I agree with readerofbooks. But I also wonder to what degree expansion pushes modernization just as a logistical matter. If a country expands geographically, it needs the means to move people and goods outward, and this probably drives advances. A good example is the transcontinental railroad in the United States. If we had not been pushing westward, with people and goods, would it have ever occurred to anyone that such a railroad should exist? Another example might be canals such as the Panama and the Suez. These also solved some of the logistical problems of expansion, albeit at sea, rather than on land. Necessity is the mother of invention.
This is a sophisticated question and I believe there is a direct connection between your two ideas. With the rise of expansion, we see also the growth of modernization. Whenever countries are isolationist, they tend to be less modern. But when countries open their borders and cross their own border into other nations, modernization rises. Part of the reason for his is due to human contact. In other words, there is free exchange of thoughts, ideas, and in time innovations take place. In short, there is strength and genius in many.
Part of the opening of countries has taken place by expansionism. Countries wanted to explore and to put it quite frankly expand. So, mostly Western powers went abroad. Certainly there have been many evils due to this, but one of the byproducts was modernization.
I think expansion has nothing to do with with modernization, but it can help lead up to modernization. During the great depression many times expansion lead to terrible things including:
1) not selling enough
3) default/scarce money
4) Jobs decreasing
5) Economic collapse
Actually a good example would be "the solyndra" energy investment that obama made which terribly failed which ended up become bankrupt though I can say expansion can be good, but it can also lead to failed attempt. I think we shouldn't expand unless we are confident it is a good yet sufficient idea. I think modernization is only necessary when we are changing our infrastructure and making it alot more safe and able to keep up the it. Which america has somewhat failed in certain parts of america.