The key is achieving an altered state of consciousness in which the mystic "hears" the sound of one hand clapping. Gods hand. It "sounds" like this.
Aum.
There's a lot of information of "Om" (or "Aum") in the Wikipedia article, but no description of it being the sound of one hand clapping. Can you provide any reasoning to support the assertion that your answer is correct?
Once you have achieved an altered state of consciousness, how can you be sure that you are hearing the same thing as another mystic? "Zoom" could be an equally correct answer by your logic.
But doing some research, you haven't even asked the question correctly. The traditional form of the question is:
Two hands clap and there is a sound; what is the sound of one hand?
Which is distinctly different in meaning than your version, which seems to have been taken from popular culture rather than studies into actual mysticism.
But here is an answer to the question from someone knowledgeable on the subject...
"...in the beginning a monk first thinks a kōan is an inert object upon which to focus attention; after a long period of consecutive repetition, one realizes that the kōan is also a dynamic activity, the very activity of seeking an answer to the kōan. The kōan is both the object being sought and the relentless seeking itself. In a kōan, the self sees the self not directly but under the guise of the kōan... When one realizes ("makes real") this identity, then two hands have become one. The practitioner becomes the kōan that he or she is trying to understand. That is the sound of one hand." — G. Victor Sogen Hori, Translating the Zen Phrase Book
This would seem to be at odds with your explanation.
The sound of one hand would appear to be a
metaphor for an epiphany resulting in mystic understanding, not the sound of God clapping one hand as you assert.
They are useful as mantras.
So you sit around endlessly repeating these riddles over and over again? Exactly which mystic tradition uses riddles for mantras?
And don't answer "Zen". Their kōans are not intended as riddles, and are not meant to be used as mantras.
Why should you believe a subject that you know nothing about is complete nonsense in the first place?
If I knew literally nothing about the subject, I wouldn't be assuming it to be complete nonsense in the first place, because I would lack the necessary information to make a judgment either way. If someone asked me what my thoughts were on the subject of Thransionalism, I'd have to inform them that I have no opinion on the subject because I have no knowledge about it.
I admit that I know very little about the subject of mysticism, but what little I do know is more than enough for me to conclude that the subject is nonsense, and there's no point in researching the subject any further except for the sake of idle curiosity.
If you were to provide me with further information that would lead me to conclude that my current opinion of the subject is wrong, then I might be more inclined to look into it further.
Because some debunker says so? Because some religious fundamentalist pissed you off or disappointed you in the past? Because some atheist scientist mistakenly thinks his scientific expertise qualifies him to understand religion? Because your culture programmed you to?
Because *
I* say so. Not because some authority figure told me that it's nonsense, but because
I have concluded that it's nonsense on my own.
I have developed an understanding of how the universe works (as have most people). From observation, textbooks, education, documentaries, the application of logic and researching further into areas that don't seem to make sense.
There have been times where I have realized that aspects of my understanding have been wrong, and I have corrected my view of the universe to incorporate this new understanding.
I am fully aware that my understanding is incomplete, and possibly in some ways flawed, but I'm very sure that the underlying framework of my understanding is sound.
The few details I do know about mysticism, and of the events you claim to have experienced, are profoundly incompatible with my understanding of the universe.
So either my understanding of the universe is completely and fundamentally flawed, or the mystical understanding of the universe is completely and fundamentally flawed.
So how do I decide which one is more likely to be accurate? I simply ask "What is the basis of this understanding?"
For my understanding of the universe, the information used ultimately derives from reasoning and information derived from reliable and independently verifiable sources.
For the mystical understanding of the universe, the information used ultimately derives from bold assertion and information derived from uncertain and unverifiable sources.
Given this, it seems obvious to me that the mystical understanding of the universe has little merit.