Barier in the sea

This property of the seas, that is, that they meet and yet do not intermix, has only very recently been discovered by oceanographers. Because of the physical force called "surface tension," the waters of neighbouring seas do not mix. Caused by the difference in the density of their waters, surface tension prevents them from mingling with one another, just as if a thin wall were between them.60

It is interesting that, during a period when there was little knowledge of physics, and of surface tension, or oceanography, this truth was revealed in the Qur'an.

This phenomenon occurs in several places, including the divider between the Mediterranean and the Atlantic Ocean at Gibralter. A white bar can also be clearly seen at Cape Point, Cape Peninsula, South Africa where the Atlantic Ocean meets the Indian Ocean.
But when the Qur’an speaks about the divider between fresh and salt water, it mentions the existence of “a forbidding partition” with the barrier.

“It is He Who has let free the two bodies of flowing water: one palatable and sweet, and the other salty and bitter; yet has He made a barrier between them, to be passed. [Al-Qur’an Furkan 25:53]

Modern science has discovered that in estuaries, where fresh (sweet) and salt water meet, the situation is somewhat different from that found in places where two salt water seas meet. It has been discovered that what distinguishes fresh water from salt water in estuaries is a “pycnocline zone with a marked density discontinuity separating the two layers.”
This partition (zone of separation) has a salinity different from both the fresh water and the salt water.
This phenomenon occurs in several places, including Egypt, where the river Nile flows into the Mediterranean Sea. These scientific phenomena mentioned in the Qur’an was also confirmed by Dr. William Hay, a well-known marine scientist and Professor of Geological Sciences at the University of Colorado, U.S.A.

Finger (print)

The emphasis on fingerprints has a very special meaning. This is because shapes and details on everyone's fingerprint are unique to each individual. Every person who is alive or who has ever lived in this world has a set of unique fingerprints. Furthermore, even identical twins having the very same DNA sequence have their own set of fingerprints.

Fingerprints attain their final shape before birth and remain the same for a lifetime unless a permanent scar appears. That is why fingerprints are accepted as a very important proof of identity, exclusive to their owner. 

However, what is important is that this feature of fingerprints was only discovered in the late 19^th century. Before then, people regarded fingerprints as ordinary curves without any specific importance or meaning. However in the Qur'an, Allah points to the fingertips, which did not attract anyone's attention at that time, and calls our attention to their importance. This importance has only been fully understood in our day.

The star Sirius

When certain concepts mentioned in the Qur'an are studied in the light of 21st century scientific discoveries we find ourselves imparted with yet more miracles of the Qur'an. One of these is the star Sirius, mentioned in Surat an-Najm 49:

The fact that the Arabic word "shiaara," the equivalent of the star Sirius, appears only in Surat an-Najm, meaning only "star," 49 is particularly striking.