SPEED OF LIGHT Definition & Meaning

speed of light

[ speed uhv lahyt ]

Phonetic (Standard)IPA

noun

Physics, Optics. a fundamental universal constant, the speed at which light and all forms of electromagnetic radiation travel in a vacuum, standardized as 186,282.4 miles per second (299,792,458 meters per second):
The speed of light, often represented by the letter c, figures prominently in modern physics, as in Einstein’s famous equation E = mc2, which expresses the relation between mass (m) and energy (E).
an extremely fast rate:
They gobbled those appetizers up at the speed of light.

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51�Թ� History and Origins

Origin of speed of light¹

First recorded in 1820–25

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Example Sentences

Examples have not been reviewed.

Inside this huge machine, which is called a synchrotron, electrons are accelerated to almost the speed of light to produce a powerful X-ray beam that can probe the scroll without damaging it.

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Solar flares are made up of electromagnetic radiation that travel from the Sun at the speed of light and can reach Earth in about eight minutes.

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Their picture shows the galaxy NGC 5128 and its relativistic jet - beams of radiation and particles travelling close to the speed of light.

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The signal crossed the solar system at the speed of light, covering a distance of about 158 million miles in just 14 minutes.

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A particle that has no mass usually moves at the speed of light.

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