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Yeah. It shouldn't be that surprising that when you arbitrarily assume that part of the wavefunction magically disappears sometimes, you get weird results like

by MBlume 14y ago

Yeah. It shouldn't be that surprising that when you arbitrarily assume that part of the wavefunction magically disappears sometimes, you get weird results like non-locality.

Osmium 14y ago
Could you expand on this a little more? I'm not quite sure I follow.
- Symmetry 14y ago
  Lets say you have some experiment which gives you a 1 or a 0, and you have two entangled particles which will give the same result depsite the result being random and the measurements being taken outside each other's lightcones. In Collapse QM there was some instantanious communication making that possible. In Many Worlds you'd find that for each measurement the wavefunction split into two branches, one corresponding to 1 and one to 0, in each location. From the sites of both measurements the decoherence spreads outwards as particle interactions happen, and when they finally touch the two 1 segments and the two 0 segments merge, and there is one area split along 1/0 in the wave function instead of two. That's all horribly simplified, but should get the idea across.
- btilly 14y ago
  The many world's interpretation is based on the assumption that both the observed system and the observer is modeled by a wavefunction. In that case observation is entanglement, which seems weird to us, but which makes perfect logical sense. Other interpretations of quantum mechanics start with the assumption that the world is fundamentally like our naive experience leads us to think of it as. Therefore when we observe something, we couldn't really be thrown into a superposition of states, each of which observed a different thing and which cannot meaningfully interact due to quantum mechanical principles. If we can't be thrown into such a superposition, then there must be some sort of underlying reality, or quantum collapse, or other weirdness that is not explained by QM. All of the weirdness of interpretations other than many worlds can be understood as the conflict between how they would like to understand the world (there is a reality that happened), and how quantum mechanics described things. All of the weirdness of the many worlds interpretation can be understood as, "We can't perceive the process of quantum superposition, so it seems really, really weird to us."
IvoDankolov 14y ago
It's always amusing to see the kind of excuses that pop up when you try to explain entanglement or interference in the mindset of wavefunction collapse. I'm still not entirely sure why so many people consider collapse to be simpler. Is it too daunting to think of the world as an amplitude distribution that propagates in a way that we're not intuitively used to? Too hard to think of ourselves as part of quantum mechanics, because that thing I see there on the measuring device must be the reality, damn it, and what the hell do you mean I've just entangled myself and the device along with the system? Or maybe just tradition and accepting the "scripture" coming from the established authority. How could we best test that?
kinghajj 14y ago
The Bohm interpretation has a universal wavefunction and non-locality, though.

by MBlume 14y ago

Yeah. It shouldn't be that surprising that when you arbitrarily assume that part of the wavefunction magically disappears sometimes, you get weird results like non-locality.

Osmium 14y ago

Could you expand on this a little more? I'm not quite sure I follow.

Symmetry 14y ago
Lets say you have some experiment which gives you a 1 or a 0, and you have two entangled particles which will give the same result depsite the result being random and the measurements being taken outside each other's lightcones. In Collapse QM there was some instantanious communication making that possible. In Many Worlds you'd find that for each measurement the wavefunction split into two branches, one corresponding to 1 and one to 0, in each location. From the sites of both measurements the decoherence spreads outwards as particle interactions happen, and when they finally touch the two 1 segments and the two 0 segments merge, and there is one area split along 1/0 in the wave function instead of two. That's all horribly simplified, but should get the idea across.
btilly 14y ago
The many world's interpretation is based on the assumption that both the observed system and the observer is modeled by a wavefunction. In that case observation is entanglement, which seems weird to us, but which makes perfect logical sense. Other interpretations of quantum mechanics start with the assumption that the world is fundamentally like our naive experience leads us to think of it as. Therefore when we observe something, we couldn't really be thrown into a superposition of states, each of which observed a different thing and which cannot meaningfully interact due to quantum mechanical principles. If we can't be thrown into such a superposition, then there must be some sort of underlying reality, or quantum collapse, or other weirdness that is not explained by QM. All of the weirdness of interpretations other than many worlds can be understood as the conflict between how they would like to understand the world (there is a reality that happened), and how quantum mechanics described things. All of the weirdness of the many worlds interpretation can be understood as, "We can't perceive the process of quantum superposition, so it seems really, really weird to us."

IvoDankolov 14y ago

It's always amusing to see the kind of excuses that pop up when you try to explain entanglement or interference in the mindset of wavefunction collapse. I'm still not entirely sure why so many people consider collapse to be simpler. Is it too daunting to think of the world as an amplitude distribution that propagates in a way that we're not intuitively used to? Too hard to think of ourselves as part of quantum mechanics, because that thing I see there on the measuring device must be the reality, damn it, and what the hell do you mean I've just entangled myself and the device along with the system? Or maybe just tradition and accepting the "scripture" coming from the established authority. How could we best test that?

kinghajj 14y ago

The Bohm interpretation has a universal wavefunction and non-locality, though.