  A thought experiment, proposed by Karl Popper, which has been experimentally
realized recently, is critically examined. A basic flaw in Popper's argument
which has also been prevailing in subsequent debates, is pointed out. It is
shown that Popper's experiment can be understood easily within the Copenhagen
interpretation of quantum mechanics. An alternate experiment, based on discrete
variables, is proposed, which constitutes Popper's test in a clearer way. It
refutes the argument of absence of nonlocality in quantum mechanics.
