Mark all true statements concerning cosmology.
A. In the big-bang theory, the universe emerged from a big explosion that occurred at a certain point in space many billions of years ago.
B. In the big-bang theory, the universe expands, occupying a volume
where there was only a vacuum before.
C.Hubble's law states that the speed with which other galaxies move
away from our galaxy is proportional to the distance of these
galaxies. This law applies to any other galaxies, such as, for
example, the Andromeda galaxy, our Milky Way's neighbor.
D.The Friedmann-Lemaître metric is a solution of the Einstein field
equation where the “cosmological principle” is applied, which
assumes that the universe is homogeneous and isotopic. This metric
describes a universe that starts out in an extremely dense state
and then immediately expands.
E. The cosmological constant term was later added by Einstein to
his 1915 field equation with the intention of obtaining a
stationary solution for the universe. It is said that he later
regretted it, because he thought that if he had relied on the
original field equation he would have been able to theoretically
have predicted the expansion of the universe, prior to observations
in this regard.
F. The cosmic microwave background consists mainly of microwaves
coming from all directions in space and can be associated with a
black body at a temperature of the order of 3 kelvin. Its
cosmological origin fits the big-bang model, in which the universe
expanded from an extremely dense and hot initial state.
G. The cosmic microwave background originated when the temperature
of the universe was lower than 3×103 kelvin, allowing the formation
of neutral atoms.
H.Einstein's field equation, with the inclusion of the cosmological
constant term, allows the description of a universe in accelerated
expansion.