Gravity is not considered the strongest force in the universe; rather, it is one of the weakest fundamental forces. The four fundamental forces in nature are gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. Of these, gravity is the weakest.
The strength of a force is determined by the coupling constant associated with it. The coupling constant represents the strength of the interaction between particles mediated by a particular force-carrying particle. In the case of gravity, the force is mediated by the hypothetical particle called the graviton.
Compared to the other three fundamental forces, gravity has an extremely small coupling constant. For example, the coupling constant for gravity is approximately 10^-40, while the coupling constant for electromagnetism is about 1/137. This means that the gravitational force between two objects is significantly weaker compared to the electromagnetic force between charged particles.
The reason gravity appears more noticeable in everyday life is that it has an additive effect over long distances and acts on all objects with mass or energy. On cosmological scales, such as the interactions between planets, stars, and galaxies, the cumulative effect of gravity becomes significant and dominates other forces.
However, at the microscopic level, such as interactions between subatomic particles, gravity becomes negligible compared to the other fundamental forces. In particle physics experiments, gravitational effects are typically extremely small and can be safely ignored.
So, while gravity plays a crucial role in the large-scale structure of the universe, it is not the strongest force at the fundamental particle level.