宇宙八大謎題

晴朗的夜空，無數星辰閃閃發光，仿佛藏著無窮奧秘，引誘人們一探究竟。可是，人們越是探索，就會遇見越多難題，也就越發沉迷。那么，目前讓天文學家們迷惑不解、急欲破解的宇宙謎題有哪些呢？

1. Rectangular Galaxy

\"Look， up in the sky! It's a ... rectangle?\" Earlier this year， astronomers spotted a celestial1) body， roughly 70 million light-years away， with an appearance that is unique in the visible universe2): The galaxy LEDA 074886 is shaped more or less like a rectangle. While most galaxies are shaped like discs， three-dimensional ellipses3) or irregular blobs4)， this one seems to have a regular rectangle or diamond5)-shaped appearance. Some have speculated6) that the shape results from the collision of two spiral7)-shaped galaxies， but no one knows for now.

2. The Moon's Magnetic Field

One of the moon's greatest mysteries—why only some parts of the crust8) seem to have a magnetic field—has intrigued9) astronomers for decades， even inspiring the mythical \"monolith\" in the novel and film 2001: A Space Odyssey10). But some scientists finally think they may have an explanation. After using a computer model to analyze the moon's crust， researchers believe the magnetism may be a relic11) of a 120-mile-wide asteroid that collided with the moon's southern pole about 4.5 billion years ago， scattering magnetic material. Others， though， believe the magnetic field may be related to other smaller， more recent impacts.

3. Why Do Pulsars12) Pulse?

Pulsars are distant， rapidly spinning neutron stars13) that emit a beam of electromagnetic radiation at regular intervals， like a rotating14) lighthouse beam sweeping over a shoreline. Although the first one was discovered in 1967， scientists have struggled for decades to understand what causes these stars to pulse—and， for that matter15)， what causes pulsars to occasionally stop pulsing. In 2008， though， when one pulsar suddenly shut off for 580 days， scientists' observations allowed them to determine that the \"on\" and \"off\" periods are somehow related to magnetic currents16) slowing down the stars' spin. Astronomers are still at work trying to understand why these magnetic currents fluctuate17) in the first place.

4. What Is Dark Matter?

Astrophysicists are currently trying to observe the effects of dark energy， which accounts for18) some 70 percent of the universe. But it's not the only dark stuff in the cosmos19): Roughly 25 percent of it is made up of an entirely separate material called dark matter. Completely invisible to telescopes and the human eye， it neither emits nor absorbs visible light (or any form of electromagnetic radiation)， but its gravitational effect is evident in the motions of galaxy clusters20) and individual stars. Although dark matter has proven extremely difficult to study， many scientists speculate that it might be composed of subatomic21) particles that are fundamentally22) different from those that create the matter we see around us.

5. Galactic Recycling

In recent years， astronomers have noticed that galaxies form new stars at a rate that would seem to consume more matter than they actually have inside them. The Milky Way， for example， appears to turn about one sun's worth of dust and gas into new stars every year， but it doesn't have enough spare matter to keep this up long-term. A new study of distant galaxies might provide the answer: Astronomers noticed that gas had been expelled23) by the galaxies flowing back into the center. If the galaxies recycle this gas to produce new stars， it might be a piece of the puzzle in solving the question of the missing raw matter.

6. Is There Anybody out There?

In 1961， astrophysicist Frank Drake devised a highly controversial equation: By multiplying together a series of terms relating to the probability of extraterrestrial24) life (the rate of star formation in the universe， the fraction25) of stars with planets， the fraction of planets with conditions suitable for life， etc.) he surmised26) that the existence of intelligent life on other planets is extremely likely. One problem: Roswell conspiracy27) theorists notwithstanding， we haven't heard from any aliens to date. Recent discoveries of distant planets that could theoretically harbor life， though， have raised hopes that we might detect extraterrestrials if we just keep looking.

7. How Will the Universe End?

We now believe the universe started with the Big Bang28). But how will it end? Based on a number of factors， theorists conclude that the fate of the universe could take one of several wildly different forms. If the amount of dark energy is not enough to resist the compressing force of gravity， the entire universe could collapse into a singular point—a mirror image of the Big Bang， known as the Big Crunch. Recent findings， though， indicate a Big Crunch is less likely than a Big Chill， in which dark energy forces the universe into a slow， gradual expansion and all that remains are burned-out stars and dead planets， hovering29) at temperatures barely above absolute zero. If enough dark energy is present to overwhelm all other forces， a Big Rip scenario30) could occur， in which all galaxies， stars and even atoms are torn apart.

