Gravity: The Force That Links Everything

The Moon circling the Earth, following its path along the curved fabric of spacetime.

Gravity is the force of attraction between two masses. All objects with mass pull on other objects, but we mainly notice the effects of gravity when one of the objects, like the Earth, is very large relative to the other object. Simply put, the heavier object will pull more strongly on the lighter object. In order to calculate the force of attraction between two objects, scientists use a simple formula:

F = (G)(M1)(M2) ÷ r^2

In this equation, “F” is the force of attraction, “G” is the gravitational constant, “M1” is the mass of the first object, “M2” is the mass of the second object, and “r” is the distance between the two objects. Even very small things attract each other, but the force is usually too small to feel or think about for human beings.

Around the 17th century, Isaac Newton is known for creating the first scientific explanation for gravity. Watching an apple falling to the ground, he realized that the same force pulling the apple down is what pulled the Moon to the Earth and the Earth to the Sun. His Law of Gravitation taught the general public that the force depends on the mass of the objects and the distance between them. This idea and thought were a key starting point for understanding the universe and its associated forces.

In the early twentieth century, Albert Einstein expanded on Newton’s ideas with his research and combined them to make the groundbreaking theory of General Relativity. This theory was not about looking at gravity as simply a force between masses. Instead, Einstein saw gravity as the warping of space and time by massive objects. This more complex understanding explained some observations that weren’t able to be explained previously, including the bending of light.

Even though Einstein's theory is more specific and complete, Newton's formulas are still used in everyday engineering, science, and many other fields due to their simplicity, which allows the general public to be able to understand the formulas and the idea behind them. Understanding and applying gravity is crucial for the development of many thing. For example, we need to understand gravity for safely constructing bridges, figuring out how much fuel is needed for a rocket, and much more. Gravity shapes much of our daily environment in ways we often don’t notice.

Gravity is also the reason for stars, planets, and galaxies. It keeps celestial bodies in orbit and is what clumps together particles into a cohesive unit. Without gravity, the universe would just be a chaotic mix of particles floating about on their own.

Compared to other forces like electromagnetism, gravity is actually extremely weak, as the force it exhibits is significantly lower. Many scientists still don’t understand why this is and are still currently looking for breakthroughs. Gravity is much more than the reason for why objects fall to the ground. It shapes the structure of the universe and influences everything from the Earth revolving around the Sun to an apple falling to the ground.