According to Quran 31:10 :
He has created the skies without the pillars that you may see, and placed mountains on the earth, lest it shakes with you, and spread over it all kinds of creatures. And We sent down water from the heavens, and caused to grow in it every noble pair.
The sky is just the color we see. It is not a structure, or a roof over our heads. So what is the Quran referring to when it mentions, "He has created the skies without the pillars"?
We don't understand whole Qur'an Ayah by Ayah. Our belief to Qur'an doesn't go through understanding of all Ayahs and finding such intangible Ayahs (that are called Mutashabih) won't refute our belief.
Any interpretation for such Ayah today will be ridiculous in future. Read some old tafsir and you find a lot. Some people in old times may asked why Allah says that he is able even to reconstruct our finger tips? What is so special in our finger tips? Now we know those unique identification codes in our fingerprints. In such cases we just say we don't understand it yet. As Qur'an says:
لِّكُلِّ نَبَإٍ مُّسْتَقَرٌّ ۚ وَسَوْفَ تَعْلَمُونَ وَإِذَا رَأَيْتَ الَّذِينَ يَخُوضُونَ فِي آيَاتِنَا فَأَعْرِضْ عَنْهُمْ حَتَّىٰ يَخُوضُوا فِي حَدِيثٍ غَيْرِهِ ۚ وَإِمَّا يُنسِيَنَّكَ الشَّيْطَانُ فَلَا تَقْعُدْ بَعْدَ الذِّكْرَىٰ مَعَ الْقَوْمِ الظَّالِمِينَ (الانعام/67-68)
Every tiding has its time appointed; you will surely know. When thou seest those who plunge into Our signs, turn away from them until they plunge into some other talk; or if Satan should make thee forget, do not sit, after the reminding, with the people of the evildoers.
Maybe the atmosphere is one layer of the sky? What do you mean the sky is just the color we see? The color we see, as we postulate today, is due to reflection and refraction of sunlight through the atmosphere.
Further supporting my claim is that Earth is the only known planet that has an atmosphere that can enable humans (or animals) to live under. If you study some cosmology, then you will see how rare Earth is and how many conditions it has to meet for us to sustain, and miraculously, by Allah's will it does.
Just because 'the sky' is not solid does not mean it is not a structure, just because 'the sky' is intangible does not mean it is not a structure. We know too little to decide that.
And Allah knows the best.
It simply means that there are no pillars holding up the sky. It's a reference to the Chinese who had an old myth spreading throughout ancient Asia that the sky was held up by eight mountains that were pillars. Allah is making us clear in the Ayah that there are no pillars holding up the sky. In other words, there are no pillars that you can see but the sky still remains up there as Allah created it to be. One day the sky will depart LIKE a scroll rolled up. The meaning there of of optical illusion. It is meant to be taken allegorically and not literally as the sky is not made of scroll paper either. As Salam Alaikam.
The heavens (universe) are supported by invisible (dark) pillars (matter and energy). The dark energy pulls the universe outward, the dark matter pulls it inward.
As you have already mentioned in your question the verse [31:10] doesn't states that Allah has created the skies without pillars, but without pillars that you may (or, can) not see. That is, there are pillars but we cannot see, invisible pillars! you may instead ask what is meant by these invisible pillars. According to a hadeeth from Imam Ali ar-Ridha --peace be upon him-- there are pillars but not visible to us. According to a Hadeeth from Imam Ali --peace be upon him-- the pillars are pillars of light, maybe one should interpret it like gravitons (or gravitational waves) in new Physics, maybe not, but anyway, there are pillars! For further reading please see here and here.
Godspeed.
Don't you know the earth has a roof without pillars sheltering us from many dangerous things in outer space. The magnetic field is the roof for the earth. We build homes with roofs to shelter us from the weather.
Pillar is something that carries a weighty object over the strength of ground. In Quran, the Earth (Ard) symbolizes the life of dunya which is the life dynamics that we perceive with our five basic senses and desires of our bodies (e.g.; like thinking something smelling good is always beneficial to our body). And the sky (sama), almost always mistranslated as heavens, symbolizes the perception of the world beyond the life of dunya.
So, the meaning of sky wouldn't need pillar is that in order to understand the real face of the world, we do not have to indulge into dunya, because it is independent of dunya.
There is no end of explaining these symbolic expressions. Everything (water forming salty seas, ship floating on it, ship moving by wind, clouds, sun, moon, stars, ...) is tied up together. One should keep moving forward by studying all of these terms simultaneously.
