  Springer resolution of the set of nilpotent elements in a semisimple Lie
algebra plays a central role in geometric representation theory. A new
structure on this variety has arisen in several representation theoretic
constructions, such as the (local) geometric Langlands duality and modular
representation theory. It is also related to some algebro-geometric problems,
such as the derived equivalence conjecture and description of T. Bridgeland's
space of stability conditions. The structure can be described as a
noncommutative counterpart of the resolution, or as a $t$-structure on the
derived category of the resolution. The intriguing fact that the same
$t$-structure appears in these seemingly disparate subjects has strong
technical consequences for modular representation theory.
