什么时候夜空中的灯光会永远熄灭?

什么时候夜空中的灯光会永远熄灭?

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.

在遥远的未来的某个凄凉的时刻，宇宙将继续膨胀，直到所有的东西都离得如此遥远，以至于夜空中最后可见的闪烁将永远消失。

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.

那的确是黑暗的一天。不过，幸运的是，这一天在数万亿年后都不太可能到来。

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.

事实上，克莱姆森大学的科学家们刚刚做出了迄今为止最精确的测量，那一天可能会在什么时候发生，这要归功于最先进的技术。Phys.org报道。

"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."

“宇宙学是关于理解我们的宇宙的演变——它在过去是如何演变的，它现在在做什么，以及将来会发生什么，”克莱姆森大学物理学和天文学副教授马可·阿杰洛说。“我们的团队分析了从轨道望远镜和地面望远镜获得的数据，得出了宇宙膨胀速度的最新测量数据。”

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.

在这项研究中，研究小组将目标对准了哈勃常数，这是一项以美国著名天文学家埃德温·哈勃命名的计算，旨在描述宇宙膨胀的速度。哈勃自己最初估计这个数字大约是每百万秒每秒500公里(百万秒每秒相当于大约326万光年)，但是随着我们测量它的仪器的改进，这个数字被大大篡改了。

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.

即使我们改进了仪器，计算哈勃常数仍然是一项难以捉摸的冒险。我们已经把范围缩小到每百万秒50到100公里每秒，但这还远远不够精确。

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，现在克莱姆森团队的这项新努力可能最终确定了这个数字。使这一努力与众不同的是费米伽马射线空间望远镜和切伦科夫大气成像望远镜提供的最新伽马射线衰减数据。伽玛射线是光的最活跃的形式，这使得它们特别有用的基准进行更严格的测量。

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.

克莱姆森小组最后决定了什么?根据他们的数据，宇宙的膨胀速度大约是每百万秒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.

换句话说，我们还有一些时间直到灯熄灭。如果你考虑到我们的宇宙只有不到140亿年的历史，那么即使无处不在的黑暗是不可避免的，我们仍有数万亿年的星空在前方等着我们，这种想法是令人欣慰的。

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，确定哈勃常数不仅仅是一个有趣的事实。这是了解我们的宇宙如何运作的关键信息，甚至可能有一天有助于回答为什么事物是它们的样子，而不是其他的方式。例如，虽然我们可以观察到宇宙正在以一个加速的速度膨胀，但我们仍然无法解释为什么这种膨胀会首先发生。

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.

这就是“暗能量”的神秘之处，我们用暗能量这个术语来描述把万物分开的神秘力量。我们不知道暗能量是什么…然而。但是我们越精确地测量哈勃常数，我们就越能更好地测试我们关于暗能量的理论。

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

克莱姆森的科学家们的这项研究是一个重大的进步。

"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.

“我们对这些基本常数的理解定义了我们现在所知道的宇宙。当我们对规律的理解变得更精确时，我们对宇宙的定义也会变得更精确，这将带来新的见解和发现，”团队成员迪特尔哈特曼(Dieter Hartmann)教授说。

The study was published in The Astrophysical Journal.

这项研究发表在《天体物理学杂志》上。