Quantum Physics Trivia
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90 free Quantum Physics trivia questions with answers — science & nature quiz, new questions added Oct 2026.
Quantum physics is the one branch of science where the experts admit they do not understand what the equations mean, yet the predictions have never once failed. A cat that is alive and dead, particles that tunnel through walls, pairs that seem to signal faster than light: every one of these is a real experiment, not a metaphor. These 90 questions follow the story from Planck's reluctant quanta in 1900 through Einstein, Bohr, Heisenberg and Schrödinger to Bell tests, Nobel prizes and the quantum bits inside today's quantum computers. Each answer comes with a short explanation and a source, so you leave knowing why it matters, not just which letter was right. It suits anyone curious about how the universe works at its smallest scale, from students revising for an exam to pub-quiz regulars who want to stop guessing on the science round. Play it online or print it for a classroom or trivia night.
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Q 01Schrödinger's 1935 thought experiment has a Geiger counter release a hammer onto a flask of which poison?
Hydrocyanic acid
Hydrocyanic acid in a small flask puts the cat's life at the mercy of one atom's random decay. Schrödinger called the case burlesque: he offered it as a critique of the theory, not as a serious proposal.
Q 02Albert Einstein's 1921 Nobel Prize in Physics cited which discovery, rather than his theory of relativity?
Photoelectric effect
The photoelectric effect won because the Nobel committee still doubted relativity, so the citation pointedly avoided it. Einstein had already promised the prize money to his first wife Mileva in their 1919 divorce settlement.
Q 03Einstein's 1926 letter saying God does not play dice went to which pioneer of the wave function's statistical reading?
Max Born
Max Born, whose probability rule the remark questioned, waited until 1954 for a Nobel Prize awarded 'especially for his statistical interpretation of the wavefunction'. The two men stayed friends and correspondents for life.
Q 04Which polymath, a Rosetta Stone decipherer, devised the two-slit experiment that shows light interfering like a wave?
Thomas Young
Thomas Young's wave theory met scepticism in England because it contradicted Newton, yet his two-slit setup later showed even single electrons building up interference fringes.
Q 05Max Planck's 1900 idea that energy comes in discrete quanta was devised to fit the spectrum of what?
Black-body radiation
Black-body radiation from a heated cavity refused to match classical physics, which predicted infinite energy at high frequencies, the so-called ultraviolet catastrophe. Planck won the 1918 Nobel Prize for the discovery of energy quanta.
Q 06Heisenberg's 1927 uncertainty principle says which two properties of a particle cannot both be known precisely?
Position and momentum
Position and momentum uncertainties multiply to at least ħ/2, so a particle pinned to a tiny region must carry a wildly uncertain velocity. This is a property of waves, not a flaw in instruments.
Q 07Which term, coined in jest by Benjamin Schumacher in 1995, names the basic unit of quantum information?
Qubit
A qubit can sit in a superposition of 0 and 1 at once, which is why a few hundred of them could outrun any classical computer. Schumacher said the word came up in a conversation with William Wootters.
Q 08Niels Bohr's 1913 atom model derived the Rydberg formula for the spectral lines of which element?
Hydrogen
Hydrogen's single electron made the model tractable: it explained Balmer's 1885 formula, a puzzle for nearly thirty years, yet it failed for atoms with more electrons. Bohr won the 1922 Nobel Prize.
Q 09Einstein derided which quantum effect, since confirmed by Bell tests, as 'spooky action at a distance'?
Entanglement
Entanglement links particles so that measuring one instantly fixes the other's result, yet nothing usable can be signalled that way, so relativity survives. Einstein thought so strange a link could not be the whole story.
Q 10Which QED pioneer dunked a clamped O-ring in ice water during the televised 1986 Challenger hearings?
Richard Feynman
Richard Feynman showed the rubber stayed stiff when cold, exposing why the booster seals failed on the freezing launch morning. He shared the 1965 Nobel Prize with Schwinger and Tomonaga for quantum electrodynamics.
Q 11Which chemist, a perennial Nobel nominee who never won, gave the light quantum the name 'photon' in 1926?
Gilbert Lewis
Gilbert Lewis was not the first to use the word, and his own idea of the photon was very different from Einstein's light quantum, yet physicists adopted his name for it anyway.
Q 12Which SI unit, long defined by a platinum–iridium cylinder near Paris, was redefined in 2019 via Planck's constant?
Kilogram
The kilogram was the last SI unit tied to a physical object, and the Paris prototype had drifted by tens of micrograms against its copies. A Kibble balance now realises it by weighing mass against electromagnetic force.
Q 13The 1922 Stern–Gerlach experiment, later read as the first sign of electron spin, split a beam of which metal's atoms in two?
Silver
Q 21Which French physicist's 1924 doctoral thesis proposed that electrons, like light, behave as waves?
Louis de Broglie
Louis de Broglie, later the 7th Duke of Broglie, won the 1929 Nobel Prize once electron diffraction confirmed his idea in 1927. A copy of the thesis had been sent to Einstein, who backed it from the start.
Q 22The 1927 Davisson-Germer experiment at Bell Labs saw electrons diffract like waves off a crystal of which metal?
