I Learned This Today

#1142 Who was Typhoid Mary?
#1141 What causes a peanut allergy?
#1140 Why do Monarch butterflies migrate so far?
#1139 Where did the Great Fire of London start?
#1138 How can we 3D print organs?
#1137 Why does a memory palace work?
#1136 Why are there so many camels in Australia?
#1135 What is a supervolcano?
#1134 What happened to the dodo?
#1133 How did London Bridge end up in America?
#1132 Why do rechargeable batteries lose power as they age?
#1131 What is the oldest still spoken language?
#1130 Why can warm air carry more moisture?
#1129 What is snuff?
#1128 Why does America use the Electoral College system?
#1127 How does the color of a bird’s wings help it fly?
#1126 How does the magnetic strip on a credit card work?
#1125 Are electric planes possible?
#1124 Why do planes use halon fire extinguishers?
#1123 What caused the Irish potato famine?
#1122 What is Angkor Wat?
#1121 Why do peacocks have such long tails?
#1120 Why does soap produce foam?
#1119 Are pasta and noodles the same thing?
#1118 Why is the Forbidden City forbidden?
#1117 Why are many mushrooms dangerous?
#1116 Why is a sandwich called a sandwich?
#1115 Why do some fish create their own light?
#1114 What is leukemia?
#1113 Do larger animals have a faster metabolism?
#1112 Do guilt and shame have a purpose?
#1111 What is a thorium reactor?
#1110 Why are the White Cliffs of Dover white?
#1109 How do weight loss drugs work?
#1108 How does a CT scan work?
#1107 When did we start using taxis?
#1106 How do ultramassive black holes form?
#1105 What causes a fire tornado?
#1104 Why can you graft onto a plant?
#1103 How do you get a star in Hollywood?
#1102 Is category 5 the strongest a hurricane can be?
#1101 Why do we use A4 as a paper size?
#1100 Does the Vatican have a secret library?
#1099 Why do teeth have nerves?
#1098 How good is an elephant’s sense of smell?
#1097 How much weight could a human lift?
#1096 How did the Great Lakes form?
#1095 When were buses invented?
#1094 What is a syrinx?
#1093 Do Brazil nuts come from Brazil?
#1092 Why are the majority of people right handed?
#1091 How can a salamander regenerate?
#1090 Why do they add a smell to gas?
#1089 What shape is the Earth?
#1088 How does a two-way mirror work?
#1087 Are big leaves better than small leaves?
#1086 When did diplomatic immunity start?
#1085 What is the fastest insect?
#1084 Why does the corpse plant smell so bad?
#1083 When did people first use mirrors?
#1082 Why doesn’t honey spoil?
#1081 How do snakes use their tongues?
#1080 How big could a plane or helicopter be?
#1079 What is the difference between volts, amps, ohms, and watts?
#1078 What are gallstones?
#1077 What is fool’s gold?
#1076 How did humans spread across the world?
#1075 What happens if you drink too much water?
#1074 What causes acid rain?
#1073 How does carbon dating work?
#1072 Why was the Cold War called a “cold” war?
#1071 Why don’t army ants make nests?
#1070 How quickly does your blood regenerate after you donate it?
#1069 How long can a cable car be?
#1068 Why does Canada have two official languages?
#1067 Why are so many arrowheads made of flint?
#1066 Why don’t bats get sick?
#1065 What is a superconductor?
#1064 Why did people think Australia was there?
#1063 Why is there a statute of limitations?
#1062 Why do volcanoes become dormant?
#1061 What noise would the sun make?
#1060 How did McCarthyism reach such a level?
#1059 Why do some things smell good and some things smell bad?
#1058 Why is Lake Titicaca so high up?
#1057 Why is stainless steel stainless?
#1056 What causes the monsoon?
#1055 Why do we get diarrhea?
#1054 Why does entropy happen?
#1053 When did exams start?
#1052 Why are coconut crabs so big?
#1051 Which came first, the chicken or the egg?
#1050 Why is carbon dioxide the main greenhouse gas?
#1049 What is pneumonia?
#1048 Why didn’t French decimal time last?
#1047 What are tails for?
#1046 When was the wheel invented?
#1045 Why is Mexico City sinking?
#1044 How do painkillers work?
#1043 Why are flamingos pink?
#1042 What causes an ice cream headache?
#1041 Why do snails have teeth?
#1040 Why is breakdancing called breakdancing?
#1039 Why do male seahorses give birth?
#1038 Manor, mansion, villa, stately home or hall?
#0137 What is a cavity?
#1036 Why did we lose all our fur?
#1035 Why do flies buzz and cicadas and crickets chirp?
#1034 What languages became English?
#1033 How can hippos sleep underwater?
#1032 Why do shoes smell?
#1031 Why are mince pies called mince pies and why are puddings called puddings?
#1030 Why are the police called cops?
#1029 What is the Mercator projection?
#1028 What were punks rebelling against?
#1027 How do animals sense earthquakes?
#1026 Why did the Louvre become a museum and art gallery?
#1025 How can sunflowers clean up radiation?
#1024 Why are more plane crashes survivable?
#1023 What are the doldrums?
#1022 Why is a duck-billed platypus so odd?
#1021 How is a mongoose immune to snake venom?
#1020 Why do we get déjà vu?
#1019 How do planes refuel in the air?
#1018 Why are the Secret Service in charge of protecting the president of the USA?
#1017 How do rats find landmines?
#1016 What is Zipf’s Law?
#1015 How do our hearts and lungs work automatically?
#1014 Who were Sotheby and Christie?
#1013 Why can owls turn their heads so far?
#1012 Why are Adidas and Puma rivals?
#1011 What is talcum powder?
#1010 What is Lou Gehrig’s disease?
#1009 Does a tugboat tug?
#1008 What is acid reflux?
#1007 How quickly does a river cut through rock?
