversy over “underlying reality” continues because all theories of underlying reality reproduce identical experimental predictions, so arguments in this area are philosophy rather than physics, and so rather inconclusive.
Of course we don’t know how to reconcile our empirically valid theory of quantum mechanics with our empirically valid theory of gravity, so at least one of the theories is wrong.
I think my standards for epistemic footing are exactly what you mention. What Ii’m saying is that, without an explanation of why quantum mechanics works as it does, it’s not really a privileged level of explanation. Explanations at higher levels of analysis—chemical, psychological, etc—can all have those properties and be adequate in themselves. Coherence across levels is of course valuable as it’s more logical coherence.
I guess maybe it is just an abstraction like any other. I can’t put my finger on it but it seems weird in a way that abstracting fingers into a “hand” does not. Maybe something to do with the connotation of “explosion” as “uncontrolled and destructive” when internal combustion is neither.