EhsanZ

I gave you the answer on another forum. You made a mistake my friend! This term is correct.

With Hobson's notation: H=(da/dt)/a dH/dt = ((d2a/dt2)/a) - ((da/dt)/a)2 If ((d2a/dt2)/a) is negative, (dH/dt) is certainly negative. But if ((d2a/dt2)/a) is positive, (dH/dt) can be positive or negative. What is your interpretation?

What is the exact calculation of Particle horizon in Lemaître model? Does it exist? Is it finite or infinite? Can anyone calculate that integral? Thanks