Energy

The term energy has been widely used by writers and practitioners of various <a href="http://en.wikipedia.org/wiki/Esoteric" title="Esoteric" class="mw-redirect" >esoteric</a> forms of <a href="http://en.wikipedia.org/wiki/Spirituality" title="Spirituality" >spirituality</a> and <a href="http://en.wikipedia.org/wiki/Alternative_medicine" title="Alternative medicine" >alternative medicine</a><a href="http://en.wikipedia.org/wiki/Energy(esotericism)#cite_note-NCCAM-0" >[1]</a><a href="http://en.wikipedia.org/wiki/Energy(esotericism)#cite_note-Atwood-1" >[2]</a> to refer to a variety of phenomena. Such "energy" is often seen as a continuum that unites body and mind. The term "energy" also has a scientific context, and the scientific foundations of <a href="http://en.wikipedia.org/wiki/Physical_energy" title="Physical energy" class="mw-redirect" >physical energy</a> are often confused or misused to justify a connection to a scientific basis for physical manifestations, properties, detectability, or sensing of <a href="http://en.wikipedia.org/wiki/Parapsychology" title="Parapsychology" >psychic energy</a>and other physic phenomena where no presently known scientific basis exists.<a href="http://en.wikipedia.org/wiki/Energy(esotericism)#cite_note-2" >[3]</a> It is sometimes conceived of as a universal life force running within and between all things, as in some forms of <a href="http://en.wikipedia.org/wiki/Vitalism" title="Vitalism" >vitalism</a>, doctrines of <a href="http://en.wikipedia.org/wiki/Subtle_bodies" title="Subtle bodies" class="mw-redirect" >subtle bodies</a> or concepts such as <a href="http://en.wikipedia.org/wiki/Qi" title="Qi" >qi</a>, <a href="http://en.wikipedia.org/wiki/Prana" title="Prana" >prana</a>, or <a href="http://en.wikipedia.org/wiki/Kundalini" title="Kundalini" >kundalini</a>.<a href="http://en.wikipedia.org/wiki/Energy(esotericism)#cite_note-energy-3" >[4]</a>

Spiritual energy is often closely associated with the metaphor of life as breath - the words 'qi', 'prana', and 'spirit', for instance, are all related in their respective languages to the verb 'to breathe'. Sometimes it is equated with the movement of breath in the body, sometimes described as visible "<a href="http://en.wikipedia.org/wiki/Aura(paranormal)" title="Aura (paranormal)" >auras</a>", "rays", or "fields" or as audible or tactile "vibrations".<a href="http://en.wikipedia.org/wiki/Energy(esotericism)#cite_note-4" >[5]</a> These are often held to be perceptible to anyone, though this may be held to require training or sensitization through various practices.

In <a href="http://en.wikipedia.org/wiki/Physics" title="Physics" >physics</a>, energy (<a href="http://en.wikipedia.org/wiki/Ancient_Greek" title="Ancient Greek" >Ancient Greek</a>: ἐνέργεια <a href="http://en.wikipedia.org/wiki/Energeia" title="Energeia" class="mw-redirect" >energeia</a> "activity, operation"<a href="http://en.wikipedia.org/wiki/Energy#cite_note-0" >[1]</a>) is an indirectly observed quantity. It is often understood as the ability a <a href="http://en.wikipedia.org/wiki/Physical_system" title="Physical system" >physical system</a> has to do <a href="http://en.wikipedia.org/wiki/Work_(physics)" title="Work (physics)" >work</a> on other physical systems.<a href="http://en.wikipedia.org/wiki/Energy#cite_note-1" >[2]</a><a href="http://en.wikipedia.org/wiki/Energy#cite_note-2" >[3]</a> Since work is defined as a <a href="http://en.wikipedia.org/wiki/Force" title="Force" >force</a> acting through a distance (a length of space), energy is always equivalent to the ability to exert pulls or pushes against the basic forces of nature, along a path of a certain length.

The total energy contained in an object is identified with its <a href="http://en.wikipedia.org/wiki/Mass" title="Mass" >mass</a>, and energy (like mass), cannot be created or destroyed. When <a href="http://en.wikipedia.org/wiki/Matter" title="Matter" >matter</a> (ordinary material particles) is changed into energy (such as energy of motion, or into radiation), the mass of the system does not change through the transformation process. However, there may be mechanistic limits as to how much of the matter in an object may be changed into other types of energy and thus into <a href="http://en.wikipedia.org/wiki/Work(thermodynamics)" title="Work (thermodynamics)" >work</a>, on other systems. Energy, like mass, is a<a href="http://en.wikipedia.org/wiki/Scalar(physics)" title="Scalar (physics)" >scalar</a> physical quantity. In the <a href="http://en.wikipedia.org/wiki/International_System_of_Units" title="International System of Units" >International System of Units</a> (SI), energy is measured in <a href="http://en.wikipedia.org/wiki/Joule" title="Joule" >joules</a>, but in many fields other units, such as <a href="http://en.wikipedia.org/wiki/Kilowatt-hour" title="Kilowatt-hour" class="mw-redirect" >kilowatt-hours</a> and <a href="http://en.wikipedia.org/wiki/Kilocalorie" title="Kilocalorie" class="mw-redirect" >kilocalories</a>, are customary. All of these units translate to units of work, which is always defined in terms of forces and the distances that the forces act through.

