What is the universe made of? Science can’t say for sure. Most cosmologists believe that as much as 96% of the mass in the universe is invisible. Often referred to as “dark matter” and “dark energy,” its gravitational effects can be measured, but its nature remains unknown, challenging the limits of science and our own ability to grasp the fundamental mysteries of the universe.

In this series of conversations with physicists at the leading edge of their field, WIE Unbound explores the latest thinking about what constitutes dark matter and dark energy. To kick things off, WIE editor Tom Huston speaks with British physicist and popular science author Paul Davies. Davies is well known not only for his research into cosmology, astrobiology, and quantum vacuums, but also for his unusual capacity to make the complexities of physics easily understood by a lay audience. In this fascinating interview, he defines objects with such whimsical names as MACHOs and WIMPs and explains why Einstein’s famous “cosmological constant”—which he later referred to as his “greatest mistake”—holds the key to understanding dark energy. Convinced that the invisible stuff of the universe isn’t as mysterious as some scientists believe, Davies describes his own “far out” explanations, taking us on an intriguing insider’s tour of contemporary physics along the way.

more about: