Aliens may exist as an advanced culture in the 11th or lower dimension, for they can see us all and not be seen by them. They will extend to abduct "maybe" for some reason for maybe some human has known or done something, good or bad.
aliens switch dimensions will or will not for us to see them in the future. All beings, once advanced enough will want to know about other beings so i believe we will meet, maybe not aliens but other forms of "humans" or creatures in about 3000 years or more.
Aliens are from different planets... or are they? all believe aliens are in our galaxy and on a plant by stero types but really i believe that if they were an advanced culture they would find a better place than a planet to rest in so there would be not gasses, global warming, or meteorites to pierce through their planet.
Aliens are in a different part of our universe. They probably life in space and made their own "world" made of advanced buildings and no natural and physical things can harm because they are not polluting the earth.
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If we ever meet aiens or other beings, they will either end the human civilization and have the war of all wars which will lead of the cultures to die out, or they will give us gifts and offer us to work together in one world and accept us in their home(space) which we will be able to live on.