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Time: What Is It?
A succinct definition of time is a puzzle that has challenged scientists, philosophers, and poets since the beginning of critical thinking. For such a universal and simple concept, time is a surprisingly slippery concept to grasp. We feel time flowing past us and experience the direction of time. We know when it is the right time to act and to wait. We can measure and quantify time down to the smallest fraction of a second and up to unimaginable stretches of eons, but none of this brings us any closer to a definition of time itself. What is time?
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Time: A Definition
Let's begin with the current understanding of time in modern physics. Time is a part of the space-time continuum in which the universe is populated. Space-time is characterized by four dimensions, three of which are physical and one of which is temporal, the dimension of time. While objects can move in any direction along the physical dimensions including any combination of back or forth, up or down, and forwards or backwards, an object can only move one direction in time: from the past through the present and on into the future. This limitation of time, dubbed time's arrow, greatly puzzles many physicists, for there is no such limitation to temporal movement found in the equations which explain the an objects movement through time. In a mathematic view of space-time, time works just like a physical dimension; an object can move from the past to the future and from the future to the past. However, the world in which we live prove this to be impossible: a broken egg can not return to its shell and become whole, and the old cannot regain their youth. So, in this space-time model of the universe, what is time? Time is the temporal dimension of space-time in which we move along time's arrow acting upon the world and experience events unfold along the present from the past into the future.
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Time: Our Subjective Interpretation
Although physicists have found that time's arrow is a fundamental rule of space-time, it is also dictated by our perception of time. We perceive events as they occur and only remember them was the event has passed. If time were to flow from the future toward the past, we would not have the cognitive equipment to sense this alternate arrow of time. Because our minds are so crucial to our perception of time, let's take a closer look at the perception of time by man where time becomes a less abstract and more personal matter. While we are wired with an internal clock that adequately senses the accurate hour or minute of the day, the rate at which we sense time pass seems to speed and slow in a very subjective manner. When we are truly engaged in our work or our play, that activity seems to be experience in a nearly timeless state and it is not until we look up until we again note the passage of time. If instead we are occupied by tedious tasks, the perception of time slows to a sometimes painfully slow rate, and distracting conversations or entertainments speed up time so that it passes alarmingly fast on those occasions. In order to properly answer the question of what time is, we must address the fact that time is quantifiable in one sense but almost entirely qualifiable in another.
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Time: Its Dual Nature
Past societies have answered this dual natue of time in a more straightforward manner when they asked themselves our question: what is time? For instance, the ancient Greeks split the definition of time into two separate terms: Chronos and Kairos. Chronos is the quantifiable passage of daily, worldly time that they marked by a variety of sundials and natural perceptions. Kairos, on the other hand, was the time of the Gods which was of a more qualifiable nature. A man perceived kairos at certain cusps, or special moments, in which it is the perfect moment for a particular action to be made or event to unfold. Our experience of kairos time has nothing to do with looking at our watch and everything to do with context and the moment. For instance, a jazz musician performing on improvisation is not operating so much in chronological or quantifiable time as he is in a contextual and qualitative time, and he acting upon instincts guided by education, experience, taste, and impulse. This qualitative nature of time is just as important in understanding what time is as is exploring its more measurable traits.
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Time: In Conclusion?
So, what is time to us? Giving considerations of modern physics, the human experience, and the qualifiable nature of our experience of time, here's what we have so far:
Time is the temporal dimension of space-time that we inhabit and ride along on time's arrow along chronological time, from past into the future, along the experience of a present that is subjective to personal experience.
However, this loose definition of time is but a diving board into a deep pool of exploration into the topic of time, for we have yet to even touch upon many fundamental questions such as how time is affected by gravitational warps in space-time, the different rules of time in the quantum world, the perception of time in other living creatures, and countless other questions that are necessary to grapple with before fully answering our inquiry: what is time?