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The Curious Fu
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Here's how scientists figured out the age of the universe It took some cosmic detective work. by Passant Rabie Oct. 20, 2021 You never ask a cosmic being its age. But if that cosmic being encompasses all of space, time, and matter, you could get a little curious. Scientists have long been curious about the age of the universe and how much time has elapsed since the Big Bang. Today, scientists estimated the age of the universe to be approximately 13.8 billion years old. But how did scientists estimate how old the universe is, and are they sure of that number? It all comes down to ancient stars and the ever-expanding cosmos. How do astronomers calculate the age of the universe? To estimate the age of the universe, scientists rely on two main methods. Calculating the expansion rate of the universe Determining the ages of the oldest stars The Hubble Constant: Since its conception, the universe has been expanding at an accelerating rate. The universe’s expansion rate is known as the Hubble Constant, which is estimated at 46,200 mph per million light-years. The Hubble Constant was first calculated in the 1920s by American astronomer Edwin Hubble after discovering that several galaxies were moving away from Earth. Scientists looked to distant galaxies to measure how fast the universe was expanding. Hubble also noted that the further a galaxy was, the faster it was moving away. Based on Hubble’s observations, the astronomer came up with Hubble’s law which showed a correlation between how far an object is and the speed at which it’s receding. Using Hubble law, scientists were able to estimate the expansion rate of the universe. Scientists were then able to use the Hubble Constant to estimate the age of the universe by working backward, all the way back to the Big Bang. This extrapolation depends on the current density and composition of the universe, which shows the history of its expansion. In 2012 NASA’s Wilkinson Microwave Anisotropy Probe used that data to estimate the universe's age to be 13.772 billion years old, give or take 59 million years. A year later, The European Space Agency’s Planck spacecraft estimated the universe's age to be 13.82 billion years. Ancestral stars: Another way to determine the age of the universe is to look to the oldest stars. The universe can’t be younger than its oldest stars. Therefore, to narrow down the age of the universe, scientists measure the ages of the very first stars that formed in the cosmos. The lifecycle of a star depends on its mass, with high mass stars burning fuel at a faster rate and therefore dying out faster while low mass stars can live up to 20 billion years. Globular clusters are a dense stellar collection of around a million stars which all formed roughly around the same time. These clusters can then serve as timekeepers for the universe. By determining the masses of their stars, scientists can estimate when the globular cluster formed. The oldest globular clusters contain stars that are 0.7 times less massive than the Sun, which suggests that they are between 11 to 18 billion years old. What came before the Big Bang? Scientists can trace the universe back to its explosive birth, the Big Bang. But what happened before this theoretical birth of the cosmos? The universe may have been a singularity, all compact within a form that is smaller than a subatomic particle. It’s difficult to imagine what caused this matter to exist, but one theory even suggests that our universe was born from another universe while another imagines a series of universes being born out of one another like a formation of bubbles. Meanwhile, another theory suggests that the universe goes through an endless cycle of death and rebirth, born from its own demise. How old is the universe in seconds? If the universe is indeed cyclical, then time becomes irrelevant. But just in case you’re still attached to the modern way in which we measure the progression of life, then the age of the universe comes up to about 436,117,076,900,000,000 seconds.Title: The Adventures of Max and the Magical Computer (Shortened Version) Once upon a time, in a small town called Techville, there lived a curious fourth-grader named Max. One day, while exploring his grandma’s attic, he found an old, dusty computer. As he cleaned it, the screen lit up, and a cheerful voice said, “Hello, Max! I’m Compy, your magical computer. Let’s learn about operating systems, files, and folders!” Max was thrilled. “A talking computer? Let’s go!” Chapter 1: The World of Windows Compy explained, “I run on Windows, the brain of the computer. It uses a Graphical User Interface (GUI), so you can interact with me using icons, menus, and buttons. Let’s start by changing my desktop background—the image on the screen.” Max chose a spaceship picture. “Cool! Can I add a screen saver too?” “Of course!” said Compy. “It’s an image that appears when I’m inactive. Try this swirling galaxy!” Max set the screen saver and giggled as it appeared. “This is fun!” Chapter 2: Organizing with Folders and Files Compy’s screen filled with random icons. “Oh no! My files are a mess. Can you help?” “Sure! What are files and folders?” asked Max. “A file is information, like a picture or document. Files have names, like ‘Homework.docx.’ The part after the dot, like .docx, is the file extension. It tells you the file type,” Compy explained. Max pointed to “Game.exe.” “So, this is a program file?” “Yes!” said Compy. “To organize, we use folders—like drawers for files. You can even put folders inside folders!” Max created a “School” folder, added his homework files, and made a “Projects” folder inside it. “Now everything’s neat!” Chapter 3: The File Explorer Adventure Compy’s screen flickered. “Some files are missing. Let’s use Windows Explorer to find them. It’s like a map for files and folders.” Max opened Windows Explorer and saw a tree-like list of folders. “This is like a tree with branches!” “Exactly!” said Compy. “Search for the missing files and move them to the right folders.” Max found the files in “Downloads” and moved them. “I feel like a computer detective!” Chapter 4: The Final Challenge Compy’s screen turned into a game board. “Time for a quiz! What’s the purpose of an operating system? How do you change the desktop background? What’s the difference between a file and a folder?” Max answered all the questions correctly, and fireworks lit up the screen. “Congratulations, Max! You’re a computer whiz!” The End Max smiled. “Thanks, Compy! I can’t wait to teach my friends!” Compy replied, “Remember, Max, learning is an adventure. Keep exploring!” As Max turned off the computer, he knew his journey into technology had just begun.All living things are made up of one or more cells. A cell is the smallest unit that can carry on all of the processes of life. Beginning in the 17th century, curious naturalists were able to use microscopes to study objects too small to be seen with the unaided eye. Their studies led them to propose the cellular basis of life. Hooke In 1665, English scientist Robert Hooke studied nature by using an early light microscope, such as the one in Figure 4-1a. A light micro- scope is an instrument that uses optical lenses to magnify objects by bending light rays. Hooke looked at a thin slice of cork from the bark of a cork oak tree. “I could exceedingly plainly perceive it to be all perforated and porous,” Hooke wrote. He described “a great many little boxes” that reminded him of the cubicles or “cells” where monks live. When Hooke focused his microscope on the cells of tree stems, roots, and ferns, he found that each had similar little boxes. The drawings that Hooke made of the cells he saw are shown in Figure 4-1b. The “little boxes” that Hooke observed were the remains of dead plant cells, such as the cork cells shown in Figure 4-1c. SECTION 1 OBJECTIVES ● Name the scientists who first observed living and nonliving cells. ● Summarize the research that led to the development of the cell theory. ● State the three principles of the cell theory. ● Explain why the cell is considered to be the basic unit of life. VOCABULARY cell cell theory Robert Hooke used an early microscope (a) to see cells in thin slices of cork. His drawings of what he saw (b) indicate that he had clearly observed the remains of cork cells (300) (c). FIGURE 4-1 (a) (b) (c) Copyright © by Holt, Rinehart and Winston. All rights reserved. 70 CHAPTER 4 Leeuwenhoek The first person to observe living cells was a Dutch trader named Anton van Leeuwenhoek. Leeuwenhoek made microscopes that were simple and tiny, but he ground lenses so precisely that the magnification was 10 times that of Hooke’s instruments. In 1673, Leeuwenhoek, shown in Figure 4-2a, was able to observe a previ- ously unseen world of microorganisms. He observed cells with green stripes from an alga of the genus Spirogyra, as shown in Figure 4-2b, and bell-shaped cells on stalks of a protist of the genus Vorticella, as shown in Figure 4-2c. Leeuwenhoek called these organisms animalcules. We now call them protists. THE CELL THEORY Although Hooke and Leeuwenhoek were the first to report observ- ing cells, the importance of this observation was not realized until about 150 years later. At this time, biologists began to organize information about cells into a unified understanding. In 1838, the German botanist Matthias Schleiden concluded that all plants were composed of cells. The next year, the German zoologist Theodor Schwann concluded the same thing for animals. And finally, in his study of human diseases, the German physician Rudolf Virchow (1821–1902) noted that all cells come from other cells. These three observations were combined to form a basic theory about the cel- lular nature of life. The cell theory has three essential parts, which are summarized in Table 4-1. Anton van Leeuwenhoek (1632–1723) is shown here with one of his hand-held lenses (a). Leeuwenhoek observed an alga of the genus Spirogyra (b) and a protist of the genus Vorticella (c). FIGURE 4-2 TABLE 4-1 The Cell Theory All living organisms are composed of one or more cells. Cells are the basic units of structure and function in an organism. Cells come only from the reproduction of existing cells. (a) (b) (c) www.scilinks.org Topic: Cell Theory Keyword: HM60241 mb06se_csfs01.qxd 5/18/07 10:54 AM Page 70According to 〜によれば add to 増やす add up 合計する after a while しばらくして against the idea その考えに反対して all of a sudden 突然に all the time いつも all through the night 一晩中 along with 〜と一緒に apply for 〜に申し込む apply to 〜に適用する as a rule 原則として aside from 〜のほかに / 〜を除いて at any cost どんな犠牲を払っても at heart 心の底では at last ついに at least 少なくとも at length 詳細に at most 多くても at once すぐに / 一度に at the sight of 〜を見て at times 時々 attach to 〜に付ける / 〜に結びつける back up 支援する、バックアップする based on 〜に基づいて be absent from 〜を欠席している be against 反対する be based on 〜に基づいている be confident of 〜に自信がある be curious about 〜に好奇心を持つ be derived from 〜に由来する be filled with 〜で満たされている be full of 〜でいっぱいである be made up of 〜で構成されている be pleased with 〜に満足している be short of 不足している be similar to 〜に似ている because of 〜のせいで / 〜のおかげで before long まもなく break out 突発する break out in （急に）〜になる break up 解散する / 別れる bring out 引き出す / 公表する bring up 育てる / 持ち出す burst into 急に〜し始める by heart 暗記して by mistake 間違えて by now 今頃までには by the way ところで by way of 〜を通じて call for 要求する / 呼びかける call out 大声で呼ぶ carry on 続ける carry out 実行する、行う catch up with 〜に追いつく close to 〜に近い come across 偶然出会う / 見つける come into 〜に入る / 〜になる come out 出てくる / 公表される come up with 〜を思いつく compared with 〜と比べて depend on 〜に依存する do him good 彼に利益をもたらす drive at 意図する、狙う drop by 立ち寄る drop down 落ちる feel at home くつろぐ feel like doing 