= David Wands
{c}
<David Wands> and collaborators gave a conservation-based account of long-wavelength fluctuations in <linear cosmological perturbation theory>. Their 2000 work treated slowly varying regions as locally homogeneous expanding universes and identified the conditions for conserved <uniform-density curvature perturbations>, without selecting particular gravitational field equations.<A new approach to the evolution of cosmological perturbations on large scales by David Wands and others>[Abstract and separate-universe interpretation]{ref}
The important qualifications are negligible spatial gradients and negligible <non-adiabatic pressure perturbations>; large wavelength alone is insufficient.
Back to article page
