The Big Bang
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50 free The Big Bang trivia questions with answers — science & nature quiz, new questions added Aug 2026.
The Big Bang is the theory that the universe expanded from a hot, dense early state about 13.8 billion years ago. It was proposed by a Belgian priest, named by a man who did not believe it, and confirmed by two radio engineers who thought the hiss in their antenna was pigeon droppings. Today it rests on four pillars: the expansion Hubble measured, the microwave background, the abundance of light elements and the way galaxies have changed over time. These 50 questions run from the basics to the frontier: who coined the name and on which broadcaster, what Lemaître called his starting point, who actually found the cosmic microwave background and when they got their Nobel, what inflation is and which problems it fixes, how much of the universe is dark energy, and what the Big Crunch, Big Freeze and Big Rip would mean. Easy questions cover the age of the universe and Hubble's law; the expert tier asks about ylem, the Sakharov conditions, the lithium problem, the magazine that tried to rename the Big Bang and the astronomer who found a beginning of time 'repugnant'. Every answer is cited to a page we checked, with a short explanation. Play it solo or print it for a science night.
30 of 50 questions with answers and explanations. Play the quiz
Q 01How old do expansion-rate measurements say the universe is?
About 13.8 billion years
About 13.8 billion years. At times in the 20th century the sums made the universe look younger than its own oldest stars, a clash settled only by better measurements and the discovery of dark energy.
Q 02Which astronomer is credited with coining the term 'Big Bang' in 1949?
Fred Hoyle
Fred Hoyle. He never accepted the theory he had named, and later insisted the phrase was no insult, just a vivid image to help radio listeners tell two rival cosmologies apart.
Q 03The name 'Big Bang' was first spoken in a 1949 radio talk on which broadcaster?
BBC
BBC. The talk went out on its Third Programme and was printed days later in its magazine The Listener, yet scientists largely ignored the catchy name until the 1970s.
Q 04Which rival theory to the Big Bang had new matter continually created as the universe expands?
Steady-state model
Steady-state model. It gave the universe no beginning and no end, looking much the same forever; counts of faint radio galaxies and then the 1964 microwave hiss showed the cosmos had changed.
Q 05Which priest-physicist proposed in 1931 that the universe began as a 'primeval atom'?
Georges Lemaître
Georges Lemaître. He lived just long enough to see it confirmed: news that the theory's predicted afterglow had been detected reached him when he was already gravely ill, and he died in 1966.
Q 06Hubble's law says a galaxy's recession speed rises in proportion to what?
Its distance
Its distance. Think of raisin bread rising: as the dough swells, every raisin sees all the others move away, the far ones fastest, so the law is simply what a uniform stretching of space looks like.
Q 07Who accidentally discovered the cosmic microwave background in 1964?
Penzias and Wilson
Penzias and Wilson. They were trying to get rid of the hiss, not find it, while a team at nearby Princeton was preparing to hunt for exactly that signal; its leader told colleagues, "We've been scooped."
Q 08The discoverers of the cosmic microwave background suspected its hiss came from which birds' droppings?
Pigeons
Pigeons. The birds were nesting inside the horn antenna, so the two men evicted them and swept out the droppings; the hiss stayed, and it won the pair the 1978 Nobel Prize in Physics.
Q 09The cosmic microwave background today corresponds to a temperature of roughly what?
2.7 K
2.7 K. That is about minus 270 degrees Celsius; the same light was some 3,000 K when it was released, and the expansion of space has been stretching and cooling it ever since.
Q 10About how long after the Big Bang did the first atoms form, leaving the universe transparent to light?
380,000 years
380,000 years. Until then free electrons scattered light like a fog; once atoms captured them, light could cross space unhindered, and that first free light is still arriving today.
Q 11Minutes after the Big Bang, neutrons and protons fused into nuclei of which element?
Helium
Helium. About a quarter of all normal matter by mass became helium in roughly five minutes; then the universe grew too cool and thin for fusion, and most of today's supply dates from that burst.
Q 12Who introduced the idea of an early epoch of rapid expansion, 'inflation', in 1981?
Alan Guth
Alan Guth. He was a 32-year-old postdoc on his fourth temporary post, unable to land a permanent job, when the idea came to him late one night in December 1979.
Q 13Which space telescope, launched in 2021, was built to see the first galaxies that formed after the Big Bang?
Webb
Webb. Its gold-coated mirror, 6.5 metres across, was too wide for any rocket, so it was launched folded like origami and opened itself in space, 1.5 million kilometres from Earth.
Q 21Which former mule driver and janitor helped Hubble gather the data behind Hubble's law?
