It was impossible for modern people to travel to ancient times because modern technology was too different from ancient society. Modern science had developed for thousands of years, but ancient society had only existed for a few hundred years. Even if there was some technology that could allow one to travel back, the level of technology and environment in ancient times were very different from that of modern times, so it was not possible to travel back. However, if he really wanted to travel back to ancient times, he could try some reliable methods. First of all, he could try to find historical records and documents to understand ancient society and culture. Secondly, he could try to study ancient technology and medicine to understand their inventions and treatment methods. Lastly, they could also try to learn ancient languages and cultures to better adapt to the ancient environment. However, it was important to note that these methods could not guarantee that one could travel back to ancient times, and there might be various difficulties after traveling back. Therefore, if one really wanted to travel to ancient times, it was best to make sufficient preparations and consider future development plans.