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I am a theoretical physicist, and I am very much in tune with the author. Take quantum mechanics (my field), it is clear that even though we have a working mode

I am a theoretical physicist, and I am very much in tune with the author. Take quantum mechanics (my field), it is clear that even though we have a working model of it, it doesn't explain how nature instantiates it. Entanglement is a prime example of this: I know exactly how to describe it, but nobody has a clue of how it works. In other words, physics is a mostly coherent and certainly useful story about reality, but it isn't grounded on "bedrock" reality, rather on our perception of it.

BobaFloutist 2y ago
Correct me if I'm wrong, but I think of entanglement as less forming an actual binding relationship to two particles, and more as setting them up exactly the same way. So it's not that you have two magnetic marbles and rotating one rotates the other, it's that you're rolling two dice with identical parameters and can expect that at any given slice of time they'll be doing the same thing. Is that incorrect?
- nathan_compton 2y ago
  Entanglement is neither a bond between two objects nor a setting up of two objects in the same way. Entanglement derives from the fact that quantum mechanical systems have properties which are non-local with respect to the "process" of measurement that do not depend on the physical size of the system in question. Its actually suspect to say that "particles" are entangled at all - the entanglement is a property of the wave function in which the particles identities are (with respect to the quantity that is entangled) indistinct.
  - mikepalmer 2y ago
    Agree, "spooky action at a distance" isn't spooky at all if you just accept it as physical!
    - nathan_compton 2y ago
      I don't personally think that there is any action at a distance at all.
- ziofill 2y ago
  Yes you're on the right track: there isn't any 'action' between the two systems, it's a correlation. However, here's the thing that fries my brain: for classical systems correlation means the pre-existing value of some property is correlated (e.g. if I take a random glove out of a pair, the moment I look at the one I picked I know the handedness of the other). In the quantum case there isn't a pre-existing value for the property you're measuring (because you're free to pick the measurement basis), and you can't say one measurement outcome caused the other because you can set up the measurements to happen outside of each other's light cone (so you are free to pick which measurement happens first by changing reference frame). So: how does particle A "know" how to produce the correct correlation if 1) the value is produced 'on the spot' and 2) there isn't a well-defined causal order between measurement of A and B?
  - mathemagics 2y ago
    Eh, that's still just correlation across a state vector. Honestly, quantum entanglement is proof that the many worlds / simultaneous superposition interpretation of quantum mechanics is bollocks. Really all QM says is that there's some probability distribution of an outcome, and you don't know what outcome occurred until you take a measurement. For example, you could imagine a world simulator that uses probabilistic logic gates. Where with some probability a bit could be 0 or 1. Now you could say that the bit is in some superposition or is 0 in world A and 1 in world B, blah blah. But that's dumb. Really, the bit is 0 or 1 with some probability of the universe simulator. And you don't know which, until you observe its value.
    - ziofill 2y ago
      That's only half of the argument though. The other half is how does entanglement correctly coordinate the probabilistic outcomes, when there's no causal order? (meaning, you can't assume there's a sort of signal that travels between them, because in a different reference frame the signal would have to travel back in time)
      - mathemagics 2y ago
ChrisClark 2y ago
Basically, could I say something like, QFT is about fields, but what are the fields, are they in something, are they self instantiated, what makes the fields? We can describe the fields, but we can't get behind them, the how and why? At least we can't get behind them yet, but if we do, do we know the how of that or is it just another layer?
EvgeniyZh 2y ago
What do you mean by "how it works"? In my book, being able to predict the outcome of experiment is exactly understating how it works. Anything beyond this is the question of philosophy, not physics.

BobaFloutist 2y ago

Correct me if I'm wrong, but I think of entanglement as less forming an actual binding relationship to two particles, and more as setting them up exactly the same way. So it's not that you have two magnetic marbles and rotating one rotates the other, it's that you're rolling two dice with identical parameters and can expect that at any given slice of time they'll be doing the same thing. Is that incorrect?

nathan_compton 2y ago
Entanglement is neither a bond between two objects nor a setting up of two objects in the same way. Entanglement derives from the fact that quantum mechanical systems have properties which are non-local with respect to the "process" of measurement that do not depend on the physical size of the system in question. Its actually suspect to say that "particles" are entangled at all - the entanglement is a property of the wave function in which the particles identities are (with respect to the quantity that is entangled) indistinct.
- mikepalmer 2y ago
  Agree, "spooky action at a distance" isn't spooky at all if you just accept it as physical!
  - nathan_compton 2y ago
    I don't personally think that there is any action at a distance at all.
ziofill 2y ago
Yes you're on the right track: there isn't any 'action' between the two systems, it's a correlation. However, here's the thing that fries my brain: for classical systems correlation means the pre-existing value of some property is correlated (e.g. if I take a random glove out of a pair, the moment I look at the one I picked I know the handedness of the other). In the quantum case there isn't a pre-existing value for the property you're measuring (because you're free to pick the measurement basis), and you can't say one measurement outcome caused the other because you can set up the measurements to happen outside of each other's light cone (so you are free to pick which measurement happens first by changing reference frame). So: how does particle A "know" how to produce the correct correlation if 1) the value is produced 'on the spot' and 2) there isn't a well-defined causal order between measurement of A and B?
- mathemagics 2y ago
  Eh, that's still just correlation across a state vector. Honestly, quantum entanglement is proof that the many worlds / simultaneous superposition interpretation of quantum mechanics is bollocks. Really all QM says is that there's some probability distribution of an outcome, and you don't know what outcome occurred until you take a measurement. For example, you could imagine a world simulator that uses probabilistic logic gates. Where with some probability a bit could be 0 or 1. Now you could say that the bit is in some superposition or is 0 in world A and 1 in world B, blah blah. But that's dumb. Really, the bit is 0 or 1 with some probability of the universe simulator. And you don't know which, until you observe its value.
  - ziofill 2y ago
    That's only half of the argument though. The other half is how does entanglement correctly coordinate the probabilistic outcomes, when there's no causal order? (meaning, you can't assume there's a sort of signal that travels between them, because in a different reference frame the signal would have to travel back in time)
    - mathemagics 2y ago

ChrisClark 2y ago

Basically, could I say something like, QFT is about fields, but what are the fields, are they in something, are they self instantiated, what makes the fields? We can describe the fields, but we can't get behind them, the how and why? At least we can't get behind them yet, but if we do, do we know the how of that or is it just another layer?

EvgeniyZh 2y ago

What do you mean by "how it works"? In my book, being able to predict the outcome of experiment is exactly understating how it works. Anything beyond this is the question of philosophy, not physics.