Aadiparashakti...creator of the universe..

As laws of thermodynamics state that energy can neither be created nor be destroyed,  but can be changed from one form to another....
Similarly before the creation of the cosmos,  there was nothing...(nirakaar) only a type of formless energy (nirguna) existed which was called as adishakti or adiparashakti...
There existed vast ocean of nothingness... one day suddenly the nirakar energy changed... it started taking form... from all the darkness arose a light... and hence appeared the holy adiparashakti Mahakali... the goddess of time, death, creation,  sustainance and destruction..

In Tańtras, we find the testements of Devī as 'Ādyā' in Purāņas as well. The Śākta doctrine documented in Purāņas is primarily based upon Sāńkhya philosophy's concepts of Puruşā and Prakřti; however, the theories of duality of Sāńkhya and existence of multiple Puruşas are rejected here. Śākta Purāņas rather adopt Advaitic (monistic) approach and conceptualise Prakřti and Puruşa to be one and indistinct. Thus, Prakřti in Śākta Purāņas is not gross; rather She is Divine and Her essence is truth, consciousness and bliss. In other words, She is Brahman, who is both Saguņa as well as Nirguņa.

Mahābhāgavata Purāņa or Śākta Mahābhāgavatam is a Śākta Upapurāņa, where we find the anecdote of the birth of Brahmā, Vişņu and Śiva from Mahākālī.
Before creation there were no sun, moon or other celestial bodies and hence there were no distinctions between day or night or the cardinal directions. Even the senses were then non-existent. At that time, the one who existed was that Mahākālī, who alone is Brahman. She is the eternal Brahmavidya, who is unexplainable, blemishless, rare even to the Yogins, all pervading and self-content. When formless Mahākālī desired to create, at that time She assumed an incredeble form. This form has complexion of split-coryllium and Her lotus-like smilling face is full of bliss. She is four-armed, holding a sword & a lotus while displaying Varadā & Abhaya Mudrās, and three blood-shot eyes & flowing hair. She rides a lion. She is aadiparashakti who manifested as dakshayani and Parvati...

So how does everything come into existence? Read in the next part...