From Wikipedia, the free encyclopedia
The present is the time that is perceived directly, not as a recollection or a speculation. It is often considered as a point in space-time, often called now, but it may also be viewed as a duration (see specious present).
When comparing time in places separated by great distances, the notion of present becomes unclear. For example, we visually perceive stars to be where they were when the light now reaching our eyes was emitted, because even though light travels at approximately 3 x 108 m/s it takes many years to reach us.
Modern physics has not yet been able to explain what we normally understand by 'now'. Furthermore, there is no demonstrable reason why time should move in any one particular direction. This has led to the conclusion that the idea of a present is illusory and does not reflect the true nature of reality. The notion of "now" may be better understood as an unrealistic concept that has evolved in humans and animals to give us an understanding of reality useful only to the extent necessary for survival.
 The present according to Special Relativity
It follows from Albert Einstein's Special Theory of Relativity that there is no such thing as objective simultaneity. Therefore, if we define "present" to be the collection of events that are simultaneous with a given event, then "present" is only subjectively defined.
 A philosophical problem
"The present" also raises another difficult 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. For example, say somebody named John is experiencing a great deal of pain. John's friend Fred takes pity on John because of John's situation. The problem is: is it logical for Fred to feel bad for John at present, when there is no way to prove that both John and Fred experience the same temporal existence? (See also Solipsism and Philosophy of mind.)
 The present in Buddhism
Buddhism and many of its derivative philosophies 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 through constantly focusing on one's current position in space and time (rather than future considerations, or past reminiscence) will aid one in the attempt to abandon selfhood. A number of meditative techniques aim to help the practicer live in the present moment.
 Christianity and the Now of Eternity
God is viewed as being outside of time and from the divine perspective past, present and future are actualised in the now of eternity. Saint Thomas Aquinas used the image of a watchman, representing God, standing on a height looking down on a valley where past present and future, represented by the individuals and their actions strung out along its length, are all visible simultaneously to God.
"You shouldn't chase after the past or place expectations on the future. What is past is left behind. The future is as yet unreached. Whatever quality is present you clearly see right there, right there." -- Buddha 
 See also
- Greene, Brian, (2004). The Fabric of the Cosmos: Space, Time, and the Texture of Reality. Knopf. ISBN 0-375-41288-3
- Stepath, Katrin, (2006). Gegenwartskonzepte., Würzburg. ISBN 3-8260-3292-6