Dark matter is different from normal matter because a. it doesn't emit light. b. it doesn't absorb light. c. it doesn't scatter light. d. all of the above

The concept of electromagnetic interaction plays a crucial role in differentiating between dark matter and normal matter. In physics, electromagnetic interaction refers to the interaction between charged particles through electromagnetic fields. This interaction is responsible for various phenomena, including light emission, absorption, and scattering.
Unlike normal matter, dark matter does not engage in electromagnetic interactions. It means that dark matter doesn't emit light like stars, doesn't absorb light like dust clouds, and doesn't scatter light like air molecules. In essence, dark matter is invisible to electromagnetic waves, making it undetectable by conventional telescopes.
This lack of interaction with light (or photons) is why dark matter is called 'dark'. Its existence is inferred through gravity effects on galaxies and other cosmic structures. Without electromagnetic interaction, dark matter remains a mysterious but essential part of the universe.

Non-luminous matter, as the name suggests, refers to matter that does not emit any form of light or radiation. Dark matter falls into this category. While normal matter like stars and galaxies glow and can be seen with telescopes, dark matter eludes direct detection.
Non-luminous matter is identified through its gravitational effects. Astronomers observe that galaxies rotate faster than they should if only visible matter existed. This observation implies additional unseen mass exerting gravitational pull.
Some key characteristics of non-luminous matter (including dark matter) are:

• No emission of light or radiation
• Absence of light absorption
• Invisibility to electromagnetic waves

These properties challenge scientists to develop indirect methods to study dark matter. Techniques like cosmic microwave background analysis and gravitational lensing help learn about its distribution and effects in the universe.

Astrophysics is the branch of astronomy that focuses on understanding the physical properties and interactions of celestial objects. Dark matter has become a significant topic within astrophysics due to its mysterious nature and pervasive presence.
Through astrophysics, scientists study dark matter's role in the universe's structure and evolution. For example, dark matter is essential for explaining galaxy formation. Its gravitational influence helps hold galaxies together, providing the necessary 'glue' that prevents these massive structures from tearing apart.
Research in astrophysics also involves:

• Mapping dark matter distribution through gravitational lensing
• Investigating dark matter's impact on cosmic microwave background radiation
• Developing theoretical models to predict dark matter's behavior

Dark matter challenges the current understanding of the universe, making astrophysics an exciting field. Discoveries in this area can revolutionize our knowledge of cosmology and the fundamental forces that shape the cosmos.