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  • All the material objects around you

    你身邊一切事物

  • are composed of submicroscopic units

    都是由極微細的單位組成

  • we call molecules.

    這些單位稱為分子

  • And molecules in turn are composed

    而分子則由一粒一粒原子組成

  • of individual atoms.

    分子不斷分裂

  • Molecules frequently break apart

    然後又組成新分子

  • and then form new molecules.

    另一方面

  • On the other hand,

    你一生中所接觸到的原子

  • virtually all the atoms you come in to contact with

    大地、空氣、食物

  • through the course of your life,

    組成你和一切生物的原子

  • the ones in the ground beneath you,

    已存在數以億年

  • the air you breath, the food you eat,

    發源地與地球非常不同

  • those that make up every living thing, including you,

    以下說的就是原子如何誔生

  • have existed for billions of years

    一切源於一百四十億年前

  • and were created in places very unlike our planet.

    發生了宇宙大爆炸

  • How those atoms came about is what I want to share with you.

    產生了只有氣體的宇宙

  • It all started 14 billion years ago

    無恆星亦無行星

  • with an event we call The Big Bang,

    氣體只由原子組成

  • which resulted in a universe consisting of gas alone.

    那些原子屬於最簡單的元素

  • There were no stars and no planets.

    當中75%為氫

  • The gas was made up only of atoms

    其餘多為氦

  • belonging to the simplest elements.

    仍未有碳、氧或氮等元素

  • It was about 75 percent hydrogen

    亦無鐵、銀或金

  • and almost all the rest was helium.

    氣體密度有些地方稍高

  • No elements like carbon, oxygen or nitrogen existed.

    因萬有引力而吸引更多氣體

  • No iron, silver or gold.

    引力因而更強

  • In some places, the density of this gas was slightly higher than in others.

    再吸引更多氣體,循環不息

  • Due to gravity, those places attracted even more gas,

    最後形成大氣團

  • which further strengthened the pull of gravity,

    氣團因自身引力而萎縮

  • which then drew more gas in, and so on.

    結果內部發熱

  • Eventually, large dense gas balls formed,

    氣團核心熱到若干程度

  • shrinking under their own gravity

    就發生核融合

  • and consequently heating up on the inside.

    氫原子融合為氦

  • At some point, the core of such a ball

    同時釋放巨大能量

  • gets hot enough that nuclear fusion occurs.

    大得可對抗向內拉扯的引力

  • Hydrogen atoms smash together to form helium,

    融合所生向外推的能量

  • accompanied by a great release of energy,

    足以對抗向內拉扯的引力時

  • strong enough to counteract the shrinking force of the gravity.

    就會達平衡狀態

  • When the energy pushing out from the fusion reactions

    恆星就自此而生

  • matches the gravity pulling all the gas inwards,

    巨大恆星一生之中

  • an equilibrium occurs.

    核心的融合反應不只產生氦

  • From this a star is born.

    亦產生週期表中各元素

  • Over its lifetime,

    自碳、氧、氮至鐵止

  • the fusion reactions in the core of a massive star

    但核心最終將耗盡燃料

  • will produce not only helium,

    完全崩潰

  • but also carbon, oxygen, nitrogen

    崩潰造成巨大爆炸

  • and all the other elements in the periodic table up to iron.

    這爆炸稱為超新星爆發

  • But eventually, the core's fuel runs out,

    對超新星如何產生元素

  • leaving it to collapse completely.

    有兩點須注意

  • That causes an unbelievably powerful explosion

    一, 爆炸釋放巨大能源

  • we call a supernova.

    使融合能力變強

  • Now there are two things to note

    產生較鐵更重的原子

  • about how supernovas create elements.

    如銀、金及鈾

  • First, this explosion releases so much energy

    二,聚於恆星核心的所有元素

  • that fusion goes wild

    如碳、氧、氮、鐵

  • forming elements with atoms even heavier than iron

    和超新星爆炸所產生的所有元素

  • like silver, gold and uranium.

    均被排進星際空間

  • Second, all the elements that had been accumulating

    與空間已有的氣體混合

  • in the core of the star,

    然後前事重演

  • like carbon, oxygen, nitrogen, iron,

    氣團現在含多種元素

  • as well as all of those formed in the supernova explosion,

    不單只有氫和氦

  • are ejected in to interstellar space

    密度較高區域

  • where they mix with the gas that's already there.

    吸引更多物質,如此類推

  • History then repeats itself.

    如前所述,產生新星

  • Gas clouds, now containing many elements

    太陽就在五十億年前如此產生

  • besides the original hydrogen and helium,

    即是說,產生太陽旳氣團

  • have higher density areas

    自宇宙開始,超新星爆發時

  • that attract more matter, and so on.

    吸收過多種元素

  • As before, new stars result.

    所以現在太陽所有元素俱備

  • Our sun was born this way about 5 billion years ago.

    但氫仍佔71%

  • That means that the gas it arose from

    其餘27%為氦

  • had itself been enriched with many elements

    但請緊記

  • from supernova explosions since the universe began.

    首批恆星產生時

  • So that's how the sun wound up with all the elements.

    只有氫和氦

  • It's still mostly hydrogen at 71 percent,

    週期表中其餘元素

  • with most of the rest being helium at 27 percent.

    只佔太陽2%

  • But bear in mind

    地球又如何?

  • that while the first stars were made up

    行星是恆星產生過程的副產品

  • of hydrogen and helium alone,

    來自同一氣體

  • the remaining elements in the periodic table

    地球等小行星

  • make up two percent of the sun.

    引力不足以捉緊氫或氦氣

  • And what about Earth?

    因氫、氦均極輕

  • Planets form as an incidental process to star formation

    雖然碳、氮、氧等元素

  • out of the same gas cloud as the star itself.

    在產生地球的氣團中只佔2%

  • Small planets like ours don't have enough gravity

    這些較重的元素組成地球大部份

  • to hold on to much hydrogen or helium gas

    也組成地球各種物體一大部份

  • since both of those are very light.

    試想想:

  • So, even though carbon, nitrogen, oxygen and so on

    除氫和氦外

  • made up only two percent of the gas cloud from which Earth was formed,

    你腳下大地

  • these heavier elements form the bulk of our planet

    所吸空氣,還有你

  • and everything on it.

    當中的原子均來自恆星

  • Think about this:

    二十世紀前半

  • with the exception of hydrogen and some helium,

    科學家有此發現時

  • the ground you walk on,

    著名太空人沙普利曾說

  • the air you breath, you,

    「人與石為兄弟,與雲為表親」

  • everything is made of atoms

  • that were created inside stars.

  • When scientists first worked this out

  • over the first half of the 20th Century,

  • the famous astronomer Harlow Shapley commented,

  • "We are brothers of the boulders, cousins of the clouds."

All the material objects around you

你身邊一切事物

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B1 中級 中文 TED-Ed 元素 恆星 原子 產生 氣體

【TED-Ed】宇宙是由什麼組成的?- Dennis Wildfogel (【TED-Ed】What is the universe made of? - Dennis Wildfogel)

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    Kevin Tan 發佈於 2021 年 01 月 14 日
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