The central part of an atom, which contains Neutrons and Protons. Electrons are usually found around the Nucleus. Strictly speaking, this is the only part of an atom involved in Nuclear Reactions (Fission or Fusion).
Come, you lost Atoms, to your Centre draw, And be the Eternal Mirror that you saw: Rays that have wander'd into Darkness wide, Return and back into your Sun subside.
From Farid al-Din Attar's twelfth-century masterpiece The Conference of the Birds
The SXS project is a collaborative research effort involving multiple institutions. Our goal is the simulation of black holes and other extreme spacetimes to gain a better understanding of Relativity, and the physics of exotic objects in the distant cosmos.
The SXS project is supported by Canada Research Chairs, CFI, CIfAR, Compute Canada, Max Planck Society, NASA, NSERC, the NSF, Ontario MEDI, the Sherman Fairchild Foundation, and XSEDE.