Question 1: Define dark mass and explain how it differs from regular matter in the universe.

Answer: Dark mass, or dark matter, is a type of matter that does not emit, absorb, or reflect light, making it invisible. It differs from regular matter because it interacts gravitationally but not electromagnetically.

Question 2: What is dark energy, and how does it affect the expansion of the universe?

Answer: Dark energy is a mysterious form of energy that causes the acceleration of the universe's expansion by exerting a repulsive force on space itself.

Question 1: If the current rate of the universe's expansion is characterized by a Hubble constant of 70 km/sec/Mpc, calculate how far the universe will expand in 1 billion years. (Use the formula: Distance = Speed × Time; 1 year = 3.15 × 10^7 seconds)

Answer: Distance = 70 km/sec/Mpc × (1 × 10^9 years × 3.15 × 10^7 sec/year) = approximately 2.2 × 10^24 km

Question 2: Using the formula for cosmic acceleration due to dark energy, a = (Λc²)/3, where Λ is the cosmological constant, calculate the acceleration if Λ = 1.1 × 10⁻⁵ s⁻². Take the speed of light c = 3.0 × 10⁸ m/sec.

Answer: a = (1.1 × 10⁻⁵ s⁻² × (3.0 × 10⁸ m/sec)²) / 3 ≈ 3.3 m/sec²

Question 1: Describe a theoretical experiment to detect the presence of dark matter in a galaxy. What variables would you measure, and what safety precautions should be considered?

Answer: A possible experiment involves measuring the gravitational effects of dark matter on visible objects, such as stars or gas clouds, within a galaxy. Variables to measure include star velocities and positions. Precautions include ensuring safe operation of telescopes and avoiding exposure to intense radiation from space observatories.

Question 1: In a recent survey, scientists found that approximately 27% of the universe's total mass-energy is dark matter, while about 68% is dark energy. The rest is ordinary matter. Explain what this data suggests about the composition of the universe and its future expansion.

Answer: This data indicates that the majority of the universe's mass-energy is made up of dark energy and dark matter, suggesting the universe is dominated by unseen components that influence its expansion, likely leading to accelerated expansion in the future.

Question 1: Explain how dark energy contributes to the acceleration of the universe's expansion, using relevant scientific principles. (6 marks)

Answer: Dark energy exerts a repulsive force on space itself, counteracting gravity's pull on matter. According to Einstein's theory of general relativity, this causes space to stretch more rapidly over time, leading to accelerated expansion. The presence of dark energy's negative pressure is key to this effect.

Question 2: Which of the following best describes dark matter? (a) It emits light, (b) It interacts electromagnetically, (c) It exerts gravitational pull but does not emit light, (d) It is a form of ordinary matter.

Answer: c) It exerts gravitational pull but does not emit light