electrons, as well as a clear recognition of the coincidence of their origin.

Concluding remarks
==================

Our discussion was based on the choice  of the covariant derivative, with $e$ denoting the electron charge. This choice seems to be dictated by gauge invariance in a theory which includes the electromagnetic interactions of the electron, taking into account the noncommutativity of $\cG = \cU(M(\cE))$, the group of unitaries in the multipliers of the algebra of Quantum Spacetime $\cE$. On an $\cE$ bimodule, only the left (resp. right) action of $U$ (resp. $U^* $), or the trivial action, are allowed.

This poses a problem for the Standard Model, apparently excluding quark fields. This problem has been noticed and discussed by several Authors, see e.g. [@CJSWW]. It deserves further discussions to see whether in our context the choice made in  is really the only choice.

According to our preceding discussion, so far there seems to be no indication of visible effects of the quantum nature of spacetime at the Planck scale, except its role in solving the horizon problem [@DMP] and justifying from first principles part of the assumptions made in the inflationary scenario.

The effects considered in this note are so tiny that 