We study and classify Lie algebras, homogeneous spacetimes and
coadjoint orbits (“particles”) of Lie groups generated by spatial
rotations, temporal and spatial translations and an additional scalar
generator. As a first step we classify Lie algebras of this type in
arbitrary dimension. Among them is the prototypical Lifshitz algebra,
which motivates this work and the name “Lifshitz Lie algebras”. We
classify homogeneous spacetimes of Lifshitz Lie groups. Depending on the
interpretation of the additional scalar generator, these spacetimes fall
into three classes:1. (d+2)-dimensional Lifshitz spacetimes which have one additional
holographic direction;2. (d+1)-dimensional Lifshitz-Weyl spacetimes which can be seen as
the boundary geometry of the spacetimes in (1) and where the scalar
generator is interpreted as an anisotropic dilation;3. and (d+1)-dimensional aristotelian spacetimes with one scalar
charge, including exotic fracton-like symmetries that generalise
multipole algebras.We also classify the possible central extensions of Lifshitz Lie
algebras and we discuss the homogeneous symplectic manifolds of Lifshitz
Lie groups in terms of coadjoint orbits.