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1 Electromagnetics
2 Elements
3 Alchemy


Quintessence is a hypothetical form of energy postulated to exist in order to explain observations of an accelerating universe. This vacuum energy would act like a vacuum pressure, pushing things apart. Other attempts to explain these recent observations involve a non-zero cosmological constant, which has the same effect. Indeed, sometimes quintessence is said to result in a non-zero cosmological constant, and conversely a non-zero cosmological constant describes the effects of quintessence. Quintessence differs from dark energy in that it does not have a constant energy.


Among the classical elements, quintessence (meaning "fifth element", along with earth, air, fire, and water) was another term for aether.


In alchemy, quintessence is the purest form of a particular element. (as one would conceive them today). This is seen in the Hamlet solloquiy: "The beauty of the world, the paragon of animals and yet to me what is this quintessence of dust?"