- #1

center o bass

- 560

- 2

$$\delta = 3\Theta_0 + \text{constant}.$$

If ##\text{constant} = 0## we call these primordial perturbations

*adiabatic*and one can show that this leads to an everywhere constant ratio ##n_{dm}/n_\gamma##.

Now an

*adiabatic process*is a process that happens without the change of heat.

Question: Is there any connection between the above definition of adiabatic perturbations and the usual meaning of an adiabatic process? Why is this name chosen?