Which of the following statements about black holes is not true?

• A. The mass of a black hole can be measured by studying the motion of stars orbiting around it.
• B. Nothing, not even light, can escape from within the event horizon of a black hole.
• C. Black holes can be detected by observing the gravitational effects they have on nearby objects.
• D. Black holes emit large amounts of visible light from their interiors.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the nature of black holes. Black holes are regions in space where gravity is so strong that nothing, not even light, can escape once it crosses the event horizon.
2. Step 2: Review the statements given. The first statement says the mass of a black hole can be measured by studying the motion of stars orbiting around it. This is true because the gravitational influence of the black hole affects nearby stars, allowing us to estimate its mass.
3. Step 3: The second statement says nothing, not even light, can escape from within the event horizon. This is a fundamental property of black holes and is true.
4. Step 4: The third statement says black holes can be detected by observing their gravitational effects on nearby objects. This is also true, as black holes themselves do not emit light, but their presence is inferred from their influence on surrounding matter.
5. Step 5: The last statement claims black holes emit large amounts of visible light from their interiors. This is not true because the event horizon prevents any light from escaping, so black holes do not emit visible light from inside.