50 Fun Facts About The Scientific Method

Which drug did Alexander Fleming discover in 1928 after mould spoiled a culture plate left out over his holiday?

Penicillin began as an accident: Fleming came back from a family holiday to find bacteria destroyed around a stray fungus, and is said to have remarked, "That's funny."

Apollo 15's David Scott dropped a falcon feather on the Moon alongside which object to show both fall equally fast?

The hammer and the feather hit the lunar dust together, because the Moon has almost no atmosphere to drag on the lighter object.

Clever Hans, who amazed 1900s Germany by tapping out answers to arithmetic problems, was what kind of animal?

The horse was not doing sums: in 1907 psychologist Oskar Pfungst showed Hans was reacting to involuntary cues in his trainer's body language.

James Lind ran one of the first clinical trials in 1747, giving sailors oranges and lemons to treat which disease?

Scurvy was the target: Lind put twelve sick sailors on the same diet in six pairs, and the pair given oranges and a lemon were all but well after six days, when the fruit ran out.

In 1847 Ignaz Semmelweis slashed deaths in a Vienna maternity clinic by ordering doctors to do what?

Wash their hands, he insisted, in chlorinated lime: mortality fell from 18% to under 2%, yet offended colleagues mocked him and he died in an asylum in 1865.

What name, from the Latin for 'I shall be pleasing', is given to a dummy treatment such as a sugar pill?

Placebo tablets contain nothing active, so clinical trials use them to check how much of a new medicine's benefit comes from the drug itself.

In everyday speech a theory is just a hunch, but in science the word describes what?

A well-supported explanation is the scientific sense: evolution, plate tectonics and the germ theory of disease have each been tested repeatedly and are backed by corroborating evidence.

Russian physiologist Ivan Pavlov discovered classical conditioning while studying digestion in which animals?

Dogs in his laboratory began to drool at the mere presence of the technician who fed them, which led Pavlov to pair food with the tick of a metronome.

What do scientists call the one factor they deliberately change in an experiment, such as the dose in a drug trial?

Independent variable is the term, because the experimenter sets its value freely; whatever is then measured, such as how severe the symptoms are, depends on it.

Which garden crop did the Augustinian friar Gregor Mendel breed by the thousands to uncover the rules of heredity?

Peas gave Mendel seven clear traits to track, from seed shape to flower colour; he grew some 28,000 plants, yet the work went unrecognised for more than three decades.

In a vaccine trial, what are the volunteers called who receive a saltwater injection instead of the real shot?

Control group volunteers get no active treatment, so any difference between them and the vaccinated volunteers can be credited to the vaccine itself.

Which process, also known as refereeing, has experts in the same field check a study before a journal publishes it?

Peer review was not yet routine in 1905: Albert Einstein's four famous papers of that year went into print on the say-so of the journal's editors, with no outside referees.

Which trial design, tried in an 1835 Nuremberg salt test, keeps both patients and researchers unaware of who gets what?

Double-blind trials withhold that information until the study is over, so neither a patient's hopes nor a researcher's expectations can colour the results.

An educated guess about nature only counts as a scientific hypothesis if it has which property?

It is testable: a hypothesis must make a prediction about reality that an experiment or observation can check and that other researchers can reproduce.

Plants get different doses of fertilizer but identical pots and sunlight: which is the study's dependent variable?

Plant height is the outcome that depends on the treatment, so it is what gets measured, while pots and sunlight are held constant so that they cannot affect the result.

Which word describes observations recorded as numbers, such as a temperature of 25 degrees, rather than as descriptions?

Quantitative comes from quantity: these observations have numerical values that can be analysed with statistics, unlike properties that are observed but not measured.

Which check, failed by many published psychology studies in the 2010s, repeats a study to see whether its results hold?

Replication exposed a problem in 2015: of 97 psychology studies that had reported significant effects, only 36% produced one again when a large project repeated them.

Ice cream sales and drownings both rise in summer, a textbook case of which statistical link often mistaken for cause?

Correlation only shows that two things move together: hot weather drives both, since people buy more ice cream and also swim more, so neither one causes the other.

Which English champion of the experimental method is said to have caught a fatal chill while stuffing a hen with snow?

Francis Bacon died of pneumonia in 1626; John Aubrey's account has him stopping on the road to Highgate to try whether snow could preserve meat as salt does.

Which Italian, called the father of the scientific method, found four moons of Jupiter with his own telescope?

Galileo Galilei watched the 'stars' beside Jupiter change position night after night in January 1610 and concluded that they were orbiting the planet, not Earth.

Which French chemist used swan-necked flasks of boiled liquid to help overturn the old idea of spontaneous generation?

Louis Pasteur relied on the curved neck to let air in while trapping airborne particles, so the liquid stayed free of microbes; his work on the question won the Alhumbert Prize in 1862.

Which Italian physician covered jars of meat with fine gauze to show that maggots come from the eggs of flies?

Francesco Redi left a second set of jars open for comparison: maggots appeared only where flies could land, undermining the belief that rotting meat breeds them by itself.

John Snow plotted deaths around London's Broad Street water pump in 1854 to trace the source of which disease?

Cholera deaths clustered around the pump, and the pattern persuaded the parish to remove its handle; workers at the nearby brewery, notably, never caught the disease.

Which Greek librarian of Alexandria worked out the size of the Earth by comparing noon shadows in two Egyptian cities?

Eratosthenes knew the midsummer Sun shone straight down a well in Syene while rods in Alexandria still cast shadows, and scaled that angle up over the 5,000 stadia between them.

Arthur Eddington checked Einstein's general relativity in 1919 by photographing star positions during which event?

A total solar eclipse let expeditions to the island of Príncipe and to Brazil measure how far starlight was deflected as it passed the darkened Sun, as Einstein had predicted.

