From Cosmos, the vast majority of the universe is something we can't see, can't touch and is expanding the universe at ever-increasing speeds; Tamara Davis explains why dark energy poses more questions than answers. Can time just stop? Michael Byrne wonders. The God Particle: What explains the current wave of popular physics? Virginia Trimble reviews Gravity's Engines: The Other Side of Black Holes by Caleb Scharf. Dark matter mystery may soon be solved: Experiments to detect dark matter, which scientists believe makes up about a quarter of the universe, are underway and may yield direct evidence within a decade. What is string theory, and why should we bother finding out? Steven Gubser explains. Most fundamental clock ever could redefine kilogram: Physicists have created the first clock with a tick that depends on the hyper-regular frequency of matter itself. Rebecca J. Rosen on the largest structure ever observed in the universe: At 4 billion light years across, this quote-unquote "object" throws astronomical assumptions that go back to Einstein into doubt.