Black Hole Trivia
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This black hole trivia quiz has 57 free questions with answers and covers the science and the story: how a country clergyman in 1784 first imagined a star whose light could not escape, how Karl Schwarzschild solved Einstein's equations from a First World War trench, why Cygnus X-1 became the first black hole astronomers accepted, and how a planet-sized network of radio dishes finally photographed the shadow of M87* in 2019 and Sagittarius A* in 2022. The easy questions are ones anyone who has watched a space documentary can answer: what the event horizon is, what happens to a star that wanders too close, which 2014 film built its plot around a black hole called Gargantua. The medium ones dig into Hawking radiation, the no-hair theorem, quasars and gravitational waves. The hard and expert ones ask about photon spheres, ergospheres, the Penthouse bet, the baseball encyclopedia and the Hawaiian name given to the first black hole ever imaged. Every answer has been checked against a published reference source, and each question shows its explanation and citation once you have answered, so you can settle the argument as well as start it.
30 of 57 questions with answers and explanations. Play the quiz
Q 01What is the boundary around a black hole beyond which nothing can affect an outside observer called?
Event horizon
Event horizon: to a distant watcher, anything falling toward it seems to slow and freeze at the edge, never quite crossing, as its light fades away.
Q 02What is the name of the supermassive black hole at the centre of the Milky Way?
Sagittarius A*
Sagittarius A*: thick dust hides the galaxy's centre from ordinary telescopes, so astronomers found it in 1974 by its radio waves, which pass straight through.
Q 03The first photograph of a black hole, released in 2019, showed the object at the heart of which galaxy?
Messier 87
Messier 87: a century before the photo, astronomers had spotted a strange straight ray poking from its core, now known to be a jet of gas blasted out by that black hole.
Q 04Which physicist is credited with popularising the term "black hole" in 1967?
John Archibald Wheeler
John Archibald Wheeler: by his own account he kept saying "gravitationally completely collapsed object" in a lecture until someone in the audience suggested "black hole", and he took it up.
Q 05If the Sun were swapped for a black hole of equal mass, what would Earth's orbit do?
Stay the same
Stay the same: gravity depends on mass, not size, so Earth would keep circling exactly as before, only in the cold and dark. A black hole pulls no harder than the star it replaced.
Q 06Which English clergyman-astronomer proposed in the 1780s that a body could be too massive for light to escape?
John Michell
John Michell: he pictured light as tiny particles that a star's gravity could slow, so a big enough star would drag its own light back and stay invisible.
Q 07Karl Schwarzschild found the first exact solution of Einstein's equations while serving in which First World War army?
Germany
Germany: a volunteer in his forties, he posted the solution to Einstein from the Russian front, and a surprised Einstein replied that he had not expected the exact answer to be so simple.
Q 08An "Einstein-Rosen bridge" in the maths of black holes goes by what popular name?
Wormhole
Wormhole: Einstein and Nathan Rosen described the shortcut in 1935, but later work showed it would pinch shut too fast for even light to get through.
Q 09How does the temperature of Hawking radiation depend on how heavy the black hole is?
Inversely proportional to mass
Inversely proportional to mass: the lighter a black hole, the hotter it glows, so as one evaporates it heats up and shrinks ever faster, ending in a final burst.
Q 10Which object, discovered by a rocket-borne detector in 1964, became the first widely accepted black hole?
Cygnus X-1
Cygnus X-1: a blue giant star there whirls around an unseen partner every 5.6 days, and that partner proved far too heavy to be anything but a black hole.
Q 11Kip Thorne collected a year's subscription to which magazine when Hawking conceded their black hole bet?
Penthouse
Penthouse: Hawking called the bet an insurance policy, because if black holes turned out not to exist and his life's work was wasted, he would at least win four years of Private Eye.
Q 12Which 2014 film sends its crew to planets orbiting a supermassive black hole named Gargantua?
Interstellar
Interstellar: physicist Kip Thorne wrote the equations behind its black hole, single frames took up to 100 hours to render, and the results were accurate enough to yield published scientific papers.
Q 13The 1979 film The Black Hole was the first movie from which studio to receive a PG rating?
Walt Disney
Q 21Roger Penrose won a 2020 Nobel for showing black hole formation is a robust prediction of which theory?
General relativity
General relativity: Einstein never believed his own theory's black holes could be real, and it took Penrose, ten years after Einstein's death, to prove that they really can form.
