I decided on this title half as a joke since how sure can I really be that these are really "facts". But for many years I did not know that factoids was almost a janus word, I was so used to the north american meaning of the word.

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Note how factoids are not facts in the first definition.

So below is a collection of interesting facts I came across as I read books and browsed articles online. Lot of it is from Wikipedia.

  1. Until the discovery of diamonds in Brazil in 1726, India was the only place where diamonds were mined.
  2. The continental crust is less dense (2.83 g/$cm^3$) than oceanic crust (3 g/$cm^3$) thus it floats (the upper mantle is solid rock but is also ductile enough) higher on the mantle (3.3 g/$cm^3$), leaving the ocean on top of the oceanic crust. This is even though the continental crust (25 to 70 km) is thicker than the oceanic crust (7 - 10 km). The less-dense oceanic crust is typically subducted (partial melting) back into the mantle, the lighter material rises as magma, forming volcanoes, and adds to the continental crust ensuring it stays less dense.
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The oceanic crust is young with shorter lifecycle, mostly basalt while continetal is granite. This recycling loop of the oceanic crust is why it is more dense.

3. A nebular cloud the size of the Earth would have a total mass of only a few kilograms. A nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases.

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Hubble's Wide Field Camera 3 observed the Carina Nebula on 24 - 30 July 2009. It is located 7500 light-years away.

4. Banded iron formations account for more than 60% of global iron reserves and provide most of the iron ore presently mined. They are distinctive units of sedimentary rock that are almost always of Precambrian age. (2.4 - 1.8 bya) They are thought to have formed in seawater as the result of oxygen production by photosynthetic cyanobacteria. The oxygen combined with dissolved iron in Earth's oceans to form insoluble iron oxides, which precipitated out, forming a thin layer on the ocean floor.

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Banded Iron Formation at the Fortescue Falls, Karijini, Australia

5. Sexual concordance refers to the degree to which genital response and self-reported sexual arousal correspond with each other. Men are significantly more sexually concordant than women. Men also are better at interoception, i.e. awareness of (nonsexual) physiological states or responses such as heart rate.

6. Around 2.45 bya, cyanobacteria (the first organisms to evolve the ability to photosynthesize) started to cause $O_2$ levels to spike (Great Oxygenation Event - peaked at 1.2 bya) leading to a mass extinction. This $O_2$ combined with methane to form carbon dioxide and water, which does not retain heat as well as methane does, leading to the oldest and longest ice age (Huronian glaciation - 2.4 to 2.1 bya).

7. In the early Universe, there were no minerals because the only elements available were hydrogen, helium, and trace amounts of lithium. Before the formation of the Solar System, there were about 12 minerals. The Great Oxygenation Event provided a new opportunity for biological and mineral diversification. It might be directly responsible for more than 2,500 of the total of about 4,500 minerals found on Earth today. Most of these new minerals were formed as hydrated and oxidized forms. Despite the natural recycling of organic matter, life had remained energetically limited until the widespread availability of oxygen. Now with greatly increased free energy available to living organisms. For example, mitochondria evolved after the GOE.

8. There have been 7 Supercontinents, with the most recent being Pangaea. With each supercontinent cycle taking 300 to 500 million years, we see the quasi-periodic aggregation and dispersal of Earth's continental crust happening. Visualize it here.

The most recent supercontinent, Pangaea, formed about 300 million years ago. See it in 3D here.

9. The Cretaceous–Tertiary (K–T) extinction event killed off some three-quarters of the plant and animal species on Earth. It was caused by the impact of a massive comet or asteroid 10 to 15 km. Every living thing with a body mass over 10 kilograms became extinct, and the age of the dinosaurs came to an end. The impact would have created a dust cloud that blocked sunlight for up to a year, inhibiting photosynthesis

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The asteroid hit an area of carbonate rock containing a large amount of combustible hydrocarbons and sulphur, much of which was vaporized, thereby injecting sulfuric acid aerosols into the stratosphere, which might have reduced sunlight reaching the Earth's surface by more than 50%, and would have caused acid rain. It would take at least ten years for such aerosols to dissipate, and would account for the extinction of plants and phytoplankton, and subsequently herbivores and their predators.

10. The Permian–Triassic (P–Tr or P–T) extinction event is the Earth's most severe known extinction event, with around 81% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It was the largest known mass extinction of insects. Some 57% of all biological families and 83% of all genera became extinct. It is thought that a large meteor impact led to the Siberian Traps Volcanic eruption (2 million square kilometres covered with lava) which led to coal or gas fires and explosions (causing dust clouds and acid aerosols, which would have blocked out sunlight and thus disrupted photosynthesis) spewed carbon dioxide (causing global warming) and spewed highly toxic ash. The warming from the greenhouse effect would reduce the solubility of oxygen in seawater, causing the concentration of oxygen to decline. The oceans became so anoxic, that anaerobic sulfur-reducing organisms dominated the chemistry of the oceans and caused massive emissions of toxic hydrogen sulfide leading to oceans euxinia.

11. The history of linguistics begins not with Plato or Aristotle, but with the Indian grammarian Panini (early to mid fourth century B. C.). Pānini's theory of morphological analysis was more advanced than any equivalent Western theory before the 20th century.

12. Kopi Luwak is also called caphe cut chon (fox-dung coffee). It is coffee that is prepared using coffee cherries that have been eaten and partly digested by the Asian palm civet, then harvested from its fecal matter. The civets digest the flesh of the coffee cherries but pass the pits (beans) inside, where stomach enzymes affect the beans, which adds to the coffee's prized aroma and flavor. 0.5 kg (1 lb) can cost up to 600 USD (₹40k) in some parts of the world and about 100 USD (₹6.6k) a cup in others.

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Coffee cherries are eaten by them and their droppings contain fermented beans. Credit - Liwa, Sumatra

13. About 66 - 68 million years ago present-day India was above the hot spot and great volumes of basaltic lava erupted to produce the Deccan Traps. As the plate moved northeast over the hot spot more volcanic centers formed: the Maldives from 55-60 million years ago, the Chagos Ridge 48 million years ago, the Mascarene Plateau 40 million years ago, and the Mauritus Islands from 18-28 million years ago. The youngest volcanoes, Piton des Neiges and Piton de la Fournaise, formed in the last 5 million years. The summits of these volcanoes make the island of Reunion. It is thought that it is also responsible for the separation of Madagascar and India.

deccan traps close up pic
The original area covered by the lava flows is estimated to have been as large as 1.5 million km^2 approximately half the size of modern India. The Deccan Traps region was reduced to its current size by erosion and plate tectonics; the present area of directly observable lava flows is around 500,000 km^2.This series of eruptions may have lasted fewer than 30,000 years. Image Source.
Made using Google Earth.

14. The north and south celestial poles are the two imaginary points in the sky where the axis of rotation, indefinitely extended, intersects the Earth. The positions of the south and north celestial poles appear to move in circles against the space-fixed backdrop of stars, completing one circuit in approximately 26,000 years. Thus, while today the star Polaris lies approximately at the north celestial pole, this will change over time, and other stars will become the "north star". In approximately 3200 years, the star Gamma Cephei will be the next north star.

