Labs

The fact machine

Pull the lever for a random fact. Feed it your birthday and it makes facts about your own life. Give it a number and it takes it apart.

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Pick a topic, or leave it on All, and pull the lever.

Every fact comes with the reason it is true. The machine won't repeat a fact until it has used every one in that topic. There are 43 to find.

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The sunlight reaching you now left the Sun about 8 minutes and 20 seconds ago.The Sun is about 150 million km away and light covers about 3 lakh km every second. 150,000,000 ÷ 300,000 = 500 seconds.
Sound travels about four times faster in water than in air.Water pushes back much harder when squeezed, so a vibration passes along faster: about 1,480 m/s in water against 343 m/s in air.
GPS satellite clocks would drift by about 38 millionths of a second a day if relativity were ignored.Weaker gravity up there makes their clocks run fast, their speed makes them run slow, and the overall gain is about 38 microseconds a day. Left uncorrected, your map position would drift by kilometres within a day.
An atom is almost entirely empty space.If an atom's nucleus were a marble in the middle of a cricket stadium, the electrons would be specks moving around the outer stands.
Nothing can ever be cooled all the way to absolute zero.Temperature measures how much particles jiggle. Removing the very last jiggle would take an endless number of steps, so labs get within billionths of a degree but never reach it.
A teaspoon of neutron star would weigh billions of tonnes on Earth.A neutron star squeezes more mass than the Sun into a ball about 20 km across, crushing atoms until only tightly packed neutrons are left.
Gallium is a metal that melts in your hand.Its melting point is 29.8 °C and your skin is warmer than that, so a spoonful of gallium turns liquid if you hold it.
Only two elements are liquid at room temperature: mercury and bromine.Every other element is a solid or a gas at about 25 °C. Gallium and caesium come close, but melt just above room temperature.
Water gets about 9% bigger when it freezes.Ice molecules lock into an open, six-sided pattern that takes up more room than liquid water. That is why ice floats and frozen pipes burst.
Helium will not freeze at normal pressure, however cold it gets.Its atoms are so light and attract each other so weakly that quantum jiggling keeps them moving even near absolute zero. You need about 25 times normal air pressure to make it solid.
Bananas are very slightly radioactive.They contain potassium, and a tiny fraction of natural potassium is radioactive potassium-40. The dose is harmless; your own body contains more.
Diamond and pencil graphite are made of exactly the same element.Both are pure carbon. In diamond every atom bonds to four others in a rigid 3D frame; in graphite the atoms form flat sheets that slide off onto paper.
Liquid oxygen is pale blue and sticks to a magnet.Oxygen molecules have unpaired electrons, which makes them weakly magnetic. Poured between the poles of a strong magnet, liquid oxygen hangs there.
In a group of just 23 people, there is a better-than-even chance that two share a birthday.You are not comparing one person with everyone, but every pair. 23 people make 253 pairs, and the chance that none of them match falls just below 50%.
0.999…, with nines going on forever, is exactly equal to 1.Let x = 0.999…. Then 10x = 9.999…. Subtract the first from the second: 9x = 9, so x = 1. No number fits between them.
A well-shuffled pack of cards is almost certainly in an order nobody has ever seen before.52 cards can be ordered in 52! ways, about 8 followed by 67 zeros. Shuffling once a second since the Big Bang would not come close to trying them all.
There is no biggest prime number.Euclid's proof: multiply all the primes you know and add 1. The result leaves a remainder of 1 when divided by each of them, so it is either a new prime or is built from primes you did not have.
For every angle, sin²θ + cos²θ is exactly 1.On a circle of radius 1, cos θ and sin θ are the two short sides of a right-angled triangle whose long side is 1. Pythagoras does the rest.
One short equation links five of the most important numbers in maths: 0, 1, π, e and i.It is Euler's identity. Raising e to an imaginary power moves you round a circle, and half a turn lands on −1.
