Is there a reason why people can't just take the helicopter to mount Everest? Why is it that helicopters can't reach that high?
[Physics] Why can’t helicopters reach mount everest
everyday-lifefluid dynamics
Related Solutions
However, this same black sky effect does not occur when looking out the window of a plane.
It doesn't?
(image credit: http://www.123rf.com/photo_10994787_view-of-jet-plane-wing.html)
Why can't we reach the ends of rainbow?
The WIkipedia article you linked to contains the explanation
The rainbow is not located at a specific distance, but comes from an optical illusion caused by any water droplets viewed from a certain angle relative to a light source. Thus, a rainbow is not an object and cannot be physically approached. Indeed, it is impossible for an observer to see a rainbow from water droplets at any angle other than the customary one of 42 degrees from the direction opposite the light source.
If you go closer,they will go further. Why?
The primary rainbow is refracted at an angle of 42 degrees. If you are at an angle of say 52 degrees from some droplets you won't see any light refracted by those particular droplets.
As you walk 1 meter towards the droplets that are refracting the rainbow you initially see, you move outside the the "beam" from those specific droplets and move into the "beam" refracted by droplets 1 m further back.
Best Answer
Apparently helicopters could reach mount Everest:
https://en.wikipedia.org/wiki/Mount_Everest#2005:_Pilot_summits_Everest_with_helicopter