Black holes that formed before the Big Bang could still exist today as ‘cosmic fossils’, potentially helping to explain the mysterious dark matter that shapes galaxies across the Universe, according ...

Add Yahoo as a preferred source to see more of our stories on Google. The cosmic microwave background, the faint afterglow of the Big Bang that fills all of space, passes through massive galaxy ...

By studying galaxy clusters separated by hundreds of millions of light-years, Penn physicist Patricio Gallardo and ...

Gravity, as most people understand it, is the familiar force that pulls a falling apple toward Earth. But for astronomers and theoretical physicists, it is also a vexing invisible architect that ...

Astronomers have long struggled with a troubling puzzle: a significant portion of normal matter in the universe appeared to be missing. Scientists knew this matter had to exist based on predictions ...

Penn physicist Patricio Gallardo and collaborators tracked the speeds of distant galaxy clusters to test the strength of gravity across hundreds of millions of light-years. The verdict? Gravity neatly ...