### 1 Introduction

The question formulated in the title of this essay requires first clarification of a semantic point. An interpretation cannot be wrong in the same sense as an experimentally verifiable theoretical prediction. The term ’wrong’ is used here in the sense of ’extremely misleading’. In this sense a wrong interpretation leads to paradoxical contradictions or to internal inconsistencies such as unsolvable theoretical problems. I will first formulate some basic assumptions and explain what ’individuality interpretation’ means before I will try to answer the question.

I start by formulating the most important assumptions underlying this work. A physical theory is a set of equations together with a number of rules how to compare theoretical and experimental results. Predictions, i.e. real numbers obtained by solving the basic equations using input data referring to earlier times, represent the core of a physical theory. The interpretation of the mathematical terms is also part of a physical theory. It gives ’meaning’ to the mathematical variables, but does not affect the predictive core of the theory. Several different interpretations of one mathematical formalism are possible. They lead to slightly different physical theories but cannot make a physical theory right or wrong, since they do not affect the predictive core of the theory. We may say that a theory is given by a set of predictions (which constitute the invariant core) and an interpretation.

What, exactly, does ’individuality interpretation’ mean ? A physical theory which allows prediction of single (individual) events, in particular predictions about single particles, must necessarily be interpreted in this sense. For classical mechanics this individuality interpretation is obviously correct. Such a theory could also be called a deterministic theory, because it claims to predict the behavior of individual particles ’with certainty’. There is no room in such a theory for uncertainty, all predictions of this individualistic theory have a probability equal to one . Testing the predictions of this theory requires a single experiment.

On the other hand there are physical theories, expressed in a completely ’deterministic’ mathematical form, whose output cannot be verified in single experiments because the scattering of data is too large to be neglected. Clearly, the output of a physical theory must be testable. If it cannot be tested in individual experiments, essentially the only possibility left is a statistical test. In this case the output of the theory is given by statistical quantities like probabilities or expectation values. These numbers can be compared with experimental results and verified or falsified just as the output of the deterministic theories discussed above. But in order to do this an infinite number of individual systems, all prepared in the same way, have to be studied experimentally. This is the way statistical measurements have to be performed in principle (in practice simpler possibilities exist), no other testable meaning (namely ”frequentist probability’) can be ascribed to the term probability in a physical context. A statistical theory can obviously not be used o make predictions about individual events, because such predictions cannot be verified in individual experiments.

From the present discussion one would expect - considering the above, rather weak assumptions as evident - that no physical theory whose output is given by statistical quantities can be interpreted in an individualistic sense. In particular, one would expect that this holds true for quantum theory (QT), whose output is of a probabilistic nature. On the other hand, the dominating interpretation of QT tells us that quantum mechanics is a theory about individual particles. We have been using phrases like ’the Schrödinger equation of a single electron’ or ’the quantum mechanical description of a single particle’ an infinite number of times. This kind of talking determines our thinking. The idea that QT describes individual events and particles presents the basis for much, if not most, of current research on foundations of physics.