Except you can't link to scientists who say that. Why not?
Our theorem shows that null and timelike geodesics are past-incomplete in inflationary models, whether or not energy conditions hold, provided only that the averaged expansion condition H av > 0 holds along these past-directed geodesics. This is a stronger conclusion than the one arrived at in previous work in that we have shown under reasonable assumptions that almost all causal geodesics [i.e., as distinguished from those of higher dimensions], when extended to the past of an arbitrary point, reach the boundary of the inflating region of spacetime in a finite proper time" ( Borde-Guth-Vilenkin).
This theorem extends to cyclical inflationary models and the inflationary models of multiverse as well. The physical universe at large, regardless of the chronological or the cosmological order of its structure, cannot overcome the thermodynamics of entropy.
Joined by others, Vilenkin summarizes the matter as follows:
It is said that an argument is what convinces reasonable men and a proof is what it takes to convince even an unreasonable man. With the proof now in place, cosmologists can no longer hide behind the possibility of a past eternal universe. There is no escape, they have to face the problem of a cosmic beginning (Many World in One; New York: Hill and Wang, 2006, pg. 176).