KRABS

So technically if you went back in time to when you were like 7 and dragged your past self into an alternate reality (not this one) and killed them in that reality and then went back into this reality and time travelled back to when your grandfather was like 10 and killed him, you would create an infinite loop; in which you would be constantly dead and alive at the same time, but still conscious enough to make full independent decisions but you wouldn't need your heart to beat, or food, or water, or any of that stuff anymore since you're technically already dead and nothing could hurt you since I mean you're dead already so you're unable to get hurt so that means that TECHNICALLY you could gain immortality that way