Gravity and the Relativity of Time in a simple way.
Time.
We all think of Time in seconds, minutes and hours. Well to Science that’s not what Time is. Time is relative. It’s relative to one’s psychological conditions. Think of it this way, we’ve often heard the common phrase “We didn’t realise how quickly the time passed by”. This is what people say when they’re involved in a happy occasion. Contrary to this, when in a sad or boring state, it seems as if time has either stopped or is passing at a very slow rate. However, the definition of second is still the same, but you experience different speeds of time at different occasions and situations.
This was psychology. Now let’s talk some Science. So physics says ‘The Faster you Move through space, the slower you move through time’.
The Time Dilation Equation
This has been explained in the famous Theory of Relativity. So according to it, universe is made up of a giant fabric like structure. You can imagine a fully stretched wide and long sheet of thin rubber.
This fabric constitutes what is called ‘Space-Time’. So apparently, the universe is 4 dimensions. It has 3 dimensions of space i.e. X, Y and Z and 1 dimension of time so any change in the dimensions of space will affect Time. Now suppose you’re traveling in a Spaceship with a very high speed. So when one moves with a very high speed through space, it curves the Space-Time fabric around it and hence the dimension of Time is changed and it slows down. Now when one reaches near or at the speed of light (the fastest speed that can be achieved), time stops for you and the laws of physics breakdown.
Now, Theory of Relativity also beautifully explains the concept of Gravity. Again imagine the stretched fabric of rubber, now if you put a big and heavy steel ball on it, the fabric will curve around the steel ball. Now if you slide in some small marbles around the steel ball, the marbles will start orbiting the steel ball in an elliptical way much like how planets revolve around the Sun. Now Sun is exactly like the steel ball and all the planets are like the marbles. The mass of the Sun bends Space-Time around it and sets all the planets in an orbital motion. Now let’s do something interesting. Now instead of sliding in the marbles and setting them in motion beforehand, let’s just drop them near the steel ball. What happens when you drop it near the steel ball? Due to the curved fabric around the steel ball, the marbles will move inwards towards the steel ball due to the slope of the curved fabric. And that my people is what GRAVITY is. The Sun, black holes, meteorites, asteroids, planets, etc. all bend the Space-Time around them but the extent of curve on the Space-Time will be determined by the mass of the body. This explains why Black Holes have enormous force of Gravity. Black Holes are unimaginably heavy so their gravitational force is also unimaginable. The gravitational force is so much that not even light can escape it.
Now the planets don’t fall into The Sun because of their orbits. When orbiting, the planets exert a force in the outward direction which keeps them in their orbits.
Time also slows down around heavy objects. Enormously heavy objects distort Space-Time around them which in turn affects Time.
In the end, Theory of Relativity is extremely complex and higher level mathematical skill is required to understand it. But I guess this article will give you some idea about it.
