什么時候夜空中的燈光會永遠熄滅?

什么時候夜空中的燈光會永遠熄滅?

At some dreary point in the far distant future, the universe will continue to expand until everything is so far apart that the last visible twinkle in the night sky will get snuffed out forever.

在遙遠的未來的某個凄涼的時刻，宇宙將繼續(xù)膨脹，直到所有的東西都離得如此遙遠，以至于夜空中最后可見的閃爍將永遠消失。

Deep space, captured by the Hubble Space Telescope. (Photo: NASA/ESA)

That will be a dark day indeed. Fortunately, though, it's a day that's not likely to come for trillions of years.

那的確是黑暗的一天。不過，幸運的是，這一天在數(shù)萬億年后都不太可能到來。

In fact, scientists at Clemson University have just made the most precise measurement yet of exactly when that day of darkening will probably happen, thanks to state-of-the-art technologies , reports Phys.org.

事實上，克萊姆森大學(xué)的科學(xué)家們剛剛做出了迄今為止最精確的測量，那一天可能會在什么時候發(fā)生，這要歸功于最先進的技術(shù)。Phys.org報道。

"Cosmology is about understanding the evolution of our universe — how it evolved in the past, what it is doing now and what will happen in the future," said Marco Ajello, associate professor in physics and astronomy at Clemson. "Our team analyzed data obtained from both orbiting and ground-based telescopes to come up with one of the newest measurements yet of how quickly the universe is expanding."

“宇宙學(xué)是關(guān)于理解我們的宇宙的演變——它在過去是如何演變的，它現(xiàn)在在做什么，以及將來會發(fā)生什么，”克萊姆森大學(xué)物理學(xué)和天文學(xué)副教授馬可·阿杰洛說。“我們的團隊分析了從軌道望遠鏡和地面望遠鏡獲得的數(shù)據(jù)，得出了宇宙膨脹速度的最新測量數(shù)據(jù)。”

For the study, the team took aim at the Hubble Constant, a calculation named after famed American astronomer Edwin Hubble that is intended to describe the rate at which the universe is expanding. Hubble himself originally estimated the number to be around 500 kilometers per second per megaparsec (a megaparsec is equivalent to about 3.26 million light-years), but the number has been fiddled with significantly over the years as our instruments for measuring it have improved.

在這項研究中，研究小組將目標對準了哈勃常數(shù)，這是一項以美國著名天文學(xué)家埃德溫·哈勃命名的計算，旨在描述宇宙膨脹的速度。哈勃自己最初估計這個數(shù)字大約是每百萬秒每秒500公里(百萬秒每秒相當于大約326萬光年)，但是隨著我們測量它的儀器的改進，這個數(shù)字被大大篡改了。

Even with our improved instruments, though, calculating the Hubble Constant has proven to be an elusive venture. We had narrowed it down to between 50 and 100 kilometers per second per megaparsec, but that was far from precise.

即使我們改進了儀器，計算哈勃常數(shù)仍然是一項難以捉摸的冒險。我們已經(jīng)把范圍縮小到每百萬秒50到100公里每秒，但這還遠遠不夠精確。

Now this new effort by the Clemson team might have finally pinpointed the number, however. What made this effort different was the availability of the latest gamma-ray attenuation data from the Fermi Gamma-ray Space Telescope and Imaging Atmospheric Cherenkov Telescopes. Gamma rays are the most energetic form of light, which makes them particularly useful as benchmarks for making more scrupulous measurements.

然而，現(xiàn)在克萊姆森團隊的這項新努力可能最終確定了這個數(shù)字。使這一努力與眾不同的是費米伽馬射線空間望遠鏡和切倫科夫大氣成像望遠鏡提供的最新伽馬射線衰減數(shù)據(jù)。伽瑪射線是光的最活躍的形式，這使得它們特別有用的基準進行更嚴格的測量。

So what did the Clemson team settle on? According to their data, the universe's rate of expansion is approximately 67.5 kilometers per second per megaparsec.

克萊姆森小組最后決定了什么?根據(jù)他們的數(shù)據(jù)，宇宙的膨脹速度大約是每百萬秒67.5公里。

In other words, we've got some time until the lights go out. If you consider that our universe is only a tad under 14 billion years old, the idea that we've still got trillions of years of starry nights ahead of us is a comforting one, even if the omnipresent darkness is inevitable.

換句話說，我們還有一些時間直到燈熄滅。如果你考慮到我們的宇宙只有不到140億年的歷史，那么即使無處不在的黑暗是不可避免的，我們?nèi)杂袛?shù)萬億年的星空在前方等著我們，這種想法是令人欣慰的。

Nailing down the Hubble Constant isn't just a fun fact, though. It's crucial information for understanding how our universe works, and perhaps even one day helping answer why things are as they are, as opposed to being some other way. For instance, while we can observe that the universe is expanding at an accelerated rate, we're still at a loss to explain why this expansion is happening in the first place.

然而，確定哈勃常數(shù)不僅僅是一個有趣的事實。這是了解我們的宇宙如何運作的關(guān)鍵信息，甚至可能有一天有助于回答為什么事物是它們的樣子，而不是其他的方式。例如，雖然我們可以觀察到宇宙正在以一個加速的速度膨脹，但我們?nèi)匀粺o法解釋為什么這種膨脹會首先發(fā)生。

This is the mystery of "dark energy," which is the term we use to describe the puzzling force that is pushing everything apart. We don't know what dark energy is... yet. But the more precisely we measure the Hubble Constant, the better equipped we will become at testing our theories about dark energy.

這就是“暗能量”的神秘之處，我們用暗能量這個術(shù)語來描述把萬物分開的神秘力量。我們不知道暗能量是什么…然而。但是我們越精確地測量哈勃常數(shù)，我們就越能更好地測試我們關(guān)于暗能量的理論。

So this research by the Clemson scientists is a major advance forward.

克萊姆森的科學(xué)家們的這項研究是一個重大的進步。

"Our understanding of these fundamental constants has defined the universe as we now know it. When our understanding of laws becomes more precise, our definition of the universe also becomes more precise, which leads to new insights and discoveries," said professor Dieter Hartmann, a member of the team.

“我們對這些基本常數(shù)的理解定義了我們現(xiàn)在所知道的宇宙。當我們對規(guī)律的理解變得更精確時，我們對宇宙的定義也會變得更精確，這將帶來新的見解和發(fā)現(xiàn)，”團隊成員迪特爾哈特曼(Dieter Hartmann)教授說。

The study was published in The Astrophysical Journal.

這項研究發(fā)表在《天體物理學(xué)雜志》上。