Q 22A black hole's gravity bends the light of stars behind it, an effect astronomers name after which optical device?
Lens
Lens: the effect has exposed what looks like a lone black hole drifting through our galaxy, invisible itself, when it slid in front of a distant star and made that star brighten for months.
Q 23Which astronomer became only the fourth woman to win the physics Nobel, in 2020?
Andrea Ghez
Walt Disney: the film began years before Star Wars as Space Station One, a disaster movie in space in the mould of The Poseidon Adventure, and was shelved and reworked before it was shot.
Q 14Which Seattle band released the 1994 hit "Black Hole Sun"?
Soundgarden
Soundgarden: singer Chris Cornell said the title came from a TV news anchor he misheard, and that he wrote the whole song in his head on the drive home.
Q 15Muse's 2006 single "Supermassive Black Hole" was written by which member of the band?
Matt Bellamy
Matt Bellamy: the frontman's song turned up in the 2008 film Twilight, whose author Stephenie Meyer is a devoted Muse fan and has named the band as an inspiration for her novels.
Q 16Squeezed into a black hole, the Sun would have a Schwarzschild radius of roughly what size?
3 km
3 km: the real Sun is about 700,000 km in radius, so it would have to be crushed more than 200,000-fold, and it is far too light ever to collapse that far on its own.
Q 17The no-hair theorem describes a stationary black hole by mass, electric charge and what third number?
Angular momentum
Angular momentum: that is, its spin. "No hair" means everything else about what fell in is lost from view, so a black hole made of matter and one made of antimatter would look exactly alike.
Q 18Who found the exact solution of Einstein's equations for a rotating black hole in 1963?
Roy Kerr
Roy Kerr: the New Zealander was 29 when he cracked it, and because the stars that collapse all spin, his is the solution that describes the black holes actually out there.
Q 19What is the region around a rotating black hole in which it is impossible to stay still called?
Ergosphere
Ergosphere: space is dragged around the hole so hard that nothing inside can hold still, yet it lies outside the point of no return, so an object can dip in and leave carrying off some of the hole's spin energy.
Q 20Where around a black hole can gravity bend light into a full orbit?
Photon sphere
Photon sphere: light there can circle the black hole several times before escaping, and physicists expect it to draw a thin, bright ring around the hole's dark shadow.
Andrea Ghez: for over two decades her team followed stars whipping around something unseen at the galaxy's centre. Only Marie Curie, Maria Goeppert Mayer and Donna Strickland had won before her.
Q 24Which observatory first directly detected gravitational waves on 14 September 2015?
LIGO
LIGO: the waves came from two black holes colliding over a billion years ago, a crash that turned about three Suns' worth of mass into ripples in space within a fraction of a second.
Q 25In 2008, critics went to court to stop which machine, fearing it would create a black hole that swallowed the Earth?
The Large Hadron Collider
The Large Hadron Collider: the case was thrown out, and physicists noted that cosmic rays have struck Earth at far higher energies for billions of years, and the planet is still here.
Q 26The English clergyman who imagined light-trapping stars in the 1780s also designed the apparatus later used for what?
Weighing the Earth
Weighing the Earth: he built a delicate twisting balance for the job but died before using it, and it ended up with his friend Henry Cavendish, who finished the famous experiment in 1798.
Q 27Which celebrated astronomer told a 1935 meeting there should be a law of nature to stop stars collapsing so absurdly?
Arthur Eddington
Arthur Eddington: he was mocking a 24-year-old colleague's proof that heavy dead stars must keep collapsing. The young man was right, and Eddington's scorn may have set the idea back by decades.
Q 28The 1.44-solar-mass limit worked out by a future Nobel laureate applies to what kind of star?
White dwarf
White dwarf: a 19-year-old student worked the limit out in 1930 on the voyage from India to England, showing that a dead star any heavier cannot hold itself up and must collapse further.
Q 29NASA's Chandra space telescope, launched in 1999, is named after which physicist?
Subrahmanyan Chandrasekhar
Subrahmanyan Chandrasekhar: NASA ran a worldwide naming contest, and the winning entries came from an Idaho high-school student and a California teacher. The Raman among the options, also a Nobel winner, was his uncle.
Q 30Which Space Shuttle, later lost in an accident, carried the Chandra telescope into orbit?
Columbia
Columbia: five seconds after liftoff an electrical short knocked out two engine controllers, and only their backups kept the climb going. Eileen Collins, the first woman to command a shuttle, was in charge.