Wave functions give results that are quite different from
measurements we obtain for the location of more familiar, macroscopic
objects. We can never be sure about where exactly an electron
is at a given instant of time; rather we can only predict the
probability of finding the electron in a given region of space
at a given instant of time. The wave function of an electron
enables us to determine that probability. To obtain the probability
density we calculate the square of the wave function.
Probabilities of finding the object within a certain region
are determined from the probability densities. An important conclusion
is that we cannot state with certainty the location of an electron,
only the probability of finding it at each of many locations.
The following essay describes some of the differences between
our knowledge of large objects and our knowledge of the very