1.
Nature
; 606(7914): 463, 2022 06.
Artículo
en Inglés
| MEDLINE
| ID: mdl-35701619
2.
3.
Phys Rev Lett
; 90(15): 151301, 2003 Apr 18.
Artículo
en Inglés
| MEDLINE
| ID: mdl-12732026
RESUMEN
Many inflating spacetimes are likely to violate the weak energy condition, a key assumption of singularity theorems. Here we offer a simple kinematical argument, requiring no energy condition, that a cosmological model which is inflating--or just expanding sufficiently fast--must be incomplete in null and timelike past directions. Specifically, we obtain a bound on the integral of the Hubble parameter over a past-directed timelike or null geodesic. Thus inflationary models require physics other than inflation to describe the past boundary of the inflating region of spacetime.