Introduction

This paper, I am afraid, advocates the philosophy of technology without actually doing it. It can best be seen as a plea for the philosophical importance of technology; in this case, importance to one of the most widely discussed problems in philosophy of physics—the measurement problem in quantum mechanics. What I want to do here is to lay out a point of view that takes the measurement problem out of the abstract mathematical structure of theory, where we discuss questions about unitary operators or conditions for the disappearance of certain inner products supposed to represent interference terms, and locate it elsewhere. Where is the measurement problem? Answer: It had better be found in the quantum technology or it is not to be found at all. My view in many respects follows ideas I have learned from Willis Lamb.

The evolution of states is supposed to be governed by the Schroedinger equation. The measurement problem arises when we become convinced that there are a range of cases in which we no longer want to assign the state dictated by the Schroedinger equation but want to assign a different state instead. Why do we want to assign this second state? We call the problem “the measurement problem” and this canonical example is a good illustration. You can't measure a quantum system without coupling to it.