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You can see how in 26,000 years it will return to Polaris. Image via Tfr000/ Wikimedia Commons.

15. If the year [ % 4 == 0 && (% 100 != 0 OR % 400 == 0) ], Then its a leap year in the Gregorian calendar. Adding that extra day bring the average length of a year to be 365.2425 which is closer to the astronomical 365.2422 days.

16. The Ancient Egyptians were the first to use 24 hours to divide the day. They divided the day into 12 hours from sunrise to sunset, and the night into a further 12 hours from sunset to sunrise.

17. When the hour was divided into 60 minutes, consisting of 60 seconds, the number 60 was probably chosen for its mathematical convenience. It is divisible by a large number of smaller numbers without a remainder: 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30.

18. Our use of the seven-day week, can be traced back to the astronomically gifted Babylonians and the decree of King Sargon I of Akkad around 2300 BCE. They certainly venerated the number seven and before telescopes the key celestial bodies numbered seven (the Sun, the Moon and the five planets visible to the naked eye). The seven-day week is closely linked to Judaism (and from the Holy Book to Christianity and Islam) based on the story of Genesis with God resting on the seventh day. For the past two millennia, Western Civilisation has had a seven-day week.

19. Regardless of the culture, all lunar months approximate the average period the Moon takes to cycle through its phases - 29 to 30 days, making a lunar year of 12 months about 11 days shorter than a solar year. There is a cycle when they align.

20. The Moon's rotation and orbital periods are tidally locked with each other, so no matter when the Moon is observed from Earth, the same hemisphere of the Moon is always seen.

If the Moon didn't spin at all, then it would alternately show its near and far sides to the Earth while moving around our planet in orbit, as shown in the figure on the right. credits

21. During a total lunar eclipse, Earth completely blocks direct sunlight from reaching the Moon. The only light reflected from the lunar surface has been refracted by Earth's atmosphere. This light appears reddish for the same reason that a sunset or sunrise does: the Rayleigh scattering of bluer light over a longer path. Due to this reddish color, a totally eclipsed Moon is sometimes called a blood moon.

22. After a little more than 18 years (Saros period), the sun, moon and earth return to the same positions. Thus eclipses of the same type repeat.

23. The Uranian axis of rotation is approximately parallel with the plane of the Solar System. It is thought that some impact event whacked Uranus into retrograde rotation unlike the remaining planets except Venus which are in prograde (anti clockwise aligned with Sun). Venus probably began with a fast prograde rotation but the strong gravitational tides trying to tidally lock Venus to the Sun caused the present-day slow retrograde rotation.

24. The spoked wheel allowed the construction of lighter and swifter vehicles. It was invented in the Harappan civilization of the Indus Valley. Chalcolithic paintings (1800-1200 BC) depict them.

25. A much more common characteristic of South Indian Hindu society is permission for marriage between cross-cousins (children of brother and sister) as they are of different gotras. Thus, a man is allowed to marry his maternal uncle's daughter or his paternal aunt's daughter, but is not allowed to marry his paternal uncle's daughter. She would be considered a parallel cousin, of the same gotra, and therefore to be treated as a sister. As much as 23% of marriages might be consanguineous in South Indian Hindu society.

26. Sea otters spend most of their time in the water. They eat, sleep, hunt, mate and give birth in the water. To prevent themselves from floating away in the swirling sea while they sleep, sea otters often entangle themselves in forests of kelp or giant seaweed to provide anchorage. This is also the reason why they hold hands. They do so in order to prevent themselves from drifting away from the group.

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Sea otters, particularly mothers and pups, sometimes hold hands while floating on their backs. Hand-holding keeps the otters from drifting away from each other and their food source while they sleep.

27. On Earth, the lightning frequency is approximately 40 - 50 times a second and the average duration is 0.2 seconds made up from a number of much shorter flashes (strokes) of around 60 to 70 microseconds. Each strike causes the instantaneous release of as much as one gigajoule of energy. (The KE of 1000 1 ton vehicle moving at 161 km/h)

28. Alexander The Great had one blue and one brown eye. On either 10 or 11 June 323 BC, Alexander died aged 32, probably due to poisoning by veratrum album or calicheamicin.

29. The ability of the human brain by far exceeds what was needed for survival in the ancestral environment. One important evolutionary psychology explanation for this is that the human brain and associated traits (such as artistic ability and creativity) are the human equivalent of the peacock's tail. Superior execution of art was evolutionary important because it attracted mates.

30. By the late 19th-century, the caste system of Kerala had evolved to be the most complex to be found anywhere in India. There were over 500 groups represented in an elaborate structure of relationships and the concept of ritual pollution extended not merely to untouchability but even further, to unapproachability. Among Christians, the established Syrian Christians also practiced the rules of untouchability. Even in the 17th century, these rules were intricate - a Nair can approach but not touch a Namboodiri Brahmin: a Ezhava must remain thirty-six paces off, and a Pulayan slave ninety-six steps distant. A Ezhava must remain twelve steps away from a Nair, and a Pulayan sixty-six steps off, and a Parayan some distance farther still. The lower castes, particularly the Pulayars were not even allowed to breathe the same air as the other castes or use a public pathway. The Nair's right to kill any Pulayar (Cheraman) imminently he met on the pathway is confirmed by almost all visitors to Kerala. The demise of orthodoxy, right beliefs, has not meant the demise of orthopraxy, right practice. Caste remains endogamous.

31. The advantage metal blades have over stone ones isn’t sharpness (there was a tiny industry of stone tool manufacture for delicate eye surgery before lasers came in), but durability. Obsidian, a type of volcanic glass can produce cutting edges many times finer than even the best steel scalpels. (30 angstroms is better than the 300 to 600 angstroms of household razor blades)

32. It has been estimated that the observable universe contains between $10^{78}$ to $10^{82}$ atoms, far fewer than the number of possible legal positions that Go (the board game) can take when played on a regular board of size (19 x 19) which is to the order of $10^{170}$. Even for the smaller 13×13 board variant the number is around the number of atoms.

33. At the beginning of the nineteenth century an estimated three-quarters of all people alive were trapped in bondage against their will either in some form of slavery or serfdom. Most ethnic groups were slaves at one point, The Byzantine–Ottoman wars and the Ottoman wars in Europe resulted in the taking of large numbers of Christian slaves, the Romans took Britons as slaves, the Egyptians took Jews as slaves. It started way back in 1760 BC where the Code of Hammurabi condoned it.

34. Heritability is a measure of how much of the variation of a trait can be attributed to variation of genetic factors, as opposed to variation of environmental factors (given a particular environment and population). For human behavior, almost all estimates of heritability are in the moderate range of .30 to .60. Adult height - 0.80 (within families), 0.58 to 0.86 when it comes to IQ. Other traits have lower heritabilities, which indicate a relatively larger environmental influence like depression in men - 0.29, while it was 0.42 for women. But there are some controversies.

35. The word Juggernaut is derived from the Sanskrit Jagannātha (Devanagari जगन्नाथ) "world-lord", combining jagat ("world") and natha ("lord"), which is one of the names of Krishna found in the Sanskrit epics.

