This diagram shows the fusion reaction of the nuclei of two isotopes of hydrogen (deuterium and tritium) generating a helium nucleus (alpha particle) and a neutron. In this reaction the total mass of the products is lower than that of the interacting particles, and energy is released according to the mass-energy equivalence principle (E = mc^2). This reaction is the most promising for use in future fusion power reactors here on Earth.
This waveform (GW150914) is that of the first observation of gravitational waves on 2015-09-14. It was also the first observation of a binary black hole merger and demonstrates the existence of binary stellar-mass black hole systems.