#1006 How can a baseball player possibly hit the ball?
#1005 Do bulls really hate red?
#1004 Are plexiglass and fiberglass actually glass?
#1003 What is a bookworm?
#1002 What is the difference between AM and FM radio?
#1001 What is a hernia?
#1000 Are elephants the only source of ivory?
#999 Why does walking become harder as we get older?
#998 Why is the black market called the “black” market?
#997 Is there a land speed record limit?
#996 What are kosher and halal food?
#995 What was Antarctica like before the snow?
#994 How does braille work?
#993 What is a guard llama?
#992 Why did Mozart die so young?
#991 How is a Formula 1 pit stop so fast?
#990 Why does wine improve as it ages?
#989 How can you tell if a planet has life?
#988 Why did knights start wearing armor?
#987 What caused the Great Vowel Shift?
#986 Why do we die so quickly without water?
#985 Can we eat insects?
#984 Why do salmon swim upstream?
#983 Why is an Academy Award called an Oscar?
#982 What did the peppered moth do?
#981 How many different eye colors do people have?
#980 Why was the Great Wall of China built?
#979 What is DDT?
#978 How does a cheetah run so fast?
#977 What does it mean to impeach a president?
#976 What is the immortal jellyfish?
#975 What causes malaria?
#974 Can insects fly in the rain?
#973 Were gunslingers real?
#972 What happened to the Donner Party?
#971 Which came first, the orange fruit or the color orange?
#970 What is the biggest plant in the world?
#969 What do tonsils do?
#968 What causes dyslexia?
#967 Why do prices always go up?
#966 Did dinosaurs really have feathers?
#965 Why do we have fingerprints?
#964 Why are cockroaches so strong?
#963 How does a quantum computer work?
#962 Why was the abacus invented?
#961 How does a telescope work?
#960 Why doesn’t the Autobahn have a speed limit?
#959 Why are Omega-3 fatty acids good for us?
#958 Is modern art still modern?
#957 What is baking soda?
#956 Why can animals jump higher and farther than us?
#955 Why does champagne have bubbles but wine doesn’t?
#954 What is a blood diamond?
#953 When does a seed start growing?
#952 What are pyramids for?
#951 Do piranhas eat meat?
#950 Why did the Watergate Hotel cause the downfall of Nixon?
#949 What is a megalopolis?
#948 How do vending machines check money?
#947 What is a rebreather?
#946 How high can birds fly?
#945 Is cocaine natural?
#944 What happened to Kaiser Wilhelm?
#943 How is silk made?
#942 What could the 10 plagues in the bible have been?
#941 Why can grasshoppers jump so high?
#940 What is a failed state?
#939 What is asbestos?
#938 How does autofocus work?
#937 How do polar bears find enough food?
#936 How deep is the desert?
#935 When did people start using passports?
#934 Where did stoicism come from?
#933 Was Robin Hood real?
#932 How many countries are nuclear powers?
#931 How does anthrax kill?
#930 Why is there an obelisk in Rome?
#929 What is impressionism?
#928 How does a motion detector work?
#927 Why are prunes a laxative?
#926 Is there a planet beyond Neptune?
#925 What is a zombie virus?
#924 What happened to the water on other planets?
#923 Why did the Chinese government move to Taiwan?
#922 How does a rattlesnake rattle?
#921 How much oil is left?
#920 What are El Nino and La Nina?
#919 How do birds land?
#918 How does an oil pipeline pump oil so far?
#917 When does history start?
#916 How does a bicycle stay upright?
#915 Geoffrey Chaucer – the Father of English Literature
#914 Why is a plane’s propeller in front but a boat’s in back?
#913 What is racketeering?
#912 Why does sunburned skin peel?
#911 What causes an epileptic seizure?
#910 What is a metal?
#909 What is a limited company and a shell company?
#908 Johannes Gutenberg – inventor of the printing press
#907 What will happen to the Voyager spacecraft?
#906 Is moss one plant or many plants?
#905 What is the difference between a slave and a serf?
#904 Why do we hiccup?
#903 Why does hair turn white?
#902 Why does the medical symbol have a snake and a staff on it?
#901 Alexander Cumming – inventor of the S-bend
#900 Why are blueberries blue and strawberries red?
#899 What is a crusade?
#898 What is the golden ratio?
#897 Why are poppies a symbol of remembrance?
#896 How big was a Megalodon?
#895 When did people start writing music down?
#894 Shuji Nakamura – the inventor of the blue LED
#893 How did America build so many Liberty ships in World War 2?
#892 How many servers are in a data center?
#891 What is the Ides of March?
#890 Why are truffles so expensive?
#889 What is Bitcoin?
#888 When was the first drone?
#887 Ron Rivest, Adi Shamir, and Leonard Adleman – creators of RSA encryption
#886 How does the female lac bug make plastic?
#885 How did Israel end up where it is?
#884 What are the Queensberry rules?
#883 Why did Tyrannosaurus rex have short arms?
#882 What caused the Great Depression?
#881 Who painted the Isleworth Mona Lisa?
#880 Norman Ernest Borlaug – father of the Green Revolution
#879 What happened to the Aral Sea?
#878 What does paint primer do?
#877 Why do we have a leap year?
#876 Why does a golf ball have dimples?
#875 What happened to Detroit?
#874 Where does cork come from?
#873 Henrietta Lacks – the source of the HeLa cell line
#872 Why does dry ice fog sink?
#871 How do animals find water?
#870 Why does a pulley make weights easier to lift?
#869 Can you live without a spleen?
#868 How does an ejection seat work?
#867 What is the upper limit of a speaker?
#866 Nils Bohlin – inventor of the three-point seatbelt
#865 Why do some birds have red eyes?
#864 What causes the bends?
#863 How does chilling a patient after cardiac arrest work?
#862 What is a karat?
#861 What was the Great Stink?
#860 How does a monorail balance?