36. Amphibians (frogs, toads, salamanders), Annelids (earthworm) and some Echinoderms (sea urchin) breathe through their moist skin.

37. Moment magnitude (Mw) is now the most common measure of earthquake size for medium to large earthquake but much of the news media still refers to these as "Richter" magnitudes. But the United States Geological Survey does not use this scale for earthquakes with a magnitude of less than 3.5.

38. The northern lights or auroras are the result of disturbances in the magnetosphere caused by solar wind. They take place on an 11-year solar cycle, it is inversely affected by the sun spot cycle. The last solar minimum (few sunspots appear on Sun's surface) occurred in December 2019, marking the start of a new solar cycle. It is expected that July 2025 is the next solar maximum and that is when we can expect the northern lights to shine brightly again.

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The Aurora borealis, or northern lights, above Bear Lake, Alaska

39. Sugarcane is the world's largest crop by production quantity, global production of sugarcane in 2018 was 1.91 billion tonnes, with Brazil producing 39% of the world total, India with 20%, and China and Thailand producing about 6% each. Sugarcane accounts for 80% of sugar produced.

40. As of 2019, over 75% of cocoa produced worldwide comes from West Africa, specifically Côte D'Ivoire, Ghana, Cameroon and Nigeria. Côte D'Ivoire alone produces more than 40% of cocoa beans grown throughout the world. Chocolate might contain 30 or more insect parts and a sprinkling of rodent hair. Cockroach parts are also inevitable. At different stages of the process there is always risk of insects making its way into the chocolate, the beans are fermentated, dryed, roasted, grounded then blended with sugar. Insects are nutritious and using pesticides to stop them would actually harm us.

41. Birth rate is inversely correlated to education and income while positively to religion.

42. So every two or three years (on average about once every 2.7 years - seven times in the 19 year Metonic cycle - a period of approximately 19 years after which the phases of the moon recur on the same day of the year), there is an extra full moon in the year. The extra full moon necessarily falls in one of the four seasons, giving that season four full moons instead of the usual three, and, hence, a "blue" moon. The term "blue moon" is used colloquially to mean a rare event, as in the phrase "once in a blue moon".

43. Around 10 percent of lifelong smokers will get lung cancer. While smoking accounts for 30 percent of all cancer deaths and 80 percent of lung cancer deaths. People who smoke cigarettes are 15 to 30 times more likely to get lung cancer or die from lung cancer than people who do not smoke. Half of all smokers will die from smoking.

44. The soil in China lacked selenium, a deficiency which contributed to muscular weakness and reduced growth in horses. Consequently, horses in China were too frail to support the weight of a Chinese soldier. The Chinese needed the superior horses that nomads bred on the Eurasian steppes, and nomads wanted things only agricultural societies produced, such as grain and silk. Thus the Silk route was born.

45. Thailand mainly uses the Buddhist calendar which is 543 years ahead of the Gregorian calendar. The year 2018 CE is indicated as 2561 BE in Thailand. The first day of the week in Thailand is Sunday.

46. The high cost of failing to detect agents and the low cost of wrongly detecting them has led researchers to suggest that people possess a Hyperactive Agent Detection Device, a cognitive module that readily ascribes events in the environment to the behavior of agents.

47. Humans have a slightly over 210-degree (depth perception is possible only in 114 degrees) forward-facing horizontal arc of their visual field. The vertical range of the visual field in humans is around 150 degrees.

48. Westermarck effect or reverse sexual imprinting says that where a brother and sister are brought up separately, never meeting one another - they may find one another highly sexually attractive when they meet as adults or adolescents. Also people who live in close domestic proximity during the first few years of their lives become desensitized to sexual attraction.

