Not all UFOs are extraterrestrials – some are time travelers from future human civilization using the same network of wormholes
If a wormhole can be kept open using incredible amount of energy then theory of relativity allows artificial manipulation of time to scale the same back. In other words the entry and exit points of the wormhole may not have the same time reference. Once a civilization discovers the methods of separating time and space with the use of wormholes and electromagnetic transformations within the same, time travel at least to the past is possible.
Many of the UFOs that we see all around us are time travelers from future human and alien civilizations. They use the same wormhole network of interconnectivity but change the exit point of the wormhole to a different time reference. The time to make the time travel is shortened by million factors because advanced civilizations separate time and space within a wormhole and accelerate the time dimension backward while keeping the space same.
Traveling through the wormholes is fascinating. One can plan and program time and space separately. Then apply the entry and exit points of the wormhole to match the time and space reference points. One has to perform the time and space reference point calculations using higher dimensions (in a parallel universe) and the references will not be anything we know or can relate to in our physical universe. These time space reference points are spatial points where time and space can be plotted in a four or higher dimensional graph. Adjusting the entry and exit points of the wormholes can be comparatively easy once performed from a higher dimension in a parallel universe. It can be an extremely difficult numerical analysis problem if we try to do it in our physical universe. Once we are in one of the parallel universes, we can view time and space the same way we can differentiate length, height and width.
The time travelers from future human and alien civilizations visit us using UFOs through the network of wormholes. According to some theories they cannot alter the past. That means they cannot be harmful to us. They are also of no benefit to us. The reasoning behind this theory is that in the parallel dimension the spatial structures can be viewed but like in physical universe there is nothing to alter. The other reason is that once in space-time equations, space is fixed and time is accelerated back wards, the space cannot be altered. If space is altered while time is moved backwards, the references will be lost and the time traveler will never be able to get back to its desired point of exit. In other words no one will like to travel through a worm hole before fixing the entry and exit points. Unless some one is on a suicide mission of exploration, no one will like to travel through the wormholes where the exit points are altering wildly over space and time.