Why Do Swimming Pools Appear Shallow?
Have you ever looked into a swimming pool and thought the pool was shallow? Only to jump in and realize the water actually comes over your head? Well, if so, you’re not alone. The way light waves travel in swimming pools acts as an optical illusion, tricking us into believing our pools are much shallower than they are.
How do light waves work?
When light is emitted, it moves in a wave pattern, and as it moves, it bounces off of other objects in the space. Imagine you just dropped a rock into a body of water. You would see the waves ripple out and expand outward in a circle, right? Well, the same thing happens with light waves. Once the light emits from the source, it moves outward in a spherical form. Then when it touches an object, the object illuminates.
But what happens when it has already illuminated the surrounding water? Then the light wave needs to make the transfer from water to air. And since water and air are different mediums, the light wave needs to adapt and change its speed.
What is refraction?
Refraction occurs when the light wave changes speed. When a light wave is placed in a vacuum, which is a space where essentially nothing else exists, light waves will always travel at the same speed: the speed of light. But, when light waves exit that vacuum and get placed in the real world, objects and external forces change the speed of those light waves.
So, as we’ve said, when light moves from water to air, it changes speed. But it also changes its angle. Think about it like skiing. Imagine both your skis are going down the hill in a straight line, but then your right ski hits a small section of ice. Your right ski would speed up, and your left leg would pull your right ski in so they could stay together (and you won’t fall into the splits.) It will also change your angle because of the increase in speed on your right leg. So now, your skis would be pointing slightly to the left as you go down the hill. This is very similar to what light waves do.
Why do swimming pools appear shallower?
So, when you look down into a pool, you see the bends and angles created by light waves changing from water to air and air to water. The light we are seeing doesn’t come to us in a straight line, which distorts our view of the pool. It makes it look like the bottom of the pool is much closer than it is, but it is just an optical illusion.
One way to keep your kids from viewing this phenomenon is to have a pool safety fence. This will keep curious kids from playing around and getting in to the pool when they are not properly supervised.