What is dark matter and why is it important in cosmology?

What is dark matter and why is it important in cosmology?

Dark matter is a mysterious substance that makes up about 27% of the universe. It doesn't emit light or energy, making it invisible and detectable only through its gravitational effects. It's crucial in cosmology because it helps explain the structure and behavior of galaxies and the universe's expansion.

How do scientists know dark matter exists if we can't see it?

Scientists infer the existence of dark matter through various observations, such as the rotation curves of galaxies, gravitational lensing, and the cosmic microwave background radiation. These phenomena suggest that there is more mass present than what we can observe directly.

What are some theories about what dark matter could be?

There are several theories about dark matter, including Weakly Interacting Massive Particles (WIMPs), axions, and sterile neutrinos. Each of these candidates has different properties and implications for physics.

How does dark matter affect the formation of galaxies?

Dark matter plays a vital role in galaxy formation by providing the gravitational scaffolding that allows normal matter to clump together and form stars and galaxies. Without dark matter, the universe would look very different.