The idea of subtle energy challenges the conventional understanding of energy and raises new problems. It is a non-physical source of energy that is often characterized as being less obvious and more ephemeral than conventional forms of energy.
It is believed that this energy exists on a level that is higher than what our senses can perceive or what is typically detectable by scientific instruments.
In spite of the fact that it is difficult to pin down, subtle energy has been identified and put to use for thousands of years by a wide variety of traditional civilizations and alternative forms of medical treatment.