TED演讲:宇宙的灭亡(2)（打印版）

　　This dark energy doesn't behave like any other substance we know at all and acts more like antigravity force. 这种暗能量的性质与我们所熟知的其他物质完全不同，它更像是反重力。

　　We say that it has a gravitational pressure, which ordinary matter and dark matter do not. 暗能量具有重力压力，这是普通物质和暗物质所不具有的。

　　Instead of pulling the universe together, as we would expect gravity to do, 宇宙并没有因为引力而向一起聚集，这与我们预想的不同，

　　the universe appears to be expanding apart at an ever-increasing rate. 相反宇宙似乎是在不断膨胀，并且这种膨胀还处于一种持续增长的速度。

　　The leading idea for dark energy is that it is a cosmological constant. 暗能量的主导观点认为它是一个宇宙常量。

　　That means it has the strange property 这意味着暗能量具有一种特殊属性，

　　that it expands as the volume of space increases to keep its energy density constant. 它能够使暗能量随着宇宙体积的增长而扩大，从而使其能量密度保持不变。

　　So, as the universe expands as it is doing right now, there will be more and more dark energy. 因此，随着宇宙不断膨胀，正如此时此刻，暗能量也会随之不断增长。

　　Dark matter and baryonic matter, on the other hand, don't expand with the universe and become more diluted. 然而暗物质和重子物质，从另一方面来看，则不会随宇宙而增长，他们反而会不断减弱。

　　Because of this property of the cosmological constant, 因此，由于宇宙常量所具有的性质，

　　the future universe will be more and more dominated by dark energy, 未来的宇宙中将会充斥更多的暗能量，

　　becoming colder and colder and expanding faster and faster. 宇宙将会变得越来越冷，其膨胀速度也会越来越快。

　　Eventually, the universe will run out of gas to form stars, 最终，宇宙将会由于缺少气体而无法形成恒星，

　　and the stars themselves will run out of fuel and burn out, leaving the universe with only black holes in it. 同时恒星自身也会燃烧殆尽，宇宙中留下的只会是一个个黑洞。

　　Given enough time, even these black holes will evaporate, leaving a universe that is completely cold and empty. 如果经历足够的时间，这些黑洞甚至也会消失，那时宇宙将会是一片寒冷空虚。

　　That is what we call the heat death of the universe. 那就是我们所说的宇宙热寂说。

　　While it might sound depressing living in a universe that will end its lifetime cold and devoid of life, 尽管这听起来让人觉得生活在宇宙中十分沮丧，因为它将在寒冷和了无生气中走向灭亡，

　　the end fate of our universe actually has a beautiful symmetry to its hot, fiery beginning. 但宇宙冰冷的终结却完美地与其火热的发端相称。

　　We call the accelerating end state of the universe a de Sitter phase, 我们称宇宙加速的终结状态为德西特阶段，

　　named after the Dutch mathematician Willem de Sitter. 这是根据荷兰数学家威廉·德西特命名的。

　　However, we also believe that the universe had another phase of de Sitter expansion in the earliest times of its life. 然而，我们也相信宇宙还存在另一个德西特膨胀阶段，它发生在宇宙形成的初期。

　　We call this early period inflation, where, shortly after the Big Bang, 我们称其为早期膨胀阶段，那是大爆炸后，

　　the universe expanded extremely fast for a brief period. 宇宙急速膨胀的短暂时期。

　　So, the universe will end in much the same state as it began, accelerating. 因此宇宙将会以其产生、加速时的相同状态结束。

　　We live at an extraordinary time in the life of the universe 我们生活在一个对于宇宙生命来讲意义非凡的时代，

　　where we can start to understand the universe's journey 我们能够去了解宇宙的历程，

　　and view a history that plays itself out on the sky for all of us to see. 同时也能够去了解它那呈现在天空中，为我们每个人所展示的历史。

TED演讲:宇宙的灭亡(2)（在线收听）