Differences
This shows you the differences between two versions of the page.
| Both sides previous revisionPrevious revision | |
| wave-particle_duality [2021/02/08 21:12] – [1.vi.3 The Superposition Principle] admin | wave-particle_duality [2022/09/06 18:08] (current) – [Quantum Particles] admin |
|---|
| We observe a wave-like interference between the two possible trajectories //only// if we cannot tell which trajectory was actually taken. Otherwise, we observe particle like properties, with no interference patter. | We observe a wave-like interference between the two possible trajectories //only// if we cannot tell which trajectory was actually taken. Otherwise, we observe particle like properties, with no interference patter. |
| |
| Niels Bohr introduced the principle of //**complementarity**/// to describe this: We need both particle and wave concepts to describe quantum systems, but we can only ever observe one of them at a time, depending on the experimental arrangement. It is not a case of either/or or both/and. They are complementary aspects of the same physical system. | Niels Bohr introduced the principle of //**complementarity**// to describe this: We need both particle and wave concepts to describe quantum systems, but we can only ever observe one of them at a time, depending on the experimental arrangement. It is not a case of either/or or both/and. They are complementary aspects of the same physical system. |
| |
| Bohr, along with many physicists, would say that it is meaningless to ask which trajectory a quantum particle takes when we are observing an interference pattern. Since you cannot observe the trajectory at the same time as observing the interference, it simply does not have a trajectory. Note that in popular science accounts, it is often said that the particle travels along //both// trajectories. But the conventional view is not //both//, not //either/or//, and not //neither//, but that the particle is in a new kind of physical state where the question itself is meaningless. | Bohr, along with many physicists, would say that it is meaningless to ask which trajectory a quantum particle takes when we are observing an interference pattern. Since you cannot observe the trajectory at the same time as observing the interference, it simply does not have a trajectory. Note that in popular science accounts, it is often said that the particle travels along //both// trajectories. But the conventional view is not //both//, not //either/or//, and not //neither//, but that the particle is in a new kind of physical state where the question itself is meaningless. |