I accept that its impossible to forecast the future with certainty. Sometimes humankind makes amazing breakthroughs that domain experts did not see coming (and

I accept that its impossible to forecast the future with certainty. Sometimes humankind makes amazing breakthroughs that domain experts did not see coming (and sometimes progress is much slower that anticipated). https://en.wikipedia.org/wiki/Back_to_the_Future_Part_II https://en.wikipedia.org/wiki/Back_to_the_Future_Part_II I wouldn't assign a probability of 0 that humans make the breakthroughs needed to see many of us becoming double-centurions. However, the last hundred years of medical research hasn't made much meaningful progress in preventing the rapid death of centurions, so I assign a probability far lower than 1.