What if the libraries of Ancient Egypt had not been destroyed? They had over 3,000 years of knowledge in libraries across their territory. Some believe ancient Egypt was around even longer, maybe it was even 12,000 years old. What if the ancient Greeks, the Malian Empire, or the Khazars saved all of their knowledge up till this day (i.e. their books and art were burned by the thousands)? Where would humanity be in regards to civilization? Would we be super advanced because of the collective knowledge that had been saved for tens of thousands of years? What could we have accomplished? What leaps could we have made at this point in time?
I imagine a world where medicine is so advanced, the thought of cutting into a human to do surgery seems barbaric and unimaginable. A place where energy does not come from fossil fuels. Perhaps disease has been completely removed from the spectrum. Famine is nonexistent. Food is our medicine and using drugs to heal patients has become a last resort.
Maybe there is no such thing as a car accident death, or a war for energy. I imagine the collective knowledge has created a world where traveling to mars is either a normal occurrence, or Mars has created its own society and way of life for 100 years now. We have sent humans to the edge of the solar system. Probes excited the solar system bubble more than two centuries ago versus a few years ago. I imagine we are trying to figure out how to get humans to the nearest star. Faster than the speed of light is our goal. Or some fraction of it. Or maybe we would have figured out how to manipulate worm holes. What scientist explain as bending space to travel the far reaches of the Milky Way galaxy.
A world where billionaires are altruistic and have used their resources to push research along at unbelievable levels. I imagine a world where knowledge is at a level where we cheat death one decade or more at a time. We will upgrade eyes, brains, and vital organs.