Speed ​​of light

go at the speed of light

Surely you have heard more than once that the speed of light is the fastest in the entire universe. A large number of theories in physics make use of the speed of light. It is a measure established by the scientific community that has helped us from physics and astronomy.

In this article we are going to tell you everything you need to know about the speed of light, its history, characteristics and what it is for.

What is the speed of light

light in the universe

The speed of light is a measurement prescribed by the scientific community and is in common use in the fields of physical and astronomical sciences. The speed of light represents the distance that light travels in unit time.

Understanding celestial bodies, how they behave, how electromagnetic radiation is transmitted, and how light is perceived by the human eye is critical to studying celestial bodies.

If we know the distance, we can tell how long it takes light to travel. For example, light from the sun takes about 8 minutes and 19 seconds to reach Earth. The speed of light is considered a universal constant, invariant in time and physical space. It has a value of 299.792.458 meters per second, or 1.080 million kilometers per hour.

This speed is related to the light year, a unit of length widely used in astronomy, which is the distance light travels in one year. The speed of light that we introduce is its speed in a vacuum. However, light travels through other media, such as water, glass, or air. Its transmission depends on certain properties of the medium, such as permittivity, magnetic permeability and other electromagnetic properties. Then there are physical regions that electromagnetically facilitate its transportability, and others that hinder it.

Understanding the behavior of light is important not only for the study of astronomy, but also for understanding the physics involved in things like satellites orbiting the Earth.

Some history

speed of light

The Greeks were the first to write down the origin of light, which they believed emanated from objects before human vision was emitted to capture it.  Light was not thought to travel until the XNUMXth century, but rather as a transient phenomenon. However, this changed after the eclipse was observed. More recently, Galileo Galilei conducted certain experiments that questioned the "instantaneousness" of the distance traveled by light.

Various scientists performed various experiments, some lucky and some not, but in this early scientific era, all these physics studies pursued the goal of measuring the speed of light, even if their instruments and methods were inaccurate and the primary ones were complicated. Galileo Galilei was the first to perform experiments to measure this phenomenon, but he did not get results that would help calculate the transit time of light.

Ole Roemer made the first attempt to measure the speed of light in 1676 with relative success. By studying the planets, Roemer discovered from the Earth's shadow reflected from the body of Jupiter that the time between eclipses shortened as the distance from Earth decreased, and vice versa. It obtained a value of 214.000 kilometers per second, an acceptable figure given the level of precision with which planetary distances could be measured at the time.

Then, in 1728, James Bradley also studied the speed of light, but by observing changes in the stars, he detected the displacement associated with the movement of the Earth around the sun, from which he derived a value of 301.000 kilometers per second.

Various methods have been used to improve measurement accuracy, for example, in 1958 the scientist Froome used a microwave interferometer to obtain a value of 299.792,5 kilometers per second, which is the most accurate. From 1970, the quality of the measurements improved qualitatively with the development of laser devices with greater capacity and greater stability, and with the use of cesium clocks to improve the precision of the measurements.

Here we see the speed of light in different media:

  • Empty – 300.000 km/s
  • Air – 2999,920 km/s
  • Water – 225.564 km/s
  • Ethanol – 220.588 km/s
  • Quartz – 205.479 km/s
  • Crystal Crown – 197,368 km/s
  • Flint Crystal: 186,335 km/s
  • Diamond – 123,967 km/s

What is the use of knowing the speed of light?

speed of light

In physics, the speed of light is used as a fundamental reference to measure and compare speeds in the universe. is the speed at which it propagates electromagnetic radiation, including visible light, radio waves, X-rays, and gamma rays. The ability to quantify this speed allows us to calculate distances and times in the cosmos.

An important example of how the speed of light is used in physics is in the study of stars. Because starlight takes a finite amount of time to reach Earth, when we look at a star we are looking into the past. The further away a star is, the longer its light has taken to reach us. This property allows us to investigate the universe at different times in its history, since we can analyze the light of stars that were formed millions or even billions of years ago.

In astronomy, the speed of light is crucial to calculate distances in the cosmos. Light travels at a constant speed of approximately 299,792,458 meters per second in a vacuum. This allows us to measure the distances to distant stars and galaxies using the concept of light years. A light year is the distance that light travels in one year, and is equal to approximately 9,461 trillion kilometers. Using this unit of measurement, astronomers can determine the distance to distant astronomical objects and better understand the structure and scale of the universe.

Also, the speed of light is related to Albert Einstein's theory of relativity. According to this theory, the speed of light is constant in all reference frames, which has important implications for the way we understand time and space. Einstein's special and general relativity have revolutionized our understanding of the universe and have led to the development of technologies such as GPS.

I hope that with this information you can learn more about the speed of light and its characteristics.


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