This was posted in another forum and I was just wondering what the Physics Forum thinks should be chosen. ----------------------------- Alien trade Imagine if you will. An alien spacecraft the size of London appears suddenly over New York. After the inevitable panic, mayhem, calls to God etc, the aliens make contact with the UN. They have a proposition for us. They want to establish a small scientific base on Pluto. They promise not to land on any of the other planets in our system without our permission, or to in any way interfere with our society. In return for our agreement, they will give the world ONE of the following:- 1) 10 Machines the size of a car that can each cleanly produce 200 tons of food per day, for the next 100 years. 2) A machine the size of a house that can provide enough totally clean electricity to supply the entire world for the next 100 years. 3) Software for a genuine AI. 4) Four large craft capable of lifting 100 tons of material into Earth orbit per day. 5) One small ten man craft capable of travelling to any place in the solar system in six hours. 6) A total clean-up of the Earth's environment. Removing all toxic waste, polution etc. This is a one off. If we dirty up the world again, that's our problem. 7) A working base on Mars (but only with our current technology level). 8) A permanent cure for the top 3 world diseases. 9) A 100% accurate lie detector. 10) A machine the size of a house that can rebuild the human body. This machine can handle up to 1000 people per day. It can cure any disease, fix any disablement, and even change your body to look like another person or gender if you wish. However, it cannot change the basic human make-up. It can give you peak human fitness, but not turn you into a superhero etc. The technology of the machines in generally far beyond what we can produce. Therefore we cannot take the orbital lifters and make more. Which should we pick? Or should we say "no thank you"? or ask for something else??