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  • One day, the last star will die, and the universe will turn dark forever.

    當最後的那顆恆星熄滅的那天 宇宙將陷入永遠的黑暗

  • It will probably be a red dwarf, a tiny kind of star,

    紅矮星這種小型的恆星或許是我們

  • that's also one of our best bets to find alien life,

    得去孤注一擲去尋找外星生命得場所, 或是成為人類最後的安棲之所

  • and might be the last home of Humanity before the universe becomes uninhabitable,

    我們對紅矮星了解多少, 又為何它們是我們的最後希望?

  • so what do we know about them, and why are they our last hope?

    在宇宙中的恆星至少有70%是紅矮星

  • At least 70% of stars in the universe are red dwarfs.

    它們是宇宙中最小的恆星,值量僅有太陽的7%到50%。

  • They are the tiniest stars out there, with only about 7 to 50% of the mass of our sun,

    比起木星差不了多少,不過依然很大。

  • not that much bigger than our planet, Juptier, which is still huge, though.

    它們相當黯淡。

  • They are also very dim.

    我們很難用肉眼觀察到它

  • It's impossible to see them with the naked eye.

    當你在夜晚注視天空時,你絕對看不到它們

  • You've never seen one in the night sky.

    即使使用現在的技術,我們也只能清晰地觀察到鄰近我們的紅矮星

  • Even with all our technology,

    鄰近地球的紅矮星大約有20~30顆

  • we can only clearly observe red dwarfs in our neighborhood.

    如同所有的恆星一般, 紅矮星把氫核融合成氦

  • Approximately 20 of the 30 stars close to Earth are red dwarfs.

    其他質量較重的恆星, 會將融合成的氦聚集到核心之中。

  • Like all stars, red dwarfs fuse hydrogen into helium,

    紅矮星則是將氦分散到各處,所以紅矮 星中的氫和氦持續不斷的混合一起。

  • but while more massive stars accumulate all the fused helium in their cores,

    所以在它們死亡之前,它們使用燃料的速度出乎意料的慢

  • red dwarfs stay convective, meaning that the helium and hydrogen constantly mix,

    紅矮星燃燒得很慢,紅矮星的生命週期有一兆到十兆年不等。

  • so they use up their fuel incredibly slowly before they are extinguished.

    相較之下,我們的太陽只能再活五十億年

  • Red dwarfs burn so slowly

    因為宇宙只有一百三十七億多歲

  • that their average lifespan is between one and ten trillion years;

    尚未有任何紅矮星進入下一個發展階段

  • by comparison, the Sun will survive for another five billion years.

    每一個已存在一兆年的紅矮星 都還算是個小寶寶

  • Because the universe is only 13.75 billion years old,

    說到寶寶,在宇宙中

  • not a single red dwarf has reached later development stages.

    全宇宙中最小的恆星,紅矮星剛好符合恆星的最低標準

  • Every single one of the trillions that exist is still a baby.

    如果氫的質量再少一些,它將只是棕矮星

  • Speaking of babies, the smallest star in the entire universe

    無法持續進行融合反應,無法成為恆星

  • is also a red dwarf because small red dwarfs are right on the verge of being a star at all.

    這和外星人和人類新家有何關係?

  • Just a tiny bit less hydrogen, and they are mere brown dwarfs,

    既然太陽終將毀滅,人類將來勢必要 找新家

  • failed stars that cannot sustain a fusion reaction for long,

    宜居的行星當然也有可能存在外星人

  • so what about aliens or a new home for Humanity?

    克卜勒天文台發現半數以上的紅矮星系

  • Since our sun will die one day, we'll eventually need to look for a new home,

    都有岩質行星存在,質量從地球的一半 到四倍不等

  • and where there are habitable planets, there might also be aliens.

    多數多處於可居範圍內,在此範圍內, 水可以保持在液態

  • The Kepler space observatory found that at least half of all red dwarfs host

    但因為紅矮星以較低溫度運作

  • rock planets between half and four times the mass of our Earth.

    行星必須更靠近紅矮星才適宜居住

  • Many of them are in the habitable zone, the area around a star where water can be liquid,

    或許要像水星靠太陽那麼近才可以

  • but since red dwarfs burn at relatively cold temperatures,

    然而所有麻煩都因此而生。舉例來說 靠恆星這麼近的行星常常被「潮汐鎖定」(同步自轉)

  • a planet would need to be really close to be hospitable,

    被潮汐鎖定的行星永遠只會用同一面 面對恆星

  • probably as close as Mercury to our Sun or even closer

    向光面會熱到不得了, 背光面則會冷到凍結,大大不利生命

  • which brings with it all kinds of problems.

    如果該行星有夠大的海洋,或許可以均勻分散紅矮星的能量,帶來部分的穩定。

  • For example, a planet this close to a star would probably be tidally locked,

    行星被紅矮星重力不斷擠壓,並過度加熱之下,

  • meaning the same side would always face it.

    隨時間過去,可能會喪失所有水分。

  • This side would be incredibly hot, while the shadow side would be frozen

    這些行星最終可能會像金星一般, 變成一個灼熱的煉獄。

  • which makes it hard for life to develop;

    有些紅矮星的能量輸出變換不定, 則是另一個大麻煩。

  • although, a planet with a big enough ocean might be able to distribute the star's energy

    紅矮星有時會被星斑覆蓋,將使發出的 光芒減少最高達40%,為時數月

  • and create some kind of stability.

