“And early in the morning he came walking toward them on the sea. But when the disciples saw him walking on the sea, they were terrified, saying, “It is a ghost!” And they cried out in fear. But immediately Jesus spoke to them and said, “Take heart, it is I; do not be afraid.” Matthew 14:25-27
Notes from https://www.scienceabc.com/pure-sciences/can-you-humans-walk-on-water-myth-buoyancy-density-viscosity.html
“Miracles, like those we read about in Matthew 14 are similar to parables. Both miracles and parables prompt much wondering. In the case of miracles, many people often wonder “Could this really have happened?”
“The principle that determines whether a body can sink or not is called Archimedes’ Principle. It states that, for a body to float, it needs to displace the exact same amount of water with a weight equal to the total weight of the floating body. The weight of the displaced water exerts a force on the body, causing it to float. This force is called buoyant force and we can change its value by changing certain characteristics of water.
“The condition for floating is quite simple: the buoyant force should be greater than or equal to the weight of the body. If the value of buoyant force is large enough, then a body floats; otherwise, it sinks. The only thing we need to worry about is how we can increase this buoyant force.
“So… How Can We Walk On Water?
“Method 1: Increase The Density Of Water
The amount of water displaced by the body is equal to the volume of the submerged part of the body. Therefore, if the density of water increases somehow, then the weight of the displaced volume of water also increases, which in turn increases the buoyant force, making it easier for the body to float. Water density depends on a number of factors:
“1. The content of salt inside the water affects its density. The density of salt water is more than that of fresh water. Therefore, it is easier to float in the sea than a river.
“2. Density of water increases with a decrease in the temperature, so it is easier to float in colder water.
3. Increase the amount of water displaced by increasing the volume of the submerged body. This is why ships have a big hollow base – to give it more volume.
“Method 2: Increase The Viscosity Of Water
“When we ride a bike, the wind pushes against our bodies, slowing us down. This is due to the friction we experience from the air particles. Similarly, when we are underwater, we experience drag force. This quality of the fluid to resist force or inhibit motion is called the viscosity of the fluid. The viscosity of the fluid is directly proportional to the friction force that a moving body experiences. We can harness this feature of water to actually walk on water! But How?
“If the viscosity is strong enough, the friction force exerted upwards by the fluid could actually stop us from sinking.
“One possible way to walk on water is to run extremely fast – much faster than humanly possible. Usain Bolt, the fastest man on Earth, has a speed that tops out at about 10.4 meters per second. To run on water, you’d have to zip over the top three times as fast – around 30 meters per second!
“Method 3: Oobleck
“The viscosity of a fluid is not a constant; it changes when the characteristics of a fluid are changed. Some fluids have enough viscosity to be able to support the weight of a human body under the right conditions.
“Oobleck is nothing but a mixture of corn starch in water and can easily be made inside your kitchen. What’s special about this is that it is a non-Newtonian fluid, which means that its viscosity increases if the pressure applied on it increases. Hence, the faster we move in this fluid, the harder it is to overcome the friction force. This property of Oobleck can easily be exploited if we move over its surface with enough speed. A person walking over it at a brisk pace can easily move through without any fear of sinking, due to the high amount of reaction force from the fluid. However, on the other hand, if a person doesn’t move quick enough, the Oobleck will swallow him like quicksand.