  A local measurement extracts work as a backaction, e.g., in a system of two
entangled cavities: first cavity, $a$, comprises a piston and the measurement
is carried out on the second cavity, $b$. When no one makes a measurement on
the cavity $b$, i.e., it is simply placed in vacuum; environmental monitoring
results in the coherent states as the einselected pointer states (the
measurement basis) [PRL 70, 1187 (1993)]. This makes the measurement, that
nature itself performs, a Gaussian one with a fixed strength $\lambda=1$. We
show that this makes nature assign a \textit{fixed} amount of work to a
particular entanglement degree $0\leq \xi(r) \leq 1$, i.e.,
$W=\xi(r)\times(\bar{n}\hbar\omega_a)$, nothing that the term in parenthesis is
the entire thermal energy. Afterwards, we show that this phenomenon applies
quite generally, i.e, not restricted to a two-cavities system. We also touch on
the influence of inherited symmterization entanglement in this context. We can
arrive an additional phenomenon by considering that work is simply the process
of converting randomly moving microscopic ingredients~(vanishing mean-velocity)
into a directional one, i.e, with a nonzero mean-velocity. We show that such a
change in the character of the motion introduces curvature in spacetime
according to general relativity. This phenomenon is the first demonstration of
a quantitative relation between entanglement and curvature using solely the
quantum optics arguments.
