As you get older and more and more people around you are younger than you are, it becomes clear that your memories go back to times earlier than many others experienced. It doesn't take long for you to realize the same applies to you. Many days elapsed before you came along. What happened in those times? People came from Asia and Europe and settled parts of North America. They could never get a good cellphone signal. Way before that, people left Africa to span out to Asia and Europe. How far back can we throw our minds? How about 4,543,000,000 years?
If we place our thoughts that far back, we pre-date not only good cellphone service but writing, language, cooking and air conditioning. We might not want to set our time machine back so far that we are on the planet without an atmosphere or with too many raging volcanoes.
It seems murkier to take our minds into the future. When you were 10 or 15 years old, did you have any idea that your life would be like it has? Are you living where you expected to?
Maybe you know that in 1899, the head of the US patent office recommended closing the office down on the grounds that everything that could be invented had been. My wife says she doesn't hear that sort of comment much any more. I think maybe we are more aware that the internet of things (IOT), genetics, and many other areas are just beginning to blossom.