Is there life in outer space?
Despite listening very carefully for radio signal, scientists have not found any signs of life in space. But many of them think it likely that life has developed elsewhere. How many other planets might be inhabited? To answer this difficult question, an astronomer devised the equation :
1. Formed a stars in the Milky Way
2. Percentage of these stars form planet
3. Percentage of the planets are suitable for life
4. Percentage of these has life evolved
5. Percentage of these planets have intelligent life
6. Percentage of these can communicate
7. Communicating civilisation last