Praise be to Allah, Lord of the Worlds, and peace and blessings to our Master Muhammad, the Faithful and the Honest. O Allah, we know nothing but what You teach us, You are the All- Knower, the Wise. O Allah our Lord, teach us what is useful for us, let us make use of what You have taught us and advance us in knowledge. O Allah, show us the righteous things as righteous and help us do them, and show us the bad things as bad and help us keep away from them.  O Allah our Lord, make us amongst those who listen to the Word and follow the best meaning of It, and admit us, by Your Grace, to the ranks of Your righteous servants.

What is the barrier mentioned in Surat Ar-Rahman? 

What is the barrier mentioned in Surat Ar-Rahman? What did the scientists of seas and oceans discover about such a barrier? 

Dear believing brothers, there are two Ayaat, one of them in Surat Ar-Rahman and the other one is in Surat Al-Furqan in which the word barrier is mentioned. Allah the Almighty says in Surat Ar-Rahman:   

(He has let loosed the two seas (the salt water and the sweet) meeting together* Between them is a barrier which none of them can transgress* Then which of the Blessings of your Lord will you both (jinns and men) deny?)

[Ar-Rahman, 19-21]

Based on the famous words of Imam Ali, may Allah ennoble his face, referring to the fact that there are Ayaat in the Noble Quran which have not been interpreted yet, scholars of the interpretation of the Noble Quran were bewildered at the meaning of the barrier between the Red Sea and the Indian Ocean. They wondered where it was. Well, where is such a barrier between the Mediterranean and the Black Sea in the Bosporus? Where is it between the Mediterranean and the Atlantic Ocean, at Gibraltar? Where is this Barrier? Allah the Almighty says: 

(He has let loosed the two seas (the salt water and the sweet) meeting together* Between them is a barrier which none of them can transgress* Then which of the Blessings of your Lord will you both (jinns and men) deny?)

[Ar-Rahman, 19-21]

 
The remarkable thing is that each of the two seas has its own unchanged degree of saltiness, which neither increases nor decreases, although they both stand beside each other and are linked to each other. Each of the two seas has their own density, temperature, and color, which do not change, increase or decrease. Flying on an airplane over Bab al-Mandeb (strait between SW Arabia and Africa), Bosporus, or Gibraltar, you can see that each of the two seas differs clearly from the other. Allah the Almighty says: 

(Between them is a barrier which none of them can transgress)

[Ar-Rahman, 20]

Scientists found out that when molecules of the water of the Red Sea, for example, reach a certain presumed line (Barrier) at Bab al-Mandeb, they go back to the Red Sea. Also, they discovered the same thing about the molecules of the water of the Indian Ocean, which also go back once they reach the presumed line between the Red Sea and the Indian Ocean. Scientists also found out that neither of the adjacent seas overwhelms the other or gets mixed with it, simply because each sea has its own unchanged degree of saltiness, density, and temperature. This applies to all adjacent seas and oceans of the world, such as the Mediterranean and the Black sea, the Mediterranean and the Atlantic Ocean; none overwhelms another or gets mixed with it. I repeat the Ayaat: 

(He has let loosed the two seas (the salt water and the sweet) meeting together* Between them is a barrier which none of them can transgress)

[Ar-Rahman, 19-20]

Bear in mind that this barrier is not a solid wall, but rather it is a watery barrier that stands between the two seas and separates them.  

(He has let loosed the two seas (the salt water and the sweet) meeting together)

[Ar-Rahman, 19]

The barrier that separates the two seas is wavy. Allah the Almighty says:   

(Between them is a barrier which none of them can transgress* Then which of the Blessings of your Lord will you both (jinns and men) deny?) 

[Ar-Rahman, 20-21]

(Between them is a barrier which none of them can transgress)

[Ar-Rahman, 20]

What is the meaning of the barrier and the complete partition? 

The second Ayah is in Surat Al-Furqan, and there is something about it. Allah the Almighty says:

(And it is He Who has let free the two seas (kinds of water), one palatable and sweet, and the other salt and bitter, and He has set a barrier and a complete partition between them.)

[Al-Furqan, 53]

Undoubtedly, there is a barrier and a complete partition between rivers, which have sweet water, and seas, which have salt water. By the way, the amplitude of some rivers in America is more than 300.000 cubic meters per second. Such rivers flow 80 km's into the Atlantic Ocean, and their sweet water runs inside the salt water of the Atlantic Ocean, yet it does not mix with it. This is because "between them is a barrier which none of them can transgress." Furthermore, between the sweet water and the salt water there is a complete partition, which prevents the fish living in the sweet water of the river from going into the salt water of the ocean, and vice versa. Concerning this point, Allah the Almighty says: 

(And it is He Who has let free the two seas (kinds of water), one palatable and sweet, and the other salt and bitter, and He has set a barrier and a complete partition between them.)

 [Al-Furqan, 53]

Such a barrier and a complete partition are of Allah's Marvelous Signs that bespeak His Infinite Divine Might and Power. Seas and oceans never get mixed with one another although they are linked to one another. Can you pour into a vessel a glass of sweet water and another of salt water and keep them unmixed, i.e. separated from each other? After they get mixed, can you separate them from each other? Can you drink only the sweet part and leave the salt one? Undoubtedly, this is far beyond human ability!

(He has let loosed the two seas (the salt water and the sweet) meeting together* Between them is a barrier which none of them can transgress* Then which of the Blessings of your Lord will you both (jinns and men) deny?)

 [Ar-Rahman, 19-21]

(And it is He Who has let free the two seas (kinds of water), one palatable and sweet, and the other salt and bitter, and He has set a barrier and a complete partition between them.)

[Al-Furqan, 53]