評(píng)論
打印
It's easy to appreciate the power of the sun
在這樣炎熱的夏日，站在德州灣海邊
on a nice hot summer's day like here on the Texas Gulf Coast.
不難體會(huì)太陽的威力
And you can feel the power of the sun on your skin,
皮膚能清楚感受到太陽的熱力
sunscreens is on.
我擦了防曬乳液
But man the sun is just you know
但太陽實(shí)在…
the actual physics of what's going on inside the sun,
太陽內(nèi)部的物理作用
the power of the sun,
太陽的力量
the energy that the sun is releasing
和釋放的威力
is almost beyond comprehension.
幾乎超出我們的理解范圍
But it is only almost beyond comprehension.
但只是“幾乎”超出我們的理解范圍
And you can measure its power output with some simple apparatus.
我們可以用簡(jiǎn)單的裝置測(cè)量太陽的能量輸出
One of the earliest experiments to try and measure
最早嘗試測(cè)量太陽威力的人之一
the actual power of the sun was by astronomer William Herschel
是19世紀(jì)的天文學(xué)家
in the 19th century,
威廉赫歇耳
where he had the brilliant idea of
他的想法很高明
just watching a piece of ice melt
就是觀察一塊冰塊融化
to see how long it would take and therefore
記錄所需的時(shí)間
from the properties of the ice work out
再根據(jù)冰塊的特質(zhì)
how much sunlight was coming to the ground.
計(jì)算地面的日照量
As a demonstration of the sun's power
用這個(gè)實(shí)驗(yàn)來展現(xiàn)太陽的力量
it doesn't look that impressive.
看起來似乎沒啥了不起
But Hershel realized that he could use
但赫歇耳發(fā)現(xiàn)
the time it takes to melt one bit of ice to
他可以用冰塊融化所需的時(shí)間
calculate the sun's total power output.
計(jì)算太陽能量輸出的總量
So here we see the ice is almost completely melted
過了29分鐘…將近半小時(shí)后
in roughly 29 minutes almost half an hour.
冰塊幾乎完全融化
But Herschel was able to use this experiment
但是赫歇耳得以使用這個(gè)實(shí)驗(yàn)
and the time that it took to,
和冰塊融化所需的時(shí)間
to melt the ice to work out some basic properties of the sun.
推算出太陽的某些基本特性
Here's how Herschel's thinking worked.
赫歇耳的立論依據(jù)如下：
In the time it takes to melt a slab of ice on Earth
在融化地面冰塊所需的時(shí)間內(nèi)
the sun is radiating heat in all directions
太陽朝四面八方釋放熱力
enough to melt a complete shell of ice around it
足以融化包圍太陽的冰層
a diameter of 300 million kilometres.
冰層直徑為三億公里
A shell half a centimetre thick
厚度0.5厘米的冰層
and 300 million kilometres across contains a lot of ice.
直徑三億公里，含有大量的冰
Enough to make an ice cube bigger than the Earth.
足以形成比地球還大的冰塊
To melt that much ice in just 30 minutes
要在30分鐘內(nèi)融化這么多冰
would take an energy input of a billion billion billion watts.
所需的能量輸出，高達(dá)10的27次方瓦特
It's a rough, but surprisingly accurate experiment
這個(gè)實(shí)驗(yàn)看似粗糙，但卻出奇地精準(zhǔn)
modern satellite readings confirm the figures to within a few percent.
現(xiàn)代衛(wèi)星讀數(shù)證實(shí)了，其誤差不超過幾個(gè)百分點(diǎn)
It's an almost unimaginable amount of energy.
此能量大得幾近難以想像
If we could harness the sun's power output
要是能夠充分利用太陽能
for a single second it would satisfy the world's energy
只要短短一秒就足以滿足世界
demands for the next million years.
未來一百萬年間的能源需求
But it's one thing to know how much power the sun is producing.
但推算太陽產(chǎn)生的能量多少是一回事
It's something else to know how it is doing it.
厘清其制造過程又是另一回事
Until the middle of the 20th century no-one had any idea
在20世紀(jì)中期之前，沒有人明白
what made the sun work.
太陽的運(yùn)作原理
For scientists in Hershel's time it was a mystery.
對(duì)赫歇耳時(shí)代的科學(xué)家而言，這是個(gè)不解之謎
Well one of the issues was of course what powered the sun.
議題之一當(dāng)然是，太陽的動(dòng)力來源
And - um - some very clever people actually
有些頗有才智的人士甚至覺得
considered the fact that the sun might be powered by burning coal.
太陽的動(dòng)力可能來自燃煤
I mean it seems ludicrous but why not coal.
這種說法聽起來荒謬，但又有何不可呢？
That was an important source of energy on the earth.
畢竟在19世紀(jì)的那段時(shí)間
Er in that part of the 19th century
煤炭是地球的重要能量來源
If the sun was made entirely of coal,
但若太陽由煤炭組成
there would be one unfortunate consequence.
會(huì)產(chǎn)生一個(gè)不幸的后果
It would burn itself out in just a few thousand years.
它會(huì)在幾千年后燃燒殆盡
