To accompany ‘Ancient black holes might solve the mystery of dark matter’

SCIENCE

Before Reading:

1. What is a black hole? Identify a work of fiction, such as a film or book, that portrays a black hole. Briefly summarize how the black hole in this work of fiction affects the characters.
2. Wind is invisible, yet you know it is there. Describe three ways we might know wind exists despite being unable to see it. Just like we cannot see wind, some objects in space exist that we cannot see, yet we know they are there. One example is black holes. How might astronomers discover a new black hole, even if they cannot see the object?

During Reading:

1. If they exist, when would primordial black holes have formed?
2. Describe one of the three puzzles mentioned in the story that the discovery of primordial black holes might help scientists solve.
3. Compare the abundance of dark matter to ordinary matter. Why is it called “dark” matter?
4. Scientists detected gravitational waves for the first time in 2016. What cosmic event generated these waves?
5. How do “stellar” black holes form? How might “supermassive” black holes form from stellar ones?
6. What does inflation mean in the context of this story?
7. Considering our current understanding of black hole formation, why would scientists be surprised to discover one with relatively little mass, such as around or lower than the sun’s mass?
8. If discovered, how would a Hawking star differ from a regular star?
9. Rank the following from smallest to largest: protons, quarks, atoms.
10. What is another theory besides primordial black holes that could explain dark matter?

After Reading:

1. Why does this story say that looking far away into space “is the same as looking back in time”? Consider how scientists might use this looking-back-in-time feature to our advantage. Then, consider the possible disadvantages. What questions might scientists answer more easily, thanks to this feature? On the other hand, what questions might be out of our reach?
2. Scientists theorize about the existence of primordial black holes but have not yet discovered any. (As of this story’s publication, at least!) It’s possible that primordial black holes do not even exist. But even if they don’t, Sébastien Clesse says the work spent looking for them will not have been wasted. What do you think he means by saying this? What might be the scientific value of effort spent trying to discover some phenomenon — such as primordial black holes — even if it is not found?