Calculus was invented twice, at about the same time.Isaac Newton in England and Gottfried Leibniz in Germany each worked it out separately in the late 1600s. We still use Leibniz's dy/dx notation.
Only three regular shapes can tile a flat floor on their own: triangles, squares and hexagons.A regular shape tiles a floor only if copies of its corner angle fit exactly round a point, making 360°. That works for 60°, 90° and 120°, and no other regular polygon.
The word 'sine' started as a Sanskrit word for a bowstring.Indian astronomers called half a chord jyā or jīvā. Arabic writers spelled it jiba, which was misread as jaib, 'a fold', and translated into Latin as sinus.
Madhava of Sangamagrama found endless sums for π, sine and cosine around 250 years before European mathematicians.His Kerala school worked out infinite series such as π/4 = 1 − 1/3 + 1/5 − 1/7 + …, ideas at the heart of calculus.
One second is officially 9,192,631,770 ticks of a caesium atom.Since 1967 the second has been defined by the frequency of light that caesium-133 atoms absorb, not by the length of a day.
A day on Venus is longer than its year.Venus takes 243 Earth days to spin once, but only about 225 Earth days to go round the Sun.
Days on Earth are getting longer by about 2 milliseconds every century.The Moon raises tides that rub against the sea floor and slowly brake Earth's spin. Dinosaurs had shorter days than we do.
India's clocks are 5 hours 30 minutes ahead of world time, not a whole number of hours.IST is set by the 82.5° E line of longitude, which passes near Mirzapur. Nepal goes further, at 5 hours 45 minutes ahead.
About 1.3 million Earths would fit inside the Sun.The Sun is about 109 times wider than Earth. Volume grows as the cube, and 109 × 109 × 109 is roughly 1.3 million.
Astronauts on the space station see about 16 sunrises every day.The station circles Earth roughly every 90 minutes, and 24 hours ÷ 90 minutes is 16 laps, each with a sunrise and a sunset.
Saturn's average density is less than water's.Saturn is mostly hydrogen and helium. Given a big enough bathtub, the whole planet would float.
Olympus Mons on Mars is about two and a half times as tall as Mount Everest.Mars has no moving plates, so one volcano sat over the same hot spot for millions of years and kept piling up lava.
The fastest known pulsar spins 716 times a second.When a giant star collapses into a tiny neutron star, it spins faster, like a skater pulling in their arms.
Your body is made of about 37 trillion cells.Scientists estimated this by counting cells organ by organ. Red blood cells alone are more than 80% of them.
The fastest nerve signals in your body travel about 120 metres per second.Nerve fibres wrapped in fatty myelin let the signal jump from gap to gap instead of crawling along the whole length.
An adult has 206 bones, but a newborn baby has around 300.Many of a baby's bones, including parts of the skull, slowly join together as the child grows.
A bolt of lightning is about five times hotter than the surface of the Sun.Lightning heats the air in its path to around 30,000 K for a split second; the Sun's surface is about 5,800 K.
Earth is wider round the middle than it is tall.Its spin flings the equator outwards, so the distance across the equator is about 43 km more than from pole to pole.
Measured from its base, Mauna Kea in Hawaii is taller than Everest.Most of it is under the sea. From the ocean floor to its summit it measures just over 10 km, against Everest's 8.8 km.
Earth's inner core is about as hot as the surface of the Sun.It is a ball of iron and nickel kept solid only by the enormous pressure of everything above it.
Aryabhata gave π as 3.1416 more than 1,500 years ago.In the Aryabhatiya he wrote that a circle 20,000 across measures about 62,832 round, and 62,832 ÷ 20,000 = 3.1416.
Brahmagupta wrote the first known rules for doing arithmetic with zero.In the Brahmasphutasiddhanta he treated zero as a number in its own right, with rules such as 'a number minus itself is zero'.
India was the first country to land a spacecraft near the Moon's south pole.Chandrayaan-3's Vikram lander touched down on 23 August 2023, and its Pragyan rover confirmed sulphur in the soil there.
Mangalyaan reached Mars orbit on its very first attempt.India's Mars Orbiter Mission entered orbit in September 2014, making ISRO the first space agency to succeed at Mars on its first try.