#859 Maurice Hilleman – microbiologist specializing in vaccinology.
#858 Is palm oil bad?
#857 What is survivorship bias?
#856 How do deep sea creatures see?
#855 What is asthma?
#854 What is VO2 max?
#853 Why are there ten pins in bowling?
#852 Henry Dunant – the founder of the Red Cross
#851 What is St. Elmo’s fire?
#850 What is the Fields Medal?
#849 What are V1 and V2 on a plane?
#848 What is the sunk cost fallacy?
#847 What is a gluon?
#846 Christiaan Huygens – inventor of the pendulum clock and the balance spring.
#845 Why do we say, “pass the bar”?
#844 How do sharks sense electricity?
#843 What color is the sea?
#842 Is a killer whale a whale?
#841 Why does an atomic bomb make a mushroom cloud?
#840 When were photographs first used in newspapers?
#839 Joseph Lister – introduced antiseptics into surgery
#838 Why is there such a difference between Haiti and the Dominican Republic?
#837 When did daylight savings time start?
#836 How do some plants move?
#835 Are any plastics biodegradable?
#834 What is peat?
#833 What is your risk of dying every year?
#832 Otto Lilienthal – the first successful aviator
#831 Why are tennis scores so peculiar?
#830 What is the difference between bees and wasps?
#829 Why do we have ears on the sides of our head?
#828 What game has the best odds in a casino?
#827 How does the dome of St Paul’s Cathedral support itself?
#826 Why is looking at the sun dangerous?
#825 Euclid – The Father of Geometry
#824 How do noise cancelling headphones work?
#823 What is a Luddite?
#822 Will we ever end up with just one language?
#821 Why can mantis shrimp see so many colors?
#820 What are druids?
#819 How does mortar keep the bricks together?
#818 What is forensic facial reconstruction?
#817 Why do birds need to see ultraviolet light?
#816 Why did America lose the Vietnam War?
#815 What is a spinning jenny?
#814 What was the workhouse?
#813 What is tea?
#812 How old is Santa?
#811 Why did prehistoric insects grow so big?
#810 When was the first air conditioning invented?
#809 What do worms do?
#808 Do antibiotics kill all of the bacteria in the body?
#807 Who were Smith and Wesson?
#806 Can a binary star system have planets?
#805 Why are clouds white?
#804 What is the difference between a wigwam and a teepee?
#803 Where do modern military ranks come from?
#802 Do cows only eat grass?
#801 Why is artificial sugar sweet?
#800 What is a subprime mortgage?
#799 How is salt mined?
#798 Why are some people lactose intolerant?
#797 How does a missile shield work?
#796 Why does a cracked whip make a sound?
#795 Why is there a plastic island in the Pacific Ocean?
#794 How do weight loss drugs work?
#793 How many people do you need for a revolution?
#792 Why do beavers build dams?
#791 What is a black swan event?
#790 Are all stars inside galaxies?
#789 Do the three laws of robotics need updating?
#788 How do our organs stay where they are when we stand up?
#787 Is “I think therefore I am” true?
#786 Why do woodpeckers peck wood?
#785 How can opera singers sing so loud?
#784 How did a pterodactyl fly?
#783 Why do we say “hack writer” and “quack doctor”?
#782 Why did Michelangelo hide in a cellar?
#781 How does cold reading work?
#780 What is the steepest railway track a train can go up?
#779 Why was the First World War fought in trenches but the Second World War wasn’t?
#778 How was a mummy made?
#777 What are “Spaghetti Westerns”?
#776 How does an e-cigarette work?
#775 Why don’t more animals use two legs?
#774 Why do poppies make opium?
#773 What are totem poles for?
#772 How do hallucinations happen?
#771 What was the underground railroad?
#770 What is truth serum?
#769 How does a pipe organ work?
#768 What is the Hudson Bay Company?
#767 When did Britain become an island?
#766 How thick is the atmosphere?
#765 What happened at the Bay of Pigs?
#764 How does a TV screen display different colors?
#763 When did ultra processed food start?
#762 When were AD and BC decided?
#761 What is a nebula?
#760 Why do geese fly in a V-formation?
#759 What is a geosynchronous orbit?
#758 What are pork barrel projects?
#757 What is price elasticity of demand?
#756 How do flies perceive time?
#755 What causes turbulence?
#754 What is the difference between a herb and a spice?
#753 Are lighthouses still necessary?
#752 How does a Maglev train work?
#751 What vegetables came from the New World?
#750 What is flash memory?
#749 Did Christopher Columbus really think he had landed in India?
#748 Why does it rain in a rainforest?
#747 Why do giant redwood trees grow so big?
#746 Did Shakespeare write the plays attributed to him?
#745 Does being cold or wet increase your chance of catching a cold?
#744 Where and when did language originate?
#743 Is a whale shark a whale or a shark?
#742 Why does the Leaning Tower of Pisa lean?
#741 How fast could an electric car go?
#740 What is the smallest mammal?
#739 What is a codex?
#738 Where did freemasons come from?
#737 Why does ice have so little friction?
#736 Could telekinesis be possible?
#735 What is an algorithm?
#734 Why are emulsifiers used in processed food?
#733 Why do some plants bloom at night?
#732 Why was Mesopotamia the cradle of civilization?
#731 Would President Lincoln have survived if he had been shot today?
#730 How long do virus and bacteria live for?
#729 How do night vision goggles work?
#728 What is a sprain?
#727 What is a speakeasy?
#726 Why does Australia have so many dangerous animals?
#725 What are stalagmites and stalactites?
#724 When did sailing ships die out?
#723 What is CRISPR?
#722 Why does time go forward not backward?
#721 Who was the first king?
#720 How have sea levels changed over time?
#719 How does an octopus’s suction cup work?
#718 Why do shells form in different shapes?
#717 Is there any historical evidence for Jesus?
#716 How much height does a parachute need?
