Internet

Global glitch: Swaths of internet go down after cloud outage

Dozens of websites went down briefly around the globe Tuesday, including CNN, The New York Times and Britain's government home page, after an outage at the cloud computing service Fastly, illustrating how vital a small number ...

Security

NY transit officials confirm cyberattack; say harm limited

Hackers infiltrated computer systems for the Metropolitan Transportation Authority in New York, setting off a scramble to counter a potentially crippling cyberattack against North America's largest transit system, MTA officials ...

Automotive

Sick of dangerous city traffic? Remove left turns

To reduce travel times, fuel consumption and carbon emissions, in 2004, UPS changed delivery routes to minimize the left-hand turns drivers made. Although this seems like a rather modest change, the results are anything but: ...

Business

China tech CEOs slip off backstage to avoid Beijing's glare

Bytedance founder Zhang Yiming, the brains behind TikTok, said he preferred "daydreaming" as he stepped down as head of his own firm last week. But his departure comes as several of China's once-lauded tech entrepreneurs ...

Energy & Green Tech

Ionophobic electrode boosts energy storage performance

Using renewable energy to replace fossil energy is now considered the best solution for greenhouse gas emission and air pollution problems. As a result, the demand for new and better energy storage technology is strong.

Automotive

California places Tesla's 'Full Self-Driving' under review

California's Department of Motor Vehicles is reviewing whether Tesla is violating a state regulation by advertising its vehicles as being fully autonomous without meeting the legal definition of self-driving.

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Time

Time 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.

This text uses material from Wikipedia, licensed under CC BY-SA