The most sacred symbol in Hinduism. Aum (OM) is the sound of the infinite. This is representative of the Trinity of God in Hindu dharma Bhrahma Shakti (creation), Vishnu Shakti (preservation) and Shiva (liberation) Shakt
The three portions of AUM relate to the states of waking, dream and deep sleep and the three gunas (rajas, satva, tamas)
The three letters also indicates three planes of existence, heaven (swarga), earth/mortal world (martya) and netherworld/hell (patala)
The sound ‘AUM’ that many people chant in meditation practice is just one of many ways to anaesthetise the mind and reduce the chatter. Indigenous people across the world all have their own way of doing this, for me other good examples of this are Tibetan gongs, singing bowls and even it the wonderful didgeridoo.
While I agree than chanting ‘aum'(om) refocuses the mind back to our natural state of being for me the effect is most powerful at the end of lets say 10 mins of chanting then for just a few seconds even minutes a profound peace settles. . The more one returns to a state of ‘no thought’ or at the very least ‘less thought’ the better.
The vibration of “OM” symbolizes the manifestation of God and so everything, it is a reflection of the absolute reality, without beginning or the end and embracing all that exists, for me that is nondulism. All supposed separate parts lie within the one whole, no point in the seen or unseen universe, multiverse, the everything lies separate from any other and so for me and many ‘Om’ is another metaphor for the truth of oneness.
Om must include our supposed solid world just as much as perceived mythic realms like heaven and earth. While I may sound like a broken record oneness is everything including every thought or no thought, every word or no word, every action or no action. If you attempt to exclude anything from oneness, then it is not oneness it is duality. Duality is an illusion set up by the mind that believes in the concept of separation and opposites .
Om is unconditional, eternal and perfect. Om is union. Om is one.