Spacetime

Space-time is defined as a mathematical model in which space and time are interwoven into one single continuum. The space-time of our universe in interpreted to that of a Euclidean space, with 4 dimensions, space consisting of 3-dimensions and time is taken as the fourth dimension. A unique position in a unique time in a space-time is defined as an event. Event is the basic concept of space-time.

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          All of us are familiar with the concept of planes i.e. 2-D plane, 3-D plane etc. A point in a 2-D plane is denoted as (x,y) and that in a 3-D plane is given as (x,y,z). Here x, y and z can be identified as the unique distance between the point and x-axis for x, y-axis for y and z-axis for z.

          An event in space-time can also be defined similarly as (x,y,z,t),  x, y and z here refers to the unique position of the point in the space while t denotes the unique time of the event. This way the coordinates specify where and when event occur. However the question which arises now is why do we need to include time and make it complex?

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          In classical mechanics, the non-relativistic model, time is considered as an independent and is treated as universal with constant passage irrespective of the motion of the observer. However in relativistic model, time is considered to be inseparable from the three dimensions of space as it has been noticed that time slows at higher speeds of a reference frame with respect to another reference frame. This phenomenon is referred as time dilation.

          However the number of dimensions required for analyzing our universe is a question among scientists. Speculative string theory predicts the number of dimensions to be 10 or 26, with M-theory predicting 11 dimensions, 10- spatial and 1- temporal). The widely accepted model is that of 3- spatial and 1- temporal, which is space-time. Increase in number of dimensions from four would have significant difference only in sub-atomic level.