  Both classical and quantum electrodynamics predict the existence of
dipole-dipole long-range electrodynamic intermolecular forces; however, these
have never been hitherto experimentally observed. The discovery of completely
new and unanticipated forces acting between biomolecules could have
considerable impact on our understanding of the dynamics and functioning of the
molecular machines at work in living organisms. Here, using two independent
experiments, on the basis of different physical effects detected by
fluorescence correlation spectroscopy and terahertz spectroscopy, respectively,
we demonstrate experimentally the activation of resonant electrodynamic
intermolecular forces. This is an unprecedented experimental proof of principle
of a physical phenomenon that, having been observed for biomacromolecules and
with long-range action (up to 1000 Angstroms), could be of importance for
biology. In addition to thermal fluctuations that drive molecular motion
randomly, these resonant (and thus selective) electrodynamic forces may
contribute to molecular encounters in the crowded cellular space.
