My turn to post, yippy.
On polotics, humanities first mistake was inventing money, it is now a part of our very exsistence. kind of ironic how we have become dependent on somthing that, really doesn't exsist, its just somthing we made up in order to make trade easier. Now it has become the very core of our culture.
I am willing to bet, that this will not change, in the near or distant future. Eventualy we may reach a level at which we can practice perfect comunism (as all previous attempts have simply turned into tyrany) But thats still a ways off.
I suspect, that if we ever get off this rock, the whole colonization concept will be turned into an excuse to make more money. Because we like our money. And money is power, and we really like power.
As for space travel itsself. Once we said that humans cannot fly, now thousands of people "fly" every day.
We once thought the vast exspanse of the ocean was endless, now we have mapped nearly every square inch of the planets surface, and are working on seeing everything there is to see under water and under ground.
Once, the invention of the wheele was a great acheivement, now we are on the verge of developting nanotechnology and biogenetic engeneering. We can even create clones! somewhat flawed, but clones none the less. We aren't even far off from being able to decide how we want our children to look and what features we want to give them, before they are even born.
The problem is investing in somthing as theoretical space travel, as today, inventing stuff costs alot of money.
With no garranty that it will work, and no short term gain, or long term gain to be found that we know of, its kind of heard for a company to invest in somthing like this. If the gain doesn't come for another thousand years, why invest now? we won't get any of the money out of it?
So thats my view of it, if we ever bother to invent space travel, we will still be bound by money and greed.
And to the comment above. Railguns, not a good weapon in space. for one, you cannot fire "bullets" in space. at least not the way we do on earth. Two, objects moveing through space do not stop moveing, which makes them somewhat unstapble, as they could come raining down on a near by planet. Plasma sounds more correct, radioactive material would also work, as it would eventualy lose its energies after a while, and if it hit a planet, it would simply be absorbed.