Quote:
Originally Posted by CraigS
Thanks Steven;
Hmmm … so, the photons, (in "contact") initially, exist at a specific, unique point in spacetime. Somehow, the properties of one of the photons, gets changed by a later measurement, which then appears to cause a change in the other, no matter how much separation between, or how much later, the measurements are made (??)
If I have this right, then there are no statements in the above made about the cause of the entanglement (or initial "contact"). The thing about this entanglement thing is that the measurement of one effects the other's state after they becomes physically and temporally separated (?)
So, it seems that they are still trying to eliminate the possibility that the local environmental test conditions at the 'primary test site doesn't somehow, interact to influence the outcome at the secondary test site (?).
Once they've pinned this down, the conclusion would be as you have said .. the entanglement is established by something going on initially, rather than later (?)
But what keeps the two photons in contact ? I guess this is the BIG question, huh ?
(Gaede says 'a twisted, invisible rope' !!  … he's a legend, y'know !!  )
Cheers
PS: I'm not asserting anything here .. I'm just trying to 'align' myself with the concepts. (Except the Gaede comment  ) |
Perhaps I shouldn't have used the term "contact" (even if it was in inverted commas
) because it does convey the wrong impression.
In QM there is a role played by the experiment, the observer and in this case, the pair of photons. An experiment can produce a number of outcomes, each outcome has a particular probabilty of occurring. The role of the observer in QM is to make a measurement. When the measurement is made the outcome is determined.
Before a measurement is made the photons exist in a superimposed state of all the possible outcomes. In the case of a pair of photons in a polarization test, the photons cannot be distinguished in the superimposed state. This defines entanglement.
Entanglement doesn't mean physical contact, rather a mixing of all the possible outcomes of the experiment for each photon.
Regards
Steven