AT LAST THE PROMISED DAY WILL COME.
VERSE NO. 17-20
The first verse here is the conclusion to the last passage:-
``Verily, the sorting Day is an appointment for all.''
When Israfil blows the trumpet, there will come the appointed Day of Judgement in which the righteous from the wrong doers will be sorted out.
Calling the Day of Doom, as the Day of Sorting, or the Day of Sepatation, is very becoming; because in that Day, the truth will be separated from the falsehood. So will the believers from the non-believers, and the righteous from wrong doers be sorted out.
On that promised day, the solar system will change position, and out of their material, a new earth and a new sky will be created. The gates of the unseen will be opened to the material world and angels and spirits will be visible to Man's eyes.
On contrary to now, that it is so much difficult to overcome the attraction of gravity; the gates of ascension will be opened, and Man can easily ascend and descend.

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As to the mountains, they shall move violently and vibrate until they turn to unsubstantial mirages.
The mountains that now seem to be solid in our eyes are in fact not solid. They are rather a porous and spongy mass, the constituent paticles of which that are called atom and molecule, continuously move, spin and vibrate or revolve round each other. So, a mountain is an ocean of elementary particles in motion. Therefore, in the resurrection day, man may see the real feature and form of the mountains, which is somehow similar to a mirage and not solid.
TRANSLATOR'S NOTE