  • Men and women were twice as likely to choose a partner with the same eye color as the parent of the sex they are attracted to.
  • Mechanically speaking, our eyes see everything upside down. That’s because the process of refraction through a convex lens causes the image to be flipped, so when the image hits your retina, it’s completely inverted. For the first few days of life babies see the world upside down, as their brains just haven’t learned to flip the raw visual data yet. Wear a set of reversing glasses to flip your vision upside down, and by day five, it will have spontaneously turned up side down.
  • The image that hits each of your retinas is a flat, 2D projection. Your brain has to overlay these two images dynamically to form one seamless 3D image in your mind. At the periphery of your vision, you pretty much only see in black and white. The brain fills in the 1.5 mm blind spot.
  • The late teens or early twenties are best biologically (oocytes are fresh, lowest rates of miscarriage, ectopic pregnancy, stillbirth, and infertility) but with how society is progressing, this is getting out of sync with the the sociological "best age", humans mature a decade later,
  • According to the generalized uncertainty principle (a concept from speculative models of quantum gravity), the Planck length is, in principle, within a factor of 10, the shortest measurable length – and no theoretically known improvement in measurement instruments could change that. The smallest possible distance is the Plank lenght, 1.610^-35 (1.10^-15 is the diameter of a proton). And for that you only need around 60 digits of pi to calculate the circumference of the universe.
  • Our bodies run (on average - basal metabolic rate) at 80 watts, then a light bulb running at 100 watts is running at 1.25 human equivalents. For a few seconds, humans can summon up to two thousand watts, a few minutes, just about 1,000 watts, for an hour, around 300; for all day, 150 watts is about the maximum. An average human energy expenditure is 12,500 kJ per day (iphone 5 per year). Solar panels give us 250 watt/hr, laptops consume 60 watts, Nvidia GPU peaks at 400, electric kettle is 1 to 3 kW.
  • When Leibnitz first came up with the notation for integrals (the ∫ sign was really a capital S, standing for "summa", summation), and he wrote S^b_a f(x)dx, he was really thinking of this as a sum of products, with dx representing an "infinitesimal change in x."
  • For adults 18 and older, a normal resting heart rate is between 60 and 100 beats per minute (bpm). So 1 to 1.5 heartbeat per second makes the second a very intuitive unit of time.
  • In fact, economists estimate that only 8 percent of the world's currency exists as physical cash. The rest exists only on a computer hard drive, in electronic bank accounts around the world.
  • We cannot “see” objects smaller than the wavelength of visible light (about 5×10^(−7) meter).
  • About 1 in 5 Sun-like stars have an "Earth-sized" planet in the habitable zone. Assuming there are 200 billion stars in the Milky Way, one can hypothesize that there are 11 billion potentially habitable Earth-sized planets in the Milky Way, rising to 40 billion if planets orbiting the numerous red dwarfs are included.
  • Even in individuals who were born blind, body and facial expressions displayed are similar to those of anyone else.
  • Under stress, a human brain will shift control from the cerebral cortex to the limbic system. The limbic system is associated with the instinctual processes, such as "fight or flight" response; and behavior that is based on "deeply ingrained training". The limited input from the cerebral cortex hinders a person's creative processes, which are replaced by the behaviors associated with the limbic system. The person is often unaware of the change, which may lead them to believe they are creatively "blocked".
  • Factoids are defined as "an item of unreliable information that is reported and repeated so often that it becomes accepted as fact."
  • Auditory feedback is a slow correction mechanism since 100 milliseconds before correction is usually too slow in comparison to the production time of speech sounds. Visual feedback for movement control takes 135 msec. While auditory feedback is too slow to correct the production of a speech sound in real time. It is capable of changing speech-sound production over a series of trials (i.e. adaptation by relearning). Speech Jammers playback your speech with a delay of about 0.2 seconds which confuses the trained brain.
  • Traditionally, in the Middle Ages, an acre was defined as the area of land that could be ploughed in one day by a yoke of oxen
  • In wires (matter), electrons travel maybe 1 mm/sec. Even in vacuum tubes (space) they only travel around 1% of the speed of light. What really matters in circuits is the waves that travel through the electron fluid, not the electrons themselves.
  • Because the Earth was molten when it was formed, almost all of the gold present in the early Earth probably sank into the planetary core. Therefore, most of the gold that is in the Earth's crust and mantle is thought to have been delivered to Earth later, by asteroid impacts during the Late Heavy Bombardment, about 4 billion years ago.
  • Under dry conditions, the resistance offered by the human body may be as high as 100,000 Ohms. Wet or broken skin may drop the body's resistance to 1,000 Ohms. We can feel 1 mA in one second of contact. Above 6A can cause real damage. So 1 to 6k Volts.
  • The minimum number of photons our eyes can see is 3. Our cone cells detect those photons with wavelength in the range of about 380 to 720 nanometres. There is no intrinsic limit to the smallest or farthest thing we can see. Best resolution would be 120 pixels per degree of arc. (about a fingernail held at arm's length with 60 horizontal and vertical lines)
  • Relying on intimate contact, stable tribe size would be 50. Comparing the size of our neocortex to other primates and the sizes of the groups in which they dwell suggests the natural size of a human group is 150 people (Dunbar, 1992). This is relying on Gossip. Beyond that needs Commonly believed Fictions.
  • The decibel originates from methods used to quantify reductions in audio levels in telephone circuits. These losses were originally measured in units of Miles of Standard Cable (MSC), where 1 MSC corresponded to the loss of power over a 1 mile (approximately 1.6 km) length of standard telephone cable at a frequency of 5000 rad/sec, **this roughly matched the smallest attenuation detectable to the average listener**. 1 TU (ten times the base-10 logarithm of the ratio of measured power to a reference power level) approximately equaled 1 MSC (specifically, 1.056 TU = 1 MSC). In 1928, the Bell system renamed the TU into the decibel.
  • Our ears do not have a flat frequency response. The hearing curves show a significant increase in the range 2000-5000 Hz with a peak sensitivity around 3500 -4000 Hz. This is associated with the resonance of the auditory canal. There is another enhanced sensitivity region at about 13,500 Hz which may be associated with the third harmonic resonance of the auditory canal. The high sensitivity region at 2-5 kHz is very important for the understanding of speech.
  • The human perception of the intensity of sound and light approximates the logarithm of intensity rather than a linear relationship (Weber–Fechner law)
  • Godel had showed that incompleteness is an intrinsic feature of mathematical systems: any logic powerful enough to include arithmetic statements will necessarily contain propositions that are neither provable nor disprovable.
  • The vast majority of money (97%) comes into being when a commercial bank extends a loan. Banks create deposits in their act of lending.
  • Planets with Energy gradient, atmosphere, and water should come into existence by time the Universe is just 300 million years old. By time we arrive at the formation of Earth, though, more than 9 billion years have passed since the Big Bang first occurred.
  • Special relativity forbids the propagation of information faster than the speed of light. In a wave, the group velocity carries all the information. The phase velocity can (and often is) faster than the speed of light, as it carries no information. The refractive index is defined as the ratio between the speed of light in a vacuum and the phase velocity in a medium, so it can be less than one. Hell, in case of metamaterials, it can even be negative!
  • A typical neuron can fire and reset itself in about five milliseconds (5 ms), or around two hundred times per second. This may seem fast, but a modern silicon-based computer can do one billion operations in a second. This means a basic computer operation is five million times faster than the basic operation in your brain!
  • A tiny variety of jellyfish known as Turritopsis doohmii, or more commonly, the immortal jellyfish. It has found a way to cheat death by actually reversing its aging process, according to National Geographic. If the jellyfish is injured or sick, it returns to its polyp stage over a three-day period, transforming its cells into a younger state that will eventually grow into adulthood all over again.
  • Also known as planarian worms, are famous for their regeneration abilities, where a worm cut across or lengthwise can form two separate worms. This apparently limitless regeneration also applies to aging and damaged tissue, allowing the worms to cheat death indefinitely.
  • Green monkeys can lie. They have been observed to frighten away fellow monkeys by claiming a lion is nearby in order to steal a banana for itself.
  • Humans have hair not fur, which let the sweat freely evaporate. While we have around the same density of hair follicles, we have 10 times the number of eccrine glands that chimps have.
  • Out of 510 million square km, 155 m km2 is land. On AD 1400, farmers took up just 11 - 2% or planet surface.
  • The "Arabic" numerals were invented between the 1st and 4th centuries by Indian mathematicians.
  • Ancient Greece did not have any problem with homosexuality as evidenced in Iliad where Thetis had no objections towards her son Achille's relationship with Patroclus. Even Queen Olympias of Macedon was fine with her son Alexander the Great bringing his lover Hephaestion home for dinner.
