speed of light

[speed uhv lahyt]

noun

1. 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).

2. an extremely fast rate.

   They gobbled those appetizers up at the speed of light.

Word History and Origins

Origin of speed of light¹

First recorded in 1820–25

Example Sentences

“We are moving literally at the speed of light. Our one-year cadence is about us leapfrogging ourselves,” he said, noting Nvidia’s next AI server called Vera Rubin is slated for next year.

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Using the energy from this rotation, M87* powers a particle jet expelled at nearly the speed of light, stretching across an immense 5,000 light-years.

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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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