#715 Do other planets have tectonic plates?
#714 How are memories stored?
#713 What is the difference between a frog and a toad?
#712 What is a jungle?
#711 Is a force field possible?
#710 When was the first department store?
#709 Why do we have capital letters?
#708 What is the pH scale?
#707 Why are bridges designed to move?
#706 Why do we sneeze?
#705 Why do many Americans drink coffee and many British people drink tea?
#704 Why does iron rust?
#703 Is a starfish a fish?
#702 Why is mercury poisonous?
#701 Do all liquids expand when they freeze?
#700 How does a helicopter with two rotors work?
#699 Why does a boomerang come back?
#698 What is a nerve?
#697 What are rare earth metals?
#696 Why aren’t there flying boats anymore?
#695 Why do British people say football and Americans say soccer?
#694 Are symbiotic relationships always beneficial to both parties?
#693 Why are electromagnets stronger than permanent magnets?
#692 How thick is tank armor?
#691 What causes a heat wave?
#690 Why do some countries drive on the left?
#689 How do steroids work?
#688 Why can fish swim so fast?
#687 Why are some beaches rocky and some sandy?
#686 Why are bees transported across countries by truck?
#685 What is the Streisand Effect?
#684 Why was the Manhattan Project called the Manhattan Project?
#683 What animals and insects are pollinators?
#682 How does ceramic armor work?
#681 Why do tattoos stay in the skin forever?
#680 How does insulation in the home work?
#679 Who invented the slide rule?
#678 What is the Fermi paradox?
#677 Why did the USSR collapse?
#676 What are moles, freckles, and birthmarks?
#675 Why did some dinosaurs have such long necks?
#674 Are ants smart?
#673 When did silent movies end?
#672 How many Egyptian dynasties were there?
#671 Why do people pass out from pain?
#670 Why do we sing Auld Lang Syne at New Years?
#669 Where is the Land of Punt?
#668 What is the difference between slugs and snails?
#667 What are food additives?
#666 Why is sea level where it is?
#665 How does Ransomware work?
#664 What causes a stroke?
#663 When did archaeology start?
#662 Why do ducks float?
#661 Are ants and termites the same thing?
#660 Is Earth an open or closed system?
#659 Why were the Terracotta Warriors buried?
#658 Why is Broadway so long?
#657 How do facial expressions work?
#656 Are Inner and Outer Mongolia separate countries?
#655 How was the meter (metre) defined?
#654 Why is the Grand Canyon so deep?
#653 What will happen at the end of the universe?
#652 Why does blood show up under UV light?
#651 Why do stick insects look like plants?
#650 Why is 0 longitude in London?
#649 How much wind does a wind turbine need?
#648 When did cave paintings first appear?
#647 How does a 3D printer work?
#646 Why are deserts cold at night?
#645 How quickly do bones biodegrade?
#644 How does an iron remove wrinkles from clothes?
#643 What makes things sticky?
#642 When did people start wearing wedding rings?
#641 Why is carbon-based life common?
#640 How do spiders make webs?
#639 What is the difference between a moth and a butterfly?
#638 What are the Dead Sea Scrolls?
#637 How does cacao become chocolate?
#636 What is the difference between socialism and communism?
#635 Why do some trees make rubber?
#634 Do the gulags still exist?
#633 What is botulism?
#632 What is the difference between a castle, a fort, and a palace?
#631 When did people start using soap?
#630 Where did the Democratic and Republican parties come from?
#629 What is the immortal hydra?
#628 When did people start using nails?
#627 How can giraffes have such long necks?
#626 What is the Great Attractor?
#625 What causes Parkinson’s disease?
#624 How do cactuses survive in the desert?
#623 What are bruises?
#622 What is the difference between DVD and Blu-Ray?
#621 How long do black holes last?
#620 Why do Greenland sharks live so long?
#619 Why don’t shipping containers fall off ships?
#618 What causes the “wall” when running?
#617 How does a heat-seeking missile work?
#616 Why do hyenas have long necks?
#615 Is cryosleep possible?
#614 How much can a bladder hold?
#613 What is Munchausen Syndrome by Proxy?
#612 Why does bread need yeast?
#611 How does an ion thruster work?
#610 Why do we say eleven and twelve, and first, second and third?
#609 When did people start eating chickens?
#608 How does a breathalyzer work?
#607 Why can a Peregrine falcon fly so fast?
#606 Why do cameras have mirrors?
#605 How can an eagle see so far?
#604 Why is lead poisonous?
#603 How do people predict the weather?
#602 How long did it take for the sun to get hot?
#601 When did oxygen appear on Earth?
#600 What is a marsh and a swamp?
#599 Why do crabs walk sideways?
#598 Why was the Hoover Dam so difficult to build?
#597 What was the last Apollo mission?
#596 How can we catch a ball without looking at it?
#595 Why does the house always win in a casino?
#594 Why do we lose our voice when we are sick?
#593 What is the difference between a forest, a wood, and a copse?
#592 Why is Las Vegas in the desert?
#591 How big and how small can a mammal be?
#590 How does a joint replacement work?
#589 Where was the first artificial dam?
#588 What are runes?
#587 How does animal camouflage work?
#586 Can a tortoise live without its shell?
#585 What causes muscle cramps?
#584 Why do cars only have five gears?
#583 Why are some animals cold-blooded?
#582 How high can a plane and a helicopter fly?
#581 What is the difference between a crocodile and an alligator?
#580 How is an addict’s brain different to a non-addict’s?
#579 How do pythons kill their prey?
#578 How is sewage treated?
#577 Where did Jazz come from?
#576 Could Earth survive without the moon?
#575 How does a speedometer work?
#574 Why is a strike called a “strike”?
#573 Where is the source of the Nile?
#572 What makes our joints pop and click?
#571 What is the difference between carnivores, herbivores, and omnivores?
#570 How small is nanotechnology?
