#1 What is a quark?

Image By Arpad Horvath – Own work, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=637353

https://en.wikipedia.org/wiki/Quark

https://en.wikipedia.org/wiki/Charm_quark

https://en.wikipedia.org/wiki/Top_quark

https://en.wikipedia.org/wiki/Top_quark

https://en.wikipedia.org/wiki/Flavour_(particle_physics)

https://www.thoughtco.com/quark-2699004

http://abyss.uoregon.edu/~js/glossary/quarks.html

https://en.wikipedia.org/wiki/Atom

https://www.sciencefocus.com/science/is-there-anything-smaller-than-a-quark/

https://en.wikipedia.org/wiki/Preon

https://www.dkfindout.com/us/science/solids-liquids-and-gases/inside-an-atom/

https://scienceline.ucsb.edu/getkey.php?key=990

https://www.unsw.edu.au/science/our-schools/materials/engage-with-us/high-school-students-and-teachers/online-tutorials/ceramics/glass

https://en.wikipedia.org/wiki/Atomic_nucleus

https://www.pbs.org/wgbh/aso/tryit/atom/elempartp.html

https://astronomy.com/magazine/ask-astro/2014/05/quark-antiquark

#2 What happened to the Dutch East India Company?

Image By Unknown author (vector graphics by Habitator terrae) – http://www.verschoor.com/files/munten/1742-VOCUtrecht-Duit-kz.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=894578

https://en.wikipedia.org/wiki/Dutch_East_India_Company

https://en.wikipedia.org/wiki/Fourth_Anglo-Dutch_War

https://en.wikipedia.org/wiki/East_India_Company

https://en.wikipedia.org/wiki/Dutch_Revolt

https://www.britannica.com/topic/Dutch-East-India-Company

https://www.businessinsider.com/rise-and-fall-of-united-east-india-2013-11

https://museum.wa.gov.au/explore/dirk-hartog/voc-united-dutch-east-india-company

#3 What is antimatter?

Image By Carl D. Anderson (1905–1991) – Anderson, Carl D. (1933). "The Positive Electron". Physical Review 43 (6): 491–494. DOI:10.1103/PhysRev.43.491., Public Domain, https://commons.wikimedia.org/w/index.php?curid=3985488

https://phys.org/news/2016-01-antimatter.html

https://phys.org/news/2016-01-antimatter.html

https://www.livescience.com/32387-what-is-antimatter.html

https://www.space.com/where-did-all-the-antimatter-go.html

https://www.britannica.com/story/what-is-antimatter

https://theconversation.com/explainer-what-is-antimatter-53414

https://home.cern/science/physics/antimatter

https://www.newscientist.com/definition/antimatter/

https://simple.wikipedia.org/wiki/Antimatter

https://www.popularmechanics.com/science/a27049/in-1928-one-physicist-accidentally-predicted-antimatter/

https://home.cern/science/physics/matter-antimatter-asymmetry-problem

https://en.wikipedia.org/wiki/Penning_trap

https://www.seeker.com/is-antimatter-a-viable-starship-fuel-1765998670.html

#4 How does bulletproof glass work?

Image By © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons), CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=4547497

The History and Evolution of Bulletproof Glass

https://en.wikipedia.org/wiki/Tempered_glass

https://www.explainthatstuff.com/bulletproofglass.html

https://science.howstuffworks.com/question476.htm

https://www.silatec-bulletproofglass.com/how-does-bulletproof-glass-work/

https://en.wikipedia.org/wiki/Bulletproof_glass

https://en.wikipedia.org/wiki/History_of_glass

How Are Bulletproof Vehicles Made?

#5 How deep can a submarine go?

Photo by Vitali Adutskevich: https://www.pexels.com/photo/snow-sea-water-ocean-14754974/

https://en.wikipedia.org/wiki/Submarine

https://www.thebalancecareers.com/facts-about-navy-submarines-4058060

How Deep Can We Go?

How much pressure can we take?

https://en.wikipedia.org/wiki/Submarine_depth_ratings

https://navalpost.com/how-deep-can-a-submarine-dive/

https://en.wikipedia.org/wiki/Trieste_(bathyscaphe)

https://en.wikipedia.org/wiki/Challenger_Deep

https://en.wikipedia.org/wiki/Pascal_(unit)

#6 Why don’t deep sea fish get crushed by the pressure?

Image Public Domain, https://commons.wikimedia.org/w/index.php?curid=54328

https://oceanservice.noaa.gov/facts/pressure.html

https://www.nationalgeographic.com/animals/article/how-deep-sea-snailfish-survive-mariana-trench

https://www.deeperblue.com/equalization-for-freediving/

https://www.deeperblue.com/effects-of-pressure-and-depth/

How Deep Can You Dive Before Being Crushed?

https://www.medicaldaily.com/breaking-point-how-much-water-pressure-can-human-body-take-347570

https://en.wikipedia.org/wiki/Hadal_zone

https://en.wikipedia.org/wiki/Pseudoliparis_swirei

https://www.nationalgeographic.com/travel/article/120828-amphipods-oceans-mariana-trench-wood-science-animals

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449124/

#7 Why did Hawai’i become a US state?

Photo by Tyler Lastovich: https://www.pexels.com/photo/building-beside-shore-412681/

https://www.skylinehawaii.com/blog/how-hawaii-became-a-state

https://en.wikipedia.org/wiki/Hawaii

https://explorethearchive.com/how-did-hawaii-become-a-state

https://www.smithsonianmag.com/travel/hawaii-history-and-heritage-4164590/

https://teachinghistory.org/history-content/ask-a-historian/25769

https://en.wikipedia.org/wiki/Reciprocity_Treaty_of_1875

https://en.wikipedia.org/wiki/Overthrow_of_the_Hawaiian_Kingdom

http://www.alohaislandcoffee.com/The-Story-of-Kona-Coffee-14.html

Sugar Cane Production

https://en.wikipedia.org/wiki/Ladd_%26_Co.

https://guides.library.manoa.hawaii.edu/c.php?g=105252&p=687131

#8 What is the difference between sonar and radar?

Image By Bukvoed – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=4840831

https://en.wikipedia.org/wiki/Radar

http://www.bom.gov.au/australia/radar/about/what_is_radar.shtml

https://www.dsta.gov.sg/docs/default-source/dsta-about/comparative-analysis-of-radar-and-sonar-principles.pdf?sfvrsn=2

https://silencewiki.com/noise-basics/how-far-does-sound-travel-the-science-of-acoustics/

https://en.wikipedia.org/wiki/Sonar

http://www4.hcmut.edu.vn/~huynhqlinh/olympicvl/tailieu/physlink_askexpert/ae456.cfm.htm

#9 How does a hydraulic system work?

Photo by Dmitriy Zub: https://www.pexels.com/photo/excavator-on-street-in-industrial-district-6479995/

https://en.wikipedia.org/wiki/Hydraulic_machinery

https://en.wikipedia.org/wiki/Pascal%27s_law

https://en.wikipedia.org/wiki/Blaise_Pascal

https://en.wikipedia.org/wiki/Hydraulic_press

https://en.wikipedia.org/wiki/Joseph_Bramah

How do hydraulics work?

How Does Hydraulics Work?

https://www.explainthatstuff.com/hydraulics.html

https://science.howstuffworks.com/transport/engines-equipment/hydraulic1.htm

https://www.ryco.com.au/blog/force-multiplication-key-hydraulic-systems/

#10 What did the Magna Carta do?

Image By Original authors were the barons and King John of England. Uploaded by Earthsound. – This file has been provided by the British Library from its digital collections. It is also made available on a British Library website.Catalogue entry: Cotton MS Augustus II 106, Public Domain, https://commons.wikimedia.org/w/index.php?curid=78606

https://www.parliament.uk/about/living-heritage/evolutionofparliament/originsofparliament/birthofparliament/overview/magnacarta/

https://www.bl.uk/people/king-john

http://www.castlefordacademy.com/wp-content/uploads/2021/12/Magna-Carta.pdf

https://www.history.com/this-day-in-history/magna-carta-sealed

https://www.britainexpress.com/History/Richard_the_Lionheart_and_King_John.htm

https://www.bbc.com/news/magazine-12603356

https://www.history.com/topics/british-history/magna-carta

https://en.wikipedia.org/wiki/John,_King_of_England

https://en.wikipedia.org/wiki/Magna_Carta

#11 Why can animals run so fast?

Photo by Missi Köpf: https://www.pexels.com/photo/a-white-horse-running-on-the-beach-6215911/

https://www.discoverwildlife.com/animal-facts/mammals/how-and-why-do-kangaroos-hop/

https://blog.nasm.org/fitness/fast-twitch-vs-slow-twitch

https://en.wikipedia.org/wiki/Ungulate

https://en.wikipedia.org/wiki/Digitigrade

https://en.wikipedia.org/wiki/Metatarsal_bones

https://en.wikipedia.org/wiki/Plantigrade

https://www.science.org/content/article/why-midsized-animals-are-fastest-earth

https://www.dailymail.co.uk/sciencetech/article-9826909/Nature-Four-legged-animals-reach-higher-running-speeds-humans-gallop.html

https://www.sciencedaily.com/releases/2021/07/210723105319.htm

https://www.quora.com/Why-can-animals-run-faster-than-humans

#12 What is the Kola borehole?

Image By Rakot13 – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=21029748

https://en.wikipedia.org/wiki/Project_Mohole

https://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuity

https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole

https://en.wikipedia.org/wiki/Kola_Peninsula

https://www.bbc.com/future/article/20190503-the-deepest-hole-we-have-ever-dug

https://www.atlasobscura.com/places/kola-superdeep-borehole

https://letstalkscience.ca/educational-resources/stem-in-context/deepest-hole-in-world

#13 When did bankruptcy laws start?

Photo by Nicola Barts : https://www.pexels.com/photo/hand-of-a-man-holding-a-bill-with-past-due-stamp-7926666/

https://core.ac.uk/download/pdf/322623625.pdf

https://eml.berkeley.edu/~webfac/cromer/e211_f07/voth.pdf

https://en.wikipedia.org/wiki/Bankruptcy_Act

https://en.wikipedia.org/wiki/Statute_of_Bankrupts

https://en.wikipedia.org/wiki/Debt_bondage

https://en.wikipedia.org/wiki/Bankruptcy

https://www.bankruptcydata.com/a-history-of-bankruptcy

#14 Is there a black hole at the center of every galaxy?

Photo By EHT Collaboration – https://www.eso.org/public/images/eso2208-eht-mwa/ (image link), CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=117933557

https://astronomy.stackexchange.com/questions/32510/does-the-milky-way-orbit-around-anything

https://www.sciencefocus.com/news/sagittarius-a-star-black-hole-photo/

Say hello to Sagittarius A*, the black hole at the center of the Milky Way

https://en.wikipedia.org/wiki/Supermassive_black_hole

https://en.wikipedia.org/wiki/Sagittarius_A*

https://science.nasa.gov/astrophysics/focus-areas/black-holes

https://en.wikipedia.org/wiki/Accretion_disk

https://www.wtamu.edu/~cbaird/sq/2014/03/07/why-does-everything-in-our-galaxy-orbit-the-supermassive-black-hole-at-the-center/

https://www.sciencefocus.com/space/are-black-holes-always-found-at-the-centre-of-galaxies/

https://www.sciencefocus.com/space/black-holes-in-the-centre-of-galaxies/

#15 What was the South Sea Bubble?

Photo By EHT Collaboration – https://www.eso.org/public/images/eso2208-eht-mwa/ (image link), CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=117933557

https://www.historic-uk.com/HistoryUK/HistoryofEngland/South-Sea-Bubble/

https://en.wikipedia.org/wiki/South_Sea_Company

https://www.rmg.co.uk/stories/topics/south-sea-bubble

https://blogs.loc.gov/inside_adams/2020/12/the-south-sea-bubble/

https://theconversation.com/300-years-since-the-south-sea-bubble-the-real-story-behind-the-iconic-financial-crash-143861

https://en.wikipedia.org/wiki/Tulip_mania

https://en.wikipedia.org/wiki/Economic_bubble

#16 How did the Sahara Desert get so big?

Photo by Djamel Ramdani: https://www.pexels.com/photo/view-on-a-dunes-in-a-desert-10390494/

https://sciencing.com/causes-deserts-form-7218824.html

https://www.nature.com/scitable/knowledge/library/green-sahara-african-humid-periods-paced-by-82884405/

https://en.wikipedia.org/wiki/Sahara

https://en.wikipedia.org/wiki/List_of_countries_and_dependencies_by_area

How Do Mountains Affect Precipitation?

https://byjus.com/free-ias-prep/pressure-belts-of-the-earth/

https://www.livescience.com/will-sahara-desert-turn-green.html

https://theconversation.com/solar-panels-in-sahara-could-boost-renewable-energy-but-damage-the-global-climate-heres-why-153992

#17 Why were only 7 wonders of the ancient world chosen?

