1. Heavens and the Earth created in Six days
I do agree that the Qur’an says that the heavens and the earth were created in 6 days i.e. 6 epochs and it is mentioned in
Surah Al A’raf chapter 7 verse 54
Surah Yunus chapter 10 verse 3
Surah Hud chapter 11 verse 7
Surah Al Furqan chapter 25 verse 59
Surah Al Sajdah chapter 32 verse 4
Surah Qaf chapter 50 verse 38
Surah Al Hadid chapter 57 verse 4
The verses of the Qur’an which according to you say that the heavens and the earth were created in 8 days are Surah Fussilat chapter 41 verses 9 to 12
"Say: Is it that ye deny Him Who created the earth in two days? And do ye join equals With him? He is the Lord of (all) the Worlds;
He set on the (earth) mountains standing firm, High above it, and bestowed blessings on the earth, and measured therein all things to give them nourishment in due proportion, In four days, in accordance with (the needs of) Those who seek (sustenance)."
Moreover, He Comprehended in His design the sky, and it had been (as) smoke. He said to it and to the earth. "Come ye together, willingly or unwillingly. They said: "We do come (Together), in willing obedience."
So He completed them as seven firmaments in two days and He assigned to each heaven its duty and command and We adorned the lower heaven with lights, and (provided it) with guard. Such is the decree of (Him) the exalted in might, full of knowledge."
On the face of it, it seems that these verses of the Qur’an give the initial impression that the heavens and the earth were created in 8 days.
Allah says in the beginning of this verse that those who exploit this information contained in this passage to raise doubts about its authenticity are equally interested in promulgating blasphemy and denying His unity. Allah is telling us that in course of time, there will emerge unbelievers who will make use of this apparent contradiction.
2. Summa means moreover
If you analyse these verses carefully, it speaks about 2 different creations: the earth and the heaven. The earth excluding the mountains was created in 2 days and the mountains were set on the earth standing firm and blessed and measured its sustenance in 4 days. Therefore the earth along with the mountains was created in 6 days according to verse 9 and 10. Verse 11 and 12 says, moreover the heavens were created in 2 days. The Arabic word used in the beginning of verse 11 of Surah Fussilat is summa which means; ‘then’ or ‘moreover’. There are certain Qur’anic translations, which have, used ‘then’ for the word summa which, indicates ‘afterwards’. If ‘then’ is wrongly used for summa then the total of the creation of heaven and earth will be 8 days which will conflict with other verses of the Qur’an which says heavens and earth were created in 6 days and will also conflict with the Big Bang Theory as well as the verse of the Qur’an Surah Al Ambiya cha!
verse 30 which says that heavens and the earth were created simultaneously.
Therefore the correct translation of the word summa in this verse would be ‘moreover’. Abdullah Yusuf Ali has rightly translated the word summa or moreover which clearly gives an indication that while the earth along with the mountains, etc. was created in 6 days simultaneously the heavens were created in 2 days. Therefore the total does not come to 8 days but 6 days.
If a builder says that he will construct a 10 storey building and surrounding compound wall in 6 months and after completion of his project he gives a more detailed account saying that the basement of the building was built in 2 months and the 10 storeys took 4 months and simultaneously, while the basement and the building was being constructed, he also constructed the surrounding of the building along with the compound wall which took 2 months. Therefore both his first and second descriptions are not contradicting but the second statement gives a more detailed account for the construction.
3. Heavens and the Earth created simultaneously
The Qur’an describe the creation of the universe in several places, sometimes it says the heavens and the earth (7:54, 10:3, 11:7, 25:59, 32:4, 50:38, 57:4) while in other places it says earth and the heaven (49:9-12, 2:29, 20:4) thus further supplementing the verse of Surah Al Ambiya chapter 21 verse 30 which speaks about the Big-Bang and that the heavens and the earth were created simultaneously.
Similarly in Surah Al-Baqara chapter 2 verse 29
"It is He Who hath created for you all things that are on earth; Then He turned to the heaven and made them into seven firmaments. And of all things He hath perfect knowledge."
"It is who has created for you all things on the earth summa simultaneously made the heaven into seven firmaments".
Here also if you wrongly translate summa as ‘then’ only then would this verse contradict the Big-bang theory and other verses of the Qur’an. Therefore the correct translation of the word summa is ‘moreover’ or ‘simultaneously’.