The term "energy" is used by writers and practitioners of various esoteric forms of spirituality and alternative medicine to refer to a variety of claimed experiences and phenomena that defy measurement and thus can be distinguished from the scientific form of energy.^[1][2] There is no scientific evidence for the existence of such energy.^[1][2][3]

Therapies that purport to use, modify, or manipulate unknown energies are thus among the most contentious of all complementary and alternative medicines. Claims related to energy therapies are most often anecdotal (from single stories), rather than being based on repeatable empirical evidence.^[3][4][5]

Concepts such as "life force" and "élan vital" existed from antiquity and emerged from the debate over vitalism in the 18th and 19th centuries with Mesmer and the magnetism. They continued to be discussed in the 20th century by some thinkers and practitioners in the modern New Age movement.^[1][2]

As biologists studied embryology and developmental biology, particularly before the discovery of genes, a variety of organisational forces were posited to account for their observations. German biologist Hans Driesch (1867–1941), proposed entelechy, an energy which he believed controlled organic processes.^[6] However such ideas are discredited and modern science has all but abandoned the attempt to associate additional energetic properties with life.^[6]

The scientific term energy is not what is being referred to in the context of spirituality and alternative medicine. As Brian Dunning writes:

Despite the lack of scientific support, spiritual writers and thinkers have maintained ideas about energy and continue to promote them either as useful allegories or as fact.^[8] The field of energy medicine purports to manipulate energy, but there is no credible evidence to support this.^[3]

The concept of "qi" (energy) appears throughout traditional East Asian culture, such as in the art of feng shui and Chinese martial arts.^[9] Qi philosophy also includes the notion of "negative qi", typically understood as introducing negative moods like outright fear or more moderate expressions like social anxiety or awkwardness.^[10] Deflecting this negative qi through geomancy is a preoccupation in feng shui.^[11] The traditional explanation of acupuncture states that it works by manipulating the circulation of qi through a network of meridians.^[12]

There are various sacred natural sites that people of various belief systems find numinous or having an "energy" with significance to humans.^[13] The idea that some kind of "negative energy" is responsible for creating or attracting ghosts or demons appears in contemporary paranormal culture and beliefs as exemplified in the TV shows Paranormal State and Ghost Hunters.^[14]