  • When Spaniards first arrived in Mexico, natives bearing incense burners were assigned to accompany them wherever they went. The Spaniards thought it was a mark of divine honour, but we know from native sources that they found the smell unbearable. Native hygiene was far better.
  • As per current US banking law, banks are allowed to loan 10 dollars for every dollar they actually possess.
  • Aluminium was discovered in the 1820s but seperating the metal from its ore was so costly that it was more expensive than gold. In the 1860s Emperor Napoleon III of France commissioned aluminium cutlery to be laid out for this most distinguished guests, less important visitors had to make do with the gold knifes and forks.
  • Acute phenoptosis, characterized by rapid deterioration and accelerated death processes, is exemplified by the Pacific Salmon Oncorhyncus ssp. (which dies after spawning), the mayfly (which lacks a functional mouth in its adult form), and Saccharomyces cerevisiae (baker’s yeast) and Caenorhabditis elegans (under stress). Other examples include the praying mantis (the male praying mantis ejaculates only after being decapitated by the female), the adatyllidium mite (the initial food source of the mite larvae is the body tissue of their mother) and squid (male squid die immediately after mating thus providing an abundant food source for predators that would prey on their eggs).
  • The extra nutritional requirement of having larger brains and the lengthier developmental period meant there is a need for bi parental care. Monogamy also meant that men had time to ensure offspring survival rather than searching for other mates. It also reduced within-group conflict.
  • More than a thousand years before the Noah's ark story was written (Genesis 8:20 - I), we have Utnapishtim who was told by the God Enki to escape the deluge. He too sacrificed animals after surviving.
  • The Earth's surface and its ionosphere are two conducting layers separated by air. The surface-ionosphere capacitor is of particular interest in the study of sprites. Small "leaks" in the form of lightning can trigger much larger "leaks" (sprites, etc.) at high altitudes above them.
  • The vampire bats are an example of lending in nature. They remember very well to whom they loaned the blood so at a later date if he returns home hungry, he will approach his debtor.
  • The visible spectrum, is about 380 to about 740 nanometers (nm) (VIBGYOR). We never see direct sunlight, Diffused skylight
  • In ancient Egypt, each year surveyors had to redraw the boundaries of farmers field after the summer flooding of Nile. This activity gave its name to the study of shapes in general, Ge (Greek for earth) + metres (measurer)
  • Heamogoblin doesn't just transport oxygen but also carbon dioxide
  • To supress the polifiration of the invading bacteria, the veins at the bodies surface is constricted to trap the heat within the insides. We therefore experience the chills since the temperature of the extermities decrease.
  • During a typical lifespan, a person spends a total of about six years dreaming (which is about two hours each night). Most dreams only last 5 to 20 minutes.
  • We have exactly 10! Seconds in 6 weeks.
  • A million seconds is a little under 2 weeks. A billion seconds is about 32 years.
  • The coronal heating problem in solar physics relates to the question of why the temperature of the Sun's corona is millions of kelvin higher than that of the surface.
  • The genitalia of the female hyena closely resembles that of the male; the clitoris is shaped and positioned like a penis, a pseudo-penis, and is capable of erection. The male's penis enters and exits the female's reproductive tract through her pseudo-penis rather than directly through the vagina, which is blocked by the false scrotum and teste. The clitoris' birth canal is only an inch in diameter, and the tissue often tears as a 2-pound cub squeezes through the narrow opening.
  • Red blood cells live for about four months, while white blood cells live on average more than a year. Skin cells live about two or three weeks. Colon cells have it rough: They die off after about four days. Sperm cells have a life span of only about three days, while brain cells typically last an entire lifetime (neurons in the cerebral cortex, for example, are not replaced when they die).
  • Tears are the only bodily fluid humans don't find gross.
  • For some species, including humans, mortality – or the probability of dying within the next year of life – increases steadily towards the end of life. This is not, however, a regular pattern that applies to all species. The mortality of the gopher tortoise (Gopherus agassizii), which lives in the deserts of the southern United States and northern Mexico, decreases steadily with age. In other words: the older the tortoise gets, the less likely it is to die.
  • The Holocene extinction, otherwise referred to as the sixth mass extinction is ongoing with the current rate of extinction of species is estimated at 100 to 1,000 times higher than natural background rates, also 10 to 100 times higher than in any of the previous mass extinctions in the history of Earth.
  • In about one billion years, the solar luminosity will be 10% higher than at present. This will cause the atmosphere to become a "moist greenhouse", resulting in a runaway evaporation of the oceans. As a likely consequence, plate tectonics will come to an end, and with them the entire carbon cycle.
  • In about 2–3 billion years, the planet's magnetic dynamo may cease, causing the magnetosphere to decay and leading to an accelerated loss of volatiles from the outer atmosphere. In about 3.75 billion years it will become far too hot for liquid water to exist, ending all terrestrial life. Four billion years from now, the increase in the Earth's surface temperature will cause a runaway greenhouse effect, heating the surface enough to melt it.
  • The most probable fate of the planet is absorption by the Sun in about 7.5 billion years, after the star has entered the red giant phase and expanded beyond the planet's current orbit.
  • The hypothesis for the formation of the moon requires a collision between a proto-Earth about 90% of the size of present Earth, and another body the diameter of Mars (half of the terrestrial diameter and a tenth of its mass). The latter has sometimes been referred to as Theia, the name of the mother of Selene, the Moon goddess in Greek mythology. The newly formed Moon orbited at about one-tenth the distance that it does today, and spiraled outward because of tidal friction transferring angular momentum from the rotations of both bodies to the Moon's orbital motion. Along the way, the Moon's rotation became tidally locked to Earth.
  • If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years, then on a time scale of 10^19 (10 quintillion) years the remaining planets in the Solar System will be ejected from the system by violent relaxation. If this does not occur to the Earth, the ultimate fate of the planet will be that it collides with the black dwarf Sun due to the decay of its orbit via gravitational radiation, in 10^20 years.
  • The Andromeda Galaxy is approaching the Milky Way at about 110 kilometres per second as indicated by blueshift. It is expected that it will directly collide with the Milky Way in around 4.5 billion years. The central supermassive black holes will collide and converge near the centre of the newly formed galaxy over a period that may take millions of years. The energy of this explosion will equal 100 million supernovae.
  • While the Andromeda Galaxy contains about 1 trillion (10^12) stars and the Milky Way contains about 300 billion (3×10^11). The chance of even two stars colliding is negligible because of the huge distances between the stars. If the Sun were a ping-pong ball, Proxima Centauri would be a pea about 1,100 km away, and the Milky Way would be about 30 million km wide.
  • In a study, of 200,000 users found that female desirability to its male users peaks at age 21, and falls below the average for all women at 31. After age 26, men have a larger potential dating pool than women on the site; and by age 48, their pool is almost twice as large.
  • Roman authors like Catullus attest to people using both human and animal urine as a mouth rinse that helped whiten their teeth.
  • In 1591, Eufame Maclayne was burned at the stake for asking for pain relief during the birth of her twins. Devout men and women believed that the pain in childbirth was a heavenly duty. Pain relief became somewhat acceptable when Queen Victoria asked Dr. John Snow for a whiff of chloroform to ease her delivery during the birth of Prince Leopold on April 7, 1853.
  • Thanks to geneticist Ha Ji-Hong, Korea’s loyal, shaggy-haired dog breed known as the Sapsaree, or Sapsali, has gone from a population of just eight in the 1980s to 1,200 dogs living with South Korean families. They were killed in large numbers by the Japanese military between 1910-1945 during the period of Japanese colonial rule. The dogs’ fur was used to make winter coats for its soldiers serving in the extreme cold of Manchuria.
  • A single mammalian cell might contain as many as 10 million ribosomes; a single cell of the bacterium Escherichia coli, or E. coli, might get by with just tens of thousands. Each ribosome might crank out protein at the rate of about 20 amino acids (the constituent units of all proteins) per second.
  • 8 percent of our human genome consists of viral DNA inserted sideways into our lineage by retroviruses. Some of those viral genes, have even been co-opted to function in human physiology, such as creating an essential layer between the placenta and the fetus during pregnancy.
  • The variability of male scores is greater than that of female scores, resulting in more males than females in the top and bottom of the IQ distribution.
  • Perfect Pitch - less than 0.01% of the population appear to be able to recognize absolute pitches, whereas over 98% of the population can do the corresponding visual task of recognizing colors with no color standard present.
  • It takes just 5 to 10 days for our brain to once again adapt to using a set of reversing glasses that flips our vision upside down.
