Equation 42 · Part 1 · Every Crystal Has Its Own Speed of Light
Symbol c_eff
What this part means
the including.
Its job in the formula
ff is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol c_eff→Article meaning
Where the article explains it
A crystal has a ground state and a lattice, and both pick out a rest frame: no continuous symmetry carries the crystal’s description in one inertial frame into its description in another, because the lattice Hamiltonian is manifestly not invariant under a boost at any speed, including .
The passage around this formula
…frame: no continuous symmetry carries the crystal’s description in one inertial frame into its description in another, because the lattice Hamiltonian is manifestly not invariant under a boost at any speed, including . Relativity of simultaneity fails along with it outside the linear window, and so does the idea of one universal energy-momentum relation: a crystal has many bands, each with its own dispersion and its own emergent speed, so a magnon, a phonon, and a Dirac electron sharing one…
Learn the underlying idea
A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.
Open the illustrated subscripts: which member of a family? guide →
See this notation across published equations →
The article lists its research sources here.