Dark Matter and Dark Energy Explained What We Still Don’t Know Dark matter and dark energy sound like we know what they are… but we don’t. Dark matter accounts for about 85% of the universe’s gravity, yet we cannot see its source. Dark energy is an even stranger idea: a mysterious pressure in empty space that makes the universe expand faster and faster. If that acceleration continues, distant galaxies will eventually slip beyond our cosmic horizon, taking huge parts of the universe’s story with

What is dark energy? Physicist Tessa Baker at the University of Portsmouth, UK, is at the forefront of the search for elusive dark matter, using some of cosmology’s most powerful tools, including the Laser Interferometer Gravitational-Wave Observatory (LIGO). By studying ripples in space-time sent out by the most extreme events in the cosmos, such as black hole mergers, experimentalists like Baker are beginning to test radical ideas: that dark energy might stem from hidden dimensions, elusive fi