Why does regular matter dominate the universe if dark matter is so much more common?

While it is true that dark matter is more abundant than regular matter in the universe, regular matter dominates in certain regions due to the way it interacts with light and other matter.

Regular matter, also known as baryonic matter, interacts with electromagnetic radiation (such as light) in a way that allows it to emit, absorb, and scatter photons. This makes it visible to telescopes and other instruments that detect electromagnetic radiation, which is why we are able to observe and study it. Regular matter also interacts with other matter through the electromagnetic and strong forces.

On the other hand, dark matter does not interact with electromagnetic radiation, which makes it invisible to telescopes and other instruments that rely on detecting light. Additionally, dark matter only interacts with other matter through gravity, which is a relatively weak force at small scales.

Because of these properties, regular matter tends to clump together in regions of the universe where gravity is strong, such as in galaxies and galaxy clusters. Dark matter also clumps together in these regions, but because it does not interact with light or other matter, it is difficult to observe directly. The dominant presence of regular matter in these regions can mask the presence of dark matter, leading to the impression that regular matter is more abundant.

However, on larger scales such as at the level of the entire universe, dark matter dominates over regular matter. This can be seen in the way galaxies and clusters of galaxies are distributed in the universe, as well as in the cosmic microwave background radiation.