Point particle of point charges cannot be maintained in an equilibrium configuration solely by the electrostatic interaction of the charges. In quantum mechanics, there is a distinction between an elementary particle (also called "point particle") and a composite particle. An elementary particle, such as an electron, quark, or photon, is a particle with no internal structure. Whereas a composite particle, such as a proton or neutron, has an internal structure (see figure). However, neither elementary nor composite particles are spatially localized, because of the Heisenberg uncertainty principle. The particle wavepacket always occupies a nonzero volume. For example, see atomic orbital: The electron
How to Dismantle an Atomic Bomb announced that if those tracks were leaked online, they would release the album immediately via the iTunes Store. Several months later, the finished album was leaked online, but the band did not release it earlier, despite previous comments. In late 2004, "Mercy", an unreleased track taken from the "How to Dismantle an Atomic Bomb" sessions, surfaced on the Internet through a fan who had been given a copy of the album containing the extra track. The track is of less than standard audio quality, but managed to become a favorite on fan websites. It was cut from the final release,