  • Humans and Bananas share about 50 percent of our genes. Genes, which are the regions of the DNA that code for these proteins, only make up 2% of your DNA. 8% regulates genes (as to whether a gene should be turned on or off). The other 90 is junk. Humans share 85 percent DNA with a mouse and 61 percent with a fruit fly.
  • In orangutans, close human relatives, 'forced copulations' or rape may account for up to half of all observed matings
  • Engineers at the Chicago-based Boeing used sacks of potatoes as stand-ins for passengers as they worked to eliminate weak spots in in-flight wireless signals. ... It turns out that potatoes - because of their water content and chemistry - absorb and reflect radio wave signals much the same way as the human body does.
  • On December 17, 1903 the first powered, heavier-than-air aircraft covered 61 m at a speed of 10.9 km/h at 3 m above the ground. Wright brothers – Orville and Wilbur. But for years people did not believe it was possible. The Paris edition of the New York Herald summed up Europe’s opinion of the Wright brothers on Feb. 10, 1906: “The Wrights have flown or they have not flown. They possess a machine or they do not possess one. They are in fact either fliers or liars.”
  • This shortage of empirical evidence has led many scholars to regard the entire topic of "Origin of Language" as unsuitable for serious study. In 1866, the Linguistic Society of Paris banned any existing or future debates on the subject, a prohibition which remained influential across much of the Western world until late in the twentieth century.
  • Jell-O is a sweetened gelatin product made by boiling the bones and hides of animals. The collagen in gelatin does come from boiling the bones and hides of animals processed for their meat (usually cows and pigs). But hooves consist of a different protein, keratin, which can't produce gelatin.
  • Before 1955 marriages among Hindus were monogamous for the woman alone. Some references can be found in ancient Hindu texts where Sage Vashistha, Parasara and Kautilya mention certain circumstances when a woman may abandon her husband and remarry. This was permitted in cases where husband is devoid of character or impotent or has become ascetic.
  • Ovulation typically occurs around day 14 of a 28-day menstrual cycle when an egg is released from your ovary. The egg can only be fertilized in the 12 to 24 hours after it’s released, sperm can live in the reproductive tract under ideal conditions up to 5 days.
  • Today’s human population is descended from twice as many women as men. Throughout the entire history of the human race, maybe 80% of women but only 40% of men reproduced. Premature male death in war, infidelity, or rape, slavery, inequality (rich men have more wives and their kids get better living conditions) are possible reasons. For some time around 4,000 to 8,000 years ago the ratio was 17:1! https://genome.cshlp.org/content/early/2015/03/13/gr.186684.114.abstract
  • Males display greater variability in traits such as IQ, mathematical and verbal abilities than females do. The extent is about 14% greater variance than girls in science, reading, and math test scores. While females have greater variability on fear and emotionality.
  • The symptoms of pseudocyesis (false pregnancy) are similar to the symptoms of true pregnancy and are often hard to distinguish from it. Such natural signs as amenorrhoea, morning sickness, tender breasts, and weight gain may all be present. In 2010, a woman in the United States who was suspected of being in labor was given a C-section only to discover there had been no fetus.
  • In September 1554, Mary stopped menstruating. Mary continued to exhibit signs of pregnancy until July 1555, when her abdomen receded. In August, soon after the disgrace of the false pregnancy, which Mary considered to be "God's punishment" for her having "tolerated heretics" in her realm. Edward and his father had sponsored the Reformation in stages, but Mary had always been Roman Catholic and considered Protestants to be heretics. By the end of 1554, the Heresy Acts were revived and the executions began from February 1555, in total, 283 most by burning.
  • In India, the situation is probably comparable to what prevails in Brazil and South Africa, where around 60% of national income goes to the top 10% of earners. The figure in France and Germany is around 35%, according to Mr. Piketty’s data. In the U.K., it’s 40%. In the U.S., nearly 50%.
  • The average annual melanoma rate among Caucasians and African Americans is about 22 and 1 cases per 100,000 people. However, the overall melanoma survival rate for African Americans is only 77 percent, versus 91 percent for Caucasians mainly because it's harder to detect.
  • The greatest officially recorded number of children born to one mother is 69, to the wife of Feodor Vassilyev (b. 1707–c. 1782), a peasant from Shuya, Russia. In 27 confinements she gave birth to 16 pairs of twins, seven sets of triplets and four sets of quadruplets.
  • Nadya Suleman (USA) claimed headlines across the world on 26 January 2009 when she gave birth to six boys and two girls at the Kaiser Permanente Medical Center, Bellflower, California, USA.
  • Marsupials, including the most popular one, the kangaroo, are equipped with a total of three vaginas. The side-vadges are where sperm — from the males’ two-pronged penises — travel up, the middle-vadge is where the baby joey slides down to develop externally in the mother’s pouch after growing to the size of a jellybean in one of her two uteri.
  • While all 543 seats of the LS go to the polls together, only 1/3th of the seats go to the polls every 2 years. Each vidhan sabha votes for the proportional number of seats. Creating a temporal inertia and preventing a quick populist takeover of the legislative apparatus.
  • Venezuela's hyperinflation began in November 2016. Inflation of Venezuela's bolivar fuerte (VEF) in 2014 reached 69%, highest in the world. 1,698,488% in 2018 and then the govt stopped producing estimates.
  • Prof. Hanke's HHIZ measure indicated that the inflation of the Zimbabwe dollar peaked at an annual rate of 89.7 sextillion percent (89,700,000,000,000,000,000,000%) in mid-November 2008.
  • In human infants, the hemoglobin molecule is made up of 2 α chains and 2 γ chains. The gamma chains are gradually replaced by β chains as the infant grows.
  • The researchers found that children had higher physical need scores than the other groups, the love need emerged from childhood to young adulthood, the esteem need was highest among the adolescent group, young adults had the highest self-actualization level, and old age had the highest level of security.
  • Are Russians and Americans larger than Asians? This could be a cold adaptation. Individuals with larger bodies are better suited for colder climates because larger bodies produce more heat due to having more cells, and have a smaller surface area to volume ratio compared to smaller individuals, which reduces heat loss. Shorter limbs help to conserve heat, while longer limbs help to dissipate heat.
  • The temperature that requires the least amount of energy investment is 21 °C (69.8 °F). Humid heat is dangerous as the moisture in the air prevents the evaporation of sweat. The only mechanism the human body has to cool itself is by sweat evaporation. shivering, which occurs in an unclothed person when the ambient air temperature is under 25 °C (77 °F) causes skeletal muscles to shake and temperature to rise. Non-shivering thermogenesis occurs in brown adipose tissue (brown fat).
  • More than 3/8 of an inch (0.95 cm) in variation of the height of steps from one step to another is a tripping hazard.
  • Foods that are rich in protein, such as meat, poultry, eggs, fish, spinach, tofu, cheese and soybeans, contain tryptophan amino acid. This amino acid is used by the body to produce serotonin, which is responsible for drowsiness. Overeating can also cause sleepiness. Post-meal, the body streams more blood to the digestive system to better digest foods in massive amounts. This causes a temporary blood and nutrients shortage in the brain.
  • About 1000 years ago, in 900 AD, 3000 years after the the first writing - Sumerian logographs. The insertion of spaces between words made it possible, for the vast majority of readers to be able to read silently. Prior to this, most readers had to read out loud in order to be able to read at all. The few who could read text silently without these spaces between the words, like Julius Caesar and St. Ambrose, were viewed as so extraordinary that this ability is specifically recorded in historical records.
  • In 18th-century Europe, the then new practice of reading alone in bed was, for a time, considered dangerous and immoral.
  • Women find a partner’s emotional infidelity more distressing, while men find a partner’s sexual infidelity more distressing.
  • Each additional older brother increases the odds of a man being gay by 33%. Male fetuses produce H-Y antigens which are "almost certainly involved in the sexual differentiation of vertebrates". These Y-linked proteins would not be recognized in the mother's immune system because she is female, causing her to develop antibodies which would travel through the placental barrier into the fetal compartment. From here, the anti-male bodies would then cross the blood/brain barrier (BBB) of the developing fetal brain, altering sex-dimorphic brain structures relative to sexual orientation, increasing the likelihood that the exposed son will be more attracted to men than women.
  • 2400 BCE – Khnumhotep and Niankhkhnum are believed to be the first recorded same-sex couple in history. 405 – Nonnus' Dionysiaca is the last known piece of Western literature for nearly 1,000 years to celebrate homosexual passion. The Christian emperor Justinian I (527–565) made homosexuals a scapegoat for problems such as "famines, earthquakes, and pestilences. 1476 – Florentine court records of 1476 show that Leonardo da Vinci and three other young men were charged with sodomy twice, and acquitted. The Kingdom of France (Andorra, and Haiti) adopts a new penal code which no longer criminalizes sodomy. France thus becomes the first West European country to decriminalize homosexual acts between consenting adults.
