  In his sixth problem, Hilbert called for an axiomatic approach to theoretical
physics with an aim to achieve precision and rigour in scientific reasoning,
where logic and language (semantics) of physics play the pivotal role. It is
from such a point of view, we investigate the scientific value of the modern
experiments to perform quantum tests of equivalence principle. Determination of
Planck constant involves the use of acceleration due to gravity of the earth
$(g)$ that results in the force on a test mass. The equivalence between
inertial mass and gravitational mass of a test object is assumed in the process
of logically defining $g$ from the relevant hypotheses of physics.
Consequently, if Planck constant is used as input in any experiment (or in the
associated theory that founds such an experiment) that is designed to test the
equivalence between inertial and gravitational mass, then it is equivalent to
establish a scientific truth by implicitly assuming it i.e. a tautology. There
are several notable examples which plague the frontiers of current scientific
research which claim to make quantum test of equivalence principle. We question
the scientific value of such experiments from Hilbert's axiomatic point of
view. This work adds to the recently reported semantic obstacle in any
axiomatic attempt to put "quantum" and "gravity" together, albeit with an
experimental tint.
