How can jinns pass to our world? How long can a jinn passing to our world stay?

There are several reasons why jinns pass from the metaphysical world to the physical world. Either a magnetic incident takes place in our world, or a corridor arises between two worlds, or a person who carries medium capabilities causes this consciously or unconsciously due to his structure. Otherwise no jinn can pass his worlds borders with his own will.

Though we are in the same world, there is a dimension difference between us. Jinns can not pass from the metaphysical dimension to the physical one whenever they want.

When they pass to our dimension, they can not affect whoever they want arbitrarily. They only can affect the people with inborn medium features, or the people who have a vent, an opening or an illness with them. And these people generally happen to be introvert, timid, shy, psychologically unstable, and schizophrenic or having mental problems.

Jinns can not pass to our dimension to stay forever. They must return after a while. Just as a person in coma must be waked up after a while or a person in water must get out after a while, a jinni must return to his dimension after a while. Its only chance is to find a person with medium features and use his energy by affecting him, or make do a while by entering inside him, or steal energy from the weak and sick bodies, or to gain time by entering inside an animal, like a fly, insect etc.

An incident from the time of our prophet lights us upon this issue. One night Hz. Aisha (r.a.) is waken up by jinns and brought to the presence of a high court. When she asks the reason she is answered: You killed a Muslim jinni, you will be judged. When she asks Where did I kill a jinni? she is answered:
When you were reading the Quran, one of our Muslim brothers came for listening to you by entering inside a snake. When you saw that snake in your home you killed it. Therefore our brother in it was killed too. This will be judged. (Qurtubi, Al-Jami' li Ahkam il-Qur'an, 16/214,215)

This incident was brought to an end with an agreement. It is told that when we see an insect or any kind of animal at home we should not kill it at once if it is not dangerous or harmful.