#569 What is the oldest stone circle in the world?
#568 Why don’t we move when we’re dreaming?
#567 What happens in your brain when you learn a second language?
#566 Who owns the North Pole and the South Pole?
#565 Why does beer have alcohol?
#564 What is the Jevons Paradox?
#563 What is an anchorite?
#562 Why can blowing up a balloon make you pass out?
#561 Are all bones made of calcium?
#560 What is the difference between short and long-term memory?
#559 What is high fructose corn syrup?
#558 How did the Vatican become a country?
#557 How does a naval mine work?
#556 Why are hammerhead sharks shaped like that?
#555 How is decaffeinated coffee made?
#554 What is a sponge?
#553 How would a cure for cancer work?
#552 Why are organ transplants so difficult?
#551 Why is there so much gold in Fort Knox?
#550 Why are flowers different colors?
#549 How much space junk is there?
#548 How do fireflies glow?
#547 How is the Internet connected between countries?
#546 How does a cochlear implant work?
#545 When did April Fools’ Day start?
#544 Was Ferdinand Magellan really the first person to circumnavigate the world?
#543 What is lichen?
#542 Why does the USA use the dollar?
#541 What is the difference between a petrol engine and a diesel engine?
#540 What makes our hands different to other animals?
#539 Why are UK public schools actually private schools?
#538 How do millipedes control their legs?
#537 Why do fingernails keep growing?
#536 How is Easter calculated?
#535 Why is a broken neck fatal?
#534 What happened to biplanes and triplanes?
#533 Why is Greenland part of Denmark?
#532 Why are clouds at different heights?
#531 How do some animals walk up walls?
#530 What is hyperthermia?
#529 Is a photographic memory real?
#528 Why do insects have an exoskeleton?
#527 Why are there 12 signs of the Zodiac?
#526 Why do eyes get worse with age?
#525 When did people start using flushing toilets?
#524 What causes narcolepsy?
#523 How strong is armadillo armor?
#522 Why can’t we fix frostbite?
#521 How are foods frozen?
#520 Is a psychopath’s brain different?
#519 How does C-4 work?
#518 How do mountain goats climb cliffs?
#517 How do astronomers work out how far away a star is?
#516 How did the Rothchild family start?
#515 Why can you test for drugs in urine?
#514 Why can camels go so long without water?
#513 Is Krav Maga effective?
#512 How can the inner core of the Earth switch rotation?
#511 How does a laser printer work?
#510 Can you see past the horizon?
#509 Why do dry rooms have more static?
#508 What is the range of a cell phone tower?
#507 What causes a bunged-up nose and a runny nose?
#506 How is blood pressure measured?
#505 How do you get water to the top of a skyscraper?
#504 What cause rigor mortis?
#503 Why was the FBI formed?
#502 Why does the body produce fat?
#501 What is a hollow-point bullet?
#500 How do fluorescent lights work?
#499 How does computer encryption work?
#498 Can you eat the skin of all fruit and vegetables?
#497 Why is Washington DC the capital of the United States?
#496 How does a nuclear bomb work?
#495 When did the British empire end?
#494 What causes a tsunami?
#493 When did globalization start?
#492 Why did early humans leave Africa?
#491 Do any other animals cry?
#490 Why do soldiers break stride on a bridge?
#489 How do glaciers move?
#488 What are the four fundamental forces?
#487 Why do some things bounce and other things don’t?
#486 How does a canal lock work?
#485 How do parrots talk?
#484 What was the Royal African Company?
#483 Does blood volume decrease if a limb is amputated?
#482 What is a Distributed Denial of Service attack?
#481 Why can’t all animals be domesticated?
#480 Why do ostriches have two kneecaps?
#479 Why are university degrees called a bachelor’s, a master’s and a doctorate?
#478 How wild was the Wild West?
#477 How can planes fly upside down?
#476 Why is hypothermia dangerous?
#475 How does aspirin work?
#474 What was the first insurance company?
#473 How many dimensions are there?
#472 How did Galileo realize that the Earth orbits the sun?
#471 How was the Great Pyramid at Giza built?
#470 When was the first subway built?
#469 Why doesn’t silicone melt in the oven?
#468 What is cotton?
#467 What is a solid-state battery?
#466 Why are carrots orange?
#465 How does LSD work?
#464 How does a hydrogen fuel cell work?
#463 Why does hot air rise?
#462 When were glasses invented?
#461 Why is there a sunken continent underneath New Zealand?
#460 How is volcanic ash made and how dangerous is it?
#459 Why do we say “born to the purple”? What is Tyrian purple?
#458 What causes pins and needles?
#457 Is an Olympic gold medal really made of gold?
#456 When did people start using glass for windows?
#455 Why do we have goosebumps?
#454 Why do we still have wisdom teeth if we don’t need them?
#453 When were sunglasses invented?
#452 What is the densest material in the universe?
#451 What were the moa and what happened to them?
#450 Why is oil measured in barrels?
#449 What are contact lenses made of?
#448 Why is Christmas on December 25th?
#447 When did people start having lawns outside their houses?
#446 What causes thunder?
#445 Was there really going to be a black Taj Mahal?
#444 How does wireless charging work?
#443 Why are people left-handed or right-handed?
#442 Why can humans throw so fast?
#441 Why are Quakers the reason we have fixed prices?
#440 Why is the Gutenberg Bible special?
#439 When were pencils invented?
#438 Why are katana blades curved?
#437 How does a caterpillar become a butterfly?
#436 Who made the first English dictionary?
#435 What makes rain smell?
#434 Why do we have a coccyx?
#433 Does the Oort cloud exist?
#432 How does dry cleaning work?
#431 Why do the leaves on a tree change color in the autumn (fall)?
#430 Why does smoke inhalation kill people?
#429 Why do our stomachs grumble?
#428 Why are stealth bombers invisible?
#427 How far will the Voyager probes go?
