Astroparticle physics and cosmology.

Astroparticle physics is an interdisciplinary field that explores the connections between the physics of elementary particles and the large-scale properties of the universe. Particle physicists have developed a standard model to describe the properties of matter in the quantum world. This model explains the bewildering array of particles in terms of constructs made from two or three quarks. Quarks, leptons, and three of the fundamental forces of physics are the main components of this standard model. Cosmologists have also developed a standard model to describe the bulk properties of the universe. In this new framework, ordinary matter, such as stars and galaxies, makes up only around 4% of the material universe. The bulk of the universe is dark matter (roughly 23%) and dark energy (about 73%). This dark energy drives an acceleration that means that the expanding universe will grow ever larger. String theory, in which the universe has several invisible dimensions, might offer an opportunity to unite the quantum description of the particle world with the gravitational properties of the large-scale universe.