What is Matter? Not what it appears to be. Its most obvious property -- variously called resistance to motion, inertia, or mass -- can be understood more deeply in very different terms.
The mass of ordinary matter is the embodied energy of more basic building-blocks, building blocks that are themselves almost without mass.
What is Space? Is it an empty stage, where the physical world of matter acts out its drama -- an equal participant, like the classical Ether, that both provides background and has a life of its own -- or the primary reality, of which matter is a secondary manifestation? Today, the third view is triumphant. Where our eyes see nothing our brains, pondering the revelations of sharply tuned experiments, discover the Grid that powers physical reality.
In astronomy, gravity is the most important force. But fundamentally, acting between elementary particles, gravitational forces are ridiculously small compared to electric or strong forces. Our new understanding of the origin of mass suggests a way to pull gravity into the same framework as other forces. This suddenly clears our path to a unified theory of forces and particles.
Is Beauty Truth? Our new picture of gravity is logical, even beautiful. But can we embed it in a wider circle of ideas? Can we draw out testable consequences from these hints of a unified theory of all fundamental forces? To consummate this unification fully, we must imagine a new world of even more particles. Some of those predicted should be discovered, and very soon, as the great CERN accelerator comes online.