“Imagine. Our planet floating silently in space. Around it, a white dove flies-forever circling. Every one hundred years, the dove's wing gently touches the face of the earth. The time it would take for the feathered wing to wear this planet down to nothing is eternity.”
-Secret Garden, Dawn of a New Century.
Now…. let me just analyse that…
Every hundred years, the wing touches earth, so I’m guessing we can assume a few things here.
First, when the wing touches, it will rub a small piece off. Lets call it 1 gram of sand.
2nd, there is no effect on the dove, so the contact will not wear down the feathers or anything, so all energy is expended on dislodging a piece of earth
So.. lets work that out.
The mass of the earth is
5.9742 × 1024 kg, and is loosing 1gram per 100 years.
Therefore, it takes 10000 years to remove 1kg mass.
Thats 5.97x10^29 years for the planet to be ground down to nothing.
5.97 Billion Billion Billion Billion
Its a big number