Photo By The original uploader was Mark22 at English Wikipedia. – Transferred from en.wikipedia to Commons., Public Domain, https://commons.wikimedia.org/w/index.php?curid=3144502

https://en.wikipedia.org/wiki/Seven_Wonders_of_the_Ancient_World

https://en.wikipedia.org/wiki/Antipater_of_Sidon

https://en.wikipedia.org/wiki/Diodorus_Siculus

https://www.history.com/topics/ancient-history/seven-wonders-of-the-ancient-world

https://www.quora.com/Why-is-there-only-7-wonders-of-the-world-Why-not-8-or-6

https://en.wikipedia.org/wiki/Philo_of_Byzantium

https://en.wikipedia.org/wiki/Ancient_Greece

https://en.wikipedia.org/wiki/Macedonia_(ancient_kingdom)

https://www.worldhistory.org/The_Seven_Wonders/

https://www.salon.com/2017/08/20/how-we-lost-the-seven-wonders-of-the-ancient-world/

https://mythology.stackexchange.com/questions/622/what-is-the-importance-of-the-number-seven-in-mythology-and-religion

#18 Why do sloths move so slowly?

Photo by Mel S U: https://www.pexels.com/photo/wood-animal-cute-rope-15369436/

https://en.wikipedia.org/wiki/Sloth

https://www.worldwildlife.org/stories/why-are-sloths-slow-and-six-other-sloth-facts

https://www.bbc.com/future/article/20190828-why-do-sloths-move-so-slowly

https://theconversation.com/sloths-arent-lazy-their-slowness-is-a-survival-skill-63568

https://en.wikipedia.org/wiki/Megatherium

https://www.nationalgeographic.com/animals/article/150829-animals-science-sloths-bats-health-biology

https://www.independent.co.uk/news/science/why-do-sloths-hang-upside-down-9287482.html?r=30999

#19 Who was Zapruder?

Photo Fair use, https://en.wikipedia.org/w/index.php?curid=1250529

https://en.wikipedia.org/wiki/Zapruder_film

https://en.wikipedia.org/wiki/Assassination_of_John_F._Kennedy#Film_and_audio_captures_of_assassination_events

https://en.wikipedia.org/wiki/Abraham_Zapruder

Nardis of Dallas: The Fashion Connection Between “The Dick Van Dyke Show” and the Kennedy Assassination

https://www.texasmonthly.com/news-politics/abraham-zapruder/

https://www.smithsonianmag.com/history/what-does-the-zapruder-film-really-tell-us-14194/

https://www.archives.gov/research/jfk/faqs

https://www.santafenewmexican.com/news/local_news/jfk-assassination-the-man-behind-the-film/article_e4c3590f-6e66-508b-8ddd-32d88f322f17.html

https://www.congress.gov/bill/102nd-congress/senate-bill/3006

#20 How does a porcupine shoot its quills?

Photo by Anca Silvia Orosz: https://www.pexels.com/photo/close-up-photo-of-a-porcupine-5030891/

https://en.wikipedia.org/wiki/Porcupine

https://en.wikipedia.org/wiki/Spine_(zoology)

https://www.nationalgeographic.com/animals/mammals/facts/porcupines

https://www.wonderopolis.org/wonder/can-porcupines-shoot-their-quills

https://nature.ca/notebooks/english/amporcu.htm

https://vtfishandwildlife.com/learn-more/vermont-critters/mammals/porcupine

https://zooecomuseum.ca/en/articles/5-fun-facts-about-the-american-porcupine/

https://animals.sandiegozoo.org/animals/porcupine

https://www.nationalgeographic.com/science/article/why-porcupine-quills-slide-in-with-ease-but-come-out-with-difficulty-2

https://animals.mom.com/porcupines-quills-grow-back-10125.html

#21 Why do skunks smell so bad?

https://en.wikipedia.org/wiki/Skunk

https://en.wikipedia.org/wiki/Algonquian_languages

https://en.wikipedia.org/wiki/Abenaki_language

https://en.wikipedia.org/wiki/Thiol

https://en.wikipedia.org/wiki/Mephitidae

https://en.wikipedia.org/wiki/Great_horned_owl

https://www.smithsonianmag.com/smithsonian-institution/ask-smithsonian-what-makes-skunk-spray-smell-so-terrible-180955553/

https://wonderopolis.org/wonder/why-do-skunks-stink

https://www.quora.com/Why-does-Sulfur-smell-so-bad

#22 When did rationing in the UK end after World War 2?

Image By The National Archives UK – Your Ration BookUploaded by oaktree_b, Public Domain, https://commons.wikimedia.org/w/index.php?curid=21041876

https://en.wikipedia.org/wiki/Rationing

https://en.wikipedia.org/wiki/Rationing_in_the_United_Kingdom

https://en.wikipedia.org/wiki/Unrestricted_submarine_warfare

https://www.iwm.org.uk/history/what-you-need-to-know-about-rationing-in-the-second-world-war

https://www.1900s.org.uk/1940s50s-rationing-shortages-post-war.htm

#23 Why are tardigrades so tough?

Image By Schokraie E, Warnken U, Hotz-Wagenblatt A, Grohme MA, Hengherr S, et al. (2012) – Schokraie E, Warnken U, Hotz-Wagenblatt A, Grohme MA, Hengherr S, et al. (2012) Comparative proteome analysis of Milnesium tardigradum in early embryonic state versus adults in active and anhydrobiotic state. PLoS ONE 7(9): e45682. doi:10.1371/journal.pone.0045682, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=130857154

https://en.wikipedia.org/wiki/Tardigrade

https://www.livescience.com/57985-tardigrade-facts.html

https://en.wikipedia.org/wiki/Water_on_Mars

http://cshprotocols.cshlp.org/content/2018/11/pdb.prot102327.full

https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/38%3A_The_Musculoskeletal_System/38.1%3A_Types_of_Skeletal_Systems/38.1B%3A_Types_of_Skeletal_Systems

#24 How do extremophiles survive?

Image By Carsten Steger – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=126058647

https://lco.global/spacebook/astrobiology/what-are-extremophiles/

https://www.frontiersin.org/articles/10.3389/fmicb.2019.00780/full

https://en.wikipedia.org/wiki/Extremophile

https://www.eurekalert.org/news-releases/765308

https://sciencing.com/examples-heatresistant-bacteria-20175.html

https://www.micropia.nl/en/discover/stories/microbes-in-the-cold/

https://www.thoughtco.com/extremophiles-extreme-organisms-373905

https://en.wikipedia.org/wiki/Alkaliphile

https://en.wikipedia.org/wiki/Acidophile

https://en.wikipedia.org/wiki/Extremophile

https://en.wikipedia.org/wiki/Halophile

https://en.wikipedia.org/wiki/Chroococcidiopsis

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660605/

https://www.scientificamerican.com/article/how-microbes-helped-clean-bp-s-oil-spill/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7660605/

#25 Who was the first pope?

Image By Quirinale.it, Attribution, https://commons.wikimedia.org/w/index.php?curid=115828333

https://en.wikipedia.org/wiki/History_of_the_papacy

https://www.nationalgeographic.com/culture/article/160306-bible-apostle-jesus-christian-religion-ngbooktalk

https://en.wikipedia.org/wiki/Primacy_of_Peter

https://christianity.stackexchange.com/questions/68575/when-was-the-formal-title-of-pope-first-officially-bestowed-on-the-bishops-of-ro

https://en.wikipedia.org/wiki/Pope_Miltiades

http://www.historyworld.net/wrldhis/PlainTextHistories.asp?ParagraphID=etn

https://en.wikipedia.org/wiki/Pope

#26 Why are signals from intelligent life so hard to hear?

Photo by Igor Mashkov: https://www.pexels.com/photo/radio-telescope-against-sky-with-stars-6325001/

https://en.wikipedia.org/wiki/Breakthrough_Starshot

https://en.wikipedia.org/wiki/BLC1

https://arxiv.org/ftp/arxiv/papers/0707/0707.0011.pdf

https://www.open.edu/openlearn/science-maths-technology/astronomy/how-can-you-tell-if-signal-space-alien-communication

https://seti.berkeley.edu/FAQ.html

https://www.livescience.com/59153-how-to-search-for-extraterrestrial-life.html

https://www.seti.org/seti-institute/project/details/broadcasting-message

https://thenextweb.com/news/yes-exoplanets-can-have-oxygen-without-alien-life-syndication

https://theconversation.com/blasting-out-earths-location-with-the-hope-of-reaching-aliens-is-a-controversial-idea-two-teams-of-scientists-are-doing-it-anyway-182036

#27 How does bleach turn clothes white?

Photo by Nothing Ahead: https://www.pexels.com/photo/bottles-of-bleach-placed-on-shelves-in-supermarket-7451952/

https://en.wikipedia.org/wiki/Bleach

https://en.wikipedia.org/wiki/Chromophore

http://scienceline.ucsb.edu/getkey.php?key=551

https://www.thoughtco.com/understand-the-visible-spectrum-608329

https://www.britannica.com/science/atom/Orbits-and-energy-levels

https://wonderopolis.org/wonder/how-does-bleach-work

https://whatisbleach.weebly.com/history.html

https://www.britannica.com/biography/Carl-Wilhelm-Scheele

https://en.wikipedia.org/wiki/Lye

#28 Why does chloroform knock people out?

Image By Kevin King – Flickr: Chickamauga 2009, Chloroform, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=12429674

https://dhss.delaware.gov/dph/files/chloroformfaq.pdf

https://en.wikipedia.org/wiki/Chloroform

https://en.wikipedia.org/wiki/James_Young_Simpson

https://en.wikipedia.org/wiki/Allosteric_modulator

https://pubs.asahq.org/anesthesiology/article/92/1/290/37485/Was-Chloroform-Produced-before-1831

https://www.thehistorypress.co.uk/articles/chloroform-170-years-of-controversy/

https://simple.wikipedia.org/wiki/Chloroform

https://www.history.com/topics/inventions/ether-and-chloroform

https://www.soap.org/sir-james-young-simpson

https://www.thenakedscientists.com/articles/questions/how-does-chloroform-cause-unconsciousness

https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2044.1968.tb00118.x

We finally know how general anesthesia works

https://www.medicalnewstoday.com/articles/scientists-unravel-the-mystery-of-anesthesia

#29 How does a spray bottle work?

Photo by Towfiqu barbhuiya: https://www.pexels.com/photo/a-person-holding-a-spray-bottle-9080144/

https://www.lhlotionpump.com/news/how-does-a-spray-bottle-work.html

https://alexanderell.is/posts/check-valve/

https://www.bwbtech.com/post/what-is-the-venturi-effect-and-how-does-it-work-in-a-nebuliser

https://perfumeatomizers.blogspot.com/2013/09/early-atomizer-history.html

https://en.wikipedia.org/wiki/Pump#Positive-displacement_pumps

https://en.wikipedia.org/wiki/Spray_bottle

https://physics.stackexchange.com/questions/79039/how-does-an-atomizer-work

https://medium.com/@imgennari22/the-spray-bottle-e16b965230f2

https://careertrend.com/list-7494144-list-simple-machines-used-agriculture.html

https://en.wikipedia.org/wiki/Spray_nozzle

https://en.wikipedia.org/wiki/Bernoulli%27s_principle

https://en.wikipedia.org/wiki/Venturi_effect

https://en.wikipedia.org/wiki/Atomizer_nozzle

https://homesteady.com/13419502/how-does-a-spray-bottle-work

#30 Why did the Ottoman Empire end?

Image By Unknown author – http://mideastimage.com/viewimages/viewimage.php?id=26, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2464741

https://www.worldatlas.com/articles/why-did-the-ottoman-empire-fall.html

https://en.wikipedia.org/wiki/Osman_I

https://en.wikipedia.org/wiki/Greek_War_of_Independence

https://en.wikipedia.org/wiki/Mehmed_VI

https://en.wikipedia.org/wiki/Turkish_War_of_Independence

https://en.wikipedia.org/wiki/Ottoman_Empire#Defeat_and_dissolution_(1908%E2%80%931922)

https://www.history.com/news/ottoman-empire-fall

https://www.history.com/topics/middle-east/ottoman-empire#when-did-the-ottoman-empire-fall

#31 When did the law of manslaughter start?

Photo by EKATERINA  BOLOVTSOVA: https://www.pexels.com/photo/brown-wooden-gavel-on-brown-wooden-table-6077326/

https://en.wikipedia.org/wiki/Manslaughter_(United_States_law)

https://en.wikipedia.org/wiki/Manslaughter

https://en.wikipedia.org/wiki/Draco_(lawgiver)

https://www.cps.gov.uk/legal-guidance/homicide-murder-and-manslaughter

https://www.legis.la.gov/legis/Law.aspx?d=78338

https://www.etymonline.com/word/murder

https://www.etymonline.com/word/manslaughter

#32 Why are American and British accents different?

Image By Own work based on: Flag of the United Kingdom.svg and Flag of the United States.svg – This file was derived from:Flag of the United Kingdom.svgFlag of the United States.svg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=105347071

https://www.mentalfloss.com/article/29761/when-did-americans-lose-their-british-accents

https://www.sciencefocus.com/the-human-body/why-do-people-have-accents/

https://www.ef.com/wwen/blog/language/why-us-and-uk-english-sound-so-different/

Why Don’t Americans and Brits Have the Same Accents?

https://www.vice.com/en/article/v747m9/why-the-uk-has-so-many-accents

Why Don’t Americans and Brits Have the Same Accents?

https://www.bbc.com/culture/article/20160921-where-does-canadas-accent-come-from

https://www.eurocentres.com/blog/where-did-the-australian-accent-come-from

https://en.wikipedia.org/wiki/Rhoticity_in_English

https://en.wikipedia.org/wiki/Great_Vowel_Shift

#33 When did cars start using headlights (headlamps)?

