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cdaveI recently read "The Fabric of the Cosmos" by Brian Greene. It contained a rather brilliant description of the Delayed Choice Double Slit experiment, in which effect precedes cause. Rather damaging to the notion of free will I thought.
This led to me think about an Asimov story where such an experiment takes place. They wait until the experiment says that water was/will be poured on this in 24 hours, and then seal the container. They find that the universe conspires to ensure that there always was/will be someone to do just that. Be it a Janitor spilling something, or a junior lab technician not understanding, or something more.
I was wondering what would happen if the same thing was done with this Delayed Choice test. So I started writing it up as popular science essay, that I was aiming at being understood by anyone without a science background.
I was comparing this to the Bell's inequality experiment, when I finally realised what I'd missed. In the Bell's inequality tests, non-local quantum entanglement cannot be used to send information faster than light because it involves random processes, and you need to combine information from detectors on both sides of the experiment before you can see the non-local connection.
Similarly, there is no way to send information back in time using the Delayed Choice test, as the only way to show that effect has preceded cause is to combine information from both detectors at the cause and effect time of the experiment before you can see the non-temporal connection.
{ETA} This makes the weirdness of quantum mechanics really clear to me. I knew that entanglement meant that entangled particles have some faster-than-light spacial connection, but hadn't made the obvious connection that they therefore must have some faster-than-light chronological connection.
I think this implies that all events must be predetermined.
This led to me think about an Asimov story where such an experiment takes place. They wait until the experiment says that water was/will be poured on this in 24 hours, and then seal the container. They find that the universe conspires to ensure that there always was/will be someone to do just that. Be it a Janitor spilling something, or a junior lab technician not understanding, or something more.
I was wondering what would happen if the same thing was done with this Delayed Choice test. So I started writing it up as popular science essay, that I was aiming at being understood by anyone without a science background.
I was comparing this to the Bell's inequality experiment, when I finally realised what I'd missed. In the Bell's inequality tests, non-local quantum entanglement cannot be used to send information faster than light because it involves random processes, and you need to combine information from detectors on both sides of the experiment before you can see the non-local connection.
Similarly, there is no way to send information back in time using the Delayed Choice test, as the only way to show that effect has preceded cause is to combine information from both detectors at the cause and effect time of the experiment before you can see the non-temporal connection.
{ETA} This makes the weirdness of quantum mechanics really clear to me. I knew that entanglement meant that entangled particles have some faster-than-light spacial connection, but hadn't made the obvious connection that they therefore must have some faster-than-light chronological connection.
I think this implies that all events must be predetermined.
no subject
Date: 2009-07-02 10:41 am (UTC)