I've read that when two pieces of the same kind of metal touch in space, they will fuse because there is no way for the electrons to "know" that they are in different pieces of metal. What would happen if two different metals were to touch in space? Would electrons still flow freely between the two pieces? If so, I'm guessing one piece might attract electrons more strongly than the other, and the two pieces would be held together by electrostatic attraction (without fusing). Also, has anyone ever measured how long it takes for cold welding to happen? Would be close to instantaneous or would you have to press the two pieces together for a long time?