Which Vienna-born philosopher argued in The Logic of Scientific Discovery that a scientific claim must be falsifiable?

Karl Popper pointed out that no number of white swans can prove that all swans are white, yet a single black one refutes it, so a claim earns its keep by risking disproof.

Which rule of thumb, named after a 14th-century English friar, favours the explanation with the fewest assumptions?

Occam's razor honours William of Ockham, although he never used its best-known wording, "Entities must not be multiplied beyond necessity".

Which 'missing link' fossil of 1912 turned out, four decades later, to be a human skull with an orangutan's jaw?

Piltdown Man was not definitively exposed until 1953; a 2016 study pinned the hoax on its finder, amateur archaeologist Charles Dawson, apparently seeking recognition.

Which 1989 claim by chemists Fleischmann and Pons collapsed when other labs could not reproduce their tabletop results?

Cold fusion promised nuclear energy from a jar of heavy water at room temperature, but by late 1989 most scientists considered the claim dead.

Which French thinker's 1637 Discourse on the Method contains the famous line 'I think, therefore I am'?

René Descartes wrote the line in French, as "Je pense, donc je suis"; the Latin version, "Cogito, ergo sum", appeared seven years later in another of his books.

Which measure do scientists get by adding up the results of repeated trials and dividing by the number of trials?

Mean values can mislead when a few results are extreme: a handful of very high incomes pulls the average above what most people earn, so the median can describe the middle better.

What is the curved upper surface of water in a narrow glass tube called, from the Greek word for crescent?

Meniscus readings are taken at eye level from the bottom of the curve for water, which climbs the glass, but from the top for mercury, which bulges upward.

Which unit was defined until 2019 by a golf-ball-sized platinum-iridium cylinder kept in a vault in France?

Kilogram measurements everywhere traced back to that one object from 1889, but its mass proved unstable over time, so the unit is now fixed by the Planck constant.

Precision is how tightly repeated measurements cluster, but which quality is how close they come to the true value?

Accuracy is a separate matter from precision, so a set of readings can be accurate but not precise, precise but not accurate, neither, or both.

What do statisticians call a result lying far from the rest of the data, sometimes because of a measuring error?

Outlier values caused by experimental error are sometimes excluded from a data set, but one can also be the first sign of something new.

Which mental trap, studied by Peter Wason, makes people favour evidence that supports what they already believe?

Confirmation bias works at every stage: people search for, interpret and even recall information in ways that back up what they already think.

Which kind of reasoning, famously doubted by David Hume, builds a general rule from a limited set of observations?

Inductive conclusions are probable at best, never certain; Hume argued the habit has no logical basis and rests on instinct and custom, yet everyday life requires it.

What name is given to a test run only in the imagination, such as Schrödinger's cat in its sealed box?

Thought experiment is a translation of the German Gedankenexperiment, first used by Hans Christian Ørsted around 1812; the English phrase arrived in an 1897 translation of Ernst Mach.

The word 'science', used in English since the 14th century, comes from the Latin 'scientia', which translates as what?

Knowledge is the root sense: 'scientia' derives from the Latin verb 'to know', and in medieval English the word meant simply 'the state of knowing'.

Which Basra-born scholar, an early pioneer of the scientific method, wrote the Book of Optics a thousand years ago?

Ibn al-Haytham, also known as Alhazen, held that a hypothesis must be supported by experiments, five centuries before Renaissance scientists; he is called the father of modern optics.

Which phrase did Thomas Kuhn popularise in 1962 for an upheaval in the basic concepts of a scientific field?

Paradigm shift comes from Kuhn's book The Structure of Scientific Revolutions; he applied it only to the natural sciences, but it has since become an everyday English idiom.

Which London body, founded in 1660, took the motto 'Nullius in verba', or 'take nobody's word for it'?

The Royal Society says the motto expresses its fellows' determination to withstand the domination of authority and to verify all statements by an appeal to experiment.

In statistics, what name is given to the default assumption that a treatment being studied has no effect at all?

Null hypothesis is the claim a study sets out to knock down: in Ronald Fisher's words it is never proved or established, but is possibly disproved, in the course of experimentation.

Ronald Fisher's 1935 book The Design of Experiments describes a lady who claimed to taste how which drink was poured?

Tea tasted different, she insisted, when the milk went in first; Fisher's test handed her eight cups in random order, and she is reported to have identified all eight correctly.

The 1887 Michelson–Morley experiment, history's 'most famous failed experiment', found no trace of what?

Aether was the invisible medium thought to carry light waves through space; failing to detect Earth's motion through it helped open the way to special relativity.

Robert Millikan measured the charge of the electron in 1909 by suspending tiny drops of what between metal plates?

Oil droplets were held motionless by adjusting a voltage until the electric force on each one balanced gravity; Millikan received the Nobel Prize in Physics in 1923.

Which phenomenon, named after a Western Electric factory near Chicago, makes people behave differently when observed?

Hawthorne effect recalls 1920s studies at the Hawthorne Works, where output seemed to improve whenever the lighting was changed and then returned to its old level once the research ended.

Which radiation, announced by Prosper Blondlot in 1903, was still 'seen' after Robert Wood secretly removed a prism?

N-rays had been reported by some 120 scientists before Wood's account in Nature concluded they were purely subjective, recorded by observers who saw what they expected to see.

Which future Master of Trinity College, Cambridge coined the word 'scientist' in 1833, and later 'physicist'?

William Whewell had a gift for naming things: he also suggested the terms anode, cathode and ion to Michael Faraday.

Which word, from the Greek for 'experience', describes evidence gathered through the senses or by experiment?

Empirical evidence is of central importance to the sciences, because a claim is checked against what can be observed or measured and not against reasoning alone.