Answer
The abundance of heavy elements in the cosmos is attributed to the intense bursts of neutrinos accompanying supernova explosions, as theorized by Pontecorvo. These rare stellar events release an enormous flux of neutrinos that can transform protons into neutrons, facilitating the synthesis of heavier elements through nucleosynthesis. This theory provides a plausible explanation for the prevalence of heavy elements, such as gold and uranium, in the universe.