The Physical environment of the Earth and the organisms found on the Earth together act as a living unit. What is this hypothesis called?

Which place is there outside earth where human being can reside?

Which animal is responsible for creating the problem of global warming?

At the time of the formation of the planet like Earth, the environment was very hot and explosive. How much time would it have taken to cool down?

How many planets like Earth can be there in our galaxy ‘milky way’?