Milton Humason
Milton Humason. He quit school at 14 and never went back, yet he grew so skilled at the telescope that Hubble relied on him to capture the faint spectra of the remotest galaxies.
Q 22Which two associates of George Gamow predicted the cosmic background radiation?
Alpher and Herman
Alpher and Herman. In 1948 they predicted a leftover glow about 5 degrees above absolute zero, but the forecast was overlooked, and the Nobel Prize later went to the men who stumbled on it.
Q 23George Gamow added which physicist's name to a 1948 Big Bang paper purely to make the author list a Greek-alphabet pun?
Hans Bethe
Q 14Opposite sides of the sky share one temperature though seemingly never in contact, a puzzle called what?
Horizon problem
Horizon problem. Light has not had time to cross between opposite sides of the sky, so they should never have evened out; inflation says they were close neighbours before being flung apart.
Q 15Grand unified theories predicted a glut of which objects that inflation dilutes away?
Magnetic monopoles
Magnetic monopoles. Cut a bar magnet in two and each piece still has a north and a south pole; a lone pole would be a new kind of particle, and as of 2025 no search had confirmed one.
Q 16Dark matter and dark energy aside, what makes up 5% of the universe?
Ordinary atoms
Ordinary atoms. Every star, planet and person is built from them, yet they are only about a twentieth of the cosmic budget; dark energy takes roughly 68% and dark matter about 27%.
Q 17Which element, left over from the Big Bang, still makes up about three-quarters of all normal matter by mass?
Hydrogen
Hydrogen. Its nucleus is a single proton, and most protons never fused with anything in the first few minutes, so the simplest element still outweighs all the others put together.
Q 18Which mathematician derived the expanding-universe equations from general relativity in 1922?
Alexander Friedmann
Alexander Friedmann. He had flown bombing raids in the First World War, and in July 1925 he rode a balloon to a record 7,400 metres, only to die of typhoid two months later at 37.
Q 19Before Hubble, who first measured the speed of a 'spiral nebula' in 1912?
Vesto Slipher
Vesto Slipher. His first target, Andromeda, turned out to be rushing toward us at about 300 km a second; only as he added more spirals did nearly all the rest prove to be racing away.
Q 20Hubble measured galaxies' remoteness with the 100-inch Hooker reflector at which observatory?
Mount Wilson
Mount Wilson. There in California in 1923 he photographed a single flickering star in Andromeda that proved the 'nebula' lay far outside the Milky Way, a whole other galaxy.
Hans Bethe. He had contributed almost nothing to the work; Gamow added him for the joke, dismaying the student co-author, who feared the famous name would eclipse his own.
Q 24Which NASA satellite, launched in 1989, found tiny fluctuations in the CMB temperature?
COBE
COBE. Its map showed patches only a hundred-thousandth of a degree warmer or cooler than average, the first faint clumping from which galaxies, stars and eventually people would grow.
Q 25Who shared the 2006 physics Nobel for mapping the CMB's spectrum and anisotropies?
Mather and Smoot
Mather and Smoot. Their satellite needed only nine minutes of data to trace a perfect heat-glow curve, and when it was shown at an astronomy meeting the audience gave it a standing ovation.
Q 26A universe with a beginning helps resolve which old puzzle about why the night sky is dark?
Olbers' paradox
Olbers' paradox. In an endless, ageless universe every line of sight would end on a star and the whole sky would blaze; ours is dark because distant light has not had time to arrive and the oldest light is stretched out of sight.
Q 27What is the mismatch between expansion rates measured nearby and inferred from the afterglow called?
Hubble tension
Hubble tension. The universe today is expanding faster than its early conditions predict; as of 2024 repeated checks had not closed the gap, leaving open whether it is a measuring error or a sign of new physics.
Q 28In theory the Big Bang made matter in equal amounts with what else, so that neither should have survived?
Antimatter
Antimatter. The two destroy each other on contact, and nearly all of both did; a tiny unexplained surplus of matter was left over, and that remnant is every galaxy, star and person.
Q 29Whose three conditions, set out in 1967, let the infant universe end up with a surplus of matter?
Sakharov
Sakharov. The father of the Soviet H-bomb wrote them down in 1967, eight years before his campaigning for human rights at home won him the Nobel Peace Prize.
Q 30Observations of which objects revealed that the expansion of the universe is accelerating?
Type Ia supernovae
Type Ia supernovae. Two rival teams set out to measure how fast the expansion was slowing; both found the far-off explosions dimmer than expected, which meant it was speeding up instead.