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Prometheus
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Does anyone know how the speed of light from sources outside the galaxy is measured, such that we are able to recognize that even from these sources the speed of light is constant?
I would appreciate references.Chronos said:A number of experiments, some very recent, have been performed to explore your very good question. I will give references if you like.
The speed of light is a fundamental constant of the universe, and it is the speed at which electromagnetic radiation travels in a vacuum. Its value is approximately 299,792,458 meters per second.
The first successful measurement of the speed of light was done by Danish astronomer Ole Rømer in 1676. He observed the eclipses of Jupiter's moons and noticed that the time between eclipses varied depending on the distance between Earth and Jupiter. This variation was due to the time it took for light to travel from Jupiter to Earth.
Today, the most accurate method for measuring the speed of light is through the use of lasers and mirrors. A laser is directed to a rotating mirror, which reflects the beam back and forth between two stationary mirrors. By measuring the time it takes for the beam to travel back and forth, the speed of light can be calculated.
According to Einstein's theory of relativity, the speed of light is the maximum speed at which energy or information can travel. This means that no matter the observer's frame of reference, the speed of light will always appear the same. Thus, it is considered a universal constant.
The speed of light is a crucial factor in many areas of physics and technology. It is used in the fields of astronomy and cosmology to understand the vast distances in the universe. It also plays a role in telecommunications, as the speed of light determines the time it takes for signals to travel through fiber optic cables. Accurate measurements of the speed of light also help validate and refine our understanding of the laws of physics.