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Can someone explain what he means when he says there is no physical?

ukj 6y ago
It's just an all-encompassing word that's not subject to testability/falsification. Some people say the universe is physical. Other people say the universe is material. Other people yet say it's neither of those two. Nobody can explain what the observable difference would between a physical and a material universe.
tsimionescu 6y ago
The main point he is making is that this notion of "the physical universe" comes from pre-Newtonian science's attempts to model the world as a mechanical machine, where every interaction can be explained by direct physical contact between parts of the system, and the laws of motion. This project seemed largely promising and successful, especially once Descartes came up with the idea of separating the mind, which didn't seem mechanical, from the physical world. So, after Descartes, the world looked pretty simple: there is a physical world that all works like a bunch of gears, and a mental/spiritual world where the mind exists, and these two together explain the universe. However, Newton came along and discovered the law of universal attraction (gravity), which meant that the "physical world" does not in fact work like a machine, that there is no kind of physical contact that can explain the motion of the heavens. Of course, that also opened the way to the possibility that many other interactions are similarly immaterial, so the whole project falls apart. We do not in fact have a theory of the "physical world" and what it is. I would note that Quantum Mechanics, even though it is highly unsatisfactory to our intuition, does get us back to a conception of a purely mechanical physical world (though with wave-like mechanics instead of gears). Unfortunately, for now, it STILL, 400 years later, hasn't solved the problem that Newton discovered. Gravity is still not accountable for in a mechanical, contact based way like the other forces are, even though GR has given a much more detailed model of how it works, and we have discovered gravity waves that prove it is not instantaneous action at a distance. Of course, the main interpretations of QM have also given up realism , so while we do have an account of a physical world, it is unreal in a sense (that is, the world does not have any definite properties until you measure something; in QM a tree falling a in a forest really doesn't make any sound unless someone/something hears it). We also don't yet have any idea of how to define measurement, even though it is a kind of physical process.

ukj 6y ago

It's just an all-encompassing word that's not subject to testability/falsification. Some people say the universe is physical. Other people say the universe is material. Other people yet say it's neither of those two. Nobody can explain what the observable difference would between a physical and a material universe.

tsimionescu 6y ago

The main point he is making is that this notion of "the physical universe" comes from pre-Newtonian science's attempts to model the world as a mechanical machine, where every interaction can be explained by direct physical contact between parts of the system, and the laws of motion. This project seemed largely promising and successful, especially once Descartes came up with the idea of separating the mind, which didn't seem mechanical, from the physical world. So, after Descartes, the world looked pretty simple: there is a physical world that all works like a bunch of gears, and a mental/spiritual world where the mind exists, and these two together explain the universe. However, Newton came along and discovered the law of universal attraction (gravity), which meant that the "physical world" does not in fact work like a machine, that there is no kind of physical contact that can explain the motion of the heavens. Of course, that also opened the way to the possibility that many other interactions are similarly immaterial, so the whole project falls apart. We do not in fact have a theory of the "physical world" and what it is. I would note that Quantum Mechanics, even though it is highly unsatisfactory to our intuition, does get us back to a conception of a purely mechanical physical world (though with wave-like mechanics instead of gears). Unfortunately, for now, it STILL, 400 years later, hasn't solved the problem that Newton discovered. Gravity is still not accountable for in a mechanical, contact based way like the other forces are, even though GR has given a much more detailed model of how it works, and we have discovered gravity waves that prove it is not instantaneous action at a distance. Of course, the main interpretations of QM have also given up realism , so while we do have an account of a physical world, it is unreal in a sense (that is, the world does not have any definite properties until you measure something; in QM a tree falling a in a forest really doesn't make any sound unless someone/something hears it). We also don't yet have any idea of how to define measurement, even though it is a kind of physical process.