  This paper presents the measurement problem from the point of view of the
thermal interpretation of quantum physics introduced in Part II. The
measurement of a Hermitian quantity $A$ is regarded as giving an uncertain
value approximating the q-expectation $\langle A\rangle$ rather than (as
tradition wanted to have it) as an exact revelation of an eigenvalue of $A$.
Single observations of microscopic systems are (except under special
circumstances) very uncertain measurements only. The thermal interpretation
  * treats detection events as a statistical measurement of particle beam
intensity.
  * claims that the particle concept is only asymptotically valid, under
conditions where particles are essentially free.
  * claims that the unmodeled environment influences the results enough to
cause all randomness in quantum physics.
  * allows one to derive Born's rule for scattering and in the limit of ideal
measurements; but in general, only part of Born's rule holds exactly: Whenever
a quantity A with zero uncertainty is measured exactly, its value is an
eigenvalue of A.
  * has no explicit collapse -- the latter emerges approximately in
non-isolated subsystems.
  * gives a valid interpretation of systems modeled by a quantum-classical
dynamics.
  * explains the peculiar features of the Copenhagen interpretation (lacking
realism between measurements) and the minimal statistical interpretation
(lacking realism for the single case) where these interpretations apply -- in
the microscopic domain.
  The thermal interpretation is an interpretation of quantum physics that is in
principle refutable by theoretical arguments leading to a negative answer to a
number of open issues collected at the end of the paper, since there is plenty
of experimental evidence for each of the points mentioned there.
