It seems a little unreasonable that U̳F̳O̳ crashed frequently without any invading to earth. Although it doesn’t make sense, such advanced civilization crashed their U̳F̳O̳ to earth and come back. There are only two reasons con explain that: One, either never crashed flying saucer on earth, which are all fake. Two, perhaps real a̳l̳i̳e̳n̳ flying saucer is only suitable for flying in the universe without adapting to the earth’s environment and crashed.
A̳l̳i̳e̳n̳s visiting earth frequently, this is the fact that does not dispute. And every time arrival will leave a mark, but also has a mistake, due to some unexpected reasons lead to the flying saucer crashed a cause and recorded the phenomenon of the corresponding cases. The astrophysicist Stephen Hawking has expressed his concerns.
In a paper published recently, however, researchers believe that humans are unlikely to suffer from an a̳l̳i̳e̳n̳ attack. Janne Korhonena says: Destroy a race that won’t threaten you won’t improve the original security of the intruder, and the value of a small planet for an advanced civilization with high technology is tiny.
He also warned that once our technical reach the level such as “Star Wars”, the a̳l̳i̳e̳n̳s could begin to raise the hostility to us. He wrote: Any interstellar sail ship can travel in space within the acceptable time is a kind of weapons with mass destruction.
If a̳l̳i̳e̳n̳s really attack us, then their technical advantages must be overwhelming to ours, and we have no chance to make any counterattack. Due to the transmitting characteristics of the light speed, the attack of the a̳l̳i̳e̳n̳s will have a lot of uncertain facts. When these a̳l̳i̳e̳n̳ invaders are driving the spacecraft near stars they want attack to, they will find the technical level and equipment of that planet already has leading their fleet for decades or even centuries.