#426 What is the difference between snowflakes and hail?
#425 How does an air fryer work?
#424 How do mammals keep warm in the winter?
#423 Why are there twelve months in a year?
#422 What causes quicksand?
#421 How many revolutions has France had?
#420 What is in toothpaste?
#419 What are the four laws of thermodynamics?
#418 How does a laser work?
#417 Why are rubies red, emeralds green, and sapphires blue?
#416 Who was Molotov and why was the Molotov cocktail named after him?
#415 How does a Geiger counter work?
#414 Why do fish have scales?
#413 How do throat lozenges work?
#412 How do fish breathe underwater?
#411 Why don’t cats knock things over?
#410 How do sparklers work?
#409 Why is the Dead Sea so salty?
#408 How thick are Saturn’s rings?
#407 How do scales work?
#406 Who invented the skateboard?
#405 Do ants need to sleep?
#404 How does the heating element in a toaster work?
#403 When was corrugated cardboard first used?
#402 What is the tallest a mountain can be?
#401 What exactly is cubism?
#400 Why do we get a headache when we are dehydrated?
#399 When did people first start using locks and keys?
#398 Can you cure male-pattern baldness?
#397 How long does a 747’s runway need to be?
#396 How does caffeine stop you from feeling sleepy?
#395 Why are rabbit ears so long?
#394 Why does drinking milk help after eating spicy food?
#393 Why do we get jet lag?
#392 Why are there many different types of screw head?
#391 How does LiDAR help archaeologists?
#390 Why do mustard and wasabi make your nose hurt?
#389 Why are sunsets such beautiful colors?
#388 How do metal detectors work?
#387 What is the smallest thing an electron microscope can see?
#386 How does body armor work?
#385 Why do mosquito bites itch?
#384 What is chewing gum made of and what happens if you swallow it?
#383 How do LED lights produce different colors?
#382 When did we start using tarmac (asphalt) on roads?
#381 Why is glass transparent?
#380 How quickly are the continents moving apart?
#379 Can the Mona Lisa ever be sold?
#378 What is & called and why?
#377 What is a Scramjet?
#376 How can paints be different colors?
#375 When did people start wearing wristwatches?
#374 Why does a chicken’s head stay perfectly still when you move its body around?
#373 Does ABS reduce fatalities in car accidents?
#372 How does a smoke detector work?
#371 When did the last woolly mammoth disappear?
#370 How long have humans been using rope?
#369 Why is New York called New York?
#368 How much maple tree sap do you need to make 1 liter of maple syrup?
#367 Why are steam burns worse than boiling water burns?
#366 How did the neck verse save people from being hanged in England?
#365 How big would the sun be from the surface of Mercury and from the surface of Neptune?
#364 Why do people have different blood types?
#363 Why are traffic lights red, yellow, and green?
#362 Why can we eat lettuce and spinach, but we can’t eat leaves and grass?
#361 Why were alarm clocks the first consumer goods to stop being rationed during World War 2?
#360 When were latitude and longitude invented?
#359 Why do we say north, east, south, and west?
#358 Where did the circus come from?
#357 How are tower cranes assembled?
#356 Why does an elastic band stretch?
#355 How does antibiotic resistance happen?
#354 How does a skeleton key work?
#353 When did supermarkets start?
#352 How do reflexes work?
#351 What is the Doppler effect?
#350 How do amphibians breathe underwater?
#349 When were credit cards invented?
#348 What are the Crown Jewels?
#347 How did the Polynesians navigate?
#346 What was the Carrington Event?
#345 What causes brain damage?
#344 How did the Black Death change society?
#343 How did the Black Death spread?
#342 When was shampoo invented?
#341 How does a parachute work?
#340 How much blood can you lose?
#339 Why do we say boycott?
#338 When was the Roman forum built?
#337 Why is PM 2.5 dangerous?
#336 Why are diamonds so expensive?
#335 Why did the Mayan civilization collapse?
#334 When was the penny first used?
#333 How do fossils form?
#332 Do cyanide pills kill as quickly as in the movies?
#331 What is the opposite of white?
#330 Can we cover the Sahara Desert in solar panels?
#329 Why does popcorn pop?
#328 Why do we get hot when we exercise?
#327 What is a central bank?
#326 Could a Formula One car drive upside down?
#325 Why do some liquids burn and others don’t?
#324 Could penguins fly in the past?
#323 How do chemotherapy and radiation therapy work?
#322 Why do dragonflies have four wings?
#321 How does a pressure cooker work?
#320 How does a refrigerator cool food?
#319 Why does metal spark in a microwave oven?
#318 How long has the Sahara been a desert?
#317 How does crop rotation work?
#316 How does a steam engine work?
#315 How tall could a skyscraper be?
#314 When did the Egyptian Empire start to decline?
#313 Where did the names of the continents come from?
#312 What is virgin olive oil?
#311 How does an EEG (electroencephalogram) work?
#310 Why were the Wright brothers able to fly in 1903?
#309 Is nuclear waste dangerous?
#308 Why did the Olympics restart in 1896?
#307 How does an AED work?
#306 Why are we running out of helium?
#305 When happens when you are bitten by a venomous snake?
#304 Why can we only hear certain frequencies?
#303 Where does space end?
#302 Where does space start?
#301 When were the first binmen / garbagemen?
#300 How do hummingbirds flap their wings so fast?
#299 How does a photocopier work?
#298 How big was the asteroid that killed the dinosaurs?
#297 Why do ant bites hurt?
#296 Could nuclear fusion power the Earth?
#295 When did people start using punctuation?
#294 Why do we get headaches?
#293 How does a rocket engine work?
#292 What makes us itch?
#291 Is irradiated food safe?
#290 Why does UHT milk last so long?
#289 Where did Arabic numerals come from?
#288 Why do women live longer than men?
#287 How do you build a tunnel underwater?