〜したい気分 feel sorry 気の毒に思う figure out 理解する find fault with 〜に文句をつける find out 知る、解明する for fear of 〜を恐れて for free 無料で for good 永遠に、完全に for once 一度だけ / 今回だけは for sale 売り物の for the best 最善のために get over 乗り越える get ready 準備する get rid of 〜を取り除く give away 与える、寄付する give in to 〜に屈する give off 放つ give out 配る / 発表する go ahead 続けて行う go down 下がる / 沈む hand in 提出する hand over 手渡す hang on 待つ / 頑張る hang up 受話器を置く hear from 〜から連絡をもらう help yourself 自由に取る / 自由にどうぞ hold back 控える hold on 待つ / 持ちこたえる hold up 停止させる、遅らせる in a jacket ジャケットを着て in a word 一言で言えば in advance 前もって in case 〜の場合に in common 共通して in detail 詳細に in hand 手元に in part 部分的に in place of 〜の代わりに in return 見返りに in terms of 〜の観点から in the distance 遠くに in the habit of 〜する習慣がある in the way 妨げになって instead of 〜の代わりに keep a secret 秘密を守る keep an eye on 見守る keep away from 近づかないようにする keep on Ving 〜し続ける keep pace with 〜に遅れずについていく keep the change お釣りはいりません keep track of 記録をつける / 追跡する keep up with 〜に遅れずについていく lay it down それを置く / 規定する less than 〜未満 / 〜より少ない look after 世話をする look back on 〜を振り返る look down on 〜を見下す look like 〜のように見える look up 調べる / 見上げる made up of 〜で構成されている major in 〜を専攻する make efforts 努力する make it out 理解する / 成し遂げる make out 見分ける、うまくいく make progress 進歩する make sense 理解できる、意味を成す make up your mind 決心する mind your own business 自分のことに集中しろ move on 次に進む no longer もはや〜ない not always 必ずしも〜でない nothing but ただ〜だけ on air 放送中 on behalf of 〜を代表して on business 仕事で on fire 火がついている on purpose わざと on the point 〜の点で on time 時間通りに one another お互いに out of the question 問題外で pass by 通り過ぎる pay attention 注意を払う play a part in 〜で役割を果たす pour out 注ぎ出す、溢れ出る prefer A to B BよりAを好む put away 片付ける put off 延期する put on 着る / 演じる (weightで太る） put out 消す / 発表する reach for 手を伸ばす rely on 〜に頼る result in 【自動詞】結果として〜になる run it over それをひく / 読み返す run out of 〜を使い果たす run over ひいてしまう、走り回る see about 手配する / 調べる see off 見送る see through 見抜く / 見通す set out 出発する、始める set up 設置する / 設定する show off 自慢する、見せびらかす show up 現れる / 到着する sit up 座る、起き上がる speak up はっきり話す stand out 目立つ stand out 目立つ stand up for 〜を支持する suffer from 〜に苦しむ take away 持ち去る / 奪う take in 理解する、取り入れる take notice of 注意を払う take on 引き受ける / 挑む take out 取り出す / 持ち帰る take over 引き継ぐ、乗っ取る take part 参加する take place 起こる / 開催される take risks 危険を冒す take turns 交代で行う talk over 相談する tear off 引き裂く the second largest 二番目に大きい think better of 考え直す throw away 捨てる try on 試着する turn in 提出する turn off 消す / 切る turn on （スイッチを）入れる turn out 結果的に〜になる turn over ひっくり返す under control 制御下にある up to date 最新の with ease 容易に with regard to 〜に関してCreate multiple choice questions using the following information: In November, Mrs. Baker has Holling read The Tempest. Despite his preconceptions, Holling is captivated by all the "good stuff" in the play, especially the cussing, which he decides to learn by heart. He figures that Mrs. Baker could not have read the play herself; if she had, she certainly would not have let him have it. Holling is amazed when he discovers that his teacher not only has read the play, but she knows the bad parts as well. Mrs. Baker gives Holling a one-hundred-and-fifty question test on The Tempest, and assigns him to read the play again, telling him "there is a lot more to (it) than a list of colorful curses." The deadline set by Holling's classmates for him to bring them cream puffs arrives, but although Holling's father's company has won the Baker's Sporting Emporium contract, he refuses to extend an advance on his son's allowance. Desperate, Holling goes to Goldman's Best Bakery, offering to work for the money he lacks to buy the cream puffs. Coincidentally, Mr. Goldman, who is active in Long Island's Shakespeare Company, needs a boy to perform in their upcoming Extravaganza, and because of his work with Mrs. Baker, Holling fits the bill. Mr. Goldman gives Holling the required number of cream puffs in exchange, but sadly, while the students are at recess, Caliban and Sycorax, the escaped rats who inhabit the classroom walls and ceiling, come out and decimate the treats. Somehow, the disaster is blamed on Holling; he must clean up the mess, and his classmates decree that he still owes them cream puffs. The next Wednesday, Holling brings five cream puffs to school, which is all he can afford. In addition to facing his classmates' ire, he has to deal with the fact that, in the Shakespeare Company Holiday Extravaganza, he must play the part of Ariel, who is a fairy, and wear yellow tights with white feathers on an unmentionable part of his anatomy; "not a good thing for a boy from Camillo Junior High." To Holling's surprise, just when things are at their darkest, Mrs. Baker comes through for him, bringing cream puffs for the students on his behalf. That afternoon, Mrs. Baker and Holling discuss The Tempest, and whether or not Caliban, the "monster," deserves a happy ending. Holling argues that, as the antagonist, he does not, but Mrs. Baker muses whether Shakespeare might have shown, even in a monster, the capacity of humankind to use defeat to grow. Mrs. Bigio stumbles into the classroom at this point, emitting sounds of indescribable sadness; she has just learned that her husband has been killed in a futile reconnaissance mission in Vietnam. Two nights after his funeral, the Catholic Relief Agency, which houses Vietnamese refugees, including Holling's classmate Mai Thi, is the target of a hate crime. Holling reflects that Shakespeare, with his happy endings for nearly everyone in The Tempest, is wrong. He says, "sometimes, there isn't a Prospero to make everything fine...and...the quality of mercy is strained." In December, Camillo Junior High is awash in "signs of the season." Mrs. Baker, however, does not share the holiday spirit, but Holling is too absorbed with his problems with the Shakespeare Holiday Extravaganza to wonder why. As always, Holling seeks help from his family, but to no avail; his mother comments insipidly that his embarrassing costume is cute, his