How Aliens Travel Through Space
An interesting notion comes to mind when I ponder the concept of extraterrestrial space travel and the methods and technology an alien would use to traverse our known cosmos. The notion i'm referring to here is the type of space craft and energy system that an alien would use to get from one point in the galaxy to another.
I believe one can get a better picture of alien technology by contrasting it with current human technology for space travel. The current energy system used in human earth spacecraft requires a large amount of expendable energy to propel the ship from one point to another, and this is usually accomplished in stages. Human beings have never made it further than the Moon with this energy system.
Long distance space travel from one galaxy to another would require a different approach to the way a spacecraft uses energy. If one were to reach into the treasure trove of energetics, some type of nuclear fusion propulsion like that used aboard aircraft carriers would be needed to traverse the distance between galaxies. The technology for a solar sail which harnesses the power of the sun could probably be developed but a problem exists when the spacecraft moves out of our solar system and galaxy into deep space where the sun's energy decreases. This is where I believe a solar sail would then fail simply because it would be out of range to receive adequate solar energy.
Extraterrestrial Technology shatters this human earth-based energetic paradigm by adopting a different approach to harnessing energy. The cosmos is one gigantic cauldron of energy systems - from suns, planets, stars, black holes, worm holes, commets, you name it! The cosmos is exploding with various energy sources. Highly advanced alien spacecraft are designed with shapes and materials that would allow it to absorb and transmute energy coming from various sources. The circuitry and sensors of alien craft would be such as to allow the operators to identify sources and types of energy and lock on to a particular type of energy pattern in order to harness the energy to get to the desired destination. For example, let's say I'm an alien from another galaxy and I wanted to travel to our Milky Way Galaxy. The Milky Way Galaxy produces a distinct energy signature that stands out from other galaxies. So that would be how my spacecraft's computers would identify and distinguish the energy pattern of the Milky Way versus other Galaxies and be able to lock on to that particular energy pattern and use it like a magnet or tractor beam, pulling or propelling it towards the Milky Way Galaxy. Once in the Milky Way, I could then lock on to a planet or even the sun and continue navigating using a planet such as the Earth's energy pattern. So the energy here is coming from an outside source and then transmuted by the craft's internal mechanisms in order to get to the desired destination.