Recent detection of gravitational waves from merging black holes and neutron stars opened a
new window for studying the Universe and further accelerated the tremendous progress in
multiwavelength time-domain astronomy. This talk will review exciting new developments in
the quest for uncovering the origin of chemical elements in the Universe and understanding
the birth of neutron stars and black holes. These major unsolved astrophysical problems are
associated with some of the most luminous explosions and involve a wide range of physics
such as nuclear matter at high densities, neutrinos, strong magnetic fields, and formation of
dust and molecules.