A scientific basis that UFOs can come to Earth, but aliens have not come.

1. Something that is certainly a UFO

2. The fastest speed of the instantaneous gas is 393,044 km / h and the average Mach 6 or higher, but the carbon type -based life cannot be

3. The fast motion of the warp or space -time concept must pour all the energy between the stars, so there is no reason to take the risk and come to the earth.

4. Then it is very fast but needs to be moved at a slower speed than light, but the closest antagonist in our stars to do four years at the speed of light (Alpha Sent Tauri)

5. However, it is unknown whether there will be a highly developed intellectual life in the Alpha Sen Tauri.

Conclusion: No matter how outstanding intellectual life, it is not possible to come to Earth at the speed of movement that will take a long time without exploration.