Ardhanareswara means union of shiva (pure consciousness) and shakthi (famine energy). The concept behind this Ardhanaerswara is modern and scientific. It represents saguna (active) and nirguna (inactive) nature of creator. God is the latent energy in all living and non living in the universe. Our universe is the manifestation of God.
The saguna and nirguna nature is present in every creature and object in the universe. Shiva means pure conciousness, which is inactive, innocent, unself, amorphous. And Shakthi represents the active, quality and manifesting side of God. SHAKTHI is the self awareness in SHIVA. Without Shakthi Shiva is not even able to move. In fact Shiva and Shakthi are one. They are not separable.