How does gravity affect the universe?

Only about fifty years ago, astronomers believed that the universe was slowing down due to its inherent matter—that is, that each individual particle of matter has its own gravitational pull, and that given the amount of gravity required to hold the universe together as it is, the expansion would cease and the contraction would start.

However, three things transpired in the years that followed. Firstly, scientists found that the universe is expanding faster than ever, rather than slower. Secondly, they were unable to explain this phenomenon and are still unable to do so.

Then, astronomers conducted a sort of atom count, in which they calculated the gravitational associated mass of each mass they could see throughout the universe by figuring out how much mass they could see. However, after the counting was completed, they discovered that the gravitational mass of the universe is far too great to be explained by the universe that is visible to us, with visible matter making up only about 5% of the total mass required to account for the universe's total gravity.

This is where dark matter comes into play. It is hypothesized that dark matter has a role in this, but astronomers and physicists are currently unable to explain it because dark matter has neither been detected nor its properties determined.

When one question in science is answered, ten more take its place, just like with many other things.

Gravity plays a fundamental role in shaping the universe's structure and dynamics. It governs the motion of celestial bodies, the formation of galaxies, stars, and planets, and the evolution of the cosmos over time. Without gravity, the universe would lack the cohesive force necessary for objects to attract and interact with each other, resulting in a vastly different and potentially chaotic cosmic landscape.