Imagine some inhabitants of Jerusalem at the time of Jesus, 2,000 years ago, stepping into a time machine and traveling to Ottoman-occupied Jerusalem in the 1800s. They would undoubtedly be impressed by the new city wall, the significant population increase, and the adoption of new innovations. However, although nineteenth-century Jerusalem was quite different from its predecessor in the Roman era, our time travelers would adapt relatively comfortably to their new environment. Admittedly, they would have to change their behavior to fit the new cultural norms, but they could practice the professions they had learned at the dawn of the first century and could earn a living fairly easily, since the knowledge and skills acquired in ancient Jerusalem would remain useful in the early nineteenth century. They would also discover that they faced the same dangers, diseases, and natural disasters as during the Roman period, while their life expectancy would not change significantly.
But imagine the experience our time travelers would have if they were to enter the time machine again and travel just two centuries further into the future, to early twenty-first-century Jerusalem. They would be left speechless. Their skills would now be outdated, most professions would require formal education, and technologies that would seem like magic to them would be everyday necessities. Moreover, since many deadly diseases of the past would have been eradicated, their life expectancy would immediately double, a fact that would require a different mindset and a more long-term approach to life.
