Śakticakrasandhāne viśvasaṁhāraḥ शक्तिचक्रसन्धाने विश्वसंहारः (sūtra I.6)
Śakti here means power; cakra group; sandhāne – in the/when there is/through the union; Therefore, śakticakrasandhāne means, the coming together of the group of powers. When the fusion of all the powers takes place in oneself, i.e. when one becomes united with the group of powers, viśvasaṁhāra, the second part of this sūtra unfolds. Viśva means the universe; saṁhāra – dissolution. Therefore, viśvasaṁhāra means the dissolution of the universe.
This sūtra says that when the aspirant’s awareness becomes intent, all the powers of the Self come together and the universe disappears as a reality that was different and separate from the Self. This is Śiva-realization. For example, let us assume that a river runs through a mountain range. There will be several glaciers in the mountain, and when they melt they form a river. When the glaciers have completely melted away, what remains is only the river. In the same way, when the aspirant devours the different aspects of his materialistic life, viz. when he becomes one with them all, they dissolve like glaciers revealing the true nature of Śiva. The materialistic world is nothing but the body of Śiva, as He alone pervades everywhere.
Bhairava, also known as Śiva is the Supreme Consciousness. This Supreme Consciousness of Śiva is also known as pratibhā, which is svātantrya-śakti. Svātantrya-śakti can be explained as the Free Will of Śiva, where there is no manifestation of the universe as different and separate from Himself. Svātantrya-śakti, the Free Will of Śiva, the “I”-consciousness of Śiva, the independent autonomy of Śiva, in spite of being aware of It’s nature takes control of all the powers both sequentially and simultaneously (krama and a-krama), both in the form of being empty and full or both. Though Śakti is said to be manifest in various forms, yet She assumes none of these forms.
It is only the Svātantrya-śakti, the independent power of autonomy of Śiva, i.e. Śakti, who is manifest in the form of expansion, from the lowest level to the highest level of consciousness of the aspirant’s own awareness. When an aspirant becomes united with all the powers emanating from Śakti, the entire universe disappears as a reality different and separate from himself. In other words, the lowest of the tattva-s or categories of the universal manifestation dissolve into the highest of the tattva-s, i.e. in Śiva, one's own Self. This can be explained as a state where the aspirant continues to exist with his physical body and exists in the materialistic world, still the aspirant is associated with the Supreme Consciousness, both at the same time. To explain this further, there is disappearance of the universe, as a reality different and separate of oneself and not an “absolute disappearance of the universe to be replaced with a kind of void”.
Spanda-Kārikā (I.1) says that Śiva, who is the cause of all form of cosmic powers, creates and dissolves the universe by mere winking of His eyes. Again I.19 says that nothing being material (causal, subtle or gross matter) gets in the way of the aspirant because he is Śiva or Arodhya, the One, who is never obstructed by anything at all.