Re: Communication and Travel

David Gerrolds briefly discusses some of the ramifications
of interstellar communication in his book SPACE SKIMMER.
He notes that the size of one's interstellar empire is
more or less determined by the speed of one's communications.
If it takes more than a year to get a message from an
outlying province and the imperial capital, it is an open
question whether said province is actually part of the
empire.

If the fastest form of communication is a starship, the
empire has real problems.  The frontier will expand.
In all likelyhood, for every exploration ship going 
spinward, there will be one going anti-spinward.  Therefore,
one's empire will expand at about twice the speed of one's
communications.

Gerrolds suggests a loose empire, with the emperor
issuing "letters of marque" to outlying provicial governments.
The empire is more of a clearinghouse for knowledge and information
rather than a dictatorship.