If you look deep enough, one can find the answers to all things within the wonderful nature of things.
The first step to answering this great question, are we alone in the universe? One must have some conceptual concept of how small we all are actually with in this vast universe. I have configured a scale down virtual universe based upon the speed of light. For those that do not understand the speed of light i will briefly explain. The speed of light travels at 186,000 miles per second, thats very close to 7 times around the world in one second, still at this fast rate of speed it can take light millions to billions of years to reach many areas in the universe. It takes light just a few hours to leave our small solar system. To reach the next closes star other than the sun takes light 6 years. Now if we compare the Milky Way Galaxy to our tiny solar system and remembering the fact that it takes light just a few ours to leave the entire solar sytem, will in a comparative sense the Milkyway Galaxy contains over 1/2 a trillion stars, and takes light 100,000 years to travel from one end to the other; Now if we were to scale down this system to the point were our solar system would be the size of a grain of sand, this would make the earth about a billion times smaller than the grain of sand, in which the earth would be brought down to the size of a single atom with in the grain of sand, so we humans would even be a billion times smaller than what would now be the atom planet earth.
This brings up the question of how big would the Milky Way Galaxy be? Owe it would configuratively be roughly about the current size of our pacific ocean; Now just think of dropping this tiny grain of sand that represents our whole solar system into the pacific ocean, and how small the earth is with in that grain of sand. This conceptual view gives one a tiny perception of how small we actually are in this vast universe we live in. Now think about the abundance of life that exist in the ocean, and think about if some beings somewhat intelligent a billion billion times smaller than that grain of sand, which is otherwise known as our solar system. Now consider this grain of sand lost in the pacific ocean with all of the life that exist within there; It then becomes obvious that those infintesimal little tiny humans would be a bite to small to detect any life that may exist for a long time with in the vast ocean? Now as far as space travel goes; Think of these little tiny beings building a space craft that could cross the galaxy/pacific ocean, this would be equivalent to traveling to Japan. With all of this in mind it makes it clear that linear space travel becomes more obvious that it is not the way to travel deep into space. Especially when knowning there are a 100 billion or more galaxy's like the scaled down model of the Milky Way galaxy/pacific Ocean, and when there are some galaxies much larger than ours. One may think about how long it take light to reach the next nearest galaxy/ocean. It takes light 2 million years to reach the next nearest galaxy to ours, so based upon our virtual universe just to reach the Atlantic ocean at the speed of light would take 2 million years of travel time for those tiny little beings.