    這將使該行星的海洋為之凍結

  • All the gravitational forces of the red dwarf could squeeze the planet

    有時紅矮星則散發極有威力的閃焰,這種突然暴發的能量威力無窮。

  • and heat it up so much that it might lose all its water over time.

    此時的紅矮星亮度會在數分鐘內加倍,

  • These planets could end up like Venus, a hot burning hell.

    這會奪走行星大部分的氣體,並燒了它們

  • Another problem is that many red dwarfs vary in their energy output.

    另一方面,它們極長的壽命是一大優勢

  • They can be covered in star spots that condemn their emitted light by up to 40% for months

    一個處於平穩狀態的紅矮星 就可使行星成為一個承載生命神奇的地方

  • which would cause oceans on planets to freeze over;

    地球上的生命已經存在了40億年

  • at other times, they can emit powerful solar flares,

    而且,我們有大約十億年的時間離開 太陽變得太熱,地球上的複雜的生命

  • sudden outbursts of energy incredibly powerful.

    將不復存在

  • These red dwarfs could double their brightness in minutes

    我們要麼死了,要麼離開地球尋找一個新的家

  • which could strip away sizable portions of a planet's atmosphere and burn it,

    我們可以在數萬億年中建造文明 生活在紅矮星附近

  • rendering it sterile;

    銀河系中約有5%的紅矮星可遷移居住 大致上與地球大小相差無幾

  • on the other hand, their extremely long life span is a big plus.

    總共可能超過40億個

  • A red dwarf with just moderate levels of activity

    但生態可能不會像地球一樣

  • could be an amazing place for a planet that hosts life.

    圍繞紅矮星生活的也可能有大氣衛星 (moons of Gas Giants)也稱為超級地球衛星

  • Life on Earth has existed for about four billion years,

    真正的大型岩石行星。

  • and we have about a billion years left before the Sun becomes so hot

    獨自一人 周圍的紅矮星估計還有60億潛在適合居住的行星

  • that complex life on Earth will become impossible.

    而且,這僅僅是在銀河系

  • We will either die out or leave Earth and look for a new home.

    因此,紅矮星可能成為我們未來的生存非常重要的關鍵

  • We could build a civilization for potentially trillions of years

    但在某個時候一切都會死亡,即使是紅矮星

  • around a red dwarf with the right conditions.

    當在萬億年最後一個紅矮星的生命即將結束時 它絕對不會是一個非常壯觀的事情

  • About 5% of the red dwarfs in the Milky Way may host habitable, roughly Earth-sized planets.

    當它的氫耗盡時,它會縮小成為藍矮星,最後整顆燃燒

  • That would be more than four billion in total,

    當燃燒完畢時,它變成了一個白矮星,一個如同地球大小的星球

  • but life may not even need a planet like Earth.

    構造非常密集,並主要由氦原子核組成

  • Candidates for life around a red dwarf may be the moons of gas giants,

    沒有更多得能量來源 它會在萬億年間緩慢的冷卻

  • also called Super Earths, really massive rocky planets.

    直到它成為其最終形式:一個寒冷的黑矮星

  • All alone, there are an estimated 60 billion potentially habitable planets

    白與黑矮星是如此令人著迷,他們應該擁有自己的影片

  • around red dwarfs, and that's in the Milky Way alone,

    反正......在宇宙消失前,還有許多時間

  • so red dwarfs might become really important for our survival in the future,

    如果人類成功地進軍太空,這會使任何人振奮

  • but everything has to die at some point, even red dwarfs.

    在宇宙熄滅之前,我們還有足夠的時間

  • When in trillions of years the life of the last red dwarf in the universe is about to end,

    你對Patreon.com支持是我們製作影片的動力,如果您想幫助我們製作更多影片

  • it will not be a very spectacular event.

    我們非常感謝您的支持 ; )

  • As its hydrogen runs out, it shrinks becoming a blue dwarf, burning out completely.

  • After its fuel is spent, it's transformed into a white dwarf,

  • an object about as small as Earth, packed very densely,

  • and made of degenerate gasses, mostly of Helium-4 nuclei.

  • Having no more source of energy, it will cool extremely slowly

  • over trillions of years until it becomes its final form: a cold black dwarf.

  • White and black dwarfs are so fascinating that they deserve their own video;

  • anyway, it's going to be a long time before the last stars in the universe vanish.

  • It's kind of uplifting to know that, if Humanity succeeds in venturing into Space,

  • we have plenty of time before the universe turns out the lights.

  • Our videos are made thanks to your support on Patreon.com.

  • If you want to help us make more of them, we really appreciate your support!

  • Subtitles by the Amara.org community

One day, the last star will die, and the universe will turn dark forever.

當最後的那顆恆星熄滅的那天 宇宙將陷入永遠的黑暗

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宇宙中最後一顆星--紅矮星解讀 (The Last Star in the Universe – Red Dwarfs Explained)

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    簡簡哲 發佈於 2021 年 01 月 14 日
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