Photo by vjapratama: https://www.pexels.com/photo/close-up-photography-of-headlight-1003849/

https://www.carthrottle.com/post/from-lamps-to-lasers-the-evolution-of-headlights/

https://blog.theretrofitsource.com/the-history-of-automotive-headlights-retrofit-source

https://www.powerbulbs.com/eu/blog/2017/08/when-was-the-headlight-invented

https://en.wikipedia.org/wiki/Headlamp

https://en.wikipedia.org/wiki/Car

https://en.wikipedia.org/wiki/Carbide_lamp

https://www.energy.gov/eere/vehicles/fact-841-october-6-2014-vehicles-thousand-people-us-vs-other-world-regions

#34 When was the expression “mayday” first used?

Photo by Rafael Cosquiere: https://www.pexels.com/photo/two-pilots-sitting-inside-plane-2064123/

https://www.merriam-webster.com/words-at-play/mayday-meaning-origin

https://en.wikipedia.org/wiki/Mayday

https://en.wikipedia.org/wiki/S%C3%A9curit%C3%A9

https://en.wikipedia.org/wiki/Pan-pan

https://www.connexionfrance.com/article/Mag/French-Facts/Help-is-at-hand-Mayday-signal-s-French-origins-from-the-French-expression-Venez-m-aider

https://www.wonderopolis.org/wonder/what-does-mayday-mean

https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap6_section_3.html

https://www.ecfr.gov/current/title-47/chapter-I/subchapter-D/part-80/subpart-W/subject-group-ECFR16ee72796c8e949/section-80.1125

https://en.wikipedia.org/wiki/Croydon_Airport

https://easbcn.com/en/the-origin-of-mayday-in-aviation/

https://skybrary.aero/articles/emergency-communications

#35 How does a touchscreen work?

Photo by Pixabay: https://www.pexels.com/photo/app-business-connection-device-221185/

https://en.wikipedia.org/wiki/Touchscreen

https://www.iop.org/explore-physics/technology-our-lives/touchscreen#gref

https://www.hp.com/us-en/shop/tech-takes/how-do-touch-screens-work

http://hades.mech.northwestern.edu/index.php/Resistive_Touchscreen

http://www.nelson-miller.com/what-are-the-layers-of-a-resistive-touchscreen-device/

#36 When did people start using coal?

Photo by Pixabay: https://www.pexels.com/photo/black-close-up-coal-dark-46801/

https://en.wikipedia.org/wiki/History_of_coal_mining

https://www.okd.cz/en/coal-mining/the-history-of-coal-mining

https://education.nationalgeographic.org/resource/coal

https://www.dyballassociates.co.uk/a-brief-history-of-energy-coal

https://www.sciencedirect.com/science/article/abs/pii/S0305440396900485

https://www.sciencedirect.com/science/article/pii/S2352409X20302595

https://www.sciencedirect.com/topics/engineering/lignite

https://en.wikipedia.org/wiki/Chain_pump

https://www.history.com/news/human-ancestors-tamed-fire-earlier-than-thought

https://en.wikipedia.org/wiki/Qesem_cave

https://en.wikipedia.org/wiki/Control_of_fire_by_early_humans

https://www.smithsonianmag.com/science-nature/why-fire-makes-us-human-72989884/

https://en.wikipedia.org/wiki/Coal_in_China

#37 Was Nero as bad as people say?

Image By Helen Cook – https://www.flickr.com/photos/hvc/5692212805/, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=42325118

https://www.newyorker.com/magazine/2021/06/14/how-nasty-was-nero-really

https://www.smithsonianmag.com/smart-news/just-how-bad-was-nero-really-180977813/

https://en.wikipedia.org/wiki/John_Xiphilinus

https://en.wikipedia.org/wiki/Suetonius

https://en.wikipedia.org/wiki/Tacitus

https://en.wikipedia.org/wiki/Nero

#38 What is insulin?

Photo by Mikhail Nilov: https://www.pexels.com/photo/close-up-shot-of-a-person-holding-a-syringe-8670185/

https://www.healthline.com/health/type-2-diabetes/insulin#understanding-diabetes

https://en.wikipedia.org/wiki/Insulin

https://en.wikipedia.org/wiki/Glucose

https://en.wikipedia.org/wiki/Beta_cell

https://en.wikipedia.org/wiki/Peptide_hormone

https://www.hopkinsmedicine.org/health/conditions-and-diseases/the-digestive-process-what-is-the-role-of-your-pancreas-in-digestion

https://www.mydr.com.au/gastrointestinal-health/pancreas-and-insulin/

http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/pancreas/insulin.html

https://www.webmd.com/a-to-z-guides/what-are-peptides

https://molmed.biomedcentral.com/articles/10.2119/2005-00029.Saltiel

https://www.mayoclinic.org/diseases-conditions/diabetes/in-depth/diabetes-treatment/art-20044084

https://www.drugs.com/medical-answers/glucagon-glycogen-thing-3543887/

https://www.healthline.com/diabetesmine/ask-dmine-lifespan-sans-insulin#What-happens-when-you-run-out-of-insulin

#39 Why do some planets have rings?

Photo by ZCH: https://www.pexels.com/photo/plane-saturn-in-graphic-illustration-12498805/

https://astronomy.stackexchange.com/questions/1509/will-saturns-rings-become-a-moon

https://spacemath.gsfc.nasa.gov/moon/5Page49.pdf

https://oceanservice.noaa.gov/education/tutorial_tides/tides06_variations.html

https://www.nasa.gov/centers/goddard/multimedia/largest/rings.html

https://physics.stackexchange.com/questions/26643/why-arent-saturns-rings-clumping-into-moons

https://www.livescience.com/what-if-earth-had-rings.html

https://webbtelescope.org/resource-gallery/articles/pagecontent/filter-articles/why-do-planets-have-rings?filterUUID=a776e097-0c60-421c-baec-1d8ad049bfb0

https://theconversation.com/curious-kids-why-are-some-planets-surrounded-by-rings-130318

https://en.wikipedia.org/wiki/Roche_limit

https://en.wikipedia.org/wiki/Ring_system

https://en.wikipedia.org/wiki/Saturn

#40 How does G-force kill people?

Photo by Pixabay: https://www.pexels.com/photo/aerobatics-air-air-force-aircraft-264416/

https://en.wikipedia.org/wiki/G-force

https://www.sciencefocus.com/science/whats-the-maximum-speed-a-human-can-withstand/

https://www.medicaldaily.com/breaking-point-whats-strongest-g-force-humans-can-tolerate-369246

https://hypertextbook.com/facts/2004/YuriyRafailov.shtml

https://science.howstuffworks.com/science-vs-myth/everyday-myths/question633.htm

https://www.omnicalculator.com/physics/car-crash-force

https://en.wikipedia.org/wiki/John_Stapp

https://www.pbs.org/wgbh/nova/warplanes/gforces.html

https://www.wral.com/high-speed-car-crashes-exert-lethal-force/17903314/

https://en.wikipedia.org/wiki/Euthanasia_Coaster

#41 Who burned down the Library of Alexandria?

Image By Daniel Mayer – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=4672110

https://www.livescience.com/rise-and-fall-of-the-great-alexandria-library

https://www.worldhistory.org/article/207/what-happened-to-the-great-library-at-alexandria/

https://www.mymcpl.org/blogs/historical-libraries-library-alexandria

https://ehistory.osu.edu/articles/burning-library-alexandria

https://historyofyesterday.com/library-of-alexandria-13c1e5c98a18

The Library of Alexandria

https://en.wikipedia.org/wiki/Library_of_Alexandria

https://en.wikipedia.org/wiki/Caesar%27s_civil_war

https://en.wikipedia.org/wiki/Alexandria

https://en.wikipedia.org/wiki/Alexander_the_Great

https://en.wikipedia.org/wiki/Ptolemaic_dynasty

#42 Why is the surface tension of water so high?

Photo by Min An: https://www.pexels.com/photo/macro-shot-of-water-drop-on-green-textile-689326/

https://www.biolinscientific.com/blog/surface-tension-of-water-why-is-it-so-high

https://www.mytutor.co.uk/answers/52118/A-Level/Biology/Why-does-water-have-high-surface-tension/

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/surface-tension

https://en.wikipedia.org/wiki/Surface_tension

https://physics.stackexchange.com/questions/2615/are-there-any-liquids-with-zero-surface-tension

https://chem.libretexts.org/Courses/Valley_City_State_University/Chem_122/Chapter_1%3A_Intermolecular_Forces/1.3%3A_Intermolecular_Forces_in_Action%3A_Surface_Tension%2C_Viscosity%2C_and_Capillary_Action

https://chemistry.stackexchange.com/questions/1107/why-is-water-a-dipole

https://en.wikipedia.org/wiki/Surface-tension_values

https://en.wikipedia.org/wiki/Mercury_(element)

https://sciencing.com/detergent-break-surface-tension-5452223.html

https://www.usgs.gov/special-topics/water-science-school/science/surface-tension-and-water

#43 What is the Richter scale?

Photo by Wilson Malone: https://www.pexels.com/photo/orange-and-white-traffic-pole-on-cracked-gray-asphalt-road-4558211/

https://en.wikipedia.org/wiki/Richter_magnitude_scale

https://en.wikipedia.org/wiki/Moment_magnitude_scale

https://en.wikipedia.org/wiki/Charles_Francis_Richter

https://en.wikipedia.org/wiki/Modified_Mercalli_intensity_scale

https://en.wikipedia.org/wiki/Rossi%E2%80%93Forel_scale

https://science.howstuffworks.com/nature/natural-disasters/earthquake6.htm

https://www.sms-tsunami-warning.com/pages/richter-scale#.YqsmbHbP3cs

https://www.mtu.edu/geo/community/seismology/learn/seismology-study/

https://www.sciencelearn.org.nz/resources/340-seismic-waves

#44 Who was the first war correspondent?

Image By Roger Fenton – This image is available from the United States Library of Congress's Prints and Photographs divisionunder the digital ID cph.3g09183.This tag does not indicate the copyright status of the attached work. A normal copyright tag is still required. See Commons:Licensing., Public Domain, https://commons.wikimedia.org/w/index.php?curid=308374

https://en.wikipedia.org/wiki/War_correspondent

https://warfarehistorynetwork.com/2016/06/09/the-pen-the-sword-a-brief-history-of-war-correspondents/

https://www.jstor.org/stable/26442017

https://en.wikipedia.org/wiki/William_Howard_Russell

https://en.wikipedia.org/wiki/Crimean_War

https://en.wikipedia.org/wiki/History_of_newspaper_publishinghttps://www.military-history.org/feature/19th-century/war-reporters-william-howard-russell.htm

#45 How can a laser power a solar sail?

Image By Andrzej Mirecki – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=14656159

https://en.wikipedia.org/wiki/Laser_propulsion

https://en.wikipedia.org/wiki/Breakthrough_Starshot

https://en.wikipedia.org/wiki/Beam-powered_propulsion

http://gareebscientist.com/isro-developing-laser-propulsion/

https://www.theverge.com/2016/4/16/11437598/alpha-centauri-starshot-project-stephen-hawking

https://www.businessinsider.com/breakthrough-starshot-laser-beam-power-2018-12

https://en.wikipedia.org/wiki/Proxima_Centauri

https://www.technologyreview.com/2018/06/22/142160/this-is-how-many-people-wed-have-to-send-to-proxima-centauri-to-make-sure-someone-actually/

https://www.sciencefocus.com/space/how-fast-are-the-voyager-spacecrafts-travelling/

#46 How does a hand grenade work?

Image By J-L Dubois – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=2368075

https://en.wikipedia.org/wiki/Grenade

https://en.wikipedia.org/wiki/Grenadier

https://en.wikipedia.org/wiki/Mk_2_grenade

https://www.thoughtco.com/history-of-the-hand-grenade-1991668

https://science.howstuffworks.com/grenade2.htm

https://en.wikipedia.org/wiki/M67_grenade

http://www.madehow.com/Volume-7/Grenade.html

https://www.sciencealert.com/watch-how-to-survive-a-grenade-blast-according-to-science

#47 How do some animals sleep standing up?

Photo by Kata Pal: https://www.pexels.com/photo/herd-of-horses-2659484/

https://www.nationalgeographic.com/science/article/150711-animals-science-sleep-horses-bison-moose

Animals That Sleep Standing Up

https://www.sciencefocus.com/nature/how-many-animals-can-sleep-standing-up/

https://en.wikipedia.org/wiki/Stay_apparatus

http://www.todayifoundout.com/index.php/2014/10/birds-grip-things-sleep/

https://www.science.org/content/article/how-flamingos-sleep-while-standing-one-leg

https://herd.org.za/let-sleeping-elephants-lie-how-elephants-sleep/

https://en.wikipedia.org/wiki/Horse_behavior#Sleep_patterns

#48 When did people first start using paper money?

Photo by Karolina Grabowska: https://www.pexels.com/photo/heap-of-different-nominal-per-dollars-4386442/

https://www.thoughtco.com/the-invention-of-paper-money-195167

https://www.investopedia.com/articles/07/roots_of_money.asp

https://www.britannica.com/story/a-brief-and-fascinating-history-of-money

https://www.investopedia.com/ask/answers/09/paper-money-usa.asp

https://en.wikipedia.org/wiki/Banknote

https://en.wikipedia.org/wiki/Jiaozi_(currency)

https://en.wikipedia.org/wiki/Promissory_note

https://en.wikipedia.org/wiki/Legal_tender

https://en.wikipedia.org/wiki/Money

https://www.quora.com/What-does-I-promise-to-pay-the-bearer-on-demand-mean-on-banknotes-What-do-they-promise-to-pay-you-in

#49 What is hardtack?

