Energy

Energy

In physics, energy (Ancient Greek: ἐνέργεια energeia "activity, operation") 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.

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Famous quotes containing the word energy:

    Three elements go to make up an idea. The first is its intrinsic quality as a feeling. The second is the energy with which it affects other ideas, an energy which is infinite in the here-and-nowness of immediate sensation, finite and relative in the recency of the past. The third element is the tendency of an idea to bring along other ideas with it.
    Charles Sanders Peirce (1839–1914)

    Crime is naught but misdirected energy. So long as every institution of today, economic, political, social, and moral, conspires to misdirect human energy into wrong channels; so long as most people are out of place doing the things they hate to do, living a life they loathe to live, crime will be inevitable.
    Emma Goldman (1869–1940)

    Long before Einstein told us that matter is energy, Machiavelli and Hobbes and other modern political philosophers defined man as a lump of matter whose most politically relevant attribute is a form of energy called “self-interestedness.” This was not a portrait of man “warts and all.” It was all wart.
    George F. Will (b. 1941)