#286 What did the last emperor of China do later in life?
#285 How much of your liver can you live without?
#284 When did people start eating cereal for breakfast?
#283 Why are some places more humid than others?
#282 When was the first passenger train?
#281 Why do horses need horseshoes?
#280 How does fly spray work?
#279 How does a virus infect the body?
#278 How does a desalination plant work?
#277 When was instant coffee invented?
#276 Why do mosquitoes come out at night?
#275 How does radiation sickness happen?
#274 How is scaffolding attached to a building?
#273 How were the Nazca Lines made?
#272 Why did the Iron Age start?
#271 Why do pandas eat bamboo?
#270 What was the Tunguska event?
#269 When were the first lawyers?
#268 What are vitamins?
#267 Why did Rome become a republic?
#266 Who invented ice cream?
#265 What is a superfluid?
#264 Why are the aurora borealis those colors?
#263 Why do trees have rings?
#262 What is hardtack?
#261 When did people first start using paper money?
#260 How do some animals sleep standing up?
#259 How does a hand grenade work?
#258 How can a laser power a solar sail?
#257 Who was the first war correspondent?
#256 What is the Richter scale?
#255 Why is the surface tension of water so high?
#254 Who burned down the Library of Alexandria?
#253 How does G-force kill people?
#252 Why do some planets have rings?
#251 What is insulin?
#250 Was Nero as bad as people say?
#249 When did people start using coal?
#248 How does a touchscreen work?
#247 When was the expression “mayday” first used?
#246 When did cars start using headlights (headlamps)?
#245 Why are American and British accents different?
#244 When did the law of manslaughter start?
#243 Why did the Ottoman Empire end?
#242 How does a spray bottle work?
#241 Why does chloroform knock people out?
#240 How does bleach turn clothes white?
#239 Why are signals from intelligent life so hard to hear?
#238 Who was the first pope?
#237 How do extremophiles survive?
#236 Why are tardigrades so tough?
#235 When did rationing in the UK end after World War 2?
#234 Why do skunks smell so bad?
#233 How does a porcupine shoot its quills?
#232 Who was Zapruder?
#231 Why do sloths move so slowly?
#230 Why were only seven wonders of the ancient world chosen?
#229 How did the Sahara Desert get so big?
#228 What was the South Sea Bubble?
#227 Is there a black hole at the center of every galaxy?
#226 When did bankruptcy laws start?
#225 What is the Kola borehole?
#224 Why can animals run so fast?
#223 What did the Magna Carta do?
#222 How does a hydraulic system work?
#221 What is the difference between sonar and radar?
#220 Why did Hawai’i become a US state?
#219 Why don’t deep sea fish get crushed by the pressure?
#218 How deep can a submarine go?
#217 How does bulletproof glass work?
#216 What is antimatter?
#215 What happened to the Dutch East India Company?
#214 What is a quark?
#213 What is the language gene, FOXP2?
#212 What is a Higgs boson?
#211 What is a dwarf galaxy?
#210 What problems does aging in humans cause?
#209 How do statins work?
#208 How do cows produce milk?
#207 What is the gambler’s fallacy?
#206 Why do things taste different?
#205 When was the first stamp?
#204 What causes a nuclear electromagnetic pulse (EMP)?
#203 How does a pacemaker work?
#202 What was Sumerian Cuneiform script?
#201 Why can fish drink saltwater but we can’t?
#200 Why are plants green?
#199 What effect did the 1815 Mt. Tambora eruption have?
#198 Why do the sun’s poles flip every 11 years?
#197 What is Jupiter’s Great Red Spot?
#196 When did the CIA start?
#195 How do fiber optic cables work?
#194 When did people start using tissues?
#193 How many times can you recycle something?
#192 How does a pearl form?
#191 What is Maslow’s Hierarchy of Needs?
#190 What is the core of Jupiter like?
#189 Why does our voice change when we inhale helium?
#188 What was the Teapot Dome scandal?
#187 Is it possible to make a new element?
#186 What is vellum?
#185 What started the California Gold Rush?
#184 When did the Roman Empire end?
#183 Could Mars be terraformed?
#182 How do pineapples grow?
#181 Why are some metals not magnetic?
#180 Where did the Stetson hat come from?
#179 How do we vomit?
#178 How many species of human have their been?
#177 What happened to the Hindenburg?
#176 How did Rasputin gain so much influence over Tsar Nicholas II of Russia?
#175 When was the parachute invented?
#174 How did New Delhi become the capital of India?
#173 Why does gravity exist?
#172 Why does concrete go hard?
#171 Why do octopuses have blue blood?
#170 What is a concussion?
#169 When did the UK finish paying its World War 1 and 2 debts?
#168 Will we lose our moon?
#167 Is Antarctica a desert?
#166 How does bamboo grow so fast?
#165 How do humans make energy from food?
#164 Why did Russia sell Alaska to the United States?
#163 Why did the assassination of Archduke Franz Ferdinand start World War 1?
#162 What causes Alzheimer’s Disease?
#161 What is a nut?
#160 What is West Point?
#159 How does a battery work
#158 How could dinosaurs grow so big?
#157 When did we start using fire extinguishers?
#156 How does superglue work?
#155 What is Reuters?
#154 What is liquefied natural gas?
#153 What is the dark web and how does it work?
#152 What is the difference between Celsius, Centigrade, Fahrenheit, and Kelvin?
#151 How do run-flat tires work?
#150 What is Polaris?
#149 Why do cats sleep for so long?
#148 What is a tokamak?
#147 Why did the Bronze Age start?
#146 How do gas masks work?
#145 Why did the Portuguese royal family end up in Brazil?
#144 How do people know the age of the universe?
#143 When did people start putting drinks in cans?
#142 Why do Venus and Uranus spin the wrong way?
#141 Where did the stones of Stonehenge come from?
#140 How does an eraser work?
#139 What are the six great mass extinction events?
