There is a question that is bothering me for some time.... I know that Allah tell the thing to be and it happen. So he can create anything instantaneously. What is the best explanation why Allah say in Quran that the creation of earth took 6 days?
This question is two folds:
- You want to know first why six days: a question about the number of days (why not five or two?)
- You want to know why the time limit at all: considering that Allah says:
إِنَّمَا أَمْرُهُ إِذَا أَرَادَ شَيْئًا أَن يَقُولَ لَهُ كُن فَيَكُونُ
His command is only when He intends a thing that He says to it, "Be," and it is.
First you should know that day doesn't mean the day as we know, it has a completely different meaning.
A day corresponds to the rotation of the earth on its axis. At that stage, the earth wasn't created, so the concept of time is very different than what we define. The word day here most probably means a stage.
God created the earth and the sky in six stages. Still we ask why?
God wanted to create the universe in the most complete system, this system is about creating everything due to reasons and causes, in other words the law of cause and effect.
You can see this law everywhere, for example he created the human being in stages too:
ثُمَّ خَلَقْنَا النُّطْفَةَ عَلَقَةً فَخَلَقْنَا الْعَلَقَةَ مُضْغَةً فَخَلَقْنَا الْمُضْغَةَ عِظَامًا فَكَسَوْنَا الْعِظَامَ لَحْمًا ثُمَّ أَنشَأْنَاهُ خَلْقًا آخَرَ ۚ فَتَبَارَكَ اللَّـهُ أَحْسَنُ الْخَالِقِينَ
Then We made the sperm-drop into a clinging clot, and We made the clot into a lump [of flesh], and We made [from] the lump, bones, and We covered the bones with flesh; then We developed him into another creation. So blessed is Allah, the best of creators.
Why did he do that? Can’t he just say be?
[...] and has created each thing and determined it with [precise] determination.
Of course there are many other explanations, for example: Al Imam Al Rida (a.s) says (translation):
He [Allah] created the skies and the earth in six days even though he was able to create them in a blink to show angels what he is creating one after the other.
At first pay attention that "Day" means "a period", whether that period is a year or a hundred years or a million years or billions of years, and there is evidence to prove this,for example:
Qur'an repeatedly used the word "Day" for the long term, such as "Yom Alqyamh" which takes at least fifty thousand years.
Then God's power is infinite. Whatever He desires to do, He does it, and whatever He does not desire to do, He does not do it. Nothing falls out of the premises of God's power and command. Without doubt, God's creation of the universe in six days or six stages does not in any way negate the infiniteness of His power. Never does it imply weakness or deficiency on the part of God, the Exalted. In other words, it is not impossible for God to create the world in an instant.
However, the universe operates on cause-and-effect system and God does not want to make things run against the rules which pervade and permeate the entire universe.(Cited from Collection of Works by Ayatollah Mutahhari,vol:1,pg:408 (Majma'ul Bahrain, the word 'Sabab'))
It is for the same underlying reason that God created the world in six days. In fact, we know that this gradual creation is owing to the characteristic of the universe itself not because He was not able to create it instantaneously.
Conclusively, if the Qur'an says that God created the universe in six days, it does not mean that God's action is gradual and that the creation took place in a gradual way, nor does it mean that God could not create the universe at once and as a whole because He needed time to pass. Such an assumption in regards to God's essence is completely wrong. In fact, gradualness is an essential quality of the creature not of Creator.