Thomas Young was a really smart man who lived a long time ago. He was born in 1773 and grew up in England. Thomas Young was interested in lots of different things, but he became famous for his work in science.
One of the things that Thomas Young was really good at was studying how light works. He knew that light travels in waves, just like sound does. But he also knew that light waves are different from sound waves because they travel through space, even when there is no air for them to travel in.
Young came up with a way to measure the colors of different light waves, which he called the theory of colors. He discovered that there are seven colors in light: red, orange, yellow, green, blue, indigo, and violet.
Young also studied how our eyes work. He learned that there are three different types of cells in our eyes that help us see different colors. He called them red, green, and blue cells.
Thomas Young did a lot of other cool things too. He was a doctor and helped people who were sick. He also knew many different languages, so he could talk to people from all over the world.
Young was a very important scientist, and his work helped us to understand how light works and how we see colors.