Imagine a universe where objects could magically repel each other instead of attracting - a world where gravity works in reverse. While this might sound like science fiction, researchers have long pondered why gravity seems to operate in only one direction.

Gravity stands alone among fundamental forces as a uniquely attractive phenomenon. Unlike electromagnetic forces that can both attract and repel, gravitational interactions appear to have only one mode: pulling objects together. This intriguing characteristic has puzzled scientists and curious minds for generations.

At the heart of this cosmic mystery lies a simple yet profound principle: gravitational 'charge' exists only in positive form. Every known physical entity - from subatomic particles to massive celestial bodies - demonstrates mass and energy as fundamentally positive quantities. No scientist has ever documented a true 'negative mass' that would enable gravity to push instead of pull.

The classic demonstration of gravity's behavior often involves the 'bowling ball on a bedsheet' analogy. In this visualization, massive objects create a curvature in spacetime, causing smaller objects to be drawn toward the point of greatest deformation. But why can't this deformation happen in the opposite direction, creating a repulsive effect?

Quantum physicists explain this phenomenon through the concept of spacetime as a flexible, three-dimensional grid. Imagine this grid as a network of strings that can be pulled inward by massive objects, creating a consistent gravitational attraction. This model helps explain why gravity consistently acts as a pulling force across cosmic scales.

What makes this gravitational behavior truly remarkable is its universal consistency. Whether examining subatomic interactions or observing galaxy clusters, gravity maintains its attractive nature. No exceptions have been discovered that would challenge this fundamental principle of our universe.

For curious minds like Alex Gebethner, who originally posed this fascinating question, the answer reveals the elegant simplicity underlying cosmic mechanics. Gravity's one-way attraction isn't a limitation but a fundamental characteristic that helps structure our universe, guiding the formation of stars, planets, and entire galaxies.

As scientific understanding continues to evolve, the mystery of gravity remains a testament to the profound and often counterintuitive nature of physical reality. Each discovery brings us closer to comprehending the remarkable forces that shape our cosmic existence.