Surely there may be life outside elsewhere on the universe, but the problem is the size of universe and the limit of speed of light, even for a signal (radio wave - electromagnetic wave), that travels at light speed, sent from Mars to Earth by some Nasa device, there is a delay of more than 5 minutes! So if any form of advanced life send a signal to us, from the nearest galaxy, it will take more than 25 thousands years to arrive. That is the reason why is pretty unlikely that anyone in our life time will ever see an UFO or contact an UFO or extra terrestrial entity.