Novel Directions in Physical Cosmology: Theory versus Observations

WMAP和普朗克卫星等当前和即将进行的宇宙学观测的空前灵敏度和角度分辨率为我们提供了检验宇宙学理论的绝佳机会。这使得我们比以往任何时候都更迫切需要准备具体的模型来推断物质和引力的性质。这个研究项目的一个主要目标是研究早期宇宙的物理学，它决定了我们今天的宇宙是什么样子。一个理想的早期宇宙理论应该是基于我们对基础物理学的理解，为宇宙的后期阶段设定了正确的初始条件，而不需要微调，并且还提供了可检验的预测，使其可证伪。暴胀论是早期宇宙最著名的理论范式，目前仍在研究中，有待证实或证伪。寻找实现这一目标的最佳策略是我的研究计划的目标之一，该计划已经产生了有价值的结果。经验表明，暴胀模型在适应各种观测预测方面是相当宽容的。我的方法的新颖性在于以一种新的方式利用我们从观察和理论中获得的知识来推导早期宇宙历史的特征，并研究暴胀是否可以被证实。我的研究项目还侧重于修正重力和暗能量模型的不同方面。暗能量的本质可能是当今天文学中最重要的问题，它的发现导致了去年的诺贝尔物理学奖。虽然在观测方面，未来的实验，如WFIRST天文台和EUCLID正在计划中，但该理论尚未配备适当解释数据的方法，以阐明暗能量的本质。我最感兴趣的项目是寻找最佳方法来帮助我们区分不同的宇宙膨胀明显加速的范例。一种全面的方法将采用宇宙几何探测、大规模结构形成、引力透镜观测和宇宙微波背景特征。

The unprecedented sensitivity and angular resolution of current and upcoming cosmological observations such as WMAP and Planck satellites provide us great opportunities to test cosmological theories. This makes it more urgent than ever that we are prepared with concrete models to infer properties of matter and gravity. A primary objective of this research program is to study the physics of the early universe which determines how our cosmos looks like today. An ideal theory of the early universe would be well-motivated from our understanding of fundamental physics, sets the right initial conditions for later stages of the cosmos without fine tuning, and also provides testable predictions that makes it falsifiable. Inflation, the most prominent paradigm of the early universe, still remains under scrutiny and needs to be confirmed or falsified. Finding the best strategy to achieve this ambition is one of the objectives of my research program, which has already produced valuable results. As experience has shown, inflationary models are quite forgiving in accommodating a variety of observational predictions. The novelty of my approach relies on using the knowledge we have from observation and theory in a new way to derive the characteristic features of the history of the early universe and investigate whether inflation can be confirmed.My research program also focuses on different aspects of modified gravity and dark energy models. The nature of dark energy is probably the most important question in astronomy today, and its discovery led to last year's Nobel prize in Physics. While, on the observational front, future experiments such as WFIRST Observatory and EUCLID are being planned, the theory is yet to be equipped with methods to interpret the data properly, in order to shed light on the nature of dark energy. The program that I am most interested to continue is finding optimum methods that can help us distinguish between different paradigms for apparent acceleration of cosmic expansion. A comprehensive approach would employ probes of cosmic geometry, as well as large scale structure formation, gravitational lensing observations and features in cosmic microwave background.