For the purposes of this post, I am going to assume that humans are alone in the universe.
Also, while any solar system will have iron and ice, they will each have different levels of various materials, the atmospheres and climates will be different, meaning that different crops will grow relatively well or poorly. Different gravities will make things like wood with different properties (straight and very springy wood in low-g, denser and stronger for high). Different atmospheric mixes will impact the flavors of meat and other produce. Some planets will have higher tolerances for polluting industry, others will have lower overall labor costs... Essentially, all the reasons that people trade with other nations now will remain true. The question is, how high a value are the goods being traded, and that depends on the cost of transportation.
Now, why would we have voluntary empires? The main and obvious one is defense. Anytime you have 3 groups, 2 will team up against the third. 20 groups, 30, whatever, there will always be shifting alliances. Another possibility is technological monopoly, ALA "old man's war". And this is neglecting the possibilities of alien hostilities.
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Date: 2014-03-19 02:37 am (UTC)Also, while any solar system will have iron and ice, they will each have different levels of various materials, the atmospheres and climates will be different, meaning that different crops will grow relatively well or poorly. Different gravities will make things like wood with different properties (straight and very springy wood in low-g, denser and stronger for high). Different atmospheric mixes will impact the flavors of meat and other produce. Some planets will have higher tolerances for polluting industry, others will have lower overall labor costs... Essentially, all the reasons that people trade with other nations now will remain true. The question is, how high a value are the goods being traded, and that depends on the cost of transportation.
Now, why would we have voluntary empires? The main and obvious one is defense. Anytime you have 3 groups, 2 will team up against the third. 20 groups, 30, whatever, there will always be shifting alliances. Another possibility is technological monopoly, ALA "old man's war". And this is neglecting the possibilities of alien hostilities.