Nickel
Nickel gave the result by accident: after air leaked into the vacuum tube, heating the oxidised target grew big crystals whose neat planes produced the diffraction peaks. Davisson shared the 1937 Nobel Prize; Germer was left out.
Q 23The orthodox reading of quantum theory, shaped by Bohr and Heisenberg in the 1920s, is named for which city?
Silver atoms split into two beams where classical physics predicted a smear; Stern and Gerlach credited the old Bohr–Sommerfeld theory, and only after spin was proposed in 1925 was the split traced to a single outer electron.
Q 14Which Austrian's 1925 exclusion principle bars two electrons in one atom from sharing all four quantum numbers?
Wolfgang Pauli
Wolfgang Pauli's rule is why atoms have shells and chemistry has a periodic table, since electrons cannot all crowd into the lowest orbit. Colleagues joked that his mere presence broke laboratory equipment, the 'Pauli effect'.
Q 15Paul Dirac's 1928 equation implied which antiparticle, found by Carl Anderson in cosmic-ray tracks in 1932?
Positron
The positron is the electron's antimatter twin, and Anderson's discovery earned him the 1936 Nobel Prize at just 31. Hospital PET scanners now rely on positrons annihilating with electrons inside the body.
Q 16George Gamow's 1928 tunnelling theory explained which radioactive decay, whose particles a sheet of paper stops?
Alpha
Alpha particles are helium nuclei trapped behind an energy barrier they could never classically climb, yet they leak out with a tiny probability on each bounce. The same theory explains half-lives from microseconds to billions of years.
Q 17Binnig and Rohrer invented the scanning tunnelling microscope in 1981 at which company's Zurich laboratory?
IBM
IBM's Zurich pair shared the 1986 Nobel Prize just five years after the invention. Company scientists later used the microscope to drag single xenon atoms into place, spelling out its three-letter name.
Q 18Which state of matter was first made in 1995 by chilling rubidium gas?
Bose–Einstein condensate
Bose–Einstein condensate forms when atoms merge into one quantum state, a 'superatom'; the Colorado team got there by cooling rubidium to under a millionth of a degree above absolute zero. Einstein had predicted it seven decades earlier.
Q 19Which company claimed 'quantum supremacy' in 2019 with a Sycamore chip it said outran any supercomputer?
Google's 200-second sampling task, it said, would take a supercomputer 10,000 years, though a rival argued its Summit machine could do it in 2.5 days. Physicist John Preskill had coined the phrase 'quantum supremacy' years earlier.
Q 20A 1926 rule of quantum mechanics sets a particle's probability density equal to what?
Square of the wave function's modulus
The square of the wave function's modulus is all experiment can ever see, so the phase stays invisible unless two paths interfere. Attempts to derive the rule from deeper principles remain contested; most textbooks take it as a postulate.
Copenhagen
Copenhagen became the label only in 1955, when Heisenberg apparently coined it while criticising rival interpretations such as David Bohm's. There is still no agreed statement of what the interpretation actually says.
Q 24Whose 1957 Princeton thesis launched the many-worlds interpretation, though he gave up physics for Pentagon work?
Hugh Everett
Hugh Everett's branching universes were ignored for a decade, and he never returned to academia; his son is Mark Oliver Everett, frontman of the band Eels. His adviser John Wheeler had the thesis cut sharply before submission.
Q 25Which Austrian shared the 2022 Nobel Prize with Alain Aspect and John Clauser for Bell-inequality experiments?
Anton Zeilinger
Anton Zeilinger's Innsbruck team teleported the quantum state of a photon in 1997, and his group later teleported states 143 km through open air between two Canary Islands, a rehearsal for satellite links.
Q 26Bell's 1964 theorem showed which kind of theory, the sort Einstein hoped for, cannot match all quantum predictions?
Local hidden variables
Local hidden variables would let each particle carry a secret pre-set answer, but Bell showed such theories obey an inequality that experiments violate. Bell said the paradox was resolved 'in the way which Einstein would have liked least'.
Q 27Which Dutch physicist predicted in 1948 that two uncharged metal plates in a vacuum would pull towards each other?
Hendrik Casimir
Hendrik Casimir's force comes from vacuum fluctuations: fewer wavelengths fit between the plates than outside, so the outside pushes harder. It was first measured to within 5% of theory only in 1997.
Q 28Peter Shor's 1994 quantum algorithm threatens RSA encryption because it speeds up which mathematical task?
Factoring large integers
Factoring large integers is the hard problem RSA keys rest on, and Shor's method does it exponentially faster than any known classical approach. The first demonstration, in 2001, factored 15 into 3 × 5 on a seven-spin NMR machine.
Q 29Which 1996 quantum algorithm finds one entry among a million unsorted ones in about a thousand steps?
Grover's algorithm
Grover's algorithm needs only about √N steps where a classical search needs N, a quadratic speed-up. It halves the effective length of symmetric encryption keys, so doubling their length is enough to stay safe.
Q 30Which cryogenic device cools superconducting quantum chips to about a hundredth of a degree above absolute zero?
Dilution refrigerator
Dilution refrigerators cool by diluting one helium isotope in another: helium-3 absorbs heat as it crosses into a helium-4-rich liquid, which makes the mixing chamber where that happens the coldest point in the machine.