Pretty Interesting. But me and my Dad always had our own theories on the subject. We believe that couldn't it be more likely that Aliens were infact evolved humans from the future, that could travel back in time. Most people would be like "Wow! What are you talking about travel back in time?". But if you really think about it. What would an evolved human look like whose planet had been destroyed over thousands of years and the only way of survival was to travel in Space.
1) Hairless. As we wear clothes we would no longer need alot of body hair to keep us warm
2) Pale or Grey skinned - due to lack of sunlight and Vitamin D
3) Skinny body shape no muscles and weak looking - where manual labour was no longer required we would have a skinnier body type.
4) Huge Brain/Head - Brain would be used alot more rather than the body perhaps we would be telepathic in the future.
Pretty much all these features are found in the most commonly mentioned alien sighting that alien abductees claim etc. These are known as the 'Greys' Picture below. These sort of faces are also found carved and painted into walls in Egyptian times along with other cultures from thousands of years ago.
Now for the time travel. Albert Einstein the German genius. Claimed that the faster we travel the slower time would go. If we could slow down time maybe we could even reverse time. Think of how advanced our travel systems will be in thousands of years time. Its an interesting and scary thought. Another theory are wormholes see the vid below...
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