If we accept the existance of UFOS, then we  must be able to explain their strange behavior. The witnesses report for them instant fast accelerations, sharp turns of 90 degrees with enormous speed, change of shape or colour and even disappearance, like they jump from one world to another. UFOS are clearly violating the laws of today’s physics. No human spacecraft could imitate their strange and magical behavior. So it is obvious that if we want the possibility of interstellar travelling and be able to explain the phenomenon of UFOS at the same time, we will have to move on with courage to the creation of a New Physics, that will allow all the above, and abandon the ancient perception of the ''impossible'' from our classic theories.
 
Even conservative Nasa, by recognising the important weakness of our today's theories, was forced to innovate and set a programme of investigation at 1966 for the possibility of new ''revolutionary systems of space promotion'', as long as it does not violate some fundamental principals of physics, like the principle of conservation of momentum and energy.