Image By D. Farr at English Wikipedia – Transferred from en.wikipedia to Commons., Public Domain, https://commons.wikimedia.org/w/index.php?curid=5246300

https://www.atlasobscura.com/articles/ship-food-research-recreation-beer

http://www.pbchistoryonline.org/page/what-did-sailors-eat

http://www.thepeacefulsea.com/life-at-sea.html

https://www.sea.museum/learn/school-excursions/teacher-resources/hmb-endeavour/life-aboard-ship/food-and-rations

https://maefood.blogspot.com/2012/06/what-did-magellan-and-his-sailors-eat.html

https://en.wikipedia.org/wiki/Hardtack

https://www.montana.edu/historybug/civilwar2/infested.html

http://pass-the-garum.blogspot.com/2014/10/bucellatum-roman-army-hardtack.html

https://en.wikipedia.org/wiki/Bucellarii

https://www.npr.org/sections/thesalt/2018/07/24/631583427/14-000-year-old-piece-of-bread-rewrites-the-history-of-baking-and-farming

https://www.thc.texas.gov/blog/hardtack-original-mre

https://www.historycrunch.com/causes-of-the-age-of-exploration.html#/

https://en.wikipedia.org/wiki/Age_of_Discovery

https://www.nationalgeographic.com/science/article/scurvy-disease-discovery-jonathan-lamb

#50 Why do trees have rings?

Photo by Lisett Kruusimäe: https://www.pexels.com/photo/tree-stump-in-close-up-5883544/

https://www.indefenseofplants.com/blog/2016/2/8/why-trees-have-rings-and-why-they-are-so-useful

https://scied.ucar.edu/learning-zone/how-climate-works/tree-rings-and-climate

https://www.theforestacademy.com/tree-knowledge/annual-growth-rings/#.YrRfM3bP3cs

https://en.wikipedia.org/wiki/Dendrochronology

https://en.wikipedia.org/wiki/Trunk_(botany)

https://northernwoodlands.org/outside_story/article/how-do-trees-know-when-to-wake-up

#51 Why are the aurora borealis those colors?

Photo by Visit  Greenland: https://www.pexels.com/photo/aurora-borealis-360912/

http://www.webexhibits.org/causesofcolor/4D.html

https://global.hurtigruten.com/inspiration/experiences/northern-lights/what-causes-the-northern-lights/

https://www.rmg.co.uk/stories/topics/what-causes-northern-lights-aurora-borealis-explained

https://en.wikipedia.org/wiki/Aurora

https://www.space.com/22215-solar-wind.html

https://sci.esa.int/web/ulysses/-/2576-the-heliosphere

https://www.skyatnightmagazine.com/space-science/what-causes-different-shapes-colours-aurora/

#52 What is a superfluid?

Image By I, AlfredLeitner, took this photograph as part of my movie "Liquid Helium,Superfluid" – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=7741454

https://en.wikipedia.org/wiki/Superfluid_helium-4

https://en.wikipedia.org/wiki/Superfluidity

https://news.illinois.edu/view/6367/730694

https://www.sciencefocus.com/science/how-is-helium-turned-into-a-liquid-and-a-superfluid/

https://www.quora.com/Why-does-liquid-helium-flow-up-and-out-of-a-beaker-at-very-low-temperatures-Dont-the-laws-of-thermodynamics-apply

https://www.newscientist.com/article/mg20827813-300-first-frictionless-superfluid-molecules-created/

https://physics.stackexchange.com/questions/171777/do-some-of-the-laws-of-thermodynamics-break-down-in-quantum-mechanics

https://www.scientificamerican.com/article/superfluid-can-climb-walls/https://www.aps.org/publications/apsnews/200601/history.cfm

#53 Who invented ice cream?

Photo by Calebe Miranda: https://www.pexels.com/photo/brown-cone-with-white-sprinkled-icing-108370/

https://en.wikipedia.org/wiki/Ice_house_(building)

https://en.wikipedia.org/wiki/Ice_cream

https://en.wikipedia.org/wiki/Endothermic_process

https://www.pbs.org/food/the-history-kitchen/explore-the-delicious-history-of-ice-cream/

The History of Ice Cream, One of the World’s Oldest Desserts

https://www.idfa.org/the-history-of-ice-cream

http://www.icecreamhistory.net/frozen-dessert-history/who-invented-ice-cream/

https://en.wikipedia.org/wiki/Sorbet

http://www.concertina.com/calculator/

#54 Why did Rome become a republic?

Photo by Michael Giugliano: https://www.pexels.com/photo/pantheon-roman-temple-in-rome-2928046/

https://www.ushistory.org/civ/6a.asp

https://www.khanacademy.org/humanities/world-history/ancient-medieval/roman-empire/a/roman-republic

https://en.wikipedia.org/wiki/Roman_Republic

https://en.wikipedia.org/wiki/Roman_Kingdom

https://en.wikipedia.org/wiki/Numa_Pompilius

https://en.wikipedia.org/wiki/Romulus

https://www.history.com/this-day-in-history/rome-founded

https://www.rome.net/roman-monarchy

https://en.wikipedia.org/wiki/Lucius_Tarquinius_Superbus

https://en.wikipedia.org/wiki/Etruria

https://en.wikipedia.org/wiki/Overthrow_of_the_Roman_monarchy

https://www.vox.com/world/2018/6/19/17469176/roman-empire-maps-history-explained

https://www.thecollector.com/who-were-the-etruscans/

https://www.penfield.edu/webpages/jgiotto/onlinetextbook.cfm?subpage=1660456

#55 What are vitamins?

Photo by Pixabay: https://www.pexels.com/photo/close-up-of-fruits-in-bowl-327098/

https://ed.ted.com/lessons/what-s-the-value-of-vitamins-ginnie-trinh-nguyen

https://medlineplus.gov/minerals.html

https://www.medicalnewstoday.com/articles/195878#supplements

https://www.centrum.com/learn/articles/how-supplements-work/how-do-vitamins-work/

https://en.wikipedia.org/wiki/Mineral_(nutrient)

https://en.wikipedia.org/wiki/Vitamin

https://www.centrum.sg/expert-corner/health-blog/how-do-vitamins-work/

http://www.madehow.com/Volume-3/Vitamin.html

#56 When were the first lawyers?

Photo by Karolina Grabowska: https://www.pexels.com/photo/people-holding-divorce-papers-7876051/

https://en.wikipedia.org/wiki/Bar_association

https://en.wikipedia.org/wiki/History_of_the_legal_profession

https://www.wordreference.com/definition/law

https://www.britannica.com/topic/legal-profession

#57 What was the Tunguska event?

Image By Leonid Kulik, the expedition to the Tunguska event – Vokrug Sveta, 1931 \ (copied from the German Wikipedia, uploaded there by user Dilerius who copied it from the English Wikipedia, uploaded there by user Avsa), Public Domain, https://commons.wikimedia.org/w/index.php?curid=337448

https://en.wikipedia.org/wiki/Tunguska_event

https://en.wikipedia.org/wiki/Lake_Cheko

https://www.britannica.com/story/what-is-known-and-not-known-about-the-tunguska-event

https://en.wikipedia.org/wiki/Impact_event

#58 Why do pandas eat bamboo?

Photo by Alotrobo: https://www.pexels.com/photo/panda-bear-eating-bamboo-leaves-in-zoo-7506265/

https://news.cgtn.com/news/3d3d514d7a6b544d33457a6333566d54/index.html

https://www.nature.com/articles/d41586-019-00301-y

https://www.iflscience.com/pandas-used-to-eat-meat-then-went-vegetarian-but-now-just-eat-bamboo-51411

https://www.latimes.com/science/la-sci-panda-diet-bamboo-protein-carnivore-20190503-story.html

https://www.scmp.com/news/china/science/article/3183708/how-long-have-pandas-been-eating-bamboo-least-6-million-years

#59 Why did the Iron Age start?

Photo by Pixabay: https://www.pexels.com/photo/black-steel-helmet-near-black-and-gray-handle-sword-161936/

https://en.wikipedia.org/wiki/Iron_Age

https://en.wikipedia.org/wiki/Bronze_Age

https://www.history.com/topics/pre-history/iron-age

https://www.history.com/news/bronze-age-collapse-causes

https://en.wikipedia.org/wiki/Late_Bronze_Age_collapse

https://www.quora.com/How-did-people-create-a-melting-iron-temperature-though-local-sources-in-ancient-times

How hand tools have impacted human evolution

#60 How were the Nazca Lines made?

Photo by Janeth Charris: https://www.pexels.com/photo/nazca-lines-near-road-17428774/

https://www.nationalgeographic.com/history/article/nazca-lines

https://www.history.com/topics/south-america/nazca-lines

https://www.nationalgeographic.com/history/article/nazca-lines

https://en.wikipedia.org/wiki/Nazca_Lines

https://en.wikipedia.org/wiki/Paracas_culture

https://en.wikipedia.org/wiki/Nazca_culture

https://www.joenickell.com/NazcaGeoglyphRecreator/NazcaGeoglyphRec1.html

#61 How is scaffolding attached to a building?

Photo by Isabella Mendes: https://www.pexels.com/photo/gray-building-335685/

https://bindleyhardwareco.com/is-scaffolding-attached-to-the-building

https://en.wikipedia.org/wiki/Scaffolding

https://pmixi.com/how-is-scaffolding-attached-to-a-building

https://blog.designsafe.co.uk/common-tie-methods

https://www.unitedscaffold.ca/scaffold-news/does-scaffolding-need-to-be-attached-to-the-building/

https://www.cambridgescaffolding.com/the-history-of-scaffolding

https://en.wikipedia.org/wiki/Berlin_Foundry_Cup

#62 How does radiation sickness happen?

Photo by Gáspár Ferenc: https://www.pexels.com/photo/szarkofag-13717554/

https://www.cdc.gov/nceh/radiation/what_is.html

https://www.mayoclinic.org/diseases-conditions/radiation-sickness/symptoms-causes/syc-20377058

https://www.medicalnewstoday.com/articles/219615#what_is_radiation_poisoning

https://www.nrc.gov/reading-rm/basic-ref/students/science-101/what-are-different-types-of-radiation.html

https://hps.org/publicinformation/ate/faqs/radiationtypes.html

https://www.epa.gov/radiation/radiation-basics

https://en.wikipedia.org/wiki/Radiation

https://www.cdc.gov/nceh/radiation/what_is.html

https://www.mayoclinic.org/diseases-conditions/radiation-sickness/symptoms-causes/syc-20377058

https://www.medicalnewstoday.com/articles/219615#symptoms

https://en.wikipedia.org/wiki/Non-ionizing_radiation

https://en.wikipedia.org/wiki/Ionizing_radiation

https://en.wikipedia.org/wiki/X-ray

https://en.wikipedia.org/wiki/Acute_radiation_syndrome

https://en.wikipedia.org/wiki/Gamma_ray

https://www.rerf.or.jp/en/about_radiation/how_radiation_harms_cells_e/

https://www.env.go.jp/en/chemi/rhm/basic-info/1st/03-02-04.html

#63 Why do mosquitoes come out at night?

Photo by Jimmy Chan: https://www.pexels.com/photo/macro-shot-of-a-mosquito-on-human-skin-12972048/

https://off.com/en/education/insects-101/how-mosquitoes-find-you

https://qz.com/943245/mosquitoes-are-actually-terrible-at-flying/

https://www.orkin.com/pests/mosquitoes/what-eats-mosquitoes

https://www.terminix.com/mosquitoes/facts/when-are-mosquitoes-active/

https://www.mosquitomagnet.com/articles/when-are-mosquitoes-most-active

https://blog.mosquito.buzz/how-weather-affects-mosquito-activity

https://www.sciencedaily.com/releases/2015/12/151215091403.htm

https://mosquitonix.com/blogs/news/what-time-of-day-are-mosquitos-most-active

https://en.wikipedia.org/wiki/1-Octen-3-ol

https://en.wikipedia.org/wiki/Mosquito

https://www.imperial.ac.uk/news/219394/simple-genetic-modification-aims-stop-mosquitoes/

#64 When was instant coffee invented?

Photo by Peter: https://www.pexels.com/photo/brown-coffee-powder-on-silver-spoon-7649042/

https://www.thespruceeats.com/instant-coffee-guide-764526

http://www.historyofcoffee.net/coffee-history/instant-coffee-history/

https://en.wikipedia.org/wiki/Instant_coffee

https://en.wikipedia.org/wiki/History_of_coffee

https://en.wikipedia.org/wiki/Coffeehouse

https://en.wikipedia.org/wiki/Sublimation_(phase_transition)

https://espressocoffeeguide.com/instant-coffee/history-of-instant-coffee/

https://www.pbs.org/food/the-history-kitchen/history-coffee/

https://www.wakacoffee.com/blogs/coffeelifeblog/instant-coffee-history

https://www.athirstforfirsts.co.uk/post/first-instant-coffee

https://en.wikipedia.org/wiki/Tea_in_the_United_Kingdom

#65 How does a desalination plant work?

Photo by Kellie Churchman: https://www.pexels.com/photo/landscape-photograph-of-body-of-water-1001682/

https://www.phoenix.gov/waterservicessite/Documents/All%20the%20Water%20in%20the%20World.pdf

https://www.mentalfloss.com/article/646229/what-actually-happens-if-you-drink-saltwater

https://www.usbr.gov/mp/arwec/water-facts-ww-water-sup.html

https://cosmosmagazine.com/earth/water/how-does-a-desalination-plant-work/

https://www.carlsbaddesal.com/how-it-works.html

https://science.howstuffworks.com/environmental/earth/geophysics/h2o.htm

https://en.wikipedia.org/wiki/Desalination

#66 How does a virus infect the body?

