Isaac Newton changed the way we understand the universe.

In the 1600s, he discovered that every object attracts every other object with a force called gravity.

The strength of this force depends on the masses of the objects and the distance between them.

His famous formula explained how the Moon orbits the Earth, how the planets move around the Sun, and even why an apple falls to the ground.

For Newton, gravity was an invisible force that acted instantly between two objects, no matter how far apart they were.

For more than 200 years, Newton's theory worked very well.

But in the early 1900s, scientists found a few problems it couldn‘t explain.

One example was Mercury's orbit, which moved slightly differently from Newton's prediction.

Another was how light bent when it passed near the Sun.

These mysteries led Albert Einstein to create a new idea about gravity.

In 1915, Einstein introduced the General Theory of Relativity.

He said that space and time are not separate things but are connected together as spacetime.

Massive objects like planets and stars bend this spacetime around them, just like a heavy ball placed on a rubber sheet makes a curve.

Other objects, and even light, move along the curved paths created by this bending.

So, according to Einstein, gravity is not really a pulling force it is the curvature of spacetime itself.

The two theories work in different ways.

Newton's law is very accurate when gravity is weak and objects move slowly.

It is still used to send rockets to space or calculate satellite orbits.

But Einstein's theory is needed when gravity is very strong or when things move close to the speed of light, like near a black hole.

It also explains that time runs slower in stronger gravity, which modern GPS satellites must consider to work correctly.