Spend enough time in the martial arts world and you will eventually come across a reference to something called “kong jing,” which means “empty force,” or it’s common Western name, “no touch knockouts.”
From time to time, people will pop up claiming to be able to move, or knock people out, without touching them. They do this by using high level qigong (chi gong) skills with which they can manipulate other people’s qi. Moving and knocking out other people are just or demonstration, but the goal of this art is to be able to stop a hostile attacker without touching him, ideally while he is still far away and cannot hurt you.
A simple YouTube search will reveal many demonstrations of this “skill.”
Most of the demos are pretty similar: the master does some exercises to charge up his qi, and one or more of his students will come up for the demo, and he will use his qi and intention to cause his student to move, and often even knock the student back a few feet!
One thing you will notice is that all of these demonstrations almost always take place with students from that particular school. In the rare instances when other people have been used, whether spectators in the audience, or challengers from another school, it tends to not work. Again, you can see most of this on YouTube, including a pretty well-known clip where a no touch knockout guy challenged an MMA fighter, and the MMA fighter beat him up pretty badly because none of his kong jing or empty force techniques worked.
Ironically, it is possible to affect people without touching them, make them move and even knock them out, but it has nothing to do with kong jing, qigong, or empty force, and has everything to do with the power of suggestion. Mentalists and hypnotists can demonstrate the same skill without attributing it to “qi power.”
Some students can also be convinced that their instructor has mystical power. You will sometimes see demos where the master is fending off multiple students at once using kong jing. For whatever reason, these students have been so convinced that their master can actually do this that it works on them. But it’s just the power of suggestion, or perhaps mass hypnosis, and has nothing to do with qigong.
So, the only “real” no touch knockouts rely on belief from the students or audience members. In other words, it’s not going to work on an attacker who is actually trying to hurt you and doesn’t care about your qigong powers, and because of that, it’s not really useful at all in any possible martial application.
Not to mention, there are various people (for example, James Randi) who are offering large sums of money (up to $1,000,000) to anyone who can do this in a controlled environment. It may not surprise you that no one has succeeded yet.