It is always said now that "Universe is all history". Elaborate.

Explanation

The light travels with a speed of `3 xx 10^(8) m//s` in vacuum. Thus, when we are observing any faraway star, galaxy or some other planetary system several light years away, the light coming to us took several light years to reach us. Thus, whatever we are observing in the universe is past. For example, if we are observing a planetary system 100 million light years away, it means light took 13 million years to reach us thus what we observe now is 100 million years old.