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 the main challenge scientists face with dark matter?

• It is too far away to study.

• It is invisible and its nature is unknown.

• It is constantly changing form.

• It is too small to detect.

What do observations of spiral galaxies suggest?

• Galaxies are made entirely of dark matter.

• Galaxies are moving away from each other.

• There is more material in galaxies than visible.

• Galaxies are shrinking over time.

Why do physicists believe in the existence of undiscovered particles?

• They are visible through telescopes.

• They have been seen in laboratory experiments.

• They are predicted by ancient texts.

• They explain gravitational effects not accounted for by visible matter.

How do these fundamental particles interact with normal matter?

• They interact only under extreme conditions.

• They interact weakly, making them hard to detect.

• They do not interact at all.

• They interact strongly and are easily detected.

What is the significance of gravitational influence in the study of dark matter?

• It shows the age of the universe.

• It provides clues about the presence of unseen particles.

• It helps in measuring the size of galaxies.

• It indicates the speed of galaxy rotation.