Present

The present also called the present moment, is the period of time that is occurring right now. The present is in contrast to the past, the period of time that has already occurred; and the future, the period of time that has yet to occur. It is sometimes represented as a hyperplane in space-time, typically called "now", although modern physics demonstrates that such a hyperplane cannot be defined uniquely for observers in relative motion. The present may also be viewed as a duration.

The present also called the present moment, is the period of time that is occurring right now. The present is in contrast to the past, the period of time that has already occurred; and the future, the period of time that has yet to occur. It is sometimes represented as a hyperplane in space-time, typically called "now", although modern physics demonstrates that such a hyperplane cannot be defined uniquely for observers in relative motion. The present may also be viewed as a duration. ==Historiography== Contemporary history describes the historical timeframe immediately relevant to the present time and is a certain perspective of modern history. ==Philosophy and religion== ===Philosophy of time=== "The present" raises the question: "How is it that all sentient beings experience now at the same time?" There is no logical reason why this should be the case and no easy answer to the question. The present moment has also been investigated through the perspective of subjective experience, consisting of continuously changing sensory experiences and mental events, and by contrasting this first-person perspective with third-person objective conceptions of time, such as clock time. ===In Buddhism=== Buddhism and many of its associated paradigms emphasize the importance of living in the present moment—being fully aware of what is happening, and not dwelling on the past or worrying about the future. This does not mean that they encourage hedonism, but merely that constant focus on one's mindstream (rather than ruminating on future considerations or past reminiscence) will aid one in relieving suffering. They teach that those who live in the present moment are the happiest. A number of meditative techniques including mindfulness practices aim to help the practiser live in the present moment. ==Physical science== ===Special relativity=== s in 2D space. The original intent of the accompanying light cones diagram was to portray a 3-dimensional object having access to the past, present, and future in the present moment (4th dimension). It follows from Albert Einstein's Special Theory of Relativity that there is no such thing as absolute simultaneity. When care is taken to operationalise "the present", it follows that the events that can be labeled as "simultaneous" with a given event, can not be in direct cause-effect relationship. Such collections of events are perceived differently by different observers. Instead, when focusing on "now" as the events perceived directly, not as a recollection or a speculation, for a given observer "now" takes the form of the observer's past light cone. The light cone of a given event is objectively defined as the collection of events in causal relationship to that event, but each event has a different associated light cone. One has to conclude that in relativistic models of physics there is no place for "the present" as an absolute element of reality, and only refers to things that are close to us. Einstein phrased this as: "People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion". ===Cosmology=== In physical cosmology, the present time in the chronology of the universe is estimated at 13.8 billion years after the singularity determining the arrow of time. In terms of the cosmic expansion history, it is in the dark-energy-dominated era, after the universe's matter content has become diluted enough for dark energy to dominate the total energy density. It is also in the universe's Stelliferous Era, after enough time for superclusters to have formed (at about 5 billion years), but before the accelerating expansion of the universe has removed the local supercluster beyond the cosmological horizon (at about 150 billion years). ===Archaeology, geology, etc.=== In radiocarbon dating, the "present" is defined as AD 1950. ==See also== Arrow of time Contemporary history Deixis Near real-time computing Observation Philosophical presentism Self Specious present Time perception ==References== ===Bibliography=== Greene, Brian, (2004). The Fabric of the Cosmos: Space, Time, and the Texture of Reality Knopf. Stepath, Katrin, (2006). Gegenwartskonzepte, Würzburg. ==External links== The Experience and Perception of Time

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