According to the science of mantra there are four kinds of sound waves - standing waves, reverberant waves, oscillating waves, and transcendental waves. The mantra Om produces all of these waves. Om is a combination of three sounds 'A', 'U' and 'M'. 'A' creates the standing wave, 'U' the reverberant wave, and 'M' the oscillating wave. The fourth wave, being transcendental and beyond the sense of hearing or speech, is created by meditating on Om in the heart centre.
When you transcend the external sensory world, you become aware of high frequency waves which have no rest period. Ordinary waves have a rest period. When you chant the mantra Om, it begins and it ends. The beginning and the end are the rest periods for the sound wave. But when you transcend the mind, then you come to a high sound frequency which has no rest period.
The first three sound waves belong to the three dimensions of human consciousness and are interconnected. 'A' represents the waking or sense consciousness, 'U' the dream or sub-consciousness, and 'M' deep sleep or unconsciousness. The fourth wave represents the unlimited dimension of consciousness which is beyond the mind and the senses. Therefore, we can say that Om has four bases : the sensual world, the mental world, the terrestrial world, and the ultimate state.
According to the Vedas, Om is the ultimate and first mantra. It has no name and no form, and is considered to be the creative force of the universal mind. The concept of universal mind is very difficult for us to comprehend. In the scriptures it is called hiranyagarbha which is compared with an egg. In the centre of this egg is the ultimate point from which sound emanates. Nada literally means sound, but here it refers to the ultimate point of resonance. This point is a transcendental point where the sound Om is un-manifested form. There is no vibration, no rhythm, no wave, and everything seems to be completely silent and potential. It can be imagined as total inactivity.
At opposite poles of this universal egg are the forces known as time and space. Space is the positive energy force and time is the negative. When you produce the mantra Om with your mouth, or recite it in the realm of your mind, these two psychic forces attain a state of polarity and try to project themselves towards the centre nucleus. When union occurs, there is an explosion of force, which results in the whole universal creation. Therefore, the mantra Om represents the creative force, the centre in which time and space unite, and where infinity is split into a multitude of infinities.
The mantra Om is written in a particular fashion. Many have it engraved on their lockets. It consists of four curves, over which there is a crescent moon with a bindu or point. Bindu is the centre or focal point of Om. Each curve represents infinity in its different aspects of time, space, object and transcendence. Therefore, Om has within itself the other force known as prakriti or nature, as well as the spiritual force.
The yogis meditate on this symbol of Om in order to develop the spiritual and mental force within themselves. There are two manifestations of this energy: one is fulfilment which belongs to the material plane, the other is transcendence belonging to the spiritual plane. Om is a very powerful mantra for the purpose of transcendence.
Om is the first mantra which was amplified in order to form Gayatri. The 24 syllables which make up the Gayatri mantra are:
Aum Bhur Bhuvah Svah
Tat Savitur Varanyam
Bhargo Devasya Dheemahi
Dhiyo Yo Nah Prachodayat
From the 24 syllables of Gayatri, the oldest books known to man - the Vedas, emanated. Gayatri is the symbol of spiritual consciousness in man. This consciousness has three stages- the time when it dawns, when it is fully fledged, and when it enters eternal space. The sun rising at daybreak symbolises spiritual life, and the sun setting in the evening symbolises the total matter of consciousness. When there is no sun, no light, this is the dark night of the soul according to the Bible, or Shivaratri, the dark night of Shiva, to Hindus.
Gayatri has to be practised at sunrise. After years it can be repeated mentally, but at first it must be chanted aloud. Being a vedic mantra, its chanting is controlled by certain accents, not as you chant any Sanskrit mantra. According to the Hindu system, those who are pure vegetarian should practise Gayatri on a tulsi mala, and those who are non-vegetarians should practise on rudraksha.
For the practice of Gayatri, there are no restrictions concerning diet, drinking or marital status. The only restriction is that you must receive the mantra from a guru. The practice of Gayatri is the roadway to spiritual regulation. It has a powerful and simultaneous effect on the body, mind, senses and spiritual life. Whenever you practise Gayatri mantra, you should concentrate on the form of Om, the symbol of the four dimensions of human existence - consciousness, sub-consciousness, unconsciousness, and super-consciousness.
Gayatri and Om are equally powerful, but the action of Gayatri is not as speedy as the action of Om. Gayatri was intended for the general masses and the reason for this is clear. The consciousness of man is simultaneously existing in seven different planes. The purpose of mantra is to transcend the first three realms- the physical, mental and astral. This means that I am not only existing in this physical form; I have a duplicate and triplicate existence. Then there are the three higher or spiritual planes followed by the ultimate state.
When man is able to evolve, he transcends each body, until he arrives at the seventh plane. However, those people who are not able to cope with their psychic or emotional situation, will find this transcendence quite a problem. Everybody does not want to transcend, and even if one desires it, he may not have qualified himself.
Transcendence without illuminating the first three realms is a very impractical affair. The different states of human intelligence are reflected as necessities in our day to day life. Recognition, perception, recapitulation, and so many other forms of intelligence have to be developed before you try for transcendence. The Vedas are very clear in their concept. They say that one must transcend the material consciousness, but they place a condition; you should transcend the material consciousness only after you have developed it.
The whole evolution is passing through three different stages. The lowest is tamo guna, inertia and potential energy. Above that is rajo guna, dynamism manifestation. This is followed by sattwa guna, knowledge, light and equilibrium in the forces of creation. If the individual transcends prematurely, his evolution stagnates. Therefore, they have a very clear concept. The ego must be dissociated from tamo guna. Potential energy must become dynamic and manifest.
When this occurs one has desires, passions, imagination, cognition, feelings, happiness, unhappiness, fears, insecurity; he knows so many things. There is a total panorama of action, the five sense organs, motor organs, all aspects of prana, all levels of elements, talk together on the playground as if all the players have come to play in a football match. Nothing is potential, nothing is in seed state. The expression of cognition is at its fullest. Sense and motor organs are given complete freedom of expression. The mind can think endlessly and infinitely. When this full expression takes place, evolution is at the point of rajo guna. At this time, if you try to transcend, it has some relevance and meaning.
Therefore, Om is considered right only for a few, not for everybody. But Gayatri is meant for the general masses because its purpose is to create a process of expression, to illumine the different states of human consciousness.
The consciousness is in total darkness, as though it were the dark hour of midnight. Out of that dark night, comes the dawn of day, and inner vision, inner perception or awareness begins to take place. This is the concept of Gayatri. Therefore, the Hindus teach this mantra to their children at the age of 7, 8 or 9 years; before, they are not allowed to practise it. When they have fulfilled all the obligations and desires of life, when a type of distaste dawns in their minds, they discontinue the Gayatri mantra and begin to practise Om. The mantra Om is for yogis, because it is the short cut for the fulfilment of spiritual transcendence.