Final answer:
Edwin Hubble demonstrated that the universe is not flat but expanding, leading to the concept of a curved universe, with modern research indicating it is very close to flat.
Step-by-step explanation:
The scientist who revealed that the universe was not flat but instead could be curved was Edwin Hubble. Through his observations, Hubble discovered that galaxies are moving away from each other, which led to the conclusion that the universe is expanding. This expansion implies that the universe does not have a simple flat geometry.
The work of Hubble was crucial for studies on the evolution of the universe. Additionally, the experimental discovery of the cosmological constant has contributed to the current understanding that the universe is very close to flat due to its near-zero curvature, and this concept aligns with the inflationary scenario and the uniformity of the cosmic microwave background, as predicted by general relativity.