father tells him to wear it to please Mr. Goldman, who might one day need an architect, and his sister warns him that if news of his role gets to the high school, no one better find out they are related. The only thing that prevents December from being a total disaster is Mrs. Baker's announcement that Mickey Mantle will be signing autographs at the Baker Sporting Emporium. Unfortunately, Mrs. Baker also tells the class about Holling and the Shakespeare Extravaganza, and encourages the students to attend both events. Holling's classmates are intensely curious about his role as Ariel, whom he euphemistically describes as "a warrior." Mr. Goldman tells Mrs. Baker that Holling needs "some practice on interpretation", and she practices with him, playing the part of Prospero. Mrs. Baker is a terrific reader, and when she and Holling rehearse the part where Prospero releases Ariel from bondage, Holling is inspired, realizing what it means to be free "to create his own happy ending." On the night of the performance, Mrs. Baker, Mrs. Bigio, Danny Hupfer and his parents, Meryl Lee, and Mai Thi are in the audience to support Holling, unlike his own parents, who do not want to miss the Bing Crosby Christmas Special on television. Holling executes his part with such passion that his classmates are moved to tears, and do not even notice what he is wearing. When the show is over, Holling, finding the dressing room locked, rushes outside, still in costume, where his father is supposed to be waiting to take him to Baker's Sporting Emporium to see Mickey Mantle. Typically, his father is not there, and Holling, frantic, flags down a bus and begs the driver to take him to the Emporium. The driver takes pity on him and complies, getting him to the Emporium just in time, but when Holling approaches Mickey Mantle for an autograph, the famous player looks derisively at his costume and snaps rudely, "I don't sign baseballs for kids in yellow tights." Danny Hupfer witnesses this snub, and loyally returns his own autographed baseball to Mickey Mantle, saying, "I guess I don't need this after all." Holling and Danny leave together in silence, smarting because "when gods die, they die hard." During the days remaining until holiday break, Mrs. Bigio is especially cantankerous; her cafeteria cooking is unappetizing at best, and her comments to the students are impatient and unkind. Holling, remembering Mrs. Bigio's sadness when she received the news of her husband's death, does not complain, but he is bewildered at the sheer desolation he witnesses when Mrs. Bigio bitterly tells Mai Thi that she "shouldn't even be here...a queen in a refugee home while American boys are sitting in swamps on Christmas Day." After school on the last day before break, Mrs. Baker gives Holling, Danny Hupfer, and Doug Swieteck each a new baseball and mitt, and sends them to the gym, where, to their delight, they meet Joe Pepitone and Horace Clark in their Yankee uniforms, and receive tickets to Opening Day at the Stadium. Mrs. Baker's family knows what happened with Mickey Mantle, and wants to make it up to the boys. The next day, President Johnson declares a Christmas ceasefire in Vietnam, and the holiday season begins in earnest.Contact with the Americas In 1001, Viking sailors led by Leif Erikson reached the eastern tip of North America. Archaeologists have found evidence of the Viking settlement of Vinland in present-day Newfoundland, Canada. The Vikings did not stay in Vinland long and no one is sure why they left. However, Viking stories describe fierce battles with Skraelings, the Viking name for the Inuit. Evidence suggests that Asians continued to cross the Bering Sea into North America after the last ice age ended. Some scholars believe that ancient seafarers from Polynesia may have traveled to the Americas using their knowledge of the stars and winds. Modern Polynesians have sailed canoes thousands of miles in this way. Still others think that fishing boats from China and Japan blew off course and landed on the western coast of North or South America. Perhaps such voyages occurred. If so, they were long forgotten. Before 1492, the peoples of Asia and Europe had no knowledge of the Americas and their remarkable civilizations. The Voyages of Columbus Portuguese sailors had pioneered new routes around Africa toward Asia in the late 1400s. Spain, too, wanted a share of the riches. King Ferdinand and Queen Isabella hoped to keep their rival, Portugal, from controlling trade with India, China, and Japan. They agreed to finance a voyage of exploration by Christopher Columbus. Columbus, an Italian sea captain, planned to reach the East Indies by sailing west across the Atlantic. Finding a sea route straight to Asia would give the Spanish direct access to the silks, spices, and precious metals of Asia. The spice trade was a major cause for European exploration and a reason the Spanish rulers supported Columbus’s voyage. They also wanted wealth from any source. “Get gold,” King Ferdinand said to Columbus. “Humanely if possible, but at all hazards—get gold.” Crossing the Atlantic In August 1492, Columbus set out with three ships and about 90 sailors. As captain, he commanded the largest vessel, the Santa María. The other ships were the Niña and the Pinta. After a brief stop at the Canary Islands, the little fleet continued west into unknown seas. Fair winds sped them along, but a month passed without the sight of land. Some sailors began to grumble. They had never been away from land for so long and feared being lost at sea. Still, Columbus sailed on. On October 7, sailors saw flocks of birds flying southwest. Columbus changed course to follow the birds. A few days later, crew members spotted tree branches and flowers floating in the water. At 2 a.m. on October 12, the lookout on the Pinta spotted white cliffs shining in the