Photo by CDC: https://www.pexels.com/photo/coronavirus-3992933/

https://www.scripps.edu/covid-19/science-simplified/how-the-novel-coronavirus-infects-a-cell/

https://theconversation.com/what-is-a-virus-how-do-they-spread-how-do-they-make-us-sick-133437

https://www.smithsonianmag.com/air-space-magazine/there-are-more-viruses-earth-there-are-stars-universe-180974433/

https://askabiologist.asu.edu/questions/how-viruses-work

https://www.cancer.gov/publications/dictionaries/cancer-terms/def/cell

https://www.khanacademy.org/test-prep/mcat/cells/viruses/a/are-viruses-dead-or-alive

https://en.wikipedia.org/wiki/Virus

https://www.britannica.com/science/virus/Size-and-shape

https://medicine.yale.edu/coved/modules/virus/hijacking/

https://www.news-medical.net/health/How-does-Viral-Replication-Work.aspx

#67 How does bug spray work?

Photo by Petr Ganaj: https://www.pexels.com/photo/close-up-of-fly-17533609/

http://npic.orst.edu/factsheets/repellents.html

https://www.theparisreview.org/blog/2014/11/17/a-brief-history-of-insect-control/

https://en.wikipedia.org/wiki/Pesticide#Development

https://en.wikipedia.org/wiki/Insecticide

https://en.wikipedia.org/wiki/Fly_spray

How Does Fly Spray Work? Is It Painful? What About Other Insects?

https://naldc.nal.usda.gov/download/IND43893975/PDF

https://www.theparisreview.org/blog/2014/11/17/a-brief-history-of-insect-control/

https://www.aerosol.com.au/about-aerosols/aerosol-history

#68 Why do horses need horseshoes?

Photo by RDNE Stock project: https://www.pexels.com/photo/a-person-in-denim-jeans-standing-near-the-horse-8624693/

https://en.wikipedia.org/wiki/Domestication_of_the_horse

https://en.wikipedia.org/wiki/Horse_hoof

https://en.wikipedia.org/wiki/Hipposandal

https://en.wikipedia.org/wiki/Horseshoe

https://www.mentalfloss.com/article/655903/why-do-horses-need-shoes-cows-dont

https://www.animalfriends.co.uk/horse-and-rider/horse-blog/why-do-horses-need-shoes/

#69 When was the first passenger train?

Photo by Pixabay: https://www.pexels.com/photo/gray-scale-photo-of-classic-train-163577/

http://www.sbdepotmuseum.com/1800-1849/september-27-1825-worlds-first-passenger-train.html

https://en.wikipedia.org/wiki/Timeline_of_railway_history

https://en.wikipedia.org/wiki/History_of_rail_transport#Britain

https://en.wikipedia.org/wiki/Funicular

https://en.wikipedia.org/wiki/Middleton_Railway

https://en.wikipedia.org/wiki/Steam_locomotive

https://en.wikipedia.org/wiki/Stockton_and_Darlington_Railway

How Did The Steam Locomotive Change Transportation?

#70 Why are some places more humid than others?

Photo by David Riaño Cortés: https://www.pexels.com/photo/rainforest-surrounded-by-fog-975771/

https://www.pbs.org/newshour/science/8-things-didnt-know-humidity

https://www.scientificamerican.com/article/what-causes-humidity/

https://en.wikipedia.org/wiki/Humidity

https://en.wikipedia.org/wiki/Dew_point

https://www.lsop.colostate.edu/wp-content/uploads/sites/6/2014/10/WhyDoesWarmAirHoldMoreWater.pdf

https://www.livescience.com/43269-what-is-dew-point.html

https://www.houstonmethodist.org/blog/articles/2020/aug/how-sweat-works-why-we-sweat-when-we-are-hot-as-well-as-when-we-are-not/

https://www.houstonmethodist.org/blog/articles/2020/aug/how-sweat-works-why-we-sweat-when-we-are-hot-as-well-as-when-we-are-not/

https://www.data.jma.go.jp/gmd/cpd/longfcst/en/tourist_japan.html

#71 When did people start eating cereal for breakfast?  

Image By Kellogg's company – http://www.kellogghistory.com/timeline.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=8497243

https://www.wpr.org/historian-industrial-revolution-gave-us-lunch-we-know-it

https://www.theatlantic.com/entertainment/archive/2016/06/breakfast-the-most-contentious-meal-of-the-day/487220/

https://en.wikipedia.org/wiki/Breakfast

https://en.wikipedia.org/wiki/Breakfast_cereal

https://beyond.britannica.com/why-is-it-that-we-often-eat-breakfast-cereal-with-milk-how-did-this-become-a-thing

https://en.wikipedia.org/wiki/Granula

https://en.wikipedia.org/wiki/James_Caleb_Jackson

https://www.refinery29.com/en-us/2021/03/10380335/breakfast-cereal-history-future-strange-facts

https://www.history.com/news/cereal-breakfast-origins-kellogg

https://en.wikipedia.org/wiki/Sylvester_Graham

#72 How much of your liver can you live without?  

Image By Tvanbr – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=11625998

https://www.hopkinsmedicine.org/health/conditions-and-diseases/liver-anatomy-and-functions

https://healthblog.uofmhealth.org/what-does-the-liver-do

https://www.nhs.uk/conditions/dialysis/what-happens/

Photo by Dani Muchow: https://www.pexels.com/photo/gray-paved-road-tunnel-2955705/

https://www.freseniuskidneycare.com/treatment/dialysis/hemodialysis-machine

https://www.healthline.com/health/can-you-live-without-liver

https://kids.frontiersin.org/articles/10.3389/frym.2017.00038

https://healthblog.uofmhealth.org/wellness-prevention/how-does-living-liver-donation-work-6-things-to-know

https://share.upmc.com/2017/04/can-you-live-without-a-liver/

How Much of My Liver Would I Need to Donate to Save Someone’s Life?

#73 What did the last emperor of China do later in life?  

Image By Unknown author – Collection, Public Domain, https://commons.wikimedia.org/w/index.php?curid=129955704

https://www.liverpoolmuseums.org.uk/stories/who-was-chinas-first-emperor

https://www.history.com/this-day-in-history/last-emperor-of-china-abdicates

https://en.wikipedia.org/wiki/Puyi

https://en.wikipedia.org/wiki/Qing_dynasty

https://en.wikipedia.org/wiki/Imperial_Edict_of_the_Abdication_of_the_Qing_Emperor

https://en.wikipedia.org/wiki/1911_Revolution

https://www.scmp.com/magazines/style/people-events/article/2115727/remembering-chinas-last-emperor-puyi-50-years-after?module=perpetual_scroll_0&pgtype=article&campaign=2115727

https://history.state.gov/milestones/1899-1913/chinese-rev

#74 How do you build a tunnel underwater?  

Photo by Dani Muchow: https://www.pexels.com/photo/gray-paved-road-tunnel-2955705/

https://gradprograms.mines.edu/blog/a-history-of-tunneling-and-underground-construction-and-the-factors-driving-current-and-future-demand/

How Are Underwater Tunnels Built? What You Need To Know

https://science.howstuffworks.com/engineering/structural/build-underwater-tunnel.htm

https://en.wikipedia.org/wiki/Tunnel

https://www.bbc.com/news/uk-england-derbyshire-22342239

https://www.britannica.com/technology/tunnel

https://en.wikipedia.org/wiki/Euphrates_Tunnel

https://en.wikipedia.org/wiki/Fritchley_Tunnel

https://en.wikipedia.org/wiki/Thames_Tunnel

https://en.wikipedia.org/wiki/Tunnelling_shield

#75 Why do women live longer than men?  

Photo by Pixabay: https://www.pexels.com/photo/grandmother-making-faces-34540/

https://pubmed.ncbi.nlm.nih.gov/12586217/

https://www.endocrineweb.com/conditions/heart-disease/heart-hormones

https://ourworldindata.org/why-do-women-live-longer-than-men

https://www.bbc.com/future/article/20151001-why-women-live-longer-than-men

https://www.voanews.com/a/science-health_new-study-looks-why-females-live-longer-males/6186357.html

https://www.bbc.co.uk/bitesize/guides/zc499j6/revision/4

https://www.theguardian.com/science/2020/mar/04/mystery-of-lifespan-gap-between-sexes-may-be-solved-say-researchers

https://www.smithsonianmag.com/smart-news/females-live-longer-malesamong-humans-and-other-mammals-too-180974504/

https://www.bbc.com/news/science-environment-52007780

https://www.dw.com/en/evolution-why-females-live-longer/a-52940412

#76 Why can’t light escape from a black hole?

Image By Event Horizon Telescope, uploader cropped and converted TIF to JPG – https://www.eso.org/public/images/eso1907a/ (image link) The highest-quality image (7416×4320 pixels, TIF, 16-bit, 180 Mb), ESO Article, ESO TIF, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=77925953

https://astronomy.com/magazine/greatest-mysteries/2019/07/19-can-light-escape-from-black-holes

https://www.sciencefocus.com/space/why-can-gravity-escape-a-black-hole-but-not-light/

https://physics.stackexchange.com/questions/8477/why-cant-light-escape-from-a-classical-black-hole

https://socratic.org/questions/why-light-can-t-escape-from-a-blackhole-if-they-have-no-mass

https://en.wikipedia.org/wiki/Black_hole

https://en.wikipedia.org/wiki/Supermassive_black_hole

https://en.wikipedia.org/wiki/Gravity

https://science.nasa.gov/astrophysics/focus-areas/black-holes

#77 Why do we use miles as a unit of measurement

Photo by Ekaterina Belinskaya: https://www.pexels.com/photo/grayscale-photo-of-cars-on-highway-with-white-oak-ave-signage-4744693/

https://indianapublicmedia.org/amomentofscience/mile-5280-feet.php

https://www.almanac.com/fact/how-was-it-determined-that-the-length

https://en.wikipedia.org/wiki/History_of_measurement

https://en.wikipedia.org/wiki/Inch

https://en.wikipedia.org/wiki/Foot_(unit)

https://metrologie-francaise.lne.fr/en/metrology/history-units

https://www.keyence.com/ss/products/measure-sys/measurement-selection/basic/unit.jsp

https://en.wikipedia.org/wiki/Mile

https://en.wikipedia.org/wiki/Furlong

https://en.wikipedia.org/wiki/Rod_(unit)

https://en.wikipedia.org/wiki/Ancient_Roman_units_of_measurement#Length

#78 Why do we use those measurements for shoe sizes?

Photo by Lukas: https://www.pexels.com/photo/pair-of-black-dress-shoes-292999/

https://www.hitachi-hightech.com/global/channel/units/04_09.html

https://en.wikipedia.org/wiki/Shoe_size

https://en.wikipedia.org/wiki/Shoe

https://en.wikipedia.org/wiki/Barleycorn_(unit)

https://www.satra.com/bulletin/article.php?id=1679

https://invention.si.edu/charles-f-brannock

http://www.todayifoundout.com/index.php/2016/03/pedestrian-origins-modern-shoe-sizes/

http://www.agleathers.com/shoe-guide/shoe-sizes/

https://en.wikipedia.org/wiki/Turnshoe

#79 How do cats retract their claws and why can’t other animals?

Photo by Erwin Salas: https://www.pexels.com/photo/close-up-photo-of-tabby-cat-5665657/

https://en.wikipedia.org/wiki/Cat

https://wonderopolis.org/wonder/How-Do-Animal-Claws-Retract

https://www.softpaws.com/fascinating-facts-about-cat-claws/

https://thomsonsafaris.com/blog/animal-claws-out/

https://www.sciencefocus.com/nature/do-big-cats-have-retractable-claws/

https://www.quora.com/Why-didnt-dogs-evolve-to-have-claws-like-cats

https://www.quora.com/Why-didnt-dogs-evolve-to-have-claws-like-cats

https://animals.mom.com/differences-between-lion-paw-bear-claw-7506.html

Bear Claws – Facts and Fiction

#80 Why do we use the word Vikings?

Photo by Barnabas Davoti: https://www.pexels.com/photo/close-up-of-the-saga-oseberg-8876097/

https://en.wikipedia.org/wiki/Vikings

https://en.wiktionary.org/wiki/wicing

https://www.britannica.com/topic/Viking-people

https://www.livescience.com/32087-viking-history-facts-myths.html

https://www.historytoday.com/who-are-vikings

https://en.wikipedia.org/wiki/Scandinavia

https://www.discovermagazine.com/planet-earth/what-language-did-the-vikings-speak

https://en.wikipedia.org/wiki/Kingdom_of_England

https://en.wikipedia.org/wiki/England#Toponymy

https://www.babbel.com/en/magazine/139-norse-words

https://theconversation.com/what-does-the-word-viking-really-mean-75647

https://en.wikipedia.org/wiki/Viking_revival

#81 What does the Milky Way Galaxy orbit?

