  In 1958 Jan Oort remarked that the lack of old clusters in the solar
neighborhood (SN) implies that clusters are destroyed on a timescale of less
than a Gyr. This is much shorter than the predicted dissolution time of
clusters due to stellar evolution and two-body relaxation in the tidal field of
the Galaxy. So, other (external) effects must play a dominant role in the
destruction of star clusters in the solar neighborhood. We recalculated the
survival time of initially bound star clusters in the solar neighborhood taking
into account: (1) stellar evolution, (2) tidal stripping, (3) perturbations by
spiral arms and (4) encounters with giant molecular clouds (GMCs). We find that
encounters with GMCs are the most damaging to clusters. The resulting predicted
dissolution time of these combined effects, t_dis=1.7 (Mi/10^4 M_sun)^0.67 Gyr
for clusters in the mass range of 10^2 < M < 10^5 M_sun, is very similar to the
disruption time of t_dis=1.3+/-0.5 (M/10^4 M_sun)^0.62 Gyr that was derived
empirically from a mass limited sample of clusters in the solar neighborhood
within 600 pc. The predicted shape of the age distribution of clusters agrees
very well with the observed one. The comparison between observations and theory
implies a surface star formation rate (SFR) near the sun of 3.5x10^-10 M_sun
yr^-1 pc^-2 for stars in bound clusters with an initial mass in the range of
10^2 to 3x10^4 M_sun. This can be compared to a total SFR of 7-10x10^-10 M_sun
yr^-1 pc^-2 derived from embedded clusters or 3-7x10^-9 M_sun yr^-1 pc^-2
derived from field stars. This implies an infant mortality rate of clusters in
the solar neighborhood between 50% and 95%, in agreement with the results of a
study of embedded clusters.
