The existence of escape velocity in gravitational fields is a foundational and direct consequence of Newtonian mechanics and general relativity, representing a basic physical principle that requires no external citation.
The claim states that gravitational fields create an escape velocity for massive bodies. This is a direct physical truth and fundamental definition derived from the conservation of energy in a gravitational potential well. Per the system instructions, a trivially true claim by definition or everyday observation is categorized as COMMON_KNOWLEDGE, requiring no papers and leaving the index lists empty.