# What is gravity and how does it work 3D animation

### (3D  Simulations)

#### Hello everyone!

In this lecture, You’ll Learn What is gravity and how does gravity work video, how does gravity work, how does gravity work on earth, Relativity Theory, and Much More. I am also gonna show you how does gravity work in our solar system, Effect of Gravity on Light with 3D Simulations. You’ll also learn, force of gravity on earth in newtons, what is gravity in physics, how does gravity work on earth, how does gravity work video, what is gravity.

## Aristotle’s Flat Earth Concept

Aristotle Believed in a flat earth and considered the earth as the center of the universe. He believes that sun, stars and other planets are orbits around the earth. The Model of the universe is Known as Geocentric Model of Universe. To answer the question why do objects fall on the ground. Aristotle proposed that every object in the universe has its natural place. And they move towards their natural places. Just like a Swing if you displace a swing from its equilibrium position, it will try to move towards its equilibrium position. In this way, Aristotle explained that for most of the object earth is the natural place. And they tried to stay on the ground. That’s why objects fall on the ground. In this way, He explained that heavier object fall will fall faster than lighter objects.

But in 16th century Renaissance Nicolas Copernicus formulated a new model of the universe and his model of the universe he took the sun as the center of the universe rather than earth. That model of the universe is known as Heliocentric Model of Universe. After few years of Copernicus, Galileo Galilei carried out an experiment. He released two objects of the same material but different masses from the leaning tower of Pissa, (Italy). He found that both objects fall on the ground the at the same time. That’s means that heavier and lighter objects both fall on the earth with the same speed. These two ideas were controlled by What else to talk.

So this question was unanswered till the Era of “Newtonian Physics“. In 17th Century Isaac Newton begun to read about this question. When he saw an apple falling from the tree, he began to think what causes the apple to fall on the ground. as the Newton law of motion suggests that “An object at rest will stay at rest unless it is acted upon by some force”. In explanation of this question, he presents the universal law of Gravitation. He purposed that ” An object will attract every object in the universe”. And that force of attraction varies with masses of the objects. In our case, Earth is attracting the apple towards it. He called that force of attraction Gravitation force. In case of Earth, this force is revert to Gravity.

## General Theory of Relativity

So According to Newton, the answer is “Things fall because earth attracts them towards it”. yet it was a good explanation of a question but was unable to answer some questions.

i.e

Why do Objects attract each other?
Does gravity has any effect on a light?

According to Isaac Newton Gravity has no effect on light. But He was himself was confused with his observation of distant galaxies. He found that the light coming from them was showing some strange behaviors that he was unable to explain. To answer these question and present the better model of Gravity Albert Einstein with his friend Grossman, Albert Einstein presented the theory of Relativity to understand this theory you must have better understanding of space and time.

First Mathematical model of space and time was given by Sir Isaac Newton in his book.In these models of space and time, they were just a like a background stage where events happen, but it is independent of what is happening. Time was separated from the space and considered like a single line. That was infinite in both directions. And it has a universal speed. It parses with the same speed independent of where ever you are in the universe. That was a bit of history about Newton’s picture of space and time. So what is space? Well! the first image that comes to our mind is outer space but in fact, space is everywhere every single time in the Universe has the 99.99999999999996% of free space.

If we remove all space from the earth it’s size will be equal to that of an apple. So what exactly is space?
Well! Now instead of removing space from everywhere remove everything from the universe. Every single item buildings, planets, Stars, and Galaxies. Then what we left with than you think we left with nothing. But this is not true we are left with space. Let’s take an Example of a Fish Tank, Fish in the tank represent the objects in the
universe and water represent the objects in the space.

Just like water space also has its physical properties. It can be bent, it can carry waves. It was Bernard Reimann who first thought that matter and space does interact with each others matter causes the space to bent. in general theory of relativity Albert Einstein’s purposed that Space has physical properties. Time also have physical properties. Just like space, water, and other objects. And space and time are not two different things “Time is an interview with space”.

To understand this point let’s get back to the analogy of a fish tank we took the understanding space. If we add some colors to water it will mix with water just like the color in water space and time is interwoven. the Alber Einstien purposed that “It is not only space that interacts with water but it is space-time that is bents”. And that bending or curvature in space-time causes other objects in space-time to change their direction of motion.

So you put if put forward the idea that what we think of as gravitational force is just an effect that is caused by the curvatures in space-time. To see what’s that mean just have a look at the animation playing here. So if there are no other objects in the space-time the Earth will move in straight line. What is there is any mass of the object like Sun, the curvature in space-time caused by the sun will cause the object to change its direction of motion. This effect was considered as a gravitational force by Newton.

This theory also purposed that light is also affected by the curvature of space-time. To see that, How does it happen? Imagine you are observing a distant star and there is a sun b/w you and start. The light will bend when passing near the sun due to curvature in space-time. This effect is known as Gravitational lensing effect. Becuase here gravitational pull is working like a lens that was observed by the Newton. But he was unable to explain this phenomenon. To visualize how this effect looks like have a look at Animation I made here. the galaxy passes the black hole.

So the conclusion of this video is that Gravity is not a Force but just an effect caused by the curvature in space-time.