Time – is well experienced by sentient beings and especially humans with its subjective and intuitive nature. What we experience as time is not always what the clock reads i.e. the inner experience is devoid of any external measurement or criteria. The more objective handling of time, as in physical experiments, is to either use it as a parameter that characterizes events or as a dimension of a larger four dimensional space. We observe time as an interval that lapses even when we are siting still. The spatial change in the order of things is manifested as a change in time along with positions. It is a continuous progression of a number, intuitively held in our mind. The interval of time is called the duration just as the interval of space is called distance. In the Newtonian sense, the speed is just
Speed = Distance/Duration
We treat time, objectively, as a one dimensional tunnel with uninterrupted progression and no turning back, except in one’s memories. Although, the special theory of relativity puts space and time on equal footing, still the temporal dimension (despite being stated as a spatial dimension i.e. ct, where c = speed of light in vacuum and t is the time on the observer’s clock) stays peculiar in one aspect. At a macro-level, one can move back and forth, move sideways,up and down in space but one cannot do that in time. There is no turning back!
Philosophically, one is interested in non-quantitative aspect of time. P. D Ouspensky, the author of ‘Tertium Organum’ and the disciple of the mystic George Gurdjieff, writes about a worm equipped with a human mind that wriggles through a tunnel almost its size. Let us assume that the only sense available to our little fella is the sense of touch on the tip of its nose. The sensory perception are noted in its brain and helps formulate the sequence in its mind. As it moves along the tunnel, the data is registered in its brain as : now this, now that, ah! the rock, oh! the soil and so forth. It perceives the one dimensional world as a train of events registered by its sensory organ in its brain.
Let us say, that sometime along this long journey our worm also manages to generate some numbers and a certain mathematical sense and builds book keeping device. It could keep track of the things which are coming its way as the one’s about to come (anticipation) and the one’s already known (experience) to it. Now, suppose the poor guy is stuck on its way through and just experiences the same thing over and over again. What do you think would happen to its time perception? The tip of its nose is one-dimensional object. The object that helps it in temporal perception. The world of the worm can be said to comprise of 1+1 dimensions. Can you tell why? We might say that time is the perceived experience of one-dimensional space out of our 3+1 space-time but without apprehension.
The analogy could be extended easily to higher dimensional space and higher sensory appendages with appropriate perceptive abilities. The ideas of growth and decay, of creation and destruction of order and chaos can be related to our apprehension of the sequence of our three-dimensional cross sections of the four-dimensional object called space-time. In his work Tertium Organum, Ouspensky images these-dimensional analogies as a prelude to his model of enlightenment. His view is that the being encapsulated by its perceptive abilities in a lower dimensional world frees itself of those associations and moves beyond the bodily senses and experience the higher dimensions of existence through awareness alone. Although later in his life he would repudiate much written in his book, he was aware of its linkage with transcendental wisdom or enlightenment along the lines of eastern mysticism.
If you ask somebody, what time is it? you would in all probability get a suitable answer, provided that the person you ask has a certain device (based on periodicity of a certain phenomena) that registers time as a movement of needles or numbers. However, if you as What is time? You might not get a clear answer. We think we ‘know’ what time it is…its just we don’t know what time is.
An interesting link on the nature of time here.