New measurement clarifies scale of quantized gravitational energy

Nature : Confined subatomic particles exhibiting quantum behavior experience gravitational energy that is quantized. Using a new technique, Hartmut Abele at the Technical University of Vienna and his colleagues have measured quantized gravitational energy levels on the scale of a few micrometers with a precision 100 000 times better than previous measurements. To accomplish that, the researchers slowed, cooled, and trapped neutrons between two horizontal plates. The bottom plate was reflective, and the upper plate absorbed the neutrons with the highest energies, leaving only those at the lowest energy level. The bottom plate was then vibrated by a piezoelectric crystal, which bumped the neutrons to higher energy levels. The researchers found that the height of the neutrons above Earth was directly related to the plate vibration frequency needed to increase their energy level. The measurement’s sensitivity indicated that no other forces were in play other than gravity. That limits the potential range of effectiveness for hypothetical dark energy forces as well as for some forms of dark matter.