Dark matter

Dark matter is invisible and its nature is unknown. Observations of spiral galaxies suggest they contain more material than can be accounted for by visible matter. Physicists propose that this is due to the gravitational effects of yet-to-be-discovered particles that interact weakly with normal matter.

What is dark matter and why can't we see it?

How do spiral galaxies provide evidence for the existence of dark matter?

What do physicists believe about the particles that make up dark matter?

Why is it difficult to discover dark matter particles?

What implications does the existence of dark matter have for our understanding of the universe?