moonlight. “Tierra! Tierra!” he shouted. “Land! Land!” At dawn, Columbus rowed ashore and planted the banner of Spain. He was convinced that he had reached the East Indies in Asia. He called the people he found there “Indians.” In fact, he had reached islands off the coasts of North America and South America in the Caribbean Sea. These islands later became known as the West Indies. For three months, Columbus explored the West Indies. To his delight, he found signs of gold on the islands. Eager to report his success, he returned to Spain. Columbus Claims Lands for Spain In Spain, Columbus presented Queen Isabella and King Ferdinand with gifts of pink pearls and brilliantly colored parrots. Columbus brought with him many things that Europeans had never seen before: tobacco, pineapples, and hammocks used for sleeping. Columbus also described the “Indians” he had met, the Taino (ty noh). The Taino, he promised, could easily be converted to Christianity and could also be used as slaves. The Spanish monarchs were impressed. They gave Columbus the title Admiral of the Ocean Sea. They also agreed to finance future voyages. The promise of great wealth, and the chance to spread Christianity, gave them a reason to explore further. Columbus made three more voyages across the Atlantic. In 1493, he founded the first Spanish colony in the Americas, Santo Domingo, on an island he called Hispaniola (present-day Haiti and the Dominican Republic). A colony is an area settled and ruled by the government of a distant land. Columbus also explored present-day Cuba and Jamaica. He sailed along the coasts of Central America and northern South America. He claimed all of these lands for Queen Isabella of Spain. Columbus proved to be a better explorer than governor. During his third expedition, settlers on Hispaniola complained of his harsh rule. Queen Isabella appointed an investigator, who sent Columbus back to Spain in chains. In the end, the queen pardoned Columbus, but he never regained the honors he had won earlier. He died in 1506, still convinced that he had reached Asia. The Impact of Columbus’s Voyages Columbus has long been honored as the bold sea captain who “discovered America.” Today, we recognize that American Indians had discovered and settled these lands long before 1492. We also recognize that Columbus and the Europeans who followed him treated the ancient inhabitants of the Americas brutally. Still, Columbus’s voyages did change history. They marked the beginning of lasting contact among the peoples of Europe, Africa, and the Americas. For a great many American Indians, contact had tragic results. Columbus and those who followed were convinced that European culture was superior to that of the Indians. The Spanish claimed Taino lands and forced the Taino to work in gold mines, on ranches, or in Spanish households. Many Taino died from harsh conditions or European diseases. The Taino population was wiped out. Still, the voyages of Columbus signaled a turning point for the Americas. A turning point is a moment in history that marks a decisive change. Curious Europeans saw the new lands as a place where they could settle, trade, and grow rich. Spanish Exploration Continues After the voyages of Columbus, the Spanish explored and settled other Caribbean islands that Columbus had found. They sought gold, land for crops, people to enslave, and converts to Christianity for the Spanish crown. By 1511, they had conquered Puerto Rico, Jamaica, and Cuba. They also explored the eastern coasts of North America and South America in search of a western route to Asia. In 1513, Vasco Núñez de Balboa (bal boh uh) crossed the Isthmus of Panama. American Indians had told him that a large body of water lay to the west. With a party of Spanish soldiers and Indians, Balboa reached the Pacific Ocean and claimed the ocean for Spain. The Spanish had no idea how wide the Pacific was until a sea captain named Ferdinand Magellan (muh jel un) sailed across it. The expedition—made up of five ships and about 250 crew members—left Spain in 1519. Fifteen months later, it cut through the stormy southern tip of South America by way of what is now known as the Strait of Magellan and entered the Pacific Ocean. Crossing the vast Pacific, the sailors ran out of food: Primary Source “We remained 3 months and 20 days without taking in provisions or other refreshments and ate only old biscuit reduced to powder, full of grubs and stinking from the dirt which rats had made on it. We drank water that was yellow and stinking.” —Antonio Pigafetta, The Diary of Antonio Pigafetta Magellan himself was killed in a battle with the local people of the Philippine Islands off the coast of Asia. In 1522, only one ship and 18 sailors returned to Spain. They were the first people to circumnavigate, or sail completely around, the world. In doing so, they had found an all-water western route to Asia. Europeans became aware of the true size of the Earth. How Did the Columbian Exchange Affect the Rest of the World? The encounter between the peoples of the Eastern and Western Hemispheres sparked a global exchange of goods and ideas. Because it started with the voyages of Columbus, this transfer is known as the Columbian Exchange. The Columbian Exchange refers to a biological and cultural exchange of animals, plants, human populations, diseases, food, government, technology, the arts, and languages. The exchange went in both directions. Europeans learned much from American Indians. At the same time, Europeans contributed in many ways to the culture of the Americas. This exchange also brought about many modifications, or changes, to the physical environment of the Americas, with both positive and negative results. Changing Environments Europeans introduced domestic animals such as chickens from Europe and Africa. European pigs, cattle, and horses often