A few extra words for anyone who practices ki aikido
To repeat: I consider this article to be respectful and un-offensive but people read in many different ways and it is possible you might consider the tone of this article to be belittling and debunking. This was certainly not my intention and I'm genuinely sorry if you find it so. Please note that I did say that I find ki aikido to be "of real personal value" (that is why I do it) but I would add that I consider that the value of ki development is in no way dependant on a 'literalist' interpretation of 'ki'.
You would be quite justified in thinking that my opinions about aikido are not worth much. I only have a green belt and I'm a slow learner of all sports. I wish to stress (as I do in fact say in the article) that I'm not claiming any authority because I have none - especially when I compare myself with - well almost anyone in the ki fed. But I do have a bit more relevent experience than you might think.
I first started aikido in the early eighties in London and practiced assiduously for two years up to my orange belt. So I go way back. Despite my enthusiasm I found it very difficult, but I didn't consciously stop - I just 'paused' and hung on to my old gi for years as I expected to need it again one day.
Eventually, I started aikido again in the mid-nineties, at Bloomsbury ki club in London, and started again from white belt. There was another long pause after yellow and yet another long gap after green (though it started with a non-aikido injury). Anyway, the thing is, although my knowledge of aikido per se is no great shakes, I have been aware of, thinking about, and even using, ki for a very long time - far longer than the colour of my belt suggests.
To paraphrase myself, I do not think ki is a 'literal' force, an actual 'thing' like electromagnetism or gravity, but rather a manifestation of the way our minds work (the relevent science is experimental psychology not energy physics). That does not mean it is not 'real' or useful! I certainly do not think myself 'superior' to people who have another interpretation of their experience with ki. (And yes, it is possible that I might have experiences in the future that cause me to revise my interpretation).