Classification of Universe
The universe may be classified either on the basis of number of units and on the basis of existence of units as is clear from the following chart :
(1) Finite or Definite Universe: A finite universe is one in which the number of items us determinable for example number of students in Rajasthan university in2002, the population of India in 2001 etc.
(2) Infinite or Indefinite Inverse: As infinite inverse is that in which the number of items cannot be determined or the universe is so large that for all practical purposed it is regarded as infinite, for example number of stars in the sky, number of leaves on a tree, number of fish in the ocean etc.
(3) Real or True Existence Universe: If all the units or elements of the universe are true and inexistence, such inverse is called real inverse, for example number of income tax assesses, number of works in a mill, number of hospital in India etc.
(4) Hypothetical or Theoretical Universe: Where units of the universe are not in existence and we can only imagine them, is called theoretical or hypothetical universe for example throwing of dice to get six, number of times a coin falling with head upward or with tail upward on tossing the coin etc.