Really interesting thought experiment... At first I was disappointed that the first major comment threads covered bringing back pieces of art. Is that all that

Really interesting thought experiment... At first I was disappointed that the first major comment threads covered bringing back pieces of art. Is that all that we can think of that has value from the past? Then things got more interesting - variations on taking knowledge from the present and applying it to the past: buying successful stocks, investing in successful companies, etc. Finally, comments hit upon my favorite definition of "present gain" - making the world a better place by saving lives, curing diseases, etc. Someone mentioned teaching the Mayans to repel the Spanish, bringing medicine to help American natives cure smallpox, etc. How many wars could be prevented, injustices righted, and inequalities balanced with a bit of know-how and modern biology, chemistry, and tactics?