ANSWER: Black holes
Explanation:
A team of international scientists have identified the merger of two black holes yet again - just three months after their first detection, researchers announced on June 15, 2016.
- Scientists detected the cataclysmic black hole merger -- a phenomenon Albert Einstein predicted in his theory of relativity a century ago - by spotting gravitational waves, using an advanced detector known as the Laser Interferometer Gravitational-Wave Observatory, or LIGO instrument.
- Black holes form in the final stage of most massive stars' evolution. The space bodies are so dense that neither light nor matter can escape them.
- Gravitational waves are ripples in the fabric of space time permitting scientists to detect when black holes merge
- The first detection of waves in September 2015 was announced in February 2016, in a landmark discovery for physics and astronomy following decades of efforts
- Researchers announced waves a second time in December produced by black hole collision
- Mysteries which have to be explained include how do such black hole systems form.