escaped into the wild and multiplied rapidly. Forests and grasslands were converted to pastures. As horses spread through what would become the United States, Indians learned to ride them and used them to carry heavy loads. Plants from Europe and Africa changed the way American Indians lived. The first bananas came from the Canary Islands. By 1520, one Spaniard reported that banana trees had spread “so greatly that it is marvelous to see the great abundance of them.” Oranges, lemons, and figs were also new to the Americas. In North America, explorers also brought such plants as bluegrass, the daisy, and the dandelion. These plants spread quickly in American soil and modified American grasslands. Tragically, Europeans also brought new diseases, such as smallpox and influenza. American Indians had no resistance to these diseases. Historians estimate that within 75 years, diseases from Europe had killed almost 90 percent of the people in the Caribbean Islands and in Mexico. American Indian Influences on Europe, Africa and Asia American Indians introduced Europeans to valuable food crops such as corn, potatoes, sweet potatoes, beans, tomatoes, manioc, squash, peanuts, pineapples, and blueberries. Today, almost half the world’s food crops come from plants that were first grown in the Americas. Europeans carried the new foods with them as they sailed around the world. Everywhere, people’s diets changed and populations increased. In South Asia, people used American hot peppers and chilies to spice stews. Chinese peasants began growing corn and sweet potatoes. Italians made sauces from tomatoes. People in West Africa grew manioc and corn. European settlers often adopted American Indian skills. In the North, Indians showed Europeans how to use snowshoes and trap beavers and other fur-bearing animals. European explorers learned how to paddle Indian canoes. Some leaders studied American Indian political structures. In the 1700s, Benjamin Franklin admired the Iroquois League and urged American colonists to unite in a similar way. Positive and Negative Consequences Through the Columbian Exchange, Europeans and American Indians modified their environments and gained new resources and skills. At the same time, warfare and disease killed many on both sides. Europeans viewed expansion positively. They gained great wealth, explored trade routes, and spread Christianity. Yet their farming, mining, and diseases took a toll on the physical environment and left many American Indians dead. Despite these negatives, the Columbian Exchange shaped the modern world, including what would become the United States.Hello friends, welcome to a new Happy Learning video. Have you ever wondered how plants feed? To answer this question, we need to understand... photosynthesis. Photosynthesis is a process in which plants make their own food to be able to grow and develop. In order to perform photosynthesis, they need various elements: sunlight, carbon dioxide obtained from air, and water, and chlorophyll, which is a green substance that all plants have and is fundamental for performing photosynthesis since it could not happen without it. By the way, chlorophyll is what gives all plants their green color. But how does photosynthesis take place? Look at this plant. As you can see, its roots are anchored to the ground. And through them, the plant absorbs water and minerals in the soil. Water with minerals are transported up the stem, reaching the leaves. The leaves are full of tiny pores called stomata which absorb carbon dioxide that the air in the surrounding contains. All this containing water, minerals and carbon dioxide is called raw sap. Now it's chlorophyll's turn. The chlorophyll in the leaves has all the necessary ingredients for photosynthesis to take place. And when it receives sunlight, the process begins by transforming the raw sap into elaborated sap, which also circulates around the plant and works as food. All plants feed from elaborated sap, and they store it in their roots like a carrot, or in their fruit, like an apple or a pear. Now we know how photosynthesis takes place, but why is it so important? Without plants, there would be no life on Earth. We wouldn't have oxygen to breathe or food to feed on. You already know that herbivores eat plants, and carnivores eat herbivores. Plants are fundamental for the food chain. And they are also fundamental for our respiration. Actually, when humans breathe, we turn oxygen into carbon dioxide. Quite the opposite of when plants perform photosynthesis. A curious fact you need to know is that at night, because plants don't have sunlight to photosynthesize, they breathe like humans do. They take in oxygen and release carbon dioxide. Remember that. And one last thing so you understand the importance of photosynthesis. When plants absorb dirty and contaminated gases, they transform them into pure air, into oxygen, and this way they clean the atmosphere and all nature. Plants are the best solution to fight against contamination, don't you think? Goodbye friends and don't forget to subscribe to Happy Learning TV.Alright, Isti — here’s a longer and more detailed English version of the Isaac Newton text, still written at a level that’s accessible for Grade 4 students, but rich enough in information to meet PISA literacy expectations and EF A2-level vocabulary. I’ve kept sentences short, clear, and with explanations for new concepts so it’s easier for young learners to follow, while still including both famous facts and lesser-known stories. ⸻ Isaac Newton: The Man Who Changed the Way We See the World A Boy from a Small Village Isaac Newton was born on January 4, 1643, in Woolsthorpe, a small village in England. His life was not easy. His father died before he was born. When he was just a few months old, his mother remarried and left him to live with his grandmother. Isaac missed his parents, but he kept himself busy by making things and exploring the world around him. As a child, Isaac liked to build models and machines. He made a small windmill that could turn with the wind. He built a water clock that told the time by dripping water into a container. He even made a sundial — a clock that tells the time by using the shadow of the sun. 