Devi Durga - The life force

Navratri’s are auspicious days after a fortnight long hot, humid Pitrapaksh. These are the days when our energy battery starts charging and immunity builds up. These 9 days are very important for our wellbeing, hence there were lots of questions in my mind about significance of these 9 nights called Navratris. There has been lot of deliberations on the spiritual aspects of Navratris but to my scientific mind which is trained in the modern education system. It becomes difficult to adjust these facts. I am Aayush and was curious on many such facts like, Why these are for only 9 nights and not a week or 15 days after 15 days long Pitrapaksh? Why there are only 9 forms of Durga? Why Durgas are 9 when Mahavidyas are 10? Is there any secret behind her different forms having three eyes and different number of hands? I have seen her idols with 8 hands, sometimes with 10 hands and even 16 hands...