  Manipulating and cooling small particles with light are long-standing
challenges in many areas of science, from the foundations of physics to
applications in biology and nano-technology. Light fields can, in particular,
be used to isolate mesoscopic particles from their environment by levitating
them optically. These levitated particles of micron size and smaller exhibit
pristine mechanical resonances and can be cooled down to their motional quantum
ground state. Significant roadblocks on the way to scale up levitation from a
single to multiple particles in close proximity are the requirements to
constantly monitor the particles' positions as well as to engineer light fields
that react fast and appropriately to their displacements. Given the complexity
of light scattering between particles, each of these two challenges currently
seems insurmountable already in itself. Here, we present an approach that
solves both problems at once by forgoing any local information on the
particles. Instead, our procedure is based on the far-field information stored
in the scattering matrix and its changes with time. We demonstrate how to
compose from these ingredients a linear energy-shift operator, whose maximal or
minimal eigenstates are identified as the incoming wavefronts that implement
the most efficient heating or cooling of a moving ensemble of
arbitrarily-shaped levitated particles, respectively. We expect this optimal
approach to be a game-changer for the collective manipulation of multiple
particles on-the-fly, i.e., without the necessity to track them. An
experimental implementation is suggested based on stroboscopic scattering
matrix measurements and a time-adaptive injection of the optimal light fields.
