The speed at which light travels, which is equal to 186,000 miles a second or 299,000 km/s. At this speed, light travels from the Earth to the Moon and back again in less than three seconds. According to Einstein's Theory of Special Relativity, the speed of light is always constant, regardless of the reference frame of the observer, and nothing in the universe can travel faster than the speed of light.

The speed of the propagation of electromagnetic waves in a vacuum which is a physical constant equal to 299,792,458.0 meters per second (often denoted by the letter c).

Approximately 2.998 x 10^8 meters per second.

the speed at which electromagnetic radiation propagates in a vacuum; it is defined as 299 792 458 m/s (186,000 miles/second). Einstein's Theory of Relativity implies that nothing can go faster than the speed of light.

The speed of light in a vacuum (the way the term is normally used) is defined as about 300,000,000 m/s (186,000 miles/second). It is considered to be the fastest speed anything can reach. It is expressed as "c" in Einstein's famous equation: E=mc2

the speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second

believed to be the speed limit in the universe. Nothing is supposed to be able to exceed the speed of light. It is also constant at 3e8 meters per second

The speed of light in vacuum, usually represented by the letter c. c = 300,000 kilometers/second = 186,000 miles/second.

The speed at which photons travel, approximately 3×108 m/s. This speed is indicated in equations by the letter c.

A constant of Nature. This speed is precisely 299,792,458 meters per second, or roughly 670,616,629 miles per hour. One of the most unusual discoveries of science has been the fact that all Observers measure light as moving at exactly this speed, even if those observers are moving relative to each other. This fact is one of the basic ingredients in Einstein's Special Theory of Relativity.

The speed at which light and other electromagnetic waves travel. Ever since the 17th century, scientists knew from astronomic observations that light travels about 300,000 kilometres per second. Today, we know that the speed of light in a vacuum is exactly 299,792,458 metres per second. Einstein was the first to develop the absolutely constant speed of light into a theoretical concept. In this concept, the speed of light is constant even if the point from which the source of lighting is observed moves rapidly. This was one of the two fundamental statements of the special theory of relativity which Einstein formulated in 1905. As space and time are variable in the theory of relativity, the speed of light becomes the only absolute unit for space.

c, approximately 3*10 m/s; the maximum speed at which an object can travel (see relativity)

One of the constants of the nature. It is 299,792,458 m/s. According to the laws of relativity, nothing can travel faster than speed of light.

often considered a constant (3.0 x 10^8 m/s), the speed that light travels depends on the medium through which it travels. Light traveling through water goes slightly slower than through air or through the vacuum of space.

The speed at which electromagnetic radiation propagates in a vacuum. It is has been measured at 299,792,458 meters per second (186,212 miles per second). Einstein's Theory of Relativity implies that nothing can go faster than the speed of light.

2.998 x 10 meters per second. 186,000 miles per second.

The fastest possible speed, according to the currently known laws of physics. Electromagnetic radiation exists in the form of waves or photons moving at the speed of light.

3×10 meters per second (over 186,000 miles per second), represented by the letter 'c' in physics (as in E=mc2). Pretty fast, huh? Einstein's theory of relativity says that massive particles can never reach the speed of light. See also: Einstein, Albert, Advanced Topics

186,000 miles per second (or 300,000,000 meters per second).The universal "speed limit" that is the fastest that anything can go.

The speed at which light travels (186,282 miles per second). The distance light can travel in one year is called a light year.

2.998 ¡¿ 108 meters per second.

the fastest possible speed in a vacuum, equivalent to 186,000 miles per second (300,000 km per second).

299,792,458 meters/second (186,000 miles/second.) Einstein's Theory of Relativity says that nothing can go faster than the speed of light. Of course, the crew on the Starship Enterprise knows better.

(noun) A fundamental physical constant that is the speed at which electromagnetic radiation propagates in a vacuum and that has a value fixed by international convention of 299,792,458 meters per second; the symbol used is "c." (Easy as it gets, sorry!)

The speed of light is the speed at which electromagnetic waves can move in a vacuum: 299,792,458 meters/sec (186,000 miles/second). According to Einstein's Theory of Relativity, nothing can go faster than the speed of light.

In air, light travels at 300,000 million kilometers per second (186,000 million miles per second), which is over 500,000 times faster than the Concorde. In solids or liquids, light travels more slowly.

186282.4 miles/sec or 299,792,458 meters/sec.

Light speed equals 299,792,458 meters/second (186,000 miles/second). Einstein's Theory of Relativity implies that nothing can go faster than the speed of light.

Approximately 2.998x108 metres per second (in vacuum).

Without qualification usually means the speed of propagation of electromagnetic radiation of any frequency in free space, a universal constant with the value 2.99792 × 108 m s−1. Could also mean the phase velocity or group velocity of an electromagnetic wave in a material medium.

The speed at which light (photons) travels through empty space is roughly 3 * 10 meters per second or 300 million meters per second.

The speed of light in a vacuum is an important physical constant denoted by the letter c for constant or the Latin word celeritas meaning "swiftness". It is the speed of all electromagnetic radiation in a vacuum, not just visible light.