  We develop a model in which presence of entanglement in a quantum system can
be confirmed through coarse observations of the environment surrounding the
system. This counter-intuitive effect becomes possible when interaction between
the system and its environment is proportional to an observable being an
entanglement witness. While presenting intuitive examples we show that: i) a
cloud of an ideal gas, when subject to a linear potential coupled with the
entanglement witness, accelerates in the direction dictated by the sign of the
witness; ii) when the environment is a radiation field, the direction of
dielectric polarization depends on the presence of entanglement; iii)
quadratures of electromagnetic field in a cavity coupled with two qubits (or a
four-level atom) are displaced in the same manner.