#138 Did pirates really use the Jolly Roger flag?
#137 What are stem cells and how do they work?
#136 What is a letter of marque?
#135 How does Bluetooth work?
#134 How does Valium (diazepam) work on the brain?
#133 Is coral a plant or an animal?
#132 When did the Mafia come to America?
#131 How does a machine gun work?
#130 Why do we have 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute?
#129 Why is the speed of light 299,792,458 m/s?
#128 Does Moore’s Law still apply today?
#127 How does cancer kill people?
#126 Is a space elevator possible?
#125 What was Machu Picchu built for?
#124 What makes the body produce a fever?
#123 When did UK prime ministers start living in 10 Downing Street?
#122 What are wormholes?
#121 When did people start making jam?
#120 Why was gin sold from a cat in London in 1739?
#119 What is dark matter?
#118 What exactly is pykrete?
#117 Could a society without money work?
#116 Why did people storm the Bastille on July 14, 1789?
#115 What is nuclear pasta?
#114 What happened to smallpox?
#113 Why did Thomas Edison use bamboo in his light bulb?
#112 When did people first start getting married?
#111 Why don’t evergreen trees lose their leaves in the winter?
#110 Why doesn’t the Malthusian theory of population apply today?
#109 What is graphene and why is it so important?
#108 Why is the official kilogram in France no longer used?
#107 Did Adolf Hitler have any brothers or sisters?
#106 What does the Milky Way Galaxy orbit?
#105 Why do we use the word Vikings?
#104 How do cats retract their claws and why can’t other animals?
#103 Why do we use those measurements for shoe sizes?
#102 Why do we use miles as a unit of measurement
#101 Why can’t light escape from a black hole?
#100 Who came up with the phrase “flight or fight”?
#99 What is a Lagrange point?
#98 Why is cold fusion not possible?
#97 What are mail fraud and wire fraud?
#96 When was the first dentist?
#95 What happened to the ice industry?
#94 What is the caliber of a gun cartridge?
#93 Is it possible to get absolute zero?
#92 Why do bees make honey?
#91 How did the Rosetta stone help people decipher hieroglyphics?
#90 When did people in Europe start eating sugar?
#89 How does the Large Hadron Collider work?
#88 Why is Venice where it is?
#87 How do stars die?
#86 When did people start using aircraft carriers?
#85 When did people start using money?
#84 Why is London where it is?
#83 How does a quartz watch work?
#82 Why is skin waterproof?
#81 Why do whales make sounds?
#80 Why do we say Middle Ages and Dark Ages?
#79 Can dogs smell cancer?
#78 Why were steam cars so popular in 1900?
#77 How did dogs change when they were domesticated?
#76 When were the first dinosaur bones found?
#75 How does a QR code work?
#74 Why do tectonic plates move?
#73 How do solar panels generate electricity?
#72 How can whales hold their breath for so long?
#71 How do jellyfish survive without a brain?
#70 How do animals change color?
#69 How does a gyroscope work?
#68 What is the Drake equation?
#67 Why do we use a QWERTY keyboard?
#66 How much time does the Panama Canal save a ship?
#65 How can bats sleep hanging upside down?
#64 What is the difference between alternating current (AC) and direct current (DC)?
#63 Why do we feel pain when we touch cold or hot things?
#62 Why are zippers called zippers?
#61 How do antlers grow?
#60 Why do birds migrate?
#59 Why do we say “the press” to refer to journalists and newspapers?
#58 How tall could a human grow?
#57 How does spot welding work and what is it used for?
#56 Why is gold so rare?
#55 Where does Black Friday originate?
#54 Why can cats jump so high?
#53 What are the blue bits in blue cheese?
#52 Who won the first Nobel Peace Prize?
#51 Where did the symbol for the Red Cross come from?
#50 How do white blood cells kill pathogens?
#49 Why are butlers called butlers?
#48 Why is Earl Grey tea called Earl Grey?
#47 What exactly is yogurt?
#46 Why was the teabag invented?
#45 Why is slime mold so awesome?
#44 Why is Mars red?
#43 How does an MRI work?
#42 Why is the Colosseum called the “Colosseum”?
#41 Why do we become addicted to nicotine?
#40 How does GPS know where I am?
#39 How do broken bones heal?
#38 Why was the Berlin Wall first built?
#37 Why did we start using time zones?
#36 How do kidney stones form?
#35 How do fireworks work?
#34 Why do ships float?
#33 What are the 5 types of civilization?
#32 Why do wounds heal with scars?
#31 Why are Neanderthals called “Neanderthals”?
#30 How does a Venus flytrap know when to close?
#29 Why will people happily wait in a queue?
#28 Why can’t we see color at night?
#27 Why would we have evolved with our esophagus and windpipe so close together that we can choke?
#26 How did the invention of the horse collar change society?
#25 Why is Wall Street called Wall Street?
#24 What causes water mirages and heat hazes?
#23 How do electric eels make electricity
#22 Why was the piano invented?
#21 How do TV remote controllers work?
#20 Do cats blink?
#19 Are hurricanes and tornados the same thing?
#18 Why isn’t Pluto a planet?
#17 What happens when animals hibernate? Is it the same as sleeping?
#16 Where do the plus, minus, multiplication, and division symbols come from?
#15 How is food canned?
#14 How is leather made? Why is it so strong?
#13 How does a gun silencer work?
#12 How does alcohol make us drunk?
#11 How did the elevator change our lives?
#10 What causes seasickness?
#9 How can an airbag inflate so quickly?
#8 How can Vantablack be so black?
#7 How do salting and pickling preserve food?
#6 Why does the Earth have seasons?
#5 Why are labradors used as guide dogs?
#4 How can vultures eat rotten meat and not get sick?
#3 Why did men start wearing neckties?
#2 Where did ketchup come from? What did it have to do with mushrooms?
#1 Who invented sliced bread?