#taichi has many properties which are considered "hidden." Expansion is one of them. There is a misconception that Tai Chi is an expression of opposites - left and right, up and down, forward and back, folding and unfolding, expansion then compression, yin and yang. However, Tai Chi is a multidimensional practice which entails expansion in every direction, at all times, in equal proportion. THAT is the ultimate Yin/Yang!
Just imagine a balloon. When it is not expanded, it is flaccid and has no structure. When it is expanded, it does so from the inside out and in equal proportion in all directions. The resulting effect, is structure, resilience and the ability to absorb and roll off incoming energy! Have you ever tried to push a balloon??
Watch this short video for a nice visual demonstration of expansion. Then next time you practice Tai Chi.....think expand like a balloon!