From The Art and Popular Culture Encyclopedia
In physics, energy is an indirectly observed quantity that is often understood as the ability of a physical system to do work on other physical systems. However, this must be understood as an overly simplified definition, as the laws of thermodynamics demonstrate that not all energy can perform work. Depending on the boundaries of the physical system in question, energy as understood in the above definition may sometimes be better described by concepts such as exergy, emergy and thermodynamic free energy. Therefore, in the words of Richard Feynman, "It is important to realize that in physics today, we have no knowledge what energy is. We do not have a picture that energy comes in little blobs of a definite amount." However, it is clear that energy is always an indispensable prerequisite for performing work, and the concept has great importance in natural science.
Energy is necessary for things to change. All living things require available energy to stay alive; humans get such energy from food, along with the oxygen needed to metabolize the food. Human civilization requires a continual supply of energy to function, energy resources such as fossil fuels are a vital topic in economics and politics. Earth's climate and ecosystem are driven by the radiant energy Earth receives from the sun, and are delicately sensitive to changes in the amount received.
Energy in spirituality, refers to a widespread belief in an interpersonal, non-physical force or essence. Believers consider spiritual energy to be of a different type than those known to science, and therapies involved are often classed as alternative medicine. Various ideas pertaining to spiritual energy have been postulated in various cultures, prominent amongst them are:
- the Christian idea of the soul or spirit
- The traditional Chinese qi
- The Indian chakra, shakti or kundalini
- The New Age/paranormal aura
- The "orgone energy" of Wilhelm Reich
- The morphogenetic fields of biologist Rupert Sheldrake
- The Odic force of chemist Carl von Reichenbach