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.
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News tagged with time
Physicists investigate how time moves forward
Sep 05, 2008 |
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As humans, we have a very intuitive concept of time, and of the differences between the past, present, and future. But, as scientists Edward Feng of the University of California, Berkeley, and Gavin Crooks of the Lawrence ...
Unhappy people watch TV, happy people read/socialize, says study
Nov 14, 2008 |
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A new study by sociologists at the University of Maryland concludes that unhappy people watch more TV, while people who describe themselves as very happy spend more time reading and socializing. The study appears in the December ...
Counterintuitive physics may help everyone drive home quicker
Oct 02, 2008 |
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If you're trying to drive to a destination as quickly as possible, you might think that knowing the traffic conditions would help you choose the quickest route for yourself. Traffic reports and new GPS technologies ...
Physicist Proposes Solution to Arrow-of-Time Paradox
Aug 27, 2009 |
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(PhysOrg.com) -- Entropy can decrease, according to a new proposal - but the process would destroy any evidence of its existence, and erase any memory an observer might have of it. It sounds like the plot ...
Proposed Spacetime Structure Could Provide Hints for Quantum Gravity Theory
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, ...
Long-Lasting Quantum Memory Leads to Long-Distance Quantum Communication
Oct 07, 2008 |
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(PhysOrg.com) -- Physicists have taken a step closer to realizing long-distance quantum communication, in which a quantum state is transferred from one location to another by becoming entangled with a traveling ...
Caltech 4-D microscope revolutionizes the way we look at the nano world
Nov 20, 2008 |
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More than a century ago, the development of the earliest motion picture technology made what had been previously thought "magical" a reality: capturing and recreating the movement and dynamism of the world ...
The smart way to study
Medicine & Health / Psychology & Psychiatry
Nov 18, 2008 |
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Combine the aphorisms that "practice makes perfect" and "timing is everything" into one and you might get something resembling findings published in this month's issue of Psychological Science. Proper spacing of lessons, the re ...
In Twin Paradox Twist, the Accelerated Twin is Older
Jun 09, 2009 |
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Just when you thought you were beginning to understand the twin paradox (maybe), scientists have found something new to ponder. In the original version of the famous thought experiment on time dilation, one ...
'Rosetta Stone' of supervolcanoes discovered in Italian Alps
Space & Earth / Earth Sciences
Sep 21, 2009 |
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Scientists have found the "Rosetta Stone" of supervolcanoes, those giant pockmarks in the Earth's surface produced by rare and massive explosive eruptions that rank among nature's most violent events. The eruptions produce ...
Could Exotic Matter Provide an Infinite Source of Energy?
Sep 15, 2009 |
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(PhysOrg.com) -- Generally, scientists prefer to avoid the concept of perpetual motion. The idea of a machine that could produce movement that goes on forever, and using that movement to generate an endless ...
Earthquakes actually aftershocks of 19th century quakes
Space & Earth / Earth Sciences
Nov 04, 2009 |
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(PhysOrg.com) -- When small earthquakes shake the central U.S., citizens often fear the rumbles are signs a big earthquake is coming. Fortunately, new research instead shows that most of these earthquakes ...
Time Lens Speeds Up Optical Data Transmission
Sep 28, 2009 |
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(PhysOrg.com) -- Researchers at Cornell University have developed a device called a "time lens" which is a silicon device for speeding up optical data. The basic components of this device are an optical-fiber ...
Who cares about the fourth dimension?
Feb 03, 2009 |
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Austrian scientists are trying to understand the mysteries of the holographic principle: How many dimensions are there in our universe?
Major advance in organic solar cells
Oct 19, 2009 |
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Professor Guillermo Bazan and a team of postgraduate researchers at UC Santa Barbara's Center for Polymers and Organic Solids (CPOS) today announced a major advance in the synthesis of organic polymers for plastic solar cells. ...
