Dark matter

Definition

Dark matter is a form of matter that does not emit, absorb, or reflect light, making it invisible and detectable only through its gravitational effects. It constitutes about 27% of the universe's mass-energy content.

5 Must Know Facts For Your Next Test

1. Dark matter was first postulated due to discrepancies in the rotational speeds of galaxies.
2. It interacts with regular matter primarily through gravity and possibly weakly via other fundamental forces.
3. Experiments such as those conducted by the Large Hadron Collider (LHC) aim to detect dark matter particles directly.
4. Dark matter is essential for explaining the large-scale structure of the universe, including galaxy formation and clustering.
5. The leading candidate particles for dark matter include WIMPs (Weakly Interacting Massive Particles) and axions.

Review Questions

• What observational evidence led to the hypothesis of dark matter?
• How does dark matter interact with regular baryonic matter?
• Name two potential candidates for dark matter particles.

Related terms

WIMP: Stands for Weakly Interacting Massive Particle, a hypothetical particle proposed as a constituent of dark matter.

Axion: A hypothetical elementary particle proposed as another candidate for dark matter. It is extremely light and interacts very weakly with normal matter.

Gravitational Lensing: A phenomenon where light from a distant object is bent around a massive object between the source and observer, used as evidence for dark matter presence.