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Thermodynamic potentials, quantum operators, particle symbols and the tensors of relativity — four notations the catalogue held nothing for. What holds the group together is that each writes something with no everyday description compactly: a hat that turns a classical energy into an operator whose eigenvalues are the allowed levels, a dagger that is a Hermitian conjugate, a pair of indices carrying the whole geometry of spacetime. Several members exist to correct a popular account rather than to define a symbol — that the Higgs boson is not what gives things mass, that nothing locally unusual happens at a Schwarzschild radius, that redshift is not a velocity, that a strange quark's strangeness is minus one because nobody ever fixed the sign.
An italic capital S, a measure of how many ways a state can be arranged.
An italic capital H, internal energy plus pressure times volume.
An italic capital G, deciding whether a reaction proceeds.
An italic capital A or F, the constant-volume counterpart of Gibbs energy.
A Greek mu, the energy cost of adding one more particle.
An italic capital Z, a weighted count of a system's states.
An italic f, an effective pressure for a real gas.
An italic capital Z, one for an ideal gas and not otherwise.
A p with a circumflex, standing for a derivative times minus i ℏ.
A sigma with a subscript x, y or z, three two-by-two matrices.
A lowercase a with a dagger superscript, adding one quantum.
A plain lowercase a, removing one quantum.
A capital N with a circumflex, counting quanta.
A Greek rho with a circumflex, a state that may be a mixture.
A Greek lambda, the probability per second of one nucleus decaying.
A Greek sigma, an effective target area for a reaction.
Six lowercase letters u, d, c, s, t and b.
A lowercase g, the carrier of the strong force.
A capital W with a charge superscript, the charged weak carrier.
A capital Z with a nought superscript, the neutral weak carrier.
A capital H, the excitation of the field that gives mass.
An italic capital I, treating the proton and neutron as one particle.
An italic capital S, counting strange quarks with a sign flip.
An italic capital B, one third per quark.
An italic capital L, counting electrons, muons and taus.
A capital P, reflecting space through the origin.
A capital C, swapping every particle for its antiparticle.
Three capitals together, a symmetry believed exact.
A Greek gamma, how much relativity changes things.
A Greek tau, the time a clock actually reads.
A lowercase g with two lower indices, defining distance itself.
A capital gamma with one raised and two lowered indices.
A capital R with four indices, the full description of curvature.
A capital R with two indices, a contraction of the Riemann tensor.
A capital G with two indices, the geometry side of the field equations.
A capital Greek lambda, the energy of empty space.
A capital H with a nought subscript, the current expansion rate.
A lowercase z, fractional stretching of a wavelength.
An r with a subscript s, the size of a black hole's horizon.