Einstein's post suggests quantum immortality. Everett's many-worlds interpretaton and the quantum suicide experiment can explain why he still exists.
Tegmark describes the 'Quantum Suicide Experiment' as follows (I have simplified the text and removed the mathematical proofs):
The apparatus is a "quantum gun" which each time its trigger is pulled measures the z-spin of a particle [particles can be spin up or spin down, seemingly at random]. It is connected to a machine gun that fires a single bullet if the result is "down" and merely makes an audible click if the result is "up".... The experimenter first places a sand bag in front of the gun and tells her assistant to pull the trigger ten times. All [quantum mechanics interpretations] predict that she will hear a seemingly random sequence of shots and duds such as "bang-click-bang-bang-bang-click-click-bang-click-click". She now instructs her assistant to pull the trigger ten more times and places her head in front of the barrel. This time the "shut-up-and calculate" [non-manyworlds interpretations of QM] have no meaning for an observer in the dead state... and the [interpretations] will differ in their predictions. In interpretations where there is an explicit non-unitary collapse, she will be either dead or alive after the first trigger event, so she should expect to perceive perhaps a click or two (if she is moderately lucky), then "game over", nothing at all. In the MWI, on the other hand, the ... prediction is that [the experimenter] will hear "click" with 100% certainty. When her assistant has completed this unenviable assignment, she will have heard ten clicks, and concluded that the collapse interpretations of quantum mechanics [all but the MWI] are ruled out to a confidence level of 1-0.5n ˜ 99.9%. If she wants to rule them out "ten sigma", she need merely increase n by continuing the experiment a while longer. Occasionally, to verify that the apparatus is working, she can move her head away from the gun and suddenly hear it going off intermittently. Note, however, that [almost all instances] will have her assistant perceiving that he has killed his boss.
What this means is that, in most universes, there is one less experimenter, but the experimenter herself does not experience death.
The QTI is formed by reformulating the 'Quantum Suicide' experiment so that the movement of a calcium ion in a brain is used as a proxy for the spin-watching 'quantum gun', following the work of Stapp.
If the many-worlds interpretation of quantum mechanics is correct then a conscious observer can never cease to exist.