Physical immortality dating
By definition, all causes of death must be overcome or avoided for physical immortality to be achieved.There are three main causes of death: aging, disease and trauma.Ideally, any methods to achieve physical immortality would mitigate the risk of encountering trauma.Taking preventative measures by engineering inherent resistance to injury is thus relevant in addition to entirely reactive measures more closely associated with the paradigm of medical treatment.Aubrey de Grey, a researcher who has developed a series of biomedical rejuvenation strategies to reverse human aging (called SENS), believes that his proposed plan for ending aging may be implementable in two or three decades.The absence of aging would provide humans with biological immortality, but not invulnerability to death by physical trauma: Eternal life can also be defined as a timeless existence, which is also not known for certain to be achievable, or even definable, despite millennia of arguments for eternity.
Without improvements to such things, very few people would remain alive after several tens of thousands of years purely based on accident rate statistics, much less millions or billions or more.Biologists have chosen the word immortal to designate cells that are not limited by the Hayflick limit, where cells no longer divide because of DNA damage or shortened telomeres.Prior to the work of Leonard Hayflick there was the erroneous belief fostered by Alexis Carrel that all normal somatic cells are immortal.Biological immortality is an absence of aging, specifically the absence of a sustained increase in rate of mortality as a function of chronological age.
A cell or organism that does not experience aging, or ceases to age at some point, is biologically immortal.
Being the seat of consciousness, the brain cannot be risked to trauma if a continuous physical life is to be maintained.