Particle physics is a branch of physics that studies the elementary constituents of matter and radiation, and the interactions between them.
Scroll down for the Video!
It is also called "high energy physics", because many elementary particles do not occur under normal circumstances in nature, but can be created and detected during energetic collisions of other particles, as is done in particle accelerators.
Modern particle physics research is focused on subatomic particles, which have less structure than atoms.
These include atomic constituents such as electrons, protons, and neutrons (protons and neutrons are actually composite particles, made up of quarks), particles produced by radiative and scattering processes, such as photons, neutrinos, and muons, as well as a wide range of exotic particles.
The Origins of the Universe
Our universe is 13.7 billion years old, but astronomers are peering deep into its history and are getting a greater understanding of how the first stars formed, and how the earliest galaxies came together.
The universe was born with the Big Bang as an unimaginably hot, dense point. ... As space expanded, the universe cooled and matter formed. One second after the Big Bang, the universe was filled with neutrons, protons, electrons, anti-electrons, photons and neutrinos.
Astronomers think space might be infinite, with "stuff" (energy, galaxies, etc.) distributed pretty much the same as it is in the observable universe. If it is, that has some seriously weird implications for what lies out there. Beyond the Hubble Volume you won't just find more, different planets.