Accelerating medium effect as a general wave phenomenon

Already at the end of the last century theory predicted that the wave number and frequency of any wave will change when passing an accelerating refractive medium. The effect was calculated both for electromagnetic and neutron waves. As a refractive index may be introduced for waves of any nature one can speak about a very general Accelerating Medium Effect. As far as we know this effect has not yet been observed for light. Here we report on a neutron-optics experiments performed with ultra-cold neutrons where this effect has been demonstrated for the first time ever. The maximum energy transform in the experiment was ± (2÷6) ×10−10 eV which agrees with theory within less than 10%. Possibilities for future investigations of the Accelerating Medium effect will be discussed.