Einstein's principle of equivalence passed a quantum test

Einstein's principle of equivalence is of fundamental importance for the
understanding of gravity and space-time. The principle has been tested
only for systems in a well-defined, classical state of their total mass.
Now an article in Nature Communications reports the first test of the
Einstein's principle of equivalence for atoms whose total mass was in a
quantum superposition state.

The experiment realised carried out by the international team led by
Prof. Guglielmo Tino at the Department of Physics and Astronomy of the
University of Florence and National Institute for Nuclear Physics can be
seen as a quantum analogue of the apocryphal test of 16th century
Italian scientist Galileo Galilei who realized that various bodies fall
with the same gravitational acceleration considering dropping spheres of
different mass from the leaning tower of Pisa.

The collaboration includes also experimentalists from the University of
Bologna and the European Space Agency and theorists from the University
of Vienna, Austrian Academy of Sciences and the University of
Queensland.

[emotionalvideos]

I don't know why they call it Einstein's equivalence principle if what they actually put to the test is the Weak equivalence principle stated way before Einstein...

[HankusSpankus]

Taming the chaotic quantum "world" with one force of equivalence seems important if God wants to play dice . The nature of the force that is accelerating from a gravitational mass at the quantum scale seems the Holy Grail of modern physics . The accelerating universe observed could show how any force carrying particle / field could be "pulled" out of a mass to be in an equilibrium with the forces of the expanding universe . The force of deceleration has the same type of effect as acceleration and the mass for exchange of particles from an external source is not limited to the mass of an astronomical object .