8. Across the Multiverse

Theoretical physicists speculate that our universe may not be the only one of its kind. The idea is that our universe exists within a bubble， and multiple alternative universes are contained within their own distinct bubbles. In these other universes， the physical constants31)—and even the laws of physics—may differ drastically. Despite the theory's resemblance to science fiction， astronomers are now looking for physical evidence: Disc-shaped patterns in the cosmic background radiation left over from the Big Bang， which could indicate collisions with other universes.

1. 矩形星系

“快看天上！那是一個……矩形？”今年年初，天文學家發現了一個距地球約7000萬光年的天體，其外觀在可見宇宙中顯得很特別——這個名為LEDA 074886的星系的形狀與矩形相差無幾。大多數星系都呈圓盤形、橢圓球形或不規則形，但這個星系看上去卻像一個規則的矩形或菱形。一些天文學家猜測，該星系之所以呈矩形，是因兩個螺旋形的星系相撞所致，但確切的原因目前不得而知。

2. 月球的磁場

為什么只有部分月殼好似存在磁場？這是月球最大的謎團之一，幾十年來一直讓天文學家著迷，甚至連小說《2001：太空漫游》及其同名電影中那塊神秘的“黑石”也是受此啟發而來的。不過，最后終于有一些科學家認為他們或許能夠對此做出解釋。通過利用一個計算機模型對月殼進行分析后，研究人員認為月球的磁場可能源于約45億年前一個直徑120英里的小行星與月球南極相撞后留下的遺址，該遺址會向外散播磁性物質。不過，其他一些科學家則認為月球的磁場可能與距今更近、規模更小的撞擊有關。

3. 脈沖星為什么會發射電脈沖？

脈沖星距離地球很遙遠，是高速旋轉的中子星，能以一定的間隔發射電磁波，就像燈塔上掃過海岸線的旋轉光束那樣。雖然科學家在1967年就發現了第一顆脈沖星，但幾十年來，科學家一直在苦苦研究，想要弄清楚是什么原因導致它們發出電脈沖的，此外，又是什么原因導致它們偶爾停止發射電脈沖的。然而，2008年，一顆脈沖星突然停止發射電脈沖長達580天，科學家們通過對這一現象的觀察，確信脈沖星 “開”“關”的周期不知怎地與減緩脈沖星自轉的那些磁流有關。天文學家仍在努力研究，試圖先弄清楚為什么這些磁流會出現波動。

4. 暗物質是什么？

天體物理學家目前正在試圖觀測暗能量的影響。70%左右的宇宙都由暗能量構成，但它并不是宇宙中唯一的黑暗物質。約25%的宇宙由一種叫做“暗物質”的完全獨立存在的物質構成。暗物質用望遠鏡和肉眼完全看不到，它既不發光也不吸收可見光(或任何形式的電磁波)，但它對星系團和單個恒星的運動都存在明顯的引力影響。盡管事實證明，想要對暗物質展開研究非常困難，但許多科學家推測，暗物質可能是由亞原子粒子構成，與我們在周圍所見的物質的構成有本質的不同。

5. 星系回收

近年來，天文學家發現，星系中的新恒星以一定的速度形成時所消耗的物質似乎比星系本身實際所含的物質要多。例如，銀河系中每年約有相當于一個太陽的塵埃和氣體轉化成新的恒星，但銀河系并沒有足夠的多余物質來長期維持這樣的新恒星誕生速度。一項針對遙遠星系的新研究或許能給出答案：天文學家發現，那些星系已經釋放出的氣體會重新流回星系的中心。如果星系能回收這些氣體用來創造新恒星，那么這可能就是解決“失蹤的原材料”謎題所需的一部分答案。

6. 天外有人嗎？

1961年，天體物理學家弗蘭克·德雷克提出了一個極具爭議的方程式：通過將一系列涉及外星生命存在概率的項(宇宙中恒星的形成速率、擁有行星的恒星比率、具備生命存在條件的行星比率等)相乘，他推測出其他行星極有可能存在有智慧的生命。問題是，盡管不乏羅斯韋爾陰謀論者，但我們到目前為止還沒有收到外星人的任何消息。不過，科學家最近接連發現一些在理論上存在生命的遙遠行星，這又燃起了我們的希望——只要不停地尋找，或許就能發現外星人。

