In 1919, now aged thirty, he moved to California and took up a position at the Mount Wilson Observatory near Los Angeles. Swiftly, and more than a little unexpectedly, he became the most outstanding astronomer of the twentieth century.
1919年，他已經30歲。他遷到加利福尼亞州，在洛杉磯附近的威爾遜山天文臺找了個職位。非常出人意料的是，他很快成為20世紀最杰出的天文學家。
It is worth pausing for a moment to consider just how little was known of the cosmos at this time. Astronomers today believe there are perhaps 140 billion galaxies in the visible universe. That’s a huge number, much bigger than merely saying it would lead you to suppose. If galaxies were frozen peas, it would be enough to fill a large auditorium—the old Boston Garden, say, or the Royal Albert Hall. (An astrophysicist named Bruce Gregory has actually computed this.) In 1919, when Hubble first put his head to the eyepiece, the number of these galaxies that were known to us was exactly one: the Milky Way. Everything else was thought to be either part of the Milky Way itself or one of many distant, peripheral puffs of gas. Hubble quickly demonstrated how wrong that belief was.
讓我們稍停片刻，先來考慮一下當時人們對宇宙的了解是如何少得可憐，這是值得的。今天的天文學家認為，在可見的宇宙里也許有1400億個星系。這是個巨大的數字，比你聽了這話認為的還要巨大得多。假如把一個星系比做一粒凍豆子，這些豆子就可以塞滿一個大禮堂——比如，老波士頓花園或皇家艾伯特大廳。（有一位名叫布魯斯·格雷戈里的天體物理學家還真的計算過。）1919年，當哈勃第一次把腦袋伸向望遠鏡的時候，我們已知的星系數只有一個：銀河系。其他的一切要么被認為是銀河系的組成部分，要么被認為是遠方天際眾多氣體中的一團氣體。哈勃很快證明這種看法是極其錯誤的。
Over the next decade, Hubble tackled two of the most fundamental questions of the universe: how old is it, and how big? To answer both it is necessary to know two things—how far away certain galaxies are and how fast they are flying away from us (what is known as their recessional velocity). The red shift gives the speed at which galaxies are retiring, but doesn’t tell us how far away they are to begin with. For that you need what are known as“standard candles”—stars whose brightness can be reliably calculated and used as benchmarks to measure the brightness (and hence relative distance) of other stars.
在之后的10年里，哈勃著手研究有關宇宙的兩個最基本的問題：宇宙已經存在多久？宇宙的范圍有多大？為了回答這兩個問題，首先必須知道兩件事——某類星系離我們有多遠，它們在以多快的速度遠離我們而去（即現在所謂的退行速度）。紅移能使我們知道星系后退的速度，但不能使我們知道它們離得有多遠。為此，你需要有所謂的“標準燭光”——即準確測得的某個恒星的亮度，作為測算其他恒星的亮度（并由此計算其相對距離）的基準。
評論
打印
