How Gravity Works?
How Gravity Is Generated
I: Do we know how gravity is generated?
AI:
We don’t know exactly how gravity is generated at the most fundamental level. However, we have two highly successful frameworks that describe exactly what it does: Einstein's theory of General Relativity and the yet-unproven concept of quantum gravity.
Albert Einstein explained gravity not as a traditional "pulling force," but as a geometric property of space and time (spacetime). Any object with mass or energy warps and bends the fabric of spacetime around it. When other objects move through this warped spacetime, their paths bend, creating the sensation of gravity. Let's call it The Geometric View.
However, the General Relativity breaks down at the subatomic level. Physicists believe gravity should behave like other fundamental forces, which are driven by microscopic particles. They theorise a hypothetical, mass-less particle called a graviton that carries the force, though such quantum gravity has never been directly observed in the subatomic view.
Some modern physicists suggest gravity is an emergent phenomenon—similar to how gas pressure emerges from the collective movement of individual atoms. In this emergent view, (entropic) gravity arises naturally from the universe's tendency toward entropy and information exchange.
The Microscopic Gravity of Everyday Objects
I: According to general relativity, can a small object like a human body or a metal hammer generate gravity as per their mass?
AI:
Yes, absolutely. Every object with mass or energy bends spacetime.
As per a universal rule — a human body, a metal hammer, and a tiny grain of sand — all generate their own gravitational fields. The catch is that the gravity is the weakest fundamental force in nature. A typical human body creates a gravitational pull so microscopic that it is completely overridden by the Earth's massive gravity and surrounding air currents.
We can measure the gravitational pull of relatively small objects. In 1798, Henry Cavendish used a sensitive torsion balance to measure the tiny gravitational attraction between lead spheres weighing just a few kilograms. Today, physicists use ultra-precise quantum sensors to measure the gravity of objects weighing just a few grams.
A Human and a Hammer in Deep Space
I: So then, let's suppose there are no other objects in space except a human body and a hammer. The hammer would orbit or be attracted to the body because the body has higher mass than the hammer, right?
AI:
Yes, they would absolutely be attracted to each other, and the hammer could theoretically orbit the human body. Because the human has more mass, the hammer would experience a much larger acceleration toward the human than the human would toward the hammer. However, gravity is a two-way street, so both objects would move toward their common center of mass.
If you placed a 70 kg human and a 1 kg hammer exactly 1 meter apart in deep space with zero starting velocity, they would instantly begin falling toward one another. The hammer would do 98.6% of the moving because it is lighter. Because gravity is so weak at this scale, it would take roughly 8 to 9 hours for them to finally drift across that single meter and collide.
For the hammer to orbit the human instead of colliding, it would need a very precise sideways velocity. To maintain a circular orbit at a distance of 1 meter, the hammer must move sideways at a microscopic speed of just 0.000068 meters per second (about 0.24 millimeters per hour). A single orbit would take almost 4 days to complete.
While mathematically possible, a stable orbit is practically impossible with a living human. Every time your heart pumps blood, or you breathe or twitch a finger, the shifting mass alters the fragile gravitational field. A single sneeze would instantly launch the hammer out of orbit.
The Sun's Cosmic Dance
I: OK. So you are saying our Sun is also falling towards all other objects that are orbiting it?
AI:
Yes, the Sun is constantly moving and falling toward the objects orbiting it. In physics, a planet does not orbit the exact center of the Sun. Instead, both the Sun and the planet orbit a shared balancing point called the barycenter (the common center of mass).
Because the Sun holds 99.8% of all the mass in the solar system, it dominates the gravitational field. However, the remaining 0.2% of mass—mostly held by giant planets like Jupiter and Saturn—still exerts a measurable gravitational pull on the Sun.
As the planets orbit, they constantly pull the Sun toward them, causing it to loop, wobble, and dance around the solar system's barycenter. Jupiter is so massive that the barycenter between it and the Sun actually lies just outside the physical surface of the Sun. When Jupiter, Saturn, Uranus, and Neptune line up on one side of the solar system, they pull the centre of mass well away from the Sun, forcing it into a wide, looping path.
This exact "wobble" is how astronomers discover planets orbiting distant stars. By looking at a faraway star and measuring how much it moves back and forth, scientists can calculate the mass and orbit of invisible planets pulling on it.
This post is a part of my I, AI project.