  • In ancient Greece and Rome, a catamite (Latin: catamitus) was a pubescent boy who was the intimate companion of a young man, usually in a pederastic relationship. 330 BCE – Bagoas, favorite catamite to King Darius III, becomes catamite to King Alexander III of Macedon.
  • Different parts of the eye have different response speed. The corner of your eye doesn't see color, but is fast; the center sees color, and is slower.
  • 326 ppi is the upper limit for 20/20 vision at 10.5 inch + distance. But for 20/10 vision, 573 ppi is the limit at 12 inch and 458 at 15 inch. The 6.55 inch 1+7T has 1080x2400 pixels so a ppi of 402. 141 ppi for for the 1080p 15.6 inch laptop.
  • When you look back in time, the perceived duration of an event involves the way the brain laid down the memory. The networks of neurons that code for a new memory are denser than they are for something that’s not novel, he said. When you look back, those denser networks make it seem as though that memory lasted longer.
  • During the Paleolithic age ( 3.3 million to 11,650 years ago) there was only a 60% chance of reaching 15, but if you did life expectancy was an additional 39 years (total 54). Then upto 6,500 years ago, 39 dropped to 28–33 years. During the time of Greece (5th and 4th centuries BC) it increased to 37–41 years. From 1200 to 1550, if you lived till 21, you were likely to live to 60 to 70 years of age.
  • Approximately two-thirds of Americans shower daily. In Australia it’s over 80%. But in China, about half of people report bathing only twice a week. Daily showers do not improve your health, could cause skin problems or other health issues — and, importantly, they waste a lot of water.
  • One form of natural self-replication that isn't based on DNA or RNA occurs in clay crystals. Clay consists of a large number of small crystals, and clay is an environment that promotes crystal growth. Crystals consist of a regular lattice of atoms and are able to grow if e.g. placed in a water solution containing the crystal components; automatically arranging atoms at the crystal boundary into the crystalline form.
  • In the northern hemisphere, moss most often grows on the north side of trees. That's because the north side is the shadiest side in the northern hemisphere and the south side is the shadiest side south of the equator. As you move away from the tropics, the suns rays intersect the earth at an angle. Moss grows best in shady spots that are moist or humid.
  • In The Indian Evidence Act, 1872 we have a Section 114A: With regard to rape, where sexual intercourse by the accused is proved and where the woman states in her evidence before the court that she did not consent, the court shall presume that she did not consent.
  • Consanguineous marriage is traditional and respected in most communities of North Africa, the Middle East and West Asia, a transverse belt that runs from Pakistan and Afghanistan in the east to Morocco in the west, and in South India, with intrafamilial unions collectively accounting for 20–50+% of all marriages.
  • Only about 2% of the U.S. population is of full Ashkenazi Jewish descent, but 27% of United States Nobel prize winners in the 20th century, 25% of the winners of the Fields Medal (the top prize in mathematics), 25% of ACM Turing Award winners, a quarter of Regeneron Science Talent Search winners, and 38% of the Academy Award-winning film directors have either full or partial Ashkenazi Jewish ancestry. Jews comprise up to one third of the student populace at Ivy League universities, and 30% of the U.S. Supreme Court's law clerks. In Great Britain, Jews are overrepresented among Nobel prize winners by a factor of 8.0. In Hungary in the 1930s, Ashkenazi Jews comprised 6% of the country's population, but 55.7% of physicians, 49.2% of attorneys, 30.4% of engineers, and 59.4% of bank officers.
  • Goodhart's law - The Great Hanoi Rat Massacre - 1897. In the last week of April, 1902, 7,985 rats were killed—and that was just the beginning. On just June 21, the number of rates killed was was 20,112. A bounty was set—one cent per rat—and all you had to do to claim it was submit a rat’s tail to the municipal offices. It turned out the hunters would rather amputate a live animal’s tail than take a healthy rat, capable of breeding and creating so many more rats. In the countryside on the outskirts of Hanoi, pop-up farming operations dedicated to breeding rats.
  • Even Facebook’s signature royal blue reflects mark's tastes. He is red-green color-blind, and he chose blue because he sees it most vividly.
  • The Government of India raises about 80% of its total debt within the country, the state govts have taken about 94% of their total debt from internal sources. The biggest sources of internal loans to the Government of India are commercial banks (40% of the total internal debt), 24% by insurance companies, and 15% by the Reserve Bank of India. Our public debt is 70% of GDP. Of the external debt, bilateral is only 4.6%, even multilateral is only 10%. More than 80% is long term debt - Commercial Borrowings and NRI deposits. Around 80% of our bilateral debt is owned by Japan. 11% is Germany, Russia is 5.3% and USA is only 0.7%.
  • Ferrero uses 25 percent of the global hazelnut supply. Each jar of Nutella contains about 50 hazelnuts.
  • In the first year of life, almost 100% of the skeleton is replaced. In adults, remodeling proceeds at about 10% per year. Bone remodeling is not just occasional "repair of bone damage" but the bones function as a bank or storehouse in which calcium can be continually withdrawn for use or deposited for storage. This occurs with the synchronized action of osteoclasts and osteoblasts, cells that resorb and deposit bone, respectively. Bones make up only around 15% of a person”s total body weight.
  • Amazon Fire Phone was such a flop that the $200 is now being sold for just 99 cents.
  • The French Code of Criminal Procedure prohibits hearing a suspect under oath; thus, a suspect may say whatever he feels fit for his defense, without fear of sanction for perjury. This prohibition is extended to the suspect's spouse and members of his close family. Even in Italy the defendant does not take an oath. They can lie without consequences.
  • Defeat in 1918 led to the Kaiser’s abdication, a republic and a new constitution. The new Germany faced huge debts due to its punishment in the Treaty of Versailles. The Weimar government's main crisis occurred in 1923 after the Germans missed a reparations payment late in 1922. This set off a chain of events that included occupation, hyperinflation and rebellions. Prices ran out of control, for example a loaf of bread, which cost 250 marks in January 1923, had risen to 200,000 million marks in November 1923. By autumn 1923 it cost more to print a note than the note was worth. During the crisis, workers were often paid twice per day because prices rose so fast their wages were virtually worthless by lunchtime.
  • Most birds are mostly waterproof. Their feathers, combined with oil from preen glands, keep them pretty watertight. Rainstorms tend to occur when atmospheric pressure is low. (When the pressure is low, the air is free to rise into the atmosphere where it cools and condenses) Air in a low-pressure system is less dense. But it’s dense air that gives birds the aerodynamic lift they need to take flight. (Lift is proportional to the density of the air and approximately proportional to the square of the flow speed.) Falling rain and high humidity also add lots of water molecules to the air. That water takes up space in the air, making it even less dense.
  • In the past, among Eastern European Jews, when a girl told her mother that she’d got her first period, the mother would slap her daughter’s face and, at the same time, exclaim “Mazel tov!” (congratulations).
  • Filler words such as um, er, or uh are used to indicate that the other person should continue listening instead of speaking, other reasons include pausing to give time for the speaker to gather their thoughts, speaking more indirectly in order to encourage politeness, approaching delicate topics gently, emphasizing ideas, providing clues to emotions or behaviors, and communicating uncertainty. Pauses are commonly used to indicate that someone’s turn has ended, which can create confusion when someone hasn’t finished a thought but has paused to form a thought.
  • Frigatebirds spent less than 3% of their time asleep, engaging in mid-air sleeping about 42 minutes per day on average and always at night. Having the largest wing-area-to-body-weight ratio of any bird, they soar continuously, they can fly higher than 4,000 meters in freezing conditions. Frigatebirds could remain on the wing for up to 12 days while foraging.
  • To divide the seats of our legislature proportionally, Article 82 of the Indian Constitution calls for the reallocation of seats after every census based on updated population figures. The Forty-Second Amendment enacted by Indira Gandhi in 1976 suspended the revision of seats until after the 2001 Census to promote family planning. In 2002 the Eighty-Fourth Amendment extended this freeze until the next decennial census after 2026 (i.e. 2031). Right now, Members of Parliament from Tamil Nadu have 1.8 million constituents per Lok Sabha seat on average versus 3 million constituents per Lok Sabha seat on average in Uttar Pradesh.
  • Rock salt is not salt sold in the form of rock shaped chunks but Halite which usually occurs within sedimentary rocks where it has formed from the evaporation of ancient seawater or salty lake water. It usually forms isometric crystals. The world's largest underground salt mine is the Sifto Salt Mine. It produces over 7 million tons of rock salt per year using the room and pillar mining method. It is located half a kilometre under Lake Huron in Ontario, Canada.
  • As per Roman Law, children under the age of 14, a child was considered to be doli incapax (incapable of criminal intent). A child older than 10, however, still had the possibility of being held responsible for a criminal act if it could be proven that they understood their offense. The age of marriage for girls could be as young as 12, and for men, around 25.

