## Abraham Meets Abraham from a Parallel Universe

And he [Abraham] lifted up his eyes and looked, and, lo, three men stood over against him… (Genesis 18:2) On this blog, we often discuss the collapse of the wavefunction as the result of a measurement. This phenomenon is called the “measurement problem.” There are several reasons, why the collapse of the wavefunction – part and parcel of the Copenhagen interpretation of quantum mechanics – is called a problem. Firstly, it does not follow from the Schrödinger equation, the main equation of quantum mechanics that describes the evolution of the wavefunction in time, and is added ad hoc. Secondly, nobody knows how the collapse happens or how long it takes to collapse the wavefunction. This is not to mention that any notion that the collapse of the wavefunction is caused by human consciousness, [...]