Radio Experimental Cosmology at Oxford

就在大爆炸之后，天文学家认为宇宙在一个被称为“宇宙膨胀”的时期内迅速膨胀。在经历了一个更长、更温和的时期后，物质的引力开始逐渐减缓膨胀，现在宇宙似乎已经开始了第二个加速膨胀的时期。最近的这种膨胀是由天文学家所说的“暗能量”推动的。尽管天文学家相信所有这些事情，但地球上没有人理解“宇宙膨胀”或“暗能量”。这有点让人难堪。一些有声望的科学家认为，这些神秘的概念是全新物理学的标志，甚至是额外维度的存在！我们的研究旨在设计、建造和使用望远镜来观测宇宙，这将告诉我们更多关于宇宙膨胀和暗能量的信息。大多数对宇宙膨胀的解释都预测，无论是什么原因引起的宇宙膨胀，都应该以时空涟漪的形式留下活动的“指纹”，称为引力波。通过观察宇宙微波背景大爆炸遗迹辐射的偏振，可以看出这些涟漪的影响。我们研究的一个主要目标是在智利和南极洲建造望远镜，这将是第一个发现这些指纹的望远镜。这些望远镜将被称为宁静和三叶草。不幸的是，这些指纹必须在一个非常混乱的宇宙中找到。我们必须对来自我们银河系的偏振射电辐射有一个令人难以置信的了解，然后我们才能“看穿它”，找到指纹。我们将建造一种新的仪器，我们将把它带到南半球和北半球的射电望远镜上，帮助我们找到银河系最干净的地方，用宁静和三叶草来窥视。这种乐器将被称为C低音。我们还将继续致力于使我们的望远镜和仪器尽可能灵敏的技术。我们将测试使用各种聪明的量子物理和数字处理技术来尽可能干净和高效地测量来自宇宙的信号的新设备。我们希望有一天能利用这些技术来设计实验，告诉我们什么是暗能量。

Just after the Big Bang, astronomers believe the Universe expanded rapidly during a period known as `cosmic inflation'. After a longer, gentler period, during which the gravitational pull of matter began gradually to slow down the expansion, the Universe now appears to have begun a second period of accelerated expansion. This recent expansion is driven by what astronomers call `dark energy'. Although astronomers believe all these things, no person on Earth understands either `cosmic inflation' or `dark energy'. This is a bit embarassing. Some reputable scientists believe that these mysterious concepts are signatures of totally new physics, or even of the presence of extra dimensions! Our research is aimed at designing, building and using telescopes to make observations of the Universe which will tell us more about both cosmic inflation and dark energy. Most explanations of cosmic inflation predict that whatever caused it should have left `fingerprints' of its activity in the form of ripples in space-time called gravitational waves. The effects of these ripples can be seen by looking at the polarization of the relic radiation from the Big Bang, the Cosmic Microwave Background. A major goal of our research is to build telescopes in Chile and Antartica which will be the first to find these fingerprints. These telescopes will be called QUIET and CLOVER. Unfortunately, these fingerprints must be found in a very messy Universe. Polarized radio emission from our own galaxy has to be understood incredibly well before we can `see through it', and find the fingerprints. We will be building a new instrument which we will take to radio telescopes in both the southern and northern hemispheres to help us find the cleanest bit of the galaxy to peer through with QUIET and CLOVER. This instrument will be called C-BASS. We will also keep working on the technologies that make our telescopes and instruments as sensitive as possible. We will be testing out new devices that use all sorts of clever quantum physics and digital processing techniques to measure signals from the Universe as cleanly and efficiently as possible. We hope one day to use these technologies to devise experiments that will tell us what dark energy is.