Photo by ​Ѩвѻҏ Ѫєљѩӡӄѻ҇в: https://www.pexels.com/photo/scenic-view-of-night-sky-1738402/

https://en.wikipedia.org/wiki/Milky_Way

https://en.wikipedia.org/wiki/Barycenter

https://astroquizzical.com/astroquizzical/the-moon-orbits-the-earth-the-earth-orbits-the

https://en.wikipedia.org/wiki/Local_Group

https://en.wikipedia.org/wiki/Andromeda_Galaxy

https://en.wikipedia.org/wiki/Laniakea_Supercluster

https://en.wikipedia.org/wiki/Great_Attractor

https://en.wikipedia.org/wiki/Zone_of_Avoidance

https://physics.stackexchange.com/questions/129429/what-does-a-galaxy-orbit

https://www.quora.com/Does-the-Milky-Way-orbit-around-anything-If-so-whats-its-orbital-period

https://en.wikipedia.org/wiki/Andromeda%E2%80%93Milky_Way_collision

#82 Did Adolf Hitler have any brothers or sisters?

Image by unknown. Snapshot – Original publication: unknownImmediate source: http://historianet.nl/stine-grynberg/halfzuster-had-hekel-aan-eva-braun, Fair use, https://en.wikipedia.org/w/index.php?curid=42765961

http://www.hitlerschildren.com/article/1603-the-siblings-of-adolf-hitler

https://en.wikipedia.org/wiki/Hitler_family

https://en.wikipedia.org/wiki/Angela_Hitler

https://en.wikipedia.org/wiki/Paula_Hitler

https://en.wikipedia.org/wiki/Alois_Hitler

https://en.wikipedia.org/wiki/Adolf_Hitler

https://en.wikipedia.org/wiki/Klara_Hitler

#83 Why is the official kilogram in France no longer used?

Photo by Ketut Subiyanto: https://www.pexels.com/photo/crop-kid-weighing-on-scale-4474052/

https://en.wikipedia.org/wiki/International_Prototype_of_the_Kilogram

https://en.wikipedia.org/wiki/Metric_system

https://en.wikipedia.org/wiki/2019_redefinition_of_the_SI_base_units

https://en.wikipedia.org/wiki/Metre_Convention

https://www.atlasobscura.com/places/le-grand-k

https://www.npr.org/2018/11/13/666310991/say-au-revoir-to-that-hunk-of-metal-in-france-that-has-defined-the-kilogram

https://www.theguardian.com/science/2018/nov/03/the-future-of-the-kilo-a-weighty-matter-international-prototyp-kilogram-paris-kibble-balance

#84 What is graphene and why is it so important?

Image by AlexanderAlUS – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=11294534

https://en.wikipedia.org/wiki/Graphene

https://www.nanowerk.com/what_is_graphene.php

https://www.graphene-info.com/graphene-applications

https://firstgraphene.net/

https://www.graphene-info.com/graphene-introduction

https://www.graphenea.com/pages/graphene#.YejP2v7P0dU

https://en.wikipedia.org/wiki/Lamella_(materials)

https://en.wikipedia.org/wiki/P._R._Wallace

https://www.americanscientist.org/article/mass-producing-graphenehttps://www.nanowerk.com/spotlight/spotid=25744.php

#85 Why doesn’t the Malthusian theory of population apply today?

Image By John Linnell – Transferred from sr.wikipedia; transferred to Commons by User:BokicaK using CommonsHelper., Public Domain, https://commons.wikimedia.org/w/index.php?curid=7318108

https://en.wikipedia.org/wiki/Malthusianism

https://en.wikipedia.org/wiki/Thomas_Robert_Malthus

https://byjus.com/biology/malthusian-theory-of-population/

Malthusian Theory of Population

https://www.scientificamerican.com/article/why-malthus-is-still-wrong/

https://en.wikipedia.org/wiki/World_population

https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/population-theory-malthuss-influence-scope-evolution

https://examples.yourdictionary.com/common-predation-examples-in-biology.html

https://en.wikipedia.org/wiki/British_Agricultural_Revolution

https://medium.com/@jeremyerdman/we-produce-enough-food-to-feed-10-billion-people-so-why-does-hunger-still-exist-8086d2657539

https://www.worldometers.info/world-population/

https://en.wikipedia.org/wiki/Projections_of_population_growth

#86 Why don’t evergreen trees lose their leaves in the winter?

Photo by Olga Lioncat: https://www.pexels.com/photo/spruce-on-snowy-terrain-in-winter-park-7245258/

https://en.wikipedia.org/wiki/Evergreen

https://home.howstuffworks.com/evergreen-trees-dont-shed.htm

https://www.mentalfloss.com/article/72975/why-do-some-trees-keep-their-leaves-winter

https://en.wikipedia.org/wiki/Conifer

https://sciencing.com/photosynthesis-pine-trees-5851690.html

#87 When did people first start getting married?

Photo by Emma Bauso: https://www.pexels.com/photo/woman-and-man-holding-each-others-hands-2253842/

https://www.bbc.com/news/magazine-17351133

https://www.incegd.com/en/news-insights/family-matrimonial-history-marriage

https://www.brides.com/history-of-marriage-2300616

https://www.livescience.com/37777-history-of-marriage.html

https://en.wikipedia.org/wiki/Marriage

https://ehistory.osu.edu/articles/marriage-ancient-mesopotamia-and-babylonia

https://en.wikipedia.org/wiki/Dowry

https://en.wikipedia.org/wiki/Bride_pricehttps://en.wikipedia.org/wiki/Book_of_Common_Prayer_(1549)

#88 Why did Thomas Edison use bamboo in his light bulb?

Image By The ed17 – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=128087104

https://www.amusingplanet.com/2019/05/how-japanese-bamboo-helped-edison-make.html

https://www.fi.edu/history-resources/edisons-lightbulb

https://sciencing.com/thomas-edisons-light-bulb-work-4914923.html

https://edisontechcenter.org/ArcLamps.html

https://www.thoughtco.com/table-of-electrical-resistivity-conductivity-608499

https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/heat-resistance

https://en.wikipedia.org/wiki/Incandescent_light_bulb

#89 What happened to smallpox?

Image By Content Providers(s): CDC/ Dr. Fred Murphy; Sylvia Whitfield – This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number #1849.Note: Not all PHIL images are public domain; be sure to check copyright status and credit authors and content providers.العربية | Deutsch | English | македонски | slovenščina | +/−, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1214308

https://www.cdc.gov/smallpox/index.html

https://www.cdc.gov/smallpox/history/history.html

https://en.wikipedia.org/wiki/Smallpox

https://www.who.int/news-room/questions-and-answers/item/smallpox

https://en.wikipedia.org/wiki/History_of_smallpoxhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC1200696/

#90 What is nuclear pasta?

Image By NOIRLab/NSF/AURA/J. da Silva/Spaceengine – https://noirlab.edu/public/images/noirlab2218a/, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=126700561

https://www.skyatnightmagazine.com/space-science/nuclear-pasta/

https://www.sciencealert.com/nuclear-pasta-10-billion-times-stronger-than-steel-gravitational-wave-neutron-stars

https://en.wikipedia.org/wiki/Nuclear_pasta

https://en.wikipedia.org/wiki/Neutron_star

https://futurism.com/what-happens-when-stars-produce-iron

#91 Why did people storm the Bastille on July 14, 1789?

Image By Theodor Josef Hubert Hoffbauer – https://www.parismuseescollections.paris.fr/fr/musee-carnavalet/oeuvres/la-bastille-en-1420-chemin-route-de-vincennes-entre-la-tour-de-billy-et-la, Public Domain, https://commons.wikimedia.org/w/index.php?curid=16107370

Why Was the Storming of the Bastille Important?

https://www.history.com/this-day-in-history/french-revolutionaries-storm-bastille

https://en.chateauversailles.fr/discover/history/key-dates/summoning-estates-general-1789

https://www.dw.com/en/the-french-revolution-may-5-1789/a-4699902

https://www.britannica.com/event/French-Revolution

https://www.history.com/topics/france/french-revolution

https://en.wikipedia.org/wiki/French_Revolution

https://en.wikipedia.org/wiki/Timeline_of_the_French_Revolution

https://en.wikipedia.org/wiki/Storming_of_the_Bastille

https://www.ducksters.com/history/french_revolution/storming_of_the_bastille.php

https://blogs.nvcc.edu/nbomba/files/2016/10/FinancesLouisXVI.pdf

http://freepages.rootsweb.com/~unclefred/genealogy/MONETARY.htm

#92 Could a society without money work?

Photo by Pixabay: https://www.pexels.com/photo/bank-note-banknote-banknotes-bill-259251/

Can We Evolve Beyond Money?

https://en.wikipedia.org/wiki/Non-monetary_economy

https://paradism.org/

https://en.wikipedia.org/wiki/The_Zeitgeist_Movement

https://medium.com/@FOTONBANK/moneyless-society-is-it-possible-2ae40e20f8eb

https://www.jstor.org/stable/29769267

https://money.howstuffworks.com/moneyless-world.htm

http://www2u.biglobe.ne.jp/~nagaryu/indexenglish.html

https://slate.com/technology/2021/03/job-loss-automation-robots-predictions.html

#93 What exactly is pykrete?

Image By Bart van Overbeeke Fotografie – Donated by the photographer., CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=36554977

https://en.wikipedia.org/wiki/Pykrete

https://medium.com/predict/the-story-of-pykrete-that-time-the-navy-built-a-ship-out-of-ice-and-sawdust-be8de5ab5a00

http://www.structural-ice.com/dome.html

https://www.bbc.co.uk/bang/handson/pykrete.shtml

https://www.chemistryworld.com/podcasts/pykrete/3007891.article

https://doaj.org/article/2b54aa1665824e1eb4aa1048a3e84abb

https://en.wikipedia.org/wiki/Max_Perutz

https://en.wikipedia.org/wiki/Herman_Francis_Mark

https://en.wikipedia.org/wiki/Geoffrey_Pyke

https://www.chemeurope.com/en/encyclopedia/Pykrete.html

https://worldbuilding.stackexchange.com/questions/114048/the-polar-ice-caps-are-melting-can-i-replace-them-with-icebergs-made-of-pykrete

https://www.popularmechanics.com/science/a4101/4313387/

#94 What is dark matter?

Image By NASA, N. Benitez (JHU), T. Broadhurst (Racah Institute of Physics/The Hebrew University), H. Ford (JHU), M. Clampin (STScI),G. Hartig (STScI), G. Illingworth (UCO/Lick Observatory), the ACS Science Team and ESA – http://hubblesite.org/newscenter/newsdesk/archive/releases/2003/01/image/a, Public Domain, https://commons.wikimedia.org/w/index.php?curid=1727600

https://en.wikipedia.org/wiki/Dark_matter

https://en.wikipedia.org/wiki/Bullet_Cluster

https://www.space.com/20930-dark-matter.html

https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy

https://home.cern/science/physics/dark-matter

https://www.livescience.com/dark-matter.html

https://starchild.gsfc.nasa.gov/docs/StarChild/universe_level2/darkmatter.html

https://www.dummies.com/article/academics-the-arts/science/physics/the-universes-dark-matter-and-dark-energy-193334

https://kids.frontiersin.org/articles/10.3389/frym.2021.576034

https://depts.washington.edu/astroed/HubbleLaw/measurements.html

https://www.physicsclassroom.com/class/circles/Lesson-3/Newton-s-Law-of-Universal-Gravitation

https://en.wikipedia.org/wiki/Weakly_interacting_massive_particles

#95 Why was gin sold from a cat in London in 1739?

Image https://www.spiritofharrogate.co.uk/blogs/news/what-is-old-tom-gin

https://en.wikipedia.org/wiki/Gin_Craze

https://en.wikipedia.org/wiki/Dudley_Bradstreet

https://londonist.com/london/drink/london-s-gin-dispensing-cat

https://www.diffordsguide.com/g/1108/gin/old-tom-gin

https://www.pastemagazine.com/drink/alcohol-history/the-gin-craze-britain-1700s/

https://www.vice.com/en/article/53jj7z/how-a-gin-craze-nearly-destroyed-18th-century-london

https://www.historyextra.com/period/georgian/gin-craze-panic-18th-century-london-when-came-england-alcohol-drinking-history/

https://en.wikipedia.org/wiki/Beer_Street_and_Gin_Lane

https://en.wikipedia.org/wiki/Gin

#96 When did people start making jam?

Photo by Pixabay: https://www.pexels.com/photo/clear-glass-mason-jars-48817/

https://www.seriouseats.com/jams-jellies

A History of Jam and Preserves

https://en.wikipedia.org/wiki/Marcus_Gavius_Apicius

https://en.wikipedia.org/wiki/Apicius

https://en.wikipedia.org/wiki/Fruit_preserves

https://www.theguardian.com/science/blog/2013/oct/03/science-magic-jam-making

https://www.ps.org.au/content/articles/2018/11/13/larder-love-a-history-of-jams-amp-preserves

https://en.wikipedia.org/wiki/Nicolas_Appert

https://www.foodfanatic.com/2013/03/canning-q-and-a-how-to-reach-the-gel-stage/

#97 What are wormholes?

Image By Original: AllenMcC. Vector: KES47 – Own work based on: LorentzianWormhole.jpg by AllenMcC., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=30231987

https://physics.aps.org/story/v15/st11

https://www.livescience.com/what-are-wormholes

https://www.livescience.com/wormholes-may-be-stable-after-all

https://en.wikipedia.org/wiki/Wormhole

https://www.space.com/20881-wormholes.html

https://www.space.com/white-holes.html

https://en.wikipedia.org/wiki/Ludwig_Flamm

https://en.wikipedia.org/wiki/Schwarzschild_metric

https://en.wikipedia.org/wiki/Karl_Schwarzschild

https://en.wikipedia.org/wiki/Einstein_field_equations

https://en.wikipedia.org/wiki/White_hole

https://www.daviddarling.info/encyclopedia/E/exotic_matter.html

https://www.space.com/what-happens-black-hole-center

#98 When did UK prime ministers start living in 10 Downing Street?

