YDS READING PASSAGES / TEST 7 1. Soru

1.THE MYSTERIES OF THE UNIVERSE

Cosmology is the scientific inquiry into what the universe is like. By making assumptions that are not contradicted by the behaviour of the observable universe, scientists build models, or theories, that attempt to describe the universe as a whole, including its origin and its future. They use each model until something is found that contradicts it. Then the model must be modified or discarded. Cosmologists usually assume that the universe, except for small irregularities, has an identical appearance to all observers, identical to the laws of physics, irrespective of where in the universe the observers are located. This unproven concept is called the cosmological principle. One consequence of the cosmological principle is that the universe cannot have an edge, for, otherwise, an observer near the edge would have a different view from that of someone near the centre. Thus, space must be infinite and evenly filled with matter, or, alternatively, the geometry of space must be such that all observers see themselves as at the centre. Also, astronomers believe that the only motion that can occur, except for small irregularities, is a uniform expansion or contraction of the universe.

Cosmological models of the universe ------ .