  In contrast to current efforts to quantify the radiation pressure of light
using nano-micromechanical resonators in cryogenic conditions, we proposed and
experimentally demonstrated the radiation pressure measurement in ambient
conditions by utilizing a macroscopic mechanical longitudinal oscillator with
an effective mass of the order of 20 g. The light pressure on a mirror attached
to the oscillator was recorded in a Michelson interferometer and results
showed, within the experimental accuracy of 3.9%, a good agreement with the
harmonic oscillator model without free parameters.
