In this series, Life's Little Mysteries explains complex subjects in exactly 200 words.
Particle physicists smash atoms together in hopes of generating the Higgs boson, a key element of the "periodic table" of subatomic particles that define our universe. String theorists believe all those particles are actually invisibly small one-dimensional strings that each vibrate at a different frequency; the theory only works if the universe has 11 dimensions, most of which are curled up in knots too small to detect. It's an unverified "theory of everything" that attempts to incorporate the laws governing the structure and behavior of space and time (known as general relativity) with the laws governing the behavior of particles (known as quantum mechanics). Those are currently incompatible. Meanwhile, astrophysicists are wondering what dark energy is; they think it exists because the universe's expansion is accelerating, and something unseen must be driving it. Also, galaxies don't rotate at the expected rate, so dark matter, another invisible substance, is thought to be pervading their outskirts, tugging on them. Back on Earth, physicists are studying superconductors, strange objects that display zero resistance to electric currents, and trying to build quantum computers, which store information in particles whose properties are entangled. They're also making strides in understanding chaos and pattern formation in nature.