A system can transfer energy to another system by simply transferring matter to it (since matter is equivalent to energy, in accordance with its mass). However, when energy is transferred by means other than matter-transfer, the transfer produces changes in the second system, as a result of work done on it. This work manifests itself as the effect of force(s) applied through distances within the target system. For example, a system can emit energy to another by transferring (radiating) <a href="http://en.wikipedia.org/wiki/Electromagnetic_energy" title="Electromagnetic energy" class="mw-redirect" >electromagnetic energy</a>, but this creates forces upon the particles that absorb the radiation. Similarly, a system may transfer energy to another by physically impacting it, but in that case the energy of motion in an object, called <a href="http://en.wikipedia.org/wiki/Kinetic_energy" title="Kinetic energy" >kinetic energy</a>, results in forces acting over distances (new energy) to appear in another object that is struck. Transfer of <a href="http://en.wikipedia.org/wiki/Thermal_energy" title="Thermal energy" >thermal energy</a> by <a href="http://en.wikipedia.org/wiki/Heat" title="Heat" >heat</a> occurs by both of these mechanisms: heat can be transferred by electromagnetic radiation, or by physical contact in which direct particle-particle impacts transfer kinetic energy.

Energy may be stored in systems without being present as matter, or as kinetic or electromagnetic energy. Stored energy is created whenever a particle has been moved through a field it interacts with (requiring a force to do so), but the energy to accomplish this is stored as a new position of the particles in the field—a configuration that must be "held" or fixed by a different type of force (otherwise, the new configuration would resolve itself by the field pushing or pulling the particle back toward its previous position). This type of energy "stored" by force-fields and particles that have been forced into a new physical configuration in the field by doing work on them by another system, is referred to as <a href="http://en.wikipedia.org/wiki/Potential_energy" title="Potential energy" >potential energy</a>. A simple example of potential energy is the work needed to lift an object in a gravity field, up to a support. Each of the basic forces of nature is associated with a different type of potential energy, and all types of potential energy (like all other types of energy) appears as system<a href="http://en.wikipedia.org/wiki/Mass" title="Mass" >mass</a>, whenever present. For example, a compressed spring will be slightly more massive than before it was compressed. Likewise, whenever energy is transferred between systems by any mechanism, an associated mass is transferred with it.

Any form of energy may be <a href="http://en.wikipedia.org/wiki/Energy_transformation" title="Energy transformation" >transformed</a> into another form. For example, all types of potential energy are converted into kinetic energy when the objects are given freedom to move to different position (as for example, when an object falls off a support). When energy is in a form other than thermal energy, it may be transformed with good or even perfect efficiency, to any other type of energy, including <a href="http://en.wikipedia.org/wiki/Electricity" title="Electricity" >electricity</a> or production of new particles of matter. With thermal energy, however, there are often limits to the efficiency of the conversion to other forms of energy, as described by the <a href="http://en.wikipedia.org/wiki/Second_law_of_thermodynamics" title="Second law of thermodynamics" >second law of thermodynamics</a>.

In all such <a href="http://en.wikipedia.org/wiki/Energy_transformation" title="Energy transformation" >energy transformation</a> processes, the total energy remains the same, and a transfer of energy from one system to another, results in a loss to compensate for any gain. This principle, the <a href="http://en.wikipedia.org/wiki/Conservation_of_energy" title="Conservation of energy" >conservation of energy</a>, was first postulated in the early 19th century, and applies to any<a href="http://en.wikipedia.org/wiki/Isolated_system" title="Isolated system" >isolated system</a>. According to <a href="http://en.wikipedia.org/wiki/Noether%27s_theorem" title="Noether's theorem" >Noether's theorem</a>, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.<a href="http://en.wikipedia.org/wiki/Energy#cite_note-jphysics-3" >[4]</a>

Although the total energy of a system does not change with time, its value may depend on the <a href="http://en.wikipedia.org/wiki/Frame_of_reference" title="Frame of reference" >frame of reference</a>. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy (and higher total energy) relative to the <a href="http://en.wikipedia.org/wiki/Earth" title="Earth" >Earth</a>.

Energy

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