Before the industrial revolution, in many parts of the world, including India, China and Eastern Europe, women tended to marry immediately after reaching puberty, in their mid-teens. In halakha ( Jewish religious laws), the term "minor" refers to a girl under twelve years and a day. A girl aged twelve and a half was already considered an adult in all respects. Most girls were married before the age of 15, often at the start of their puberty. In the Middle Ages, under English civil laws that were derived from Roman laws, marriages before the age of 16 existed. In Imperial China, child marriage (aged 14) was the norm. Manusmriti said 8 to 12 year old (For men 24 to 30). Mahabharata said 10. Menarche (first menstrual bleeding) occurs between the ages of 10 and 16 years and most girls complete puberty at ages 15–17. Worldwide, an estimated 12 million girls are married every year before the age of 18 - nearly one girl every three seconds. Child marriage have h0rrible consequences on the girls health, education and safety.

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India has the largest number of child brides in the world – one-third of the global total. But there is progress - the prevalence of girls getting married before age 18 has declined from 47 per cent to 27 per cent between 2005-2006 and 2015-2016.
  • Evidence from 19th century Palestine suggests that husbands sometimes initiated sexual relations before their wife reached puberty, but that it was a rare occurrence, condemned socially and censured by sharia courts. Muhammad married Aisha, his third wife, when she was about six, and consummated the marriage when she was about nine. Paleolithic girls arrived at menarche - the first occurrence of menstruation - between seven and 13 years. Children in medieval England entered puberty between ten and 12 years of age. The average age of menarche is about 12.5 years in the United States, 12.7 in Canada, and 12.9 in the UK. A study of girls in Istanbul, Turkey, found the median age at menarche to be 12.7 years.
  • The typical dietary contribution of calcium and magnesium is over 80% of the total daily intake. Of this, approximately 30% of calcium and 35% of magnesium will be absorbed. The bioavailabilities of calcium and magnesium from milk and water are on the order of 50%. For calcium and magnesium, the typical contribution from water is 5–20%.
  • In his prime, champion cyclist Miguel Indurain had a resting heart rate of just 28 beats per minute. The usual range for resting heart rate is anywhere between 60 and 90 beats per minute. Above 90 is considered high.
  • The last common ancestor probably lived around 1415 BC, which will be approximately 120 generations ago, so let's say really remote people like the Karitiana tribe are, at most, something like 125th degree cousins of all of us. But practically you and that girl who lives near you are 40th to 120th degree cousins. Our last common ancestor with chimps was something like 5 to 6 million years ago. Our last common ancestor with cattle and dogs, about 92 million years ago, may be 30 million generations ago. Birds was around 310 million years ago
  • SSD read and write speeds are 500 MBps while for HHDs it is 50 MBps. SSD's cost three times as much. HDDs have moving parts and can get damaged if you drop it when it is spinning. SSD is best for data you read often and write to rarely. (You can still write 300 GB every day for 3 years)
  • An intentional delay of 7 seconds is introduced when broadcasting live material. Such a delay may be to prevent mistakes or unacceptable content from being broadcast.
  • Infant mortality is significantly higher in boys than girls in most parts of the world. This has been explained by sex differences in genetic and biological makeup, with boys being biologically weaker and more susceptible to diseases and premature death. This is why more boys are born to ensure equal genders survive. More men die due to both natural causes such as heart attacks and strokes, which account for by far the majority of deaths, and also violent causes, such as homicide and warfare, resulting in higher life expectancy of females. Natural ratio is 1.07 to 1.03 males/females.
  • Older you are when you have a baby, the more variability in the gender. If you are below 35 years of age, males have an edge. Sex ratio decreases with consecutive child.