In 1930s, astronomers noticed that in some galaxy clusters, some of the galaxies were moving extra fast than possible with available matter (and its gravitational force). The question...
Each object has its own gravity which depends on its size and mass. The objects which have highest mass in smallest size would exert most gravity. The ultimate...
The expansion rate of the universe is called the Hubble Constant in honor of Edwin Hubble (1889–1953). Currently the best measured value of the Hubble Constant is about...
The universe is all of space, time, matter, and energy that exist. Universe is not just space, but space is just the framework or the scaffolding in which...
The age-sex structure of a population refers to the number of females and males in different age groups. An age sex pyramid or population pyramid is used to...
The demographic transition theory studies the relationship between economic development and population growth. It discusses about changes in birth rate and death rate and consequently growth rate of...
