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  • Of all the spectacles mankind has viewed through a telescope,

    人類由望遠鏡觀察到的宇宙中

  • there are few lovelier than a spiral galaxy.

    螺旋星系是最美好的奇景之一

  • Majestic whirlpools of stars, they rotate in a stately and predictable dance.

    星群形成壯麗漩渦, 在其中跳著穩定恆常的舞步

  • The fact that we see many billions of them in our telescopes

    用望遠鏡便可觀察到 幾十億個以上的螺旋星系

  • tells us they are both common and stable.

    可見得它既普遍、又穩定

  • It is perhaps surprising that it is relatively easy to understand the inner workings of these cosmic pinwheels.

    可能會嚇你一跳,要了解這些 宇宙風車的內部運作

  • By combining physical principles worked out by Sir Isaac Newton in the late 17th century,

    最容易的是依據牛頓 (Sir Isaac Newton) 在十七世紀晚期研究出的物理原則

  • with the observed amount of mass in a galaxy,

    以及觀測到的星系質量

  • scientists can calculate the rates at which these galaxies rotate.

    科學家便可計算出星系旋轉速率

  • Using these techniques, astronomers predict how fast stars at different distances from the center of the galaxy should move.

    天文學家用此法預測與中心 不同距離的恆星移動的速度

  • Stars very close to the center move slowly.

    越靠近星系中心,恆星移動越慢

  • That's because there is very little mass between them and the center of the galaxy to pull them along.

    因為它們之間沒有很多質量可以甩動

  • Stars a bit further away move faster,

    遠一點的恆星移動速度較快

  • because they are being pulled by all of the stars in between them and the center.

    因為它們被它們與核心之中的所有星星 一起甩動

  • As we get really far away, the stars are predicted to move slowly again.

    到很遠以後, 恆星的移動速度又會慢下來

  • Their great distance reduces gravity to a gentle tug,

    因為距離太遠,重力變得微弱

  • so they move leisurely in their orbits.

    因此就悠閒的在軌道漫步

  • Knowing this, scientists looked at the galaxies and measured how fast stars were moving.

    科學家觀測星系中 各恆星的軌道速度

  • To their surprise, they found that while the stars closer to the center of the galaxy behaved as predicted,

    驚訝的發現,接近星系中心的恆星 速度和預測相符

  • those further away moved far too quickly.

    但較遠的恆星,速度超出預期

  • This observation was devastating to the tradtional theories of gravity and motion.

    這對傳統的重力及運動理論 帶來毀滅性打擊

  • If the stars were moving as fast as their measurement suggested,

    如果恆星移動的速度和遠近符合定律的話

  • galaxies should have torn themselves apart.

    星系早就被自己撕裂了。

  • It was a crisis, and astronomers and physicists scrambled to find a mistake in their calculation.

    這是個危機,天文學家和物理學家 拼命想找出哪裡算錯了

  • Was Newton's theory of gravity wrong?

    是牛頓的萬有引力定律錯了嗎?

  • Was his theory of motion wrong?

    還是他的三大運動定律錯了嗎?

  • Or was it possible that astronomers had incorrectly measured the galaxy's mass?

    或是天文學家算錯星系的質量呢?

  • All options were investigated, and all were ruled out. Except one.

    調查並排除所有選項後 只剩下一種可能

  • Today, scientists believe that the answer lies in a previously unknown kind of matter, called dark matter.

    如今科學家相信,答案就是 一種未知的物質,稱為「暗物質」

  • This dark matter can be envisioned as a cloud which surrounds most galaxies.

    暗物質好像一團雲 籠罩了多數的星系

  • This matter is very unusual. It is affected by gravity,

    這是很不尋常的,它受到重力影響

  • but it is invisible to visible light and all other forms of electromagnetic radiation.

    但是看不見,也沒有 任何形式的電磁輻射

  • The name "dark matter" originates in this form of matter's inability to emit or absorb light.

    「暗物質」名稱源自這種物質 不會發出或吸收光線

  • Dark matter adds to the gravity of the galaxy

    暗物質增加了星系的重力

  • and explains the orbital speed of stars far from the galactic center.

    並可解釋遠離星系中心 恆星的軌道速度

  • Dark matter has not yet been directly observed,

    暗物質從未被直接觀測到

  • but scientists believe that it is likely to be real,

    但科學家相信,它很可能是真的

  • mostly because the other options have been ruled out.

    主要因為其他可能性都已經排除

  • Using dozens of approaches, astronomers and physicists continue to search for direct evidence

    天文學家和物理學家正在嘗試 幾十種方法,想找出直接證據

  • that would prove that the dark matter hypothesis is true.

    要證明,暗物質的假設是正確的

  • This question is one of the most important physics research questions of the 21st century.

    這是 21 世紀物理學 最重要的研究課題之一

Of all the spectacles mankind has viewed through a telescope,

人類由望遠鏡觀察到的宇宙中

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B2 中高級 中文 TED-Ed 星系 恆星 物質 速度 重力

【TED-Ed】 探索宇宙的奧妙:是什麼解釋了星星移動的速度 Dark matter: How does it explain a star's speed? - Don Lincoln

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