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Content: The formation of the interference pattern requires the existence of two
slits, but how can a single photon passing through one slit `know' about
the existence of the other slit? We are stuck going back to thinking of
each photon as a wave that hits both slits. Or we have to think of the
photon as splitting and going through each slit separately (but how does
the photon know a pair of slits is coming?). The only solution is to give up the idea of a photon or an electron having
location. The location of a subatomic particle is not defined until it is
observed (such as striking a screen). Role of the Observer: since the quantum world can not be observed directly, we are forced to use instruments as extensions of our
senses
however, quantum entities are so small that even contact with one photon changes their position and momentum
= measurement problem
1st hint that the observer is an important piece of any quantum experiment, can not isolate the observer or
their effects
The quantum world can be not be perceived directly, but rather through the
use of instruments. And, so, there is a problem with the fact that the
act of measuring disturbs the energy and position of subatomic particles. This is called the measurement problem. the two slit experiment is a good test of the role of the observer in the quantum realm
any experimental design that attempts to determine which slit a photon has passed through (test for its
particle nature) destroys the interference pattern (its wavelike nature)
this is a breakdown of objective reality
each quantum entity has dual potential properties, which become an actual characteristic if and when it is observed
Thus, we begin to see a strong coupling of the properties of an quantum
object and and the act of measuring those properties.