I put in a vote for Alexandrian Library too, though like naturalplastic I would find a way to help the librarians preserve and disseminate the information and only take copies back to the present,not originals.
Cracked weighs in:
http://www.cracked.com/article_18539_7-lost-bodies-work-that-would-have-changed-everything.html
Quote:
It was simply the biggest, most famous and easily the most sorely-missed library in history. Situated in Alexandria, Egypt, the Library of Alexandria was the de facto National Archives of Antiquity. It housed anywhere between 650,000 to one million scrolls, which was basically everything ever written up until that point.
What collected human knowledge was lost? What advances could have happened if it wasn't? During the Renaissance, scholars of the time looked back to whatever ancient writings they had access to and acted on that information. What if they had access 650K scrolls (at minimum) more?
Cracked also grieves the loss of Tesla's work:
Quote:
Tesla gets mentioned on Cracked just slightly less than Batman, but we'd probably have devoted the whole site to him if half of his life's work hadn't gotten lost in a fire.
Before he moved to Colorado Springs to help Wolverine do magic tricks in 1899, the bulk of Nikola Tesla's research could be found at 35 South Fifth Avenue, New York. Within this real life mad science lab could be found Tesla's full collection of equipment, notebooks, laboratory data and a secure perimeter of Tesla coils.
For personal rather than "make the world a better place" reasons I would also like to go back and show scientists of the past how much we appreciate their work and give them "spoilers" about questions that bugged them. I want to show Galileo a picture of the spacecraft named after him and show him close-ups of the planets. I want to tell Darwin about DNA because not being able to figure out the mechanism of information transmission through the generations reportedly bugged him to his grave. I want them to know how much we appreciate what they did.