What is interesting here is that for all intents an purposes it really doesn't matter if it exist or not, no matter who is correct we will only find out when we are dead, and unlike most religions the outcome is the same for each person regardless of their beliefs, you don't "kill" your spirit if you don't believe in it. What also may be interesting is in what form this spirit or soul supposedly continues to exist in, would it be self concious, have a personality or is it simply an entity devoid of any human characteristics. The answer to this depends very much on who you ask and if it happens that the Chinese are correct and we remain concious and "alive" in the spirit world I would love to find you and admit my mistakes. But what is important is that if one is to say that it does exist and have the ability to affect anything that happens in this world, even in the smallest of ways it would have to be natural in essence, and if it is natural it would mean that we would be able to measure it, how I do not know but it would be possible. And if I am correct it really doesn't matter as we would simply no longer exist.
