Combining precision observations of the recent Universe with laboratory and space-based experiments to test for and constrain 'new physics'.

我建议继续我在博士时期开始的工作，研究“新物理学”的宇宙学含义，比如现代量子引力理论（如弦理论）所预测的。我特别感兴趣的是，我们的宇宙可能被一个或多个标量场所填充，即一种新的物质形式，在空间和时间的每个点上都有一个特定的值。这些标量场几乎总是与正常物质相互作用，而诸如此类的相互作用会导致宇宙尺度上自然的一个或多个传统“常数”的变化。我打算继续我的工作，发展模型或理论，允许自然的“常数”变化，并利用这些理论做出预测，可以在今天或不久的将来进行测试。除了“常数”的变化之外，以标量场为特征的模型通常会预测我们普遍接受的物理理论的其他小变化。这些变化只有在非常小的长度/时间尺度上或在非常高的能量下才会很大，而且它们通常超出了目前实验室实验的范围。然而，有可能在非常大的时间尺度上探测到这些偏差的总和，比如我们宇宙的寿命。正是由于这个原因，对近代宇宙的精确观测为“新物理学”提供了一个无价的试验台。这些常数的变化最近引起了很多人的兴趣，因为a)最近对类星体的大量观察似乎支持这样一种观点，即在过去的100亿到120亿年间，至少有两个常数确实发生了变化；b)它提供了一种机制来解释为什么我们这部分宇宙中的常数的值非常适合我们所理解的生命。允许变常数的理论可以做出高度可检验的预测。除了发展变常数理论之外，我还打算把对近代宇宙的最新精确观测与来自实验室和基于太阳系的实验的不断改进的数据结合起来，以检验变常数理论的预测，并通过这样做，对预测新物理学的理论施加越来越严格的约束。这是研究变化常数的一个非常激动人心的时刻，因为，由于我在博士论文中证明的结果，天文观测表明，下一代的实验室实验应该能探测到至少两个自然基本“常数”的变化。伽利略在比萨斜塔的塔顶上发表了著名的论断：只要没有空气阻力，所有物体都会以同样的速度下落：这就是等效原理。新物理学的另一个可探测的预测是，与伽利略的预期相反，物体的下落速度取决于它们的组成，等效原理被违反了。这些违反是由与正常物质相互作用的标量场引起的。由于这些标量场从未被发现，科学家们认为它们与物质的相互作用极其微弱。虽然这看起来可能违反直觉，但我最近证明了人们在实验中没有看到这些标量场的原因很可能是，它们与物质的相互作用非常强，而不是弱！这一结果可能会导致对标量场在我们的宇宙中所扮演的角色的完全不同的看法，我也建议进一步研究其潜在的重要含义。

I propose to continue the work that I began in PhD and study the cosmological implications of `new physics', such as that predicted by modern theories of quantum gravity (e.g. String Theory). I am particularly interested in the possibility that our Universe may be populated by one or more scalar fields, i.e. a new form of matter which takes one particular value at each point in space and time. These scalar fields almost always interact with normal matter, and interactions such as these lead to the variation of one or more of the traditional `constants' of Nature over cosmological scales. I intend to continue my work on developing models, or theories, that allow the `constants' of nature to vary and use these theories to make predictions which can be tested either today or in the near future. In addition to the variation of the `constants', models which feature scalar fields generally predict other small alterations to our generally accepted physical theories. These changes are only large over very small length/time scales, or at very high energies, and often they lie beyond the current reach of laboratory experiments. However, it is possible to detect the sum total of these deviations over very large time scales, such as the lifetime of our Universe. It is for this reason that precision observations of the recent Universe provide an invaluable test-bed for `new physics'. Variation of the constants has been the subject of a lot of recent interest because a) a number of recent observations of quasar seem to support the idea that at least two of the constants have indeed changed over the last 10-12 billion years, and b) it offers a mechanism to explain why the constants in our part of the universe take values that are very suited for life as we understand. Theories that allow for varying-constants make highly testable predictions. In addition to developing varying-constant theories, I intend to combine the latest precision observations of the recent Universe with the ever-improving data coming from laboratory and solar system based experiments to test the predictions of varying-constant theories and in so doing to place tighter and tighter constraints on theories that predict new physics. This is a very exciting time to study varying constants because, thanks to results that I proved in my PhD thesis, astronomical observations imply that the next generation of laboratory experiments should detect a variation in at least two of the fundamental 'constants' of nature. From the top of the tower of Pisa, Galileo famously pronounced that all objects fall at the same rate provided there is no air resistance: this is the Equivalence Principle. Another detectable prediction of new physics is that, against the expectations of Galileo, bodies fall at different rates depending on their composition and the Equivalence principle is violated. These violations would be caused by scalar fields that interact with normal matter. Since these scalar fields have never been found, scientists believe their interactions with matter to be extremely weak. Although it may seem counter-intuitive, I have recently demonstrated that the reason one has not seen these scalar fields in experiments could well be that, rather than being weak, their interaction with matter is extremely strong! This result might lead to a completely different view of the role that scalar fields play in our Universe, and I also propose to further investigate its potentially important implications.