While you are contemplating the brainwaves (EEG waves) gets slowed down. Normally brainwaves frequency, while we are fully awake to situations, remains in the range of 14 – 23 cycles/sec, which is known as Beta brain waves. But while contemplating upon some thing (focusing upon) this Beta brainwaves pattern gradually calms down to Alpha (9 – 13 cycles/sec) and on your deeper contemplation, from Alpha to Theta (5 – 8 cycles/sec) brain waves pattern further slowed down. But one need not to slip down to the extreme delta state (1.5 to 4 cycles/sec) because in this state one would be cut off totally from the external world, and fall into ‘Nirvikalpa’ Samadhi state (like in the state of coma).
In Nirvikalpa Samadhi State, with the lowering of brain wave patterns to minimum vibrations, our rate of respiration and heart beats too goes slowed down; as such the TIME SEEMS TO MOVE SLOW in this lower brainwave state and your awareness (Consciousness) goes sharpened and focused during this state.
Whatever is happening near about you seems to be ‘slowed down’ relatively (with respect to your awareness) and it reflects acutely into your awareness because of your HEIGHTENED AWARENESS and you are enabled to receive information even from inanimate things too in this state of deep contemplation or heightened awareness. With the slowing down of time (relative), even the events seem to move slowly and are therefore, noticeable acutely in our consciousness.
The perfection in Yogic practices makes one to awake fully for their heightened awareness beyond physical senses, enabling one to penetrate into others’ mind, to clairvoyance and access to future events.
In the process of meditation, mind is trained to be stilled, devoid of thoughts, where in this process, the external world, feel of own body and “self” all get annihilated, this is the state of nothingness, the “Void”, where there is no space and no time, this is what we experience in “Nirvikalpa Samadhi” State. This infers that the present, past and future all are the reflections derived from the application of thoughts and thought is nothing but memory of past on the basis of stored experiences, while the future is the drawing of inferences (an imagination) on the basis of past sum of experiences.
“Time is the creation of Thought … Timelessness means just absence of thought, an Emptiness….the Void (Shunya).
Thus, we can say that ‘Shunya’, the ‘Emptiness’ is the ultimate reality out of which an ‘Idea‘ in seed form silently creeps into the Consciousness (awareness) of the meditative mind, and that idea when picked up by the Intellect, it takes the shape of thought, through the mediation of intellect and collective net sum of individual experiences as memories.