  We introduce a new class of collider-type observables in conformal field
theories which we call generalized event shapes. They are defined as matrix
elements of light-ray operators that are sensitive to the longitudinal, or
time-dependent, structure of the state produced in the collision. Generalized
event shapes can be studied using both correlation functions and scattering
amplitudes. They are infrared finite and smoothly transit over to the familiar
event shapes. We compute them in planar ${\cal N}=4$ super-Yang-Mills theory at
weak and strong coupling, and study their physical properties. We show that at
strong coupling both the stringy and quantum-gravitational corrections to the
energy-energy correlation exhibit longitudinal broadening that manifests itself
through the presence of long-time tails in the energy flux measured by the
detectors.
