An equation of state (EOS) is a thermodynamic expression that relates pressure (P), temperature (T), and volume (V).
This equation is used to describe the state of reservoir fluids at given conditions..
This phase of early inflation (Planck era) is followed by the radiation era described by an equation of state p = ⇢c2/3 (⇢ / a 4, a / t1/2 and ⇢ = 3/32u21e.
3.
Fluid Equation tells us how the density of universe changes with time.
Friedmann Equation along with Fluid Equation models the universe.
Only relativistic materials impart pressure, matter is pressure-less..
The perfect gas equation of state may be written as The equation of state may be used in
1. ^ Hogan, Jenny. "Welcome to the Dark Side." Nature 448.7151 (2007): 240-245. http://www.nature
SOLVING THE EQUATIONS41 Faced with an equation like this, one can use formal techniques to solve it (this equation is separable, allowing it to be integrated), or alternatively make an educated guess as to the solution and confirm it by substitution
In cosmology, a good educated guess is normally a power-lawa ∝ tq
In physics and chemistry, an equation of state is a thermodynamic equation relating state variables, which describe the state of matter under a given set of physical conditions, such as pressure, volume, temperature, or internal energy
Most modern equations of state are formulated in the Helmholtz free energy
In cosmology, it is often assumed that the equation of state of a cosmological fluid is of the form p = w ρ
Why is this? Is it the equation of a perfect fluid? Why does w = 0 for matter 1 / 3 for radiation and − 1 for a cosmological constant? I take it wikipedia doesn't help? @EmilioPisanty It doesn't help much
Field equation, part of a theory that attempts to combine quantum mechanics and general relativity