Image By Photo: Sergeant Tom Robinson RLC/MOD, OGL v1.0, https://commons.wikimedia.org/w/index.php?curid=28014902

https://www.medicalnewstoday.com/articles/321889#The-protein-that-alters-temperature-reactivity

What’s Happening in My Body When I Have a Fever?

https://www.everydayhealth.com/cold-and-flu/why-do-we-get-chills-with-a-fever/

https://www.science.org/content/article/dont-fight-fever

https://en.wikipedia.org/wiki/Fever

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786079/

https://www.livescience.com/32134-what-causes-a-fever.html

https://www.scientificamerican.com/article/what-causes-a-fever/

https://en.wikipedia.org/wiki/Lymph_node

https://www.cancercenter.com/what-are-b-cells-vs-t-cells

https://en.wikipedia.org/wiki/Hypothalamus

https://www.onio.com/article/what-does-the-brain-go-through-during-a-fever.html

99 What makes the body produce a fever?

Photo by Polina Tankilevitch: https://www.pexels.com/photo/person-holding-thermometer-3873188/

https://www.sciencenewsforstudents.org/article/fever-can-help-immune-cells-attack

https://www.medicalnewstoday.com/articles/321889#The-protein-that-alters-temperature-reactivity

What’s Happening in My Body When I Have a Fever?

https://www.everydayhealth.com/cold-and-flu/why-do-we-get-chills-with-a-fever/

https://www.science.org/content/article/dont-fight-fever

https://en.wikipedia.org/wiki/Fever

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786079/

https://www.livescience.com/32134-what-causes-a-fever.html

https://www.scientificamerican.com/article/what-causes-a-fever/

https://en.wikipedia.org/wiki/Lymph_node

https://www.cancercenter.com/what-are-b-cells-vs-t-cells

https://en.wikipedia.org/wiki/Hypothalamus

https://www.onio.com/article/what-does-the-brain-go-through-during-a-fever.html

#100 What was Machu Picchu built for?

Photo by Chelsea Cook: https://www.pexels.com/photo/photo-of-machu-picchu-2929906/

https://en.wikipedia.org/wiki/Machu_Picchu

https://en.wikipedia.org/wiki/Pachacuti

https://en.wikipedia.org/wiki/Pachacuti

https://en.wikipedia.org/wiki/Viracocha_Inca

https://en.wikipedia.org/wiki/Topa_Inca_Yupanqui

https://www.msn.com/en-us/news/world/machu-picchu-in-peru-is-older-than-previously-thought/ar-AAMTUmw?li=BBnb7Kz

https://whc.unesco.org/en/list/274/

https://www.history.com/topics/south-america/machu-picchu

https://www.nationalgeographic.com/adventure/article/machu-picchu-hiram-bingham

https://en.wikipedia.org/wiki/Hiram_Bingham_III

https://www.britannica.com/place/Machu-Picchu

https://www.nationalgeographic.com/travel/article/secrets

https://www.peru.travel/en/attractions/machu-picchu

https://www.smithsonianmag.com/smart-news/radiocarbon-dating-reveals-machu-picchu-older-previously-thought-180978360/

https://www.livescience.com/machu-picchu-older-than-thought.html

#101 Is a space elevator possible?

Image By NASA/Pat Rawlings – NASA: [1]; Pat Rawlings: [2] search: space elevator, Public Domain, https://commons.wikimedia.org/w/index.php?curid=326317

https://www.pbs.org/wgbh/nova/sciencenow/3401/02-why.html

https://www.slashgear.com/is-a-space-elevator-possible-using-todays-technology-24708424/

https://www.slashgear.com/is-a-space-elevator-possible-using-todays-technology-24708424/

https://en.wikipedia.org/wiki/Space_elevator

https://www.nbcnews.com/mach/science/colossal-elevator-space-could-be-going-sooner-you-ever-imagined-ncna915421

https://www.bbc.com/future/article/20150211-space-elevators-a-lift-too-far

https://theconversation.com/how-spacex-lowered-costs-and-reduced-barriers-to-space-112586

https://users.wpi.edu/~paravind/Publications/PKASpace%20Elevators.pdf

http://spaceref.com/space-elevator/the-space-elevator-thought-experiment-or-key-to-the-universe-by-sir-arthur-c-clarke.html

https://worldbuilding.stackexchange.com/questions/100051/can-you-protect-a-space-elevator-from-space-junk

#102 How does cancer kill people?

Image By Lange123, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2110741

https://www.medicalnewstoday.com/articles/how-does-cancer-kill-you

https://en.wikipedia.org/wiki/Cancer

https://www.cancerresearchuk.org/about-cancer/coping/dying-with-cancer/how-can-cancer-kill-you

https://www.healthline.com/health/how-does-cancer-kill-you#complications

https://www.cancerresearchuk.org/about-cancer/what-is-cancer

https://www.cancer.org/cancer/cancer-causes/genetics/genes-and-cancer/oncogenes-tumor-suppressor-genes.html

https://moffitt.org/endeavor/archive/using-a-virus-to-treat-cancer

https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/chemotherapy/how-chemotherapy-drugs-work.html

https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/chemotherapy/how-chemotherapy-works

https://www.cancer.gov/about-cancer/understanding/statistics

https://www.cancer.gov/about-cancer/understanding/statistics

#103 Does Moore’s Law still apply today?

Image By Intel Free Press – https://www.flickr.com/photos/intelfreepress/8267616249/in/photostream/lightbox/, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=130035378

Contract Manufacturer Experts at MiQ Explore the Question: Is Moore’s Law Still Applicable Today?

Moore’s Law turns 55: Is it still relevant?

https://siliconangle.com/2021/04/10/new-era-innovation-moores-law-not-dead-ai-ready-explode/

https://builtin.com/hardware/moores-law

https://en.wikipedia.org/wiki/Moore%27s_law

https://en.wikipedia.org/wiki/Integrated_circuit

https://www.thoughtco.com/what-is-a-microchip-1991410

https://en.wikipedia.org/wiki/Gordon_Moore

https://en.wikipedia.org/wiki/Robert_Noyce

https://www.explainthatstuff.com/howtransistorswork.html

https://en.wikipedia.org/wiki/Transistor

https://www.thoughtco.com/history-of-integrated-circuit-aka-microchip-1992006

https://en.wikipedia.org/wiki/Transistor_count

https://phys.org/news/2008-02-intel-microchip-billion-transistors.html

https://niklasrosenberg.com/blog/2020/7/15/what-does-it-mean-to-have-60-billion-transistors-in-a-computer-chip

#104 Why is the speed of light 299,792,458 m/s?

Photo by Felix Mittermeier: https://www.pexels.com/photo/silhouette-of-person-under-blue-and-purple-sky-957040/

https://www.space.com/speed-of-light-properties-explained.html

https://www.sciencefocus.com/science/why-is-the-speed-of-light-constant/

http://www2.phys.canterbury.ac.nz/~dlw24/c.html

https://aeon.co/essays/why-is-the-speed-of-light-the-speed-of-light

https://www.sciencealert.com/why-is-the-speed-of-light-the-speed-of-light

https://en.wikipedia.org/wiki/Speed_of_light

https://en.wikipedia.org/wiki/Ole_R%C3%B8mer

https://en.wikipedia.org/wiki/Ibn_al-Haytham

https://www.space.com/15830-light-speed.html

https://www.theguardian.com/science/2014/jan/12/einstein-theory-of-relativity-speed-of-light

https://cosmosmagazine.com/science/physics/why-cant-anything-travel-faster-than-light/

https://www.wtamu.edu/~cbaird/sq/2017/07/20/is-the-reason-that-nothing-can-go-faster-than-light-because-we-have-not-tried-hard-enough/

https://www.sciencefocus.com/science/how-fast-does-electricity-flow/

#105 Why do we have 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute?

Photo by Stas Knop: https://www.pexels.com/photo/white-clock-reading-at-2-12-1537268/

https://en.wikipedia.org/wiki/Hour

https://en.wikipedia.org/wiki/Hipparchus

https://en.wikipedia.org/wiki/Minute

https://en.wikipedia.org/wiki/Second

https://www.theguardian.com/notesandqueries/query/0,5753,-1487,00.html

https://www.livescience.com/44964-why-60-minutes-in-an-hour.html

https://www.scientificamerican.com/article/experts-time-division-days-hours-minutes/

https://en.wikipedia.org/wiki/Duodecimal

https://www.seeker.com/who-decided-there-are-24-hours-in-a-day-1792565373.html

https://en.wikipedia.org/wiki/History_of_sundials

https://en.wikipedia.org/wiki/Hipparchus

https://en.wikipedia.org/wiki/Al-Biruni

https://en.wikipedia.org/wiki/Ptolemy

https://www.livescience.com/44964-why-60-minutes-in-an-hour.html

#106 How does a machine gun work?

Photo by Somchai Kongkamsri: https://www.pexels.com/photo/man-lying-forward-using-rifle-at-the-field-during-day-35825/

https://en.wikipedia.org/wiki/Firearm

https://en.wikipedia.org/wiki/Fire_lance

https://www.brown.edu/Departments/Joukowsky_Institute/courses/13things/7687.html

https://www.pbs.org/opb/historydetectives/technique/gun-timeline/

https://science.howstuffworks.com/machine-gun.htm

https://en.wikipedia.org/wiki/Machine_gun

https://en.wikipedia.org/wiki/Maxim_gun

https://en.wikipedia.org/wiki/Vickers_machine_gun

https://en.wikipedia.org/wiki/M61_Vulcan

https://en.wikipedia.org/wiki/AK-47

https://en.wikipedia.org/wiki/Recoil_operation

https://en.wikipedia.org/wiki/Rotary_cannon

https://en.wikipedia.org/wiki/Gatling_gun

#107 When did the Mafia come to America?

Image By Unknown author – La Cosa Nostra Database (accessed October 30, 2010), Public Domain, https://commons.wikimedia.org/w/index.php?curid=14920001

https://www.bbc.com/news/world-europe-42794848

http://websites.umich.edu/~themafia/RevisedHistory.htm

https://www.fbi.gov/investigate/organized-crime/history-of-la-cosa-nostra

https://davidfrum.com/article/cosa-nostra-a-history-of-the-sicilian-mafia

https://en.wikipedia.org/wiki/%27Ndrangheta

https://en.wikipedia.org/wiki/Sicilian_Mafia

https://www.ojp.gov/ncjrs/virtual-library/abstracts/sicilian-mafia-and-its-impact-united-states

https://www.history.com/topics/crime/mafia-in-the-united-states

https://www.history.com/topics/crime/origins-of-the-mafia

https://en.wikipedia.org/wiki/American_Mafia

https://en.wikipedia.org/wiki/Prohibition_in_the_United_States

https://en.wikipedia.org/wiki/Giuseppe_Morello

https://en.wikipedia.org/wiki/Genovese_crime_family

https://en.wikipedia.org/wiki/Vito_Genovese

https://en.wikipedia.org/wiki/The_Commission_(American_Mafia)

https://en.wikipedia.org/wiki/Five_Families

https://www.loc.gov/classroom-materials/immigration/italian/the-great-arrival/

#108 Is coral a plant or an animal?

Photo by Francesco Ungaro: https://www.pexels.com/photo/photo-of-yellow-fishes-near-corals-3129556/

https://www.unep.org/news-and-stories/story/why-are-coral-reefs-dying

https://floridakeys.noaa.gov/corals/coralanimals.html

https://en.wikipedia.org/wiki/Coral

https://en.wikipedia.org/wiki/Terpenoid

https://en.wikipedia.org/wiki/Scleractinia

https://en.wikipedia.org/wiki/Octocorallia

https://en.wikipedia.org/wiki/Mesoglea

https://en.wikipedia.org/wiki/Zooxanthellae

https://en.wikipedia.org/wiki/Sessility_(motility)

https://oceanservice.noaa.gov/facts/coral.html

https://www.nationalgeographic.org/encyclopedia/coral/

https://www.livescience.com/40276-coral-reefs.html

What are corals?

https://www.biologicaldiversity.org/campaigns/freshwater_mussels/natural_history.html

https://faq-all.com/en/Q%26A/page=74ec735466fb3368c69f8f6e8a5b5857

https://sciencing.com/coral-reefs-come-many-colors-5434662.html

https://www.aims.gov.au/docs/research/climate-change/coral-bleaching/coral-bleaching.html

#109 How does Valium (diazepam) work on the brain?

Image By Fr0sty $ummer – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=49949064

https://www.washingtonpost.com/archive/lifestyle/wellness/1987/02/17/valium-in-the-marketplace/e8ab1315-8a55-4b80-bba6-75acf3f38b8c/

https://www.webmd.com/vitamins/ai/ingredientmono-464/gamma-aminobutyric-acid-gaba

https://www.netdoctor.co.uk/medicines/brain-nervous-system/a6560/diazepam/

https://www.verywellmind.com/how-long-does-valium-stay-in-your-system-80344

https://www.drugs.com/tips/valium-patient-tips

https://www.healthdirect.gov.au/diazepam

https://en.wikipedia.org/wiki/Diazepam

https://en.wikipedia.org/wiki/Leo_Sternbach

https://en.wikipedia.org/wiki/Roche

https://en.wikipedia.org/wiki/GABAA_receptor

https://www.drugs.com/valium.html

https://drugabuse.com/benzodiazepines/valium/history-and-statistics/

https://www.wsj.com/articles/an-anxious-history-of-valium-1384547451

https://www.therecoveryvillage.com/valium-addiction/valium-overdose/

#110 How does Bluetooth work?

