Until you have done the above research, I suggest you accept what the Zetas are saying as they fly wherever they desire within the limits of their density and our density.
Are you able to manipulate densities? Have you been to the library Sylvia Browne writes about? Do you see beyond the mountains of our present time?
It does not matter what the disinformation people publish for money.
The trip to heaven is free for those that qualify to travel into the unseen world which is just a step away either laterally of vertically.