The idea that objects fall at the same speed regardless of their weight is generally attributed to Galileo Galilei, although it's important to note that:

* It's not a simple "discovery": Galileo's work involved a series of experiments, thought experiments, and reasoning to arrive at this conclusion. It wasn't a single "aha!" moment.

* Prior ideas existed: Aristotle, a Greek philosopher, believed heavier objects fall faster. This was the prevailing view for centuries.

* The story of the Leaning Tower of Pisa: While often told, there's no strong evidence Galileo actually conducted this experiment.

Galileo's key contributions:

* Inclined Plane Experiment: He used inclined planes to slow down the fall of objects, allowing him to make more accurate observations. He found that objects of different weights rolled down the same distance in the same time.

* Thought Experiments: Galileo famously argued that if you drop a heavy object and a light object together, the heavier one should pull the lighter one down faster, making them fall together. This reasoning challenged the Aristotelian view.

* Challenging Authority: Galileo's work was controversial, going against established scientific dogma. He faced opposition from the Church and other authorities.

In conclusion, while the exact details of the discovery are complex, Galileo's contributions through his experiments, reasoning, and challenge to existing beliefs laid the groundwork for our understanding of gravity and how objects fall.