Think you know Black Holes?

Sample Black Holes questions

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   What is the infinitely dense point at a black hole's core?

   Answer: Singularity

2. 2 Medium

   To become a black hole, Earth must shrink to what size?

   Answer: the size of a marble

3. 3 Hard

   What is the simplest type of black hole with zero charge?

   Answer: Schwarzschild black hole

   Why: Schwarzschild found the solution while serving on the Russian front and posted it to Einstein in December 1915, under five months before his death.

4. 4 Easy

   What is the name of the black hole at our galaxy's center?

   Answer: Sagittarius A*

5. 5 Medium

   How do astronomers detect black holes that are not actively feeding?

   Answer: Gravitational lensing

   Why: The one unambiguous isolated case, OGLE-2011-BLG-0462, took years of Hubble follow-up to confirm from the way it bent a background star's light.

6. 6 Hard

   What theory describes black holes as having no distinguishable outer features?

   Answer: No-hair theorem