To answer the question of the thread, Aliens exist (Life in one form or the other is there for sure), but sighting of UFO's? I don't think so.
er, no, there are many confirmed and unconfirmed UFO sightings and encounters.
First, there are certainly no signs of highly intelligent life form in this Solar System. Second, interstellar travel takes enormous amount of time.
OFC not, in this solar system, we have the only planet with a suitable environment for lifeforms like us. until we see lifeforms based on elements other than carbon, we will not be finding "life" in our solar system.
we are a carbon based life form, that means, carbon forms the most important part of our bodies.
now imagine a creature formed of chlorine, silicon, methane. oxygen would be deadly to it. water would just dissolve its structure (like acids do to us). it would prolly look like a cross between a tortoise and a rock. how would you know its "life"?
Interstellar travel takes a lot of time, but you know, there could be ways to overcome that problem. long living species comes to my mind... cryogenic freezing, bending the laws of physics.. etc.
It takes time to enhance one's technological abilities so much as to send something which would sustain any form of intelligent life.
you assume that every planetary life system had started at the same time as ours....
what if the first 3 billion years were not wasted by one celled organisms floating in the ocean? what if the cells became multicellular in just a few million years? those guys could be ruling galaxies..... what if THOSE guys think that theirs is the only life? will they look in other galaxises? our galaxy?
Robotic UFOs can be sent, but again, where will the power come from in that tiny space as UFOs are seen to be?
as i said, lots of sources. fusion, matter-antimatter reactions.
When a life form starts getting very intelligent, its way of technical evolution has to be something like that of humans, to an extent. There are social problems, ruling problems, etc..etc.. But it also gets an idea that they have limited resources, and extremely limited on the planet. They'd start to understand technology and eventually start a space program just for curiosity and then then for necessity. But with the limited resources they'd first check other stars and planets and send an unalienated machine before for checking. Considering the timeframe since the Big Bang, evolution of galaxies and stars, planetary bodies, chemical reaction, simple unicellular and multicellular life, catastrophes, emergence of intelligent life, occasional catastrophes (until aliens learn to sustain them and find ways to stop them to certain extents), re-emergence of intelligent life (or in other case annihilation), becoming technologically advanced enough for sending probes to far away stars; it would take a lot of time to reach us.
^^ read the one where i wrote about the lost 3 billion years.
Umm.. I don't think so, because if they have this level of scientific knowledge, then they certainly can create intelligence lives themselves and do things an average Joe can't imagine. But then, they know that intelligent life exist in other places and how to visit them without getting caught. If they would have wanted to show themselves, they would have done it earlier. If not, then they can easily hide themselves and not get caught in "UFO sightings" by humans.
If they cannot hide themselves properly, then why cannot any other scientific equipment on and above the Earth hint something unusual? Why are they not hiding in and above places that are not populated? A civilization that advanced can create intelligent artificial beings, not only electronic but also biological and then there's not much difference between artificial and natural life. If you stretch the time frame of a civilization, creating artificial, chemical (which when is very complex is called biological) becomes easier than thought. They could have made animal-like beings to navigate the surroundings without creating doubts.
good point