Eternal
While in the popular mind, eternity often simply means existing for an infinite, i.e., limitless, amount of time, many have used it to refer to a timeless existence altogether outside of time. There are a number of arguments for eternity, by which proponents of the concept, principally Aristotle, purported to prove that matter, motion, and time must have existed eternally.
Eternity as a timeless existence
Augustine of Hippo wrote that time exists only within the created universe, so that God exists outside of time; for God there is no past or future, but only an eternal present. One need not believe in God in order to hold this concept of eternity: for example, an atheist mathematician can maintain the philosophical tenet that numbers and the relationships among them exist outside of time, and so are in that sense eternal. Near-death experience testimonies typically speak of eternity as a timeless existence by stating that portions of experiences in the eternal world lasted, say, "an hour or a month, I don't know. There was no time."
Another facet of eternity is that it is permanent in some aspects. Supposing we are in a state of eternity; a person could not break a pencil in two, or walk from a place to another since those actions have a before and an after: a time in which the pencil was whole and a time in which it no longer was. These changes correspond to time. Basically nothing can happen in eternity in the sense we understand it. In order for actions to happen, there must be a tense that corresponds to a continuing action: a tense in which past, present, and future are combined to form a continual action. One doesn't break the pencil, but one broke the pencil, breaks the pencil, and will break the pencil all at the same instant.
God and eternity
Theists say that God is eternally existent. How this is understood depends on which definition of eternity is used. On the one hand, God may exist in eternity, a timeless existence where categories of past, present, and future just do not apply. On the other hand, God may exist for or through eternity, or at all times, having already existed for an infinite amount of time and being expected to continue to exist for an infinite amount of time.
Whichever definition of eternity is understood, it is common to observe that finite human beings cannot fully understand eternity, since it is either an infinite amount of the time we know or something other than the time and space we know. For the infinite definition, there are parallels that give some notion of an infinity -- of at least a potential infinity, or a series that begins and has not ended. A series of moments that has begun and not ended is however, not potentially eternal by that definition. A series of moments that has begun and not ended cannot be eternal, because even if it were to continue for the rest of (infinite) time, there would still be time prior to the initial moment in the series. The series of moments could not ever exist for all eternity because no matter what happened during the series of moments, nothing would ever cause the series of moments to have existed since the beginning of "eternity", and thus could never achieve the status of eternal or even potentially eternal.
Related to the notion of eternal existence in the concept of God as Creator, as a being completely independent of "everything else" that exists because he created everything else. (Contrast this with panentheism.) If this premise is true, then it follows that God is independent of both space and time, since these are properties of the universe. So according to this notion, God exists before time began, exists during all moments in time, and would continue to exist if somehow the universe and time itself were to cease to exist.
Related to 'eternal life', the biblical revelation first indicated that Man as a special created being is able to grasp the abstract concept in contrast with the lower animal world which did not have the ability to understand the concept of "eternity". See book of Ecclesiastes 3:11 "He has made everything beautiful in its time. He has also set eternity in the hearts of men .." (from Bible translation in the N.I.V.). Contrast this with the timeless existence definition, which would imply animals are blessed with eternal life from birth (because of their inability to grasp the concept of eternity or even time) , which is something mankind gave up when he was cast out of the "Garden of Eden". It is commonly believed among theists that although mankind can grasp the abstract concept of "eternity", one may only obtain "eternal life" once returned to God.
It is also equally possible that God can choose not to exist as he is all powerful, but eternity does not have this choice. After God there may be "nothing", and God himself will be powerless to prevent this so the state of "nothing" may remain forever. This is the very idea of eternity, where a state of series of events or motion or matter will continue in some way or another. This aspect of God and eternity leads to the human mind assuming that both are completely separate entities, and God himself is bound by the rules of eternity. There are no examples of this, and there never will be. Both entities in this aspect are beyond the "finite" capabilities of the human mind as mentioned above. It cannot be proven or unproven, for if it happened there would be no life or device to document this.
Science and eternity
The modern theory of relativity provides a physical description of the universe in which the past and future may exist alongside the present. Some scientific theories of consciousness such as space-time theories of consciousness propose that the space-time continuum permits consciousness.
The physics taught in most schools describes the universe in terms of Galilean relativity in which only the durationless present exists. This concept is known as presentism and is widely believed.
The modern theory of relativity provides a physical description of the universe which began at the Big Bang. NASA has been able to verify the time of the origin of the universe using the background radiation left over from the big bang. According to NASA, time, space, and matter began 13.7 billion years plus or minus 1%.Nasa WMAP AGE Since the discovery of the Big Bang scientists who agree to this theory consider time to have moved in a uni-direction forward direction. In this model the past precedes the present which precedes the future.
Opposite to the cosmic level, in the quantum world, the smallest distance that makes sense is the Planck length; at this level space-time itself becomes extremely distorted (quantum foam). Here the uncertainty principle allows particles and energy to briefly come into existence, and then annihilate, without violating conservation laws . Beyond the Planck time (1.855×1043), time itself as we know it is meaningless.
{{quotation|One finds that time just disappears from the Wheeler-deWitt equation, it is an issue that many theorists have puzzled about. It may be that the best way to think about quantum reality is to give up the notion of time - that the fundamental description of the universe must be timeless. Carlo Rovelli, physicist, University of the Mediterranean in Marseille, France. Time May Not Exist?
Symbolism and eternity
Eternity is often symbolized by the image of a snake swallowing its own tail, known as Ouroboros (or Uroboros), though the symbol can also carry a number of other connotations.
The circle is also commonly used as a symbol for eternity. The related concept, infinity, is symbolized by .
There is a folk story where a wise shepherd boy is brought to a king to answer three questions. The third question he is asked to answer is "How many seconds are in eternity?" The boy responds by telling the king there is a mountain that is one hour deep, one hour long, and one hour wide. It is comprised entirely of diamond and every century a little bird comes to sharpen its beak on the mountain. The boy tells the king that when the mountain is entirely worn down one second of eternity will have passed.
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The progression of eternity does not consist solely in spiritual development. Intellectual acquisition is also a part of universal education. The experience of the mind is broadened equally with the expansion of the spiritual horizon. Mind and spirit are afforded like opportunities for training and advancement.[1]
