Harry Percival

Comment Threads

• Mateus Araújo commented on Dude, you broke the future!
  Your last sentence is correct: the quantum state includes everything, even position and velocity. For the particles to interfere they must be completely indistinguishable, on the fundamental level. So there wouldn't be interference in your drawing. This is quite hard to do, actually, and the usual interference experiments - double-slit interferometer and Mach-Zender interferometer - are about a single particle interfering with itself. It is kind of cheating: you don't really know the quantum state of the particle, but since it is a single particle there is nothing to differ. You then split it into two paths, and now the...
• Jocelyn Ireson-Paine commented on Dude, you broke the future!
  But it is possible to interfere two different particles. The best example is the famous Hong-Ou-Mandel interferometer. Even then, you have to do a lot of work to synchronize the sources of the particles. Thanks. So that clears one thing up for me. One can interfere more than one particle: I don't need to think only of double-slit experiments and the like. Next question: where can I find something that explains what kind of mathematical entity a "world" in the Many-Worlds interpretation is?...
• JohnS commented on Dude, you broke the future!
  Do such places actually exist on Earth? https://en.wikipedia.org/wiki/Perchlorate Naturally occurring perchlorate ... can be found commingled with deposits of sodium nitrate in the Atacama Desert of northern Chile. Also Lubbock, Texas and Florida, produced by lightning discharges in the presence of chloride. https://en.wikipedia.org/wiki/Perchlorate#Contamination_in_environment...
• Mateus Araújo commented on Dude, you broke the future!
  I don't know how much mathematics are you interested in; it can get quite hairy. I think this paper does a good job of being precise without getting bogged down in details. See sections 3 and 4. In a nutshell, a world is a branch of the universal wavefunction that hardly interferes with other branches, and that follows approximately the laws of classical mechanics. Mathematically, it is a vector of complex numbers describing a massive amount of particles with very little entanglement between them, and such that its inner product with other such vectors is very small....
• Jocelyn Ireson-Paine commented on Dude, you broke the future!
  That's a nice paper. I think it's improved my understanding of emergence too. Equations (5) and (6) are the key ones, it seems. Now I need to understand decoherence well enough to see what (2) and (3) are telling me....