Time
hideTime is a component of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects. Time has been a major subject of religion, philosophy, and science, but defining it in a non-controversial manner applicable to all fields of study has consistently eluded the greatest scholars.
In physics as well as in other sciences, time is considered one of the few fundamental quantities. Time is used to define other quantities – such as velocity – and defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second, is highly useful in the conduct of both advanced experiments and everyday affairs of life. The operational definition leaves aside the question whether there is something called time, apart from the counting activity just mentioned, that flows and that can be measured. Investigations of a single continuum called spacetime brings the nature of time into association with related questions into the nature of space, questions that have their roots in the works of early students of natural philosophy.
Among prominent philosophers, there are two distinct viewpoints on time. One view is that time is part of the fundamental structure of the universe, a dimension in which events occur in sequence. Time travel, in this view, becomes a possibility as other "times" persist like frames of a film strip, spread out across the time line. Sir Isaac Newton subscribed to this realist view, and hence it is sometimes referred to as Newtonian time. The opposing view is that time does not refer to any kind of "container" that events and objects "move through", nor to any entity that "flows", but that it is instead part of a fundamental intellectual structure (together with space and number) within which humans sequence and compare events. This second view, in the tradition of Gottfried Leibniz and Immanuel Kant, holds that time is neither an event nor a thing, and thus is not itself measurable nor can it be travelled.
Temporal measurement has occupied scientists and technologists, and was a prime motivation in navigation and astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, and the beat of a heart. Currently, the international unit of time, the second, is defined in terms of radiation emitted by caesium atoms (see below). Time is also of significant social importance, having economic value ("time is money") as well as personal value, due to an awareness of the limited time in each day and in human life spans.
For more information about Time, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with time
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Medicine & Health / Psychology & Psychiatry
Dec 17, 2009 |
4.7 / 5 (3) |
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Do your kids want a Wii, a PlayStation or an Xbox 360 this year? This holiday gift season is packed with popular gaming systems and adrenaline-pumping, sharpshooting games. What's a parent to do? Is there any redeeming value ...
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Dec 16, 2009 |
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(PhysOrg.com) -- Spacetime, which consists of three dimensions of space and one time dimension, is such a large, abstract concept that scientists have a very difficult time understanding and defining it. Moreover, ...
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Why newborn babies can't walk
Medicine & Health / Neuroscience
Dec 18, 2009 |
3.9 / 5 (10) |
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(PhysOrg.com) -- The first steps of an infant is a real milestone in the development of all mammals including humans, but little is known about why some animals can walk soon after birth, while others need ...
Dyslexia defined: New study 'uncouples' reading and IQ over time
Medicine & Health / Psychology & Psychiatry
Dec 17, 2009 |
4.3 / 5 (4) |
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Contrary to popular belief, some very smart, accomplished people cannot read well. This unexpected difficulty in reading in relation to intelligence, education and professional status is called dyslexia, and ...
Five tips for stress-free exams
Dec 16, 2009 |
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(PhysOrg.com) -- It's exam time, and for many students that means long days, late nights and lots of coffee. It's easy to let the anxiety get to you, so what can you do to cope with exam tension?
Scientists decode memory-forming brain cell conversations
Medicine & Health / Neuroscience
Dec 16, 2009 |
4.5 / 5 (13) |
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The conversations neurons have as they form and recall memories have been decoded by Medical College of Georgia scientists.
Are patients losing sleep over blood pressure monitors?
Dec 17, 2009 |
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A widely used test for measuring nighttime blood pressure may interfere with patients' sleep, thus affecting the results of the test, reports a study in an upcoming issue of Clinical Journal of the American Society of Ne ...
Looking for the heartbeat of cellular networks
Dec 16, 2009 |
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Our cells' molecules form an intricate network of interactions. Today's techniques, however, can only be used to measure individual molecular reactions outside the cells. Since molecular concentrations are much higher in ...
Pre-eruption earthquakes offer clues to volcano forecasters
Space & Earth / Earth Sciences
Dec 16, 2009 |
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Like an angry dog, a volcano growls before it bites, shaking the ground and getting "noisy" before erupting. This activity gives scientists an opportunity to study the tumult beneath a volcano and may help ...
Heart drugs show promise for fighting colon cancer
Dec 16, 2009 |
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Scientists in Sweden are reporting for the first time that a group of drugs used to treat heart failure shows promise for fighting colon cancer. The study is in ACS' Journal of Natural Products. Colon cancer ...
Should flowers be banned in hospitals?
Dec 17, 2009 |
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Does flower water harbour potentially deadly bacteria? Do bedside blooms compete with patients for oxygen? Do bouquets pose a health and safety risk around medical equipment?
Raytheon turns iPhones into battlefield tools
Dec 17, 2009 |
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US defense contractor Raytheon on Wednesday unveiled the first of what it said will be a series of software applications to make iPhones or iPod touch devices into battlefield tools.
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