7. 宇宙將如何終結？

現在我們都相信宇宙是從大爆炸開始的，但它將如何終結呢？綜合各種因素，理論家得出結論，認為宇宙可能會面臨幾種全然不同的命運中的一種。如果暗能量的量不足以抵抗萬有引力的壓縮力，整個宇宙可能會坍縮成一個奇點，相當于宇宙大爆炸的逆過程，被稱為宇宙大坍縮。然而，最近的發現表明，大凍結的可能性比大坍縮更大。大凍結是指暗能量迫使宇宙不斷緩慢地膨脹，最終只剩下能量燃盡的恒星和死亡的行星，宇宙溫度勉強高于絕對零度。如果暗能量足夠多，足以壓倒其他一切力量，那就可能會出現宇宙大撕裂，屆時所有的星系、恒星甚至原子都會四分五裂。

8. 多元宇宙

理論物理學家推測，我們現在所處的宇宙可能只是眾多宇宙中的一個。這種觀點認為，我們的宇宙處在一個泡泡之中，還有其他并存的宇宙處在它們各自獨立的泡泡中。其他這些宇宙里的物理常數甚至物理定律都可能與我們宇宙里的截然不同。盡管這一理論聽起來像是科幻小說，但天文學家現在正在尋找物理上的證據：大爆炸后留下了圓盤狀宇宙背景輻射圖案，該圖案能表明我們的宇宙可能與其他宇宙發生過碰撞。

1.celestial [s??lesti?l] adj. 天的，天空的

2.visible universe: 可見宇宙，即人類已經觀測到的有限宇宙，又稱“已知宇宙”。

3.ellipse [??l?ps] n. 【數】橢圓

4.blob [bl?b] n. 無一定形狀(或難以名狀)的東西

5.diamond [?da??m?nd] n. 【數】菱形

6.speculate [?spekjule?t] vt. 推測，推斷

7.spiral [?spa?r?l] n. 螺旋形

8.crust [kr?st] n. 【地】地殼

9.intrigue [?n?tri?ɡ] vt. 激起……的好奇心(或興趣)；迷住

10.2001: A Space Odyssey: 《2011：太空漫游》，1968年的一部科幻電影，后改編為同名小說出版。影片圍繞人類與神秘“黑石”的數次邂逅展開，而人類的進化似乎與“黑石”有隱秘的聯系。

11.relic [?rel?k] n. 殘留物

12.pulsar [?p?lsɑ?(r)] n. 【天】脈沖星

13.neutron star:【天】中子星

14.rotating [r???te?t??] adj. 旋轉的

15.for that matter: 而且；此外

16.magnetic current: 磁流

17.fluctuate [?fl?kt?ue?t] vi. 波動，起伏

18.account for: (在數量或比例方面)占

19.cosmos [?k?zm?s] n. (被視作和諧體系的)宇宙

20.cluster [?kl?st?(r)] n. (人或物的)組，群

21.subatomic [?s?b??t?m?k] adj. 【物】亞原子的；原子內的

22.fundamentally [?f?nd??ment?li] adv. 從根本上

23.expel [?k?spel] vt. 排出

24.extraterrestrial [?ekstr?t??restri?l] adj. 地球(或大氣圈)外的；行星際的；宇宙的。n. 天外來客

25.fraction [?fr?k?n] n. 【數】分數；分式

26.surmise [s??ma?z] vt. 推測；猜測

27.Roswell conspiracy: 羅斯韋爾陰謀，指羅斯韋爾事件。1947年，美國新墨西哥州羅斯韋爾市發生了一起不明飛行物的墜毀事件，現場有碟形物的殘骸，還留下了奇怪的尸體。后有報紙稱空軍軍方在此發現飛碟，并尋獲飛碟殘骸，但是次日軍方又通過報紙澄清說墜落的是氣象球而非外星飛碟。至今，此事件仍沒有一個詳盡的說法。conspiracy [k?n?sp?r?si] n. 陰謀活動。

28.Big Bang: 宇宙大爆炸。一些學者認為這次爆炸發生于100～150億年前，宇宙由此形成。

29.hover [?h?v?(r)] vi. 搖擺不定

30.scenario [s??nɑ?ri??] n. 事態，局面

31.constant [?k?nst?nt] n. 【物】常數，常量，恒量