Imagine cutting a golf ball in half and placing the halves on the top and bottom of a dinner plate. Then, if you can imagine the plate being made up of spiraling arms of dust, you would have a close approximation of what our galaxy looks like. What most people don't realize is actually where our solar system is located within the Milky Way. Unfortunately, according to the astronomers who make a living figuring things like this out, it is in one of the spiral arms, far out near the edge of the galaxy, where the stars are thinly spaced and quite far apart. In other words, we're way out in the middle of nowhere. Only a small handful of stars are less than ten light years away from Earth, with the closest being Alpha Centauri, which is four light years. Yes folks, it takes light, which is incredibly, unbelievably fast, four whole years to travel from Alpha Centauri to the Earth.
Okay, so let's play a little bit with our imagination. Let's suppose that in the future, mankind were to invent a new type of propulsion that could send a space ship twenty times faster than any man made object has ever gone before. That space ship, my friends, would still not be going anywhere close to even one one hundredth of the speed of light. That gives you some idea of how fast light travels. But let's give mankind the benefit of the doubt, and assume that somehow he achieved the unbelievable speed of one one hundredth of the speed of light. That would mean that instead of four years to get to Alpha Centauri, it would take four hundred years. And yes, I have heard of suspended animation, but that is more in the realm of science fiction, not actual science. A four hundred year journey, in my opinion, would take many generations. I can only think of two reasons for a journey of this magnitude, either exploration or colonization. A journey of exploration, however, infers that the discoveries and knowledge would be brought back to Earth. But can anyone imagine such expense and effort being expended when the benefits wouldn't be arriving for over eight hundred years? I know I would have a hard time believing it.
The other possibility would be colonization. In this imaginary journey, remember, we are traveling to Alpha Centauri. With the aid of the Hubble Space telescope, scientists have been able to determine that quite a number of stars in our galaxy have gas giant planets orbiting them, due to a visible wobble of the star. Alpha Centauri is one of those wobbling stars. However, the wobble only confirms the existence of a gas giant planet, and it would still be unknown whether a rocky planet capable of being colonized exists.
The other limiting factor of colonization is the sheer magnitude of the undertaking. The size of the gene pool would need to be large enough for a necessary amount of diversity in the colonists, and though I'm certainly not an expert in this field, possibly somewhere in the neighborhood of a thousand people may be needed. How could a thousand people be fed for four hundred years on a space ship? And how much equipment and supplies would they need to take along to set up the colony when they arrive? Would any nation, or group of nations, ever consider such an undertaking when it wouldn't even be known whether there would be a planet hospitable to colonization?
Due to the immense distances between stars in this part of the galaxy, I think it is safe to say that our species will not be space travelers. Perhaps, if we had been lucky enough to have our solar system located in the much denser, central hub of the galaxy, we would be able to visit our neighboring stars, and, in turn, be visited by them. Perhaps, in that part of the galaxy, we would be able to gain new technologies and knowledge from a whole network of civilizations, but, then again, perhaps we would end up being invaded and conquered. We will never know, because the distances in our part of the galaxy are too great. We were lucky that we were the right distance from the sun for life to evolve. We were lucky that the Eurasian continent was oriented east-west so that our western civilization could develop. But our luck ran out when it came to our location in the galaxy.
Mankind is on his own, and whether we continue to survive as a species will depend on whether we can find a balance between the Earth's resources, and our exploitation of them. In my opinion, it will depend on whether we can find that balance before we end up destroying ourselves. This is the only home we will ever have. The choice is up to us.