Variable speed of light
Imagine you're playing catch with your friend. When you throw the ball, it goes at a certain speed, but sometimes it might slow down or speed up depending on the game you're playing. Now, imagine that the ball is like light, and instead of going through the air, it's going through space.
The speed of light is a bit like how fast the ball can go when you throw it. One really cool thing about light is that it's always the same speed in a vacuum (like space), and it's really fast - about 186,000 miles per second! That's like running all around the world 7.5 times in just one second.
But scientists have discovered that light can actually slow down when it passes through certain things, like water or glass. This is because the particles in these materials can absorb and re-emit light, essentially slowing it down.
Now, to understand variable speed of light, we need to imagine an imaginary substance called "aether". Long ago, scientists believed that the universe was filled with aether and all the light waves had to travel through it. They thought that this was how light got its speed, by traveling really fast through this aether substance. However, years later it was found that this was not true, and there is no such aether substance.
Scientists now know that light travels at a constant speed in a vacuum, like space. But, they also found that when the light waves pass through a gravitational field, it can change the speed of the light waves. Just like throwing a ball up a hill will slow it down, passing through a gravitational field, such as near a planet or star, can also slow down light.
This concept can be challenging to understand, but just remember that light usually travels at a constant speed, but it can slow down when it passes through certain materials or a gravitational field. Hence, variable speed of light!
The speed of light is a bit like how fast the ball can go when you throw it. One really cool thing about light is that it's always the same speed in a vacuum (like space), and it's really fast - about 186,000 miles per second! That's like running all around the world 7.5 times in just one second.
But scientists have discovered that light can actually slow down when it passes through certain things, like water or glass. This is because the particles in these materials can absorb and re-emit light, essentially slowing it down.
Now, to understand variable speed of light, we need to imagine an imaginary substance called "aether". Long ago, scientists believed that the universe was filled with aether and all the light waves had to travel through it. They thought that this was how light got its speed, by traveling really fast through this aether substance. However, years later it was found that this was not true, and there is no such aether substance.
Scientists now know that light travels at a constant speed in a vacuum, like space. But, they also found that when the light waves pass through a gravitational field, it can change the speed of the light waves. Just like throwing a ball up a hill will slow it down, passing through a gravitational field, such as near a planet or star, can also slow down light.
This concept can be challenging to understand, but just remember that light usually travels at a constant speed, but it can slow down when it passes through certain materials or a gravitational field. Hence, variable speed of light!