  We discuss three different ways to arrive at kaon condensation at n_c = 3 n_0
where n_0 is nuclear matter density: (1) Fluctuating around the n=0 vacuum in
chiral perturbation theory, (2) fluctuating around n_VM near the chiral
restoration density n_chi where the vector manifestation of hidden local
symmetry is reached and (3) fluctuating around the Fermi liquid fixed point at
n_0. They all share one common theoretical basis, "hidden local symmetry." We
argue that when the critical density n_c < n_chi is reached in a neutron star,
the electrons turn into K^- mesons, which go into an S-wave Bose condensate.
This reduces the pressure substantially and the neutron star goes into a black
hole. Next we develop the argument that the collapse of a neutron star into a
black hole takes place for a star of M = 1.5 M_sun. This means that Supernova
1987A had a black hole as result. We also show that two neutron stars in a
binary have to be within 4% of each other in mass, for neutron stars
sufficiently massive that they escape helium shell burning. For those that are
so light that they do have helium shell burning, after a small correction for
this they must be within 4% of each other in mass. Observations support the
proximity in mass inside of a neutron star binary. The result of strangeness
condensation is that there are 5 times more low-mass black-hole, neutron-star
binaries than double neutron-star binaries although the former are difficult to
observe.
