5 ms·

This is how I think about it (don't take my word for it, I don't really understand QM) QM is like lazy evaluation. The result is not computed until someone act

This is how I think about it (don't take my word for it, I don't really understand QM) QM is like lazy evaluation. The result is not computed until someone actually forces it. This is different from the result being computed but you just don't know what it is. Another way is to think of entangled states is like two virtual addresses which alias to the same physical address. The addresses could be very far apart (similar to entangled particles being very far apart), and their contents are coupled but "uncomputed", until one of the virtual addresses is accessed, faulting in the physical page. At this point, both addresses instantly point to the same contents.

arrel 11y ago
As a programmer who only vaguely understands QM, the lazy evaluation example is amazing. Any physicists want to confirm its right?
- blincoln 11y ago
  IANAP, but I think using "lazy evaluation" as an analogy is missing one of the most interesting aspects of quantum physics: it's not just that the particles (or what have you) are in an indeterminate state. The fact that they're in an indeterminate state changes the way they behave. The reason it's possible to build up interference patterns using single electrons is because the various probabilities for its path between the electron gun and target are interfering with each other. I'm pretty sure a typical "lazy evaluation" system will not exhibit that type of behaviour :).
- colanderman 11y ago
  It's not. When you're in a superposition of two states, it only appears to be "indeterminate" under measurements which are not orthogonal to the state. To measurements which are orthogonal, the state is 100% determinate. What's more, measuring with a non-orthogonal measurement makes the state orthogonal to that measurement, and not orthogonal to the other measurement! This is totally different to how lazy evaluation works.
- Jach 11y ago
  I think lazy eval is the wrong way to think about it. You might like http://oyhus.no/QuantumMechanicsForProgrammers.html http://oyhus.no/QuantumMechanicsForProgrammers.html

arrel 11y ago

As a programmer who only vaguely understands QM, the lazy evaluation example is amazing. Any physicists want to confirm its right?

blincoln 11y ago
IANAP, but I think using "lazy evaluation" as an analogy is missing one of the most interesting aspects of quantum physics: it's not just that the particles (or what have you) are in an indeterminate state. The fact that they're in an indeterminate state changes the way they behave. The reason it's possible to build up interference patterns using single electrons is because the various probabilities for its path between the electron gun and target are interfering with each other. I'm pretty sure a typical "lazy evaluation" system will not exhibit that type of behaviour :).
colanderman 11y ago
It's not. When you're in a superposition of two states, it only appears to be "indeterminate" under measurements which are not orthogonal to the state. To measurements which are orthogonal, the state is 100% determinate. What's more, measuring with a non-orthogonal measurement makes the state orthogonal to that measurement, and not orthogonal to the other measurement! This is totally different to how lazy evaluation works.
Jach 11y ago
I think lazy eval is the wrong way to think about it. You might like http://oyhus.no/QuantumMechanicsForProgrammers.html http://oyhus.no/QuantumMechanicsForProgrammers.html