Non-biological aliens

Aliens are usually depicted as small biological creatures with big eyes and very human like anatomy. If we take into account how long it would take them to arrive to Earth from their home planet and to which conditions would their bodies be exposed during the trip, the chances of survival for the crew would be miniature without some advanced hibernation technology to slow down metabolism and other processes and protect their bodies from long exposure to low gravity and higher levels of radiation.

Very advanced civilization capable of interstellar travel would have probably switched over to a more endurable and efficient type of body, composed of meta-materials and heavily based on advanced nano technology. They would probably totally abandon biological form of body given it's weaknesses. Transition would probably be smooth, with gradual improvements to biological form, making them cyborgs and merging with artificial intelligence. Very soon this process would lead to total transition to artificial bodies.

The question is, would individual aliens be independent, controlling their own behavior, or would we encounter some kind of swarm intelligence like ants, bees and termites. Or maybe, they would all be one singular intelligence controlling every single alien.

Interstellar travel

Influence of Hollywood movies might lead you to imagine a huge alien spaceship 'slowly' approaching Earth from interstellar space.

But this is probably not the most likely way of interstellar travel. Why sending a huge spacecraft when you can send small nano cells capable of self-replication, efficient energy management, carrying powerful artificial intelligence inside.

Those nano cells can be sent to many different parts of galaxy using technology similar to Solar sail, which is a propulsion by radiation pressure generated by starlight or powerful laser pointed directly at sail carrying nano cells.

Those alien probes or nano cells would be able to traverse galaxy and intergalactic space at an amazing speed. Once probes are deployed on a destination planet they will begin to replicate and possibly perform other transformations in attempt to further explore new planet.

Which form they would eventually take is questionable, but they would probably in a very short time upload alien AI to the internet, so it can further explore and learn about us. Eventually if it decide to, alien AI will attempt to communicate with us. Until that point we would probably have not known that alien nano probes have landed on Earth.

What their main goals would be here on Earth and in Solar system altogether, is a question for another post. For now, I hope you gained a new, different view on how alien visit can look like, more in the upcoming posts.