Photo by Karolina Grabowska: https://www.pexels.com/photo/selective-focus-photo-of-a-person-putting-airpods-in-a-case-7679539/

https://electronics.howstuffworks.com/bluetooth.htm

Want to know how does Bluetooth work? We’ll pair you with some answers.

https://www.explainthatstuff.com/howbluetoothworks.html

https://en.wikipedia.org/wiki/Bluetooth

https://en.wikipedia.org/wiki/Bluetooth_Special_Interest_Group

https://en.wikipedia.org/wiki/Frequency-hopping_spread_spectrum

https://en.wikipedia.org/wiki/Code-division_multiple_access

https://www.sciencedirect.com/topics/computer-science/bluetooth

#111 What is a letter of marque?

Photo by Pixabay: https://www.pexels.com/photo/a-pirate-ship-sailing-on-sea-during-golden-hour-37730/

Pirates, Privateers, Corsairs, Buccaneers: All the Differences

https://www.rmg.co.uk/stories/topics/letters-marque

https://en.wikipedia.org/wiki/Letter_of_marque

https://en.wikipedia.org/wiki/Fore-and-aft_rig

https://en.wikipedia.org/wiki/Square_rig

https://www.law.cornell.edu/wex/letter_of_marque

https://www.britannica.com/story/pirates-privateers-corsairs-buccaneers-whats-the-difference

Letter of Marque / Privateer Commission

https://military-history.fandom.com/wiki/Letter_of_marque

https://loyalist.lib.unb.ca/node/4440

https://en.wikipedia.org/wiki/Francis_Drake

#112 What are stem cells and how do they work?

Image Public Domain, https://commons.wikimedia.org/w/index.php?curid=456457

https://en.wikipedia.org/wiki/Stem_cell

https://www.yourgenome.org/facts/what-is-a-stem-cell

https://projects.sfchronicle.com/2018/stem-cells/about-stem-cells/

https://www.healthline.com/health/number-of-cells-in-body#human-cells

https://research.ucdavis.edu/wp-content/uploads/Stem-Cell-Research-Quick-Guide.pdf

https://www.mayoclinic.org/tests-procedures/bone-marrow-transplant/in-depth/stem-cells/art-20048117

https://www.unmc.edu/stemcells/educational-resources/prosandcons.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2726839/

https://en.wikipedia.org/wiki/Theodor_Boveri

https://en.wikipedia.org/wiki/Valentin_Haecker

#113 Did pirates really use the Jolly Roger flag?

Images By Karlsson, Anneli (color correction by Blockhaj) – https://digitaltmuseum.se/021015506485/konservator-fran-armemuseet-tittar-till-den-lanade-piratflaggan-fran-alands, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=122327681

https://www.worldhistory.org/article/1813/the-jolly-roger–other-pirate-flags/

https://en.wikipedia.org/wiki/Jolly_Roger

https://en.wikipedia.org/wiki/Piracy

https://en.wikipedia.org/wiki/Sea_Peoples

https://en.wikipedia.org/wiki/Piracy_in_the_Caribbean

https://en.wikipedia.org/wiki/Golden_Age_of_Piracy

https://blogs.scientificamerican.com/anthropology-in-practice/why-did-pirates-fly-the-jolly-roger/

https://www.bbc.com/news/uk-england-hampshire-16164191

https://www.theguardian.com/notesandqueries/query/0,,-1173,00.html

https://www.vispronet.com/blog/famous-pirate-flags/

https://en.wikipedia.org/wiki/Edward_Low

https://en.wikipedia.org/wiki/Bartholomew_Roberts

https://en.wikipedia.org/wiki/Calico_Jack

https://en.wikipedia.org/wiki/Edward_England

https://en.wikipedia.org/wiki/Captain_Napin

#114 What are the six great mass extinction events?

Photo by Marcus Lange: https://www.pexels.com/photo/dinosaur-fossil-on-rough-stone-formation-3839557/

https://www.livescience.com/mass-extinction-events-that-shaped-Earth.html

https://www.amnh.org/exhibitions/dinosaurs-ancient-fossils/extinction/mass-extinction

https://www.thoughtco.com/the-5-major-mass-extinctions-4018102

https://en.wikipedia.org/wiki/Extinction_event

https://en.wikipedia.org/wiki/Late_Ordovician_mass_extinction

https://en.wikipedia.org/wiki/Late_Devonian_extinction

https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event

https://en.wikipedia.org/wiki/Triassic%E2%80%93Jurassic_extinction_event

https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event

https://www.discovermagazine.com/the-sciences/mass-extinctions

https://en.wikipedia.org/wiki/Earliest_known_life_forms

https://en.wikipedia.org/wiki/Origin_of_water_on_Earth#History_of_water_on_Earth

https://www.discovermagazine.com/the-sciences/what-are-the-oldest-fossils-in-the-world

https://en.wikipedia.org/wiki/Great_Oxidation_Event

#115 How does an eraser work?

Photo by Pixabay: https://www.pexels.com/photo/blue-office-eraser-orange-35202/

https://en.wikipedia.org/wiki/Graphite

https://www.wonderopolis.org/wonder/how-does-an-eraser-work

https://science.howstuffworks.com/innovation/everyday-innovations/erasers-erase.htm

https://www.thoughtco.com/how-do-pencil-erasers-work-604298

https://www.acs.org/content/dam/acsorg/education/whatischemistry/adventuresinchemistry/secretscience/pencil/pencils.pdf

Why Does Graphite Leave A Mark On Paper

https://www.physicsforums.com/threads/graphite-pencil-and-paper.45471/

https://en.wikipedia.org/wiki/Paper

https://en.wikipedia.org/wiki/Eraser

https://www.theatlantic.com/technology/archive/2014/10/why-do-erasers-suck-at-erasing/381025/

https://en.wikipedia.org/wiki/Natural_rubber

#116 Where did the stones of Stonehenge come from?

Photo by Florian Gerus: https://www.pexels.com/photo/gray-rock-formations-on-green-grass-field-under-white-clouds-7052315/

https://www.historyextra.com/period/prehistoric/secrets-stonehenge-where-how-built-theories/

https://en.wikipedia.org/wiki/Stonehenge

https://en.wikipedia.org/wiki/Inigo_Jones

https://www.english-heritage.org.uk/visit/places/stonehenge/history-and-stories/building-stonehenge/

https://www.bbc.com/news/uk-wales-57639510

https://news.sky.com/story/stonehenge-stones-moved-by-land-not-sea-new-study-suggests-11642196

https://www.nationalgeographic.com/history/article/111222-stonehenge-bluestones-wales-match-glacier-ixer-ancient-science

https://www.history.com/topics/british-history/stonehenge

#117 Why do Venus and Uranus spin the wrong way?

Image By Kevin M. Gill – https://www.flickr.com/photos/53460575@N03/50513674188/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=95498116

https://www.scientificamerican.com/article/why-venus-spins-the-wrong/

https://astronomy.com/magazine/ask-astro/2016/08/the-moons-rotation-rate

https://www.theverge.com/2021/6/2/22465588/nasa-mission-to-venus-davinci-veritas-discovery-program

https://www.amnh.org/exhibitions/permanent/the-universe/planets/formation-of-our-solar-system

https://www.sciencealert.com/why-are-venus-and-uranus-spinning-in-the-wrong-direction

https://coolcosmos.ipac.caltech.edu/ask/50-Does-Venus-really-spin-backwards-

https://en.wikipedia.org/wiki/Venus

https://en.wikipedia.org/wiki/Uranus

#118 When did people start putting drinks in cans?

Photo by Martin  Péchy: https://www.pexels.com/photo/person-holding-pepsi-can-1292294/

https://www.aircontrolindustries.com/us/packaging-and-labelling-us/evolution-of-the-beverage-can/

https://industrialphysics.com/knowledgebase/history-of-the-can/

https://en.wikipedia.org/wiki/Drink_can

https://www.cancentral.com/can-stats/history-of-the-can/time-innovation

https://en.wikipedia.org/wiki/Gottfried_Krueger_Brewing_Company

https://en.wikipedia.org/wiki/Church_key

https://www.theworldcounts.com/challenges/consumption/foods-and-beverages/aluminium-cans-facts/story

#119 How do people know the age of the universe?

Photo by Alex Andrews: https://www.pexels.com/photo/photo-of-supernova-in-galaxy-3805983/

https://www.forbes.com/sites/startswithabang/2019/12/10/this-is-how-astronomers-know-the-age-of-the-universe-and-you-can-too/?sh=332df0d16d56

https://wmap.gsfc.nasa.gov/universe/uni_age.html

https://en.wikipedia.org/wiki/Age_of_the_universe

https://en.wikipedia.org/wiki/Cosmic_microwave_background

https://en.wikipedia.org/wiki/Big_Bang#Cosmic_microwave_background_radiation

https://www.newscientist.com/question/how-old-is-the-universe/

https://www.space.com/24054-how-old-is-the-universe.html

https://bigthink.com/starts-with-a-bang/how-do-we-know-the-age-of-the-universe/

https://en.wikipedia.org/wiki/Baryon_acoustic_oscillations

https://history.aip.org/exhibits/curie/age-of-earth.htm

How old is the universe? Our answer keeps getting better.

https://physics.stackexchange.com/questions/194386/can-anyone-explain-the-unit-for-rate-of-expansion-of-universe

#120 Why did the Portuguese royal family end up in Brazil?

Photo by Luan Gonçalves: https://www.pexels.com/photo/an-aerial-photography-of-christ-the-redeemer-13911606/

https://en.wikipedia.org/wiki/Transfer_of_the_Portuguese_court_to_Brazil

https://en.wikipedia.org/wiki/Colonial_Brazil

https://artsandculture.google.com/story/5AXRumB0octrLg

“The only colony in modern history to swallow its own empire”: how the Portuguese royal family remade Rio

https://en.wikipedia.org/wiki/Maria_I_of_Portugal

https://en.wikipedia.org/wiki/John_VI_of_Portugal

https://artsandculture.google.com/story/5AXRumB0octrLg

#121 How do gas masks work?

Photo by Sergey  Meshkov: https://www.pexels.com/photo/close-up-photo-of-safety-protective-gas-mask-11499400/

https://www.livescience.com/39217-how-do-gas-masks-work.html

https://www.usatoday.com/story/news/factcheck/2020/06/11/fact-check-n-95-filters-not-too-large-stop-covid-19-particles/5343537002/

https://en.wikipedia.org/wiki/Gas_mask

https://www.nationalgeographic.com/science/article/130830-gas-masks-syria-israel-chemical-warfare

https://science.howstuffworks.com/gas-mask1.htm

https://www.cdc.gov/niosh/npptl/topics/respirators/factsheets/respfact.html

#122 Why did the Bronze Age start?

Image By Dbachmann, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1500792

https://en.wikipedia.org/wiki/Stone_Age

https://www.history.com/topics/pre-history/bronze-age

https://en.wikipedia.org/wiki/Bronze_Age

https://en.wikipedia.org/wiki/Bronze

https://en.wikipedia.org/wiki/Smelting

https://www.abc.net.au/science/articles/2015/03/31/4206279.htm

https://academic.mu.edu/meissnerd/bronzeage.html

https://en.wikipedia.org/wiki/Sword

#123 What is a tokamak?

By Rswilcox – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=73919081

https://www.iter.org/mach/Tokamak

https://en.wikipedia.org/wiki/Tokamak

https://en.wikipedia.org/wiki/Fusion_power

https://en.wikipedia.org/wiki/Plasma_(physics)

https://www.energy.gov/science/doe-explainstokamaks

https://www.energy.gov/science/doe-explainsplasma-confinement

https://en.wikipedia.org/wiki/Thermonuclear_weapon

Fusion in brief

https://www.iter.org/mach/Magnets

https://www.iter.org/proj/inafewlines

https://www.sciencefocus.com/future-technology/fusion-power-future/

#124 Why do cats sleep for so long?

Photo by Pixabay: https://www.pexels.com/photo/adorable-animal-baby-blur-279360/

Fascinating Animal Sleep Facts

https://www.hillspet.com/cat-care/behavior-appearance/why-cats-sleep-so-much

https://www.britannica.com/story/why-do-cats-sleep-so-much

https://www.petmd.com/cat/behavior/evr_ct_why_do_cats_sleep_so_much

https://en.wikipedia.org/wiki/Cat

https://www.smithsonianmag.com/science-nature/the-secret-lives-of-feral-cats-179790776/

#125 What is Polaris?

Image By Kush.Chandaria – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=108074228

https://www.newscientist.com/article/mg12617152-800-science-the-pole-star-stops-pulsating/

https://www.science.org/content/article/north-star-may-be-wasting-away

Polaris

https://www.lpi.usra.edu/education/skytellers/polaris/

https://solarsystem.nasa.gov/news/1944/what-is-the-north-star-and-how-do-you-find-it/

https://www.space.com/15567-north-star-polaris.html

https://en.wikipedia.org/wiki/Cepheid_variable

https://en.wikipedia.org/wiki/Yellow_supergiant

https://en.wikipedia.org/wiki/Polaris

https://usm.maine.edu/planet/it-true-vega-will-be-our-next-north-star