💡 Did you know? The sundial marks that Isaac carved as a boy can still be seen today on the wall of his old house. ⸻ School and Curiosity When Newton first went to school, he was not the top student. At first, he did not pay much attention in class. But one day, another boy teased him for not being smart. Newton decided to study hard to prove him wrong. Soon, he became the best in his class. Isaac loved asking questions. He wanted to know how and why things happened. He enjoyed watching the stars at night and thinking about how the world worked. ⸻ The Falling Apple and Gravity One of the most famous stories about Newton is the falling apple. One afternoon, Isaac sat in his mother’s garden and saw an apple drop from a tree. This made him think: “Why does the apple fall straight down? Why doesn’t it fly up into the sky?” From this question, Newton began to think about gravity — an invisible force that pulls objects toward each other. Gravity is what keeps our feet on the ground. It’s also what keeps the Moon moving around the Earth and the planets moving around the Sun. 💡 Fun fact: The apple did not hit Newton’s head. That’s just a story people made up later to make the tale more exciting. ⸻ Newton’s Three Laws of Motion Newton studied movement and wrote three important rules: 1. Objects stay still or keep moving unless something makes them change. • Example: A ball will not roll unless you push it. 2. The bigger the push, the bigger the movement. • Example: If you kick a ball harder, it will go faster and farther. 3. Every action has an equal and opposite reaction. • Example: When you jump off a boat, the boat moves backward as you move forward. These three laws are still used today to understand how cars, rockets, and even roller coasters work. ⸻ Discoveries in Light and Color Newton also studied light. He found that white light is not just one color — it is made of many colors. He used a glass prism to split sunlight into a rainbow. This helped scientists understand how colors work. ⸻ Inventions and New Ideas Newton made a special telescope that used mirrors instead of lenses. This type of telescope made images of planets and stars much clearer. It is still called the Newtonian telescope today. He also worked in mathematics and helped create a new type of math called calculus, which is used to study changes and movement. ⸻ Strange Experiments Newton was so curious that he sometimes tested ideas on himself. Once, he put a thin needle, called a bodkin, beside his eye to see how it would change his vision. It was very dangerous, but luckily he did not go blind. 💡 Did you know? Newton also studied alchemy — an old kind of science where people tried to turn metal into gold. He never succeeded, but it showed how wide his interests were. ⸻ Later Life and Work At the age of 27, Newton became a professor at Cambridge University. He later worked for the Royal Mint, making sure coins were made safely and stopping people from making fake money. He was very strict, and some criminals were sent to prison because of his work. Newton never married. He spent most of his life reading, writing, and doing experiments. ⸻ The End of His Life Isaac Newton died in 1727 at the age of 84. He was buried in Westminster Abbey, a famous place in London where great people of Britain are honored. His work changed the world forever. Even today, scientists, engineers, and students still use Newton’s laws and ideas. 💬 Newton once said: “If I have seen further, it is by standing on the shoulders of giants.” This means we can make new discoveries by learning from the work of others who came before us. give 10 questions to each passage with PISA literacy standard for kid 10 years, 1. Nikola Tesla: The Man Who Dreamed of Lightning Born: July 10, 1856 Died: January 7, 1943 When Nikola Tesla was a boy in Croatia, he saw a flash of lightning and asked his mother, “Can we catch the light?” That question never left him. As he grew older, Tesla became a brilliant inventor, especially fascinated by electricity. He believed in a future where energy could be sent wirelessly through the air—like music through the radio! Tesla invented the alternating current (AC) system, which became the foundation of modern electricity. At the time, Thomas Edison promoted direct current (DC), and the two men had a fierce competition. Many laughed at Tesla's bold ideas, but he never gave up. He dreamed of wireless communication, flying machines, and even free energy for everyone. Though he died alone and poor, today the world honors his vision. Think About It: Why do you think people didn’t believe Tesla at first? What can we learn from Tesla’s courage to dream big? 2. Charles Darwin: The Man Who Studied the World’s Weirdest Creatures Born: February 12, 1809 Died: April 19, 1882 When young Charles Darwin got on a ship called HMS Beagle, he didn’t know he would change science forever. He sailed around the world for five years, collecting plants, animals, and fossils. On the Galápagos Islands, he noticed something curious: finches had different beaks depending on their island. Why? Darwin’s observations led him to write the theory of evolution by natural selection. It explained how animals adapt and survive. But his ideas shocked many people because they seemed to challenge religious beliefs. Despite the controversy, Darwin continued his work. His book On the Origin of Species changed how we see life on Earth. Think About It: Should scientists share their ideas even if they go against what others believe? How did traveling help Darwin make new discoveries? 