Who stated that the speed of light is constant?

After the speed of light was measured by Ole Roemer, different people also came up with their findings, and the speed of light was experimented to be 299 792 458 meters per second which are approximately 3.0 x 10^8m/s. However, Albert Einstein postulated that the speed of light is constant in 1905 after he studied the various experiments on the speed of light. It should be noted that Albert Einstein didn't have any experiment on this.

What he did was to make a necessary judgment about the findings of Ole Roemer and others who attempted to measure the speed of light. However, Albert Einstein postulated that the speed of light does not depend on the speed of the source and that it is constant. Meanwhile, the speed of light is only constant in a vacuum, but it is not constant if it travels through a medium. The symbol for the speed of light is 'c'.

Albert Einstein was the first to declare that the speed of light was constant. In his theory of special relativity, he calculated the rate of speed and set it as a constant, fixed speed. Einstein was only 16 years old when he began working on the special relativity theory at the end of the 19th century. His scientific contributions have enabled scientists to build on these theories and discover even more crucial information.

Today, scientists are exploring the possibility that the speed of light can change, and will become either faster or slower as the universe continues to expand. They have already shown that the speed of light will become slower when it goes through certain mediums such as glass and water. But as to what else might change this, there are as yet, no definitive answers. The timetable for this cannot be set, as the way that the universe moves and changes vary. There is still a lot of information to discover.