Now if you refuse to believe in things due to your religious or moral up bringings…or lack of knowledge…then you wouldnt believe it exits. Chi is an asian term for energy. Chi exist in everyone and everything. There is both good chi and bad chi. Just like there is Yin and Yang..and if you want get technical; there is Postive and Negative of Yin and Yang. Each of it being Chi.
Now, seeing what Tai Lee on Avatar did was just control the pressure points, chakras, etc of the Chi. Now while it isnt possible to control chi and block chi like Tai Lee does, you can still… use it to hit pressure points…but again, you would need to be quick, dexterious, agile…to a near extreme point. Now, it is possible to block ones chakra’s points, but that usually brings about bad karma on your point. It isnt good to try and block ones chakras seeing they need them to live. Now, im sure I will get a bunch of people denying it; calling me wrong, and a sinner. Hey, if you can believe in an All Powerful God; why cant you believe in Nature and all its goodness.