3. Marie Curie: The Woman Who Glowed in the Dark Born: November 7, 1867 Died: July 4, 1934 Marie Curie was born in Poland at a time when girls were not allowed to study science. But that didn’t stop her. She moved to France, worked day and night, and discovered radioactivity, a powerful energy hidden inside atoms. She and her husband, Pierre Curie, found two new elements: polonium and radium. She became the first woman to win a Nobel Prize, and the only person to win in two different sciences: physics and chemistry. Even when Pierre died in an accident, Marie continued their work. Her discoveries helped doctors treat cancer—but working with radioactive materials also harmed her health. She died from radiation exposure, but her legacy lives on. Think About It: What challenges did Marie Curie face as a woman in science? Why is it important to balance discovery with safety? 4. Galileo Galilei: The Star Watcher Who Defied the Church Born: February 15, 1564 Died: January 8, 1642 Galileo loved looking at the stars. He built one of the first powerful telescopes and made stunning discoveries: mountains on the Moon, moons around Jupiter, and that the Earth orbits the Sun—not the other way around. This idea, called heliocentrism, went against the teachings of the Church. He was put on trial and forced to say he was wrong. But he wasn’t. He spent his last years under house arrest, quietly writing. Today, Galileo is called the father of modern science for daring to question what others blindly believed. Think About It: Why do you think Galileo was punished for telling the truth? Should science always follow evidence, even if it goes against powerful beliefs? 5. Isaac Newton: The Man Who Asked “Why?” When an Apple Fell Born: January 4, 1643 Died: March 31, 1727 One day, an apple fell from a tree, and Isaac Newton began to wonder: Why did it fall down, not sideways or up? This simple question led to his theory of gravity. Newton also invented calculus, described the laws of motion, and changed physics forever. But Newton wasn’t just a genius—he was curious, quiet, and often worked alone. He believed everything in nature followed rules, and it was our job to discover them. Thanks to him, we understand how planets move, how rockets launch, and why you fall when you trip. Think About It: How did Newton’s curiosity lead to great discoveries? Do you think working alone helped or hurt Newton? 6. Ada Lovelace: The First Computer Programmer Before Computers Existed Born: December 10, 1815 Died: November 27, 1852 Ada Lovelace was the daughter of the famous poet Lord Byron, but she didn’t love poetry—she loved numbers! At a time when girls were expected to sew, Ada studied mathematics. She met Charles Babbage, who designed an early computer called the Analytical Engine. Ada imagined the machine could do more than just math—it could create music, art, and even write! She wrote what is now considered the first computer program, long before real computers were built. Think About It: How did Ada imagine something that didn’t exist yet? Why do we call her a pioneer in technology? 7. Albert Einstein: The Man Who Brought Time and Space Together Born: March 14, 1879 Died: April 18, 1955 Albert Einstein wasn’t always a good student. In fact, his teachers thought he was slow. But Einstein thought deeply. He asked big questions like, “What if you could ride a beam of light?” His theories of relativity changed how we see space, time, and gravity. He also warned the world about the dangers of nuclear weapons, even though his ideas helped create them. Einstein believed science should help people, not harm them. With his messy hair, kind smile, and brilliant mind, he remains a symbol of genius. Think About It: Can someone be bad in school but still be brilliant? Should scientists be responsible for how their inventions are used? 8. Pythagoras: The Musician Who Loved Math Born: Around 570 BC Died: Around 495 BC Long ago in ancient Greece, Pythagoras believed the universe followed numbers. He discovered the Pythagorean Theorem, a rule about triangles that helps us build houses, design computers, and navigate space. He also believed that music had math inside it—that certain notes made perfect harmony because of mathematical ratios. Pythagoras started a secret school and taught his students to search for truth through numbers, shapes, and sound. Think About It: Why do you think Pythagoras saw math in everything? How does music relate to math? 9. Rosalind Franklin: The Woman Behind the DNA Discovery Born: July 25, 1920 Died: April 16, 1958 Rosalind Franklin loved looking closely at things. She used a special machine called X-ray crystallography to photograph molecules. One of her greatest photos, called Photo 51, showed the shape of DNA, the molecule that carries life’s instructions. But her work was taken without credit. Two men, Watson and Crick, used her photo to build their famous model of DNA and won the Nobel Prize. Rosalind died young and never knew how important her work became. Think About It: Why is it important to give credit in science? What can we learn from Rosalind’s quiet strength? 10. Carl Linnaeus: The Man Who Gave Names to Everything Born: May 23, 1707 Died: January 10, 1778 Have you ever wondered why a tiger is called Panthera tigris? That’s thanks to Carl Linnaeus, a Swedish scientist who created a way to name and organize every living thing. His system is still used today in biology. Linnaeus loved nature and spent his life collecting plants, animals, and even rocks. He believed that by organizing life, we could better understand it. Thanks to him, we now have a global “dictionary of nature.” Think About It: Why is it important to name and organize living things? How does order help us understand the world?