The Cosmology of the Early and Late Universe

早期和晚期宇宙的宇宙学

• 批准号: ST/X000672/1
• 负责人: Edmund Copeland
• 金额: $ 103.03万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FX000672%2F1
• 关键词: Cosmology; Early; Late; Universe

The Particle Cosmology and Gravity groups at Nottingham aim to understand the fundamental particles and forces in our universe. We do this by working on the fundamental theoretical underpinning of our understanding of physics, and also by modelling the behaviour of the physics we know, and the physics proposed to solve fundamental cosmological mysteries, so that this can be compared with experimental data and cosmological observations.We live in a Universe in which distant galaxies are accelerating apart from one another, but the cause for this cannot be the ordinary matter present in it as the universe should be slowing down due to the attractive pull of gravity on the matter it contains. We call whatever is causing this acceleration dark energy (DE) and the leading candidate is the Cosmological Constant (CC). There can't be much of it around today because if there was, it would have caused galaxies to blow apart by now, yet most quantum theories predict far too much of it. We are trying to resolve this imbalance and have proposed a solution to the problem in which the CC is cancelled, effectively removing it. We intend to develop our understanding of the model and ask both whether it can be found to exist in particle theory models of our Universe and whether we can see direct evidence of it in compact objects. We will also be working on other DE models. In one of them known as Quintessence we will establish whether it exists in fundamental theory, and in another class where the force driving the acceleration is screened from view in regions of high density such as here on Earth, we have established a number of features they have that would allow us to test for them in the laboratory and on galactic scales. An alternative point of view to DE driving the acceleration of our universe, is to modify Einstein's General Theory of Relativity (GR) on large scales, and we work on such models. We will be testing them, both on cosmological scales and by seeing how they affect the formation of massive objects like neutron stars. We will also constrain models of Dark Matter, the key component of the universe which keeps galaxies together. We have yet to find out what DM really is, and one of our aims is to help uncover the mysterious particle that is binding our galaxy together. We will be working on the possibility that there may be primordial black holes (PBH) formed in the early universe, maybe an extremely light particle called the axion, or possibly another type of particle known as a domain wall formed in the early universe. Many people think the early Universe underwent a phase of almost exponential expansion for a brief period of time, known as Inflation. We will work on models of inflation to establish whether or not successful models can be found in string theory. A new area which has emerged here at Nottingham recently is the possibility of testing theories of gravity in the laboratory by creating analogue experiments. Although at a completely different energy scale to the early universe, they enjoy similar equations, hence the hope that by doing such experiments we can mimic early universe effects and even use the experiments to make predictions about those earliest moments. Gravity is at its strongest around Black holes and neutron stars. We will make use of this feature both to test for modified gravity theories and to look for new signatures of gravity - such as scalar field hair growing from the BHs! We will use numerical simulations involving quantum theory to demonstrate how black holes actually evaporate by emitting Hawking radiation once they have formed. We are developing models of cosmology that allow us to talk about the earliest moments in the universe, where the role of Gravity and Quantum Mechanics are vital, and intend to develop methods to constrain and test these models with astronomical data such as the fluctuations seen in the thermal radiation associated with the Big Bang.

诺丁汉的粒子宇宙学和引力小组旨在了解我们宇宙中的基本粒子和力。我们通过研究我们对物理学理解的基本理论基础来做到这一点，也通过模拟我们所知道的物理学行为，以及为解决基本宇宙学之谜而提出的物理学，以便与实验数据和宇宙学观测进行比较。我们生活在一个宇宙中，遥远的星系正在加速远离彼此，但造成这种现象的原因不可能是宇宙中存在的普通物质，因为宇宙应该是由于引力对它所包含的物质的吸引而减速的。我们把引起这种加速的东西称为暗能量（DE），最主要的候选者是宇宙常数（CC）。今天不可能有太多的它，因为如果有，它会导致星系现在吹开，但大多数量子理论预测太多了。我们正在试图解决这种不平衡，并提出了一个解决方案，其中CC被取消的问题，我们打算发展我们对模型的理解，并询问它是否可以在我们宇宙的粒子理论模型中找到，我们是否能在致密物体中看到它的直接证据。我们还将研究其他DE模型。在其中一个被称为Quintessence的类别中，我们将确定它是否存在于基础理论中，而在另一个类别中，驱动加速度的力在高密度区域（如地球上）被屏蔽，我们已经确定了它们所具有的一些特征，这些特征将允许我们在实验室和银河系尺度上测试它们。另一种观点，以DE驱动我们的宇宙加速，是修改爱因斯坦的广义相对论（GR）在大尺度上，我们的工作在这样的模型。我们将测试它们，无论是在宇宙尺度上，还是通过观察它们如何影响中子星等大质量物体的形成。我们还将限制暗物质的模型，暗物质是宇宙的关键组成部分，它使星系聚集在一起。我们还没有弄清楚DM到底是什么，我们的目标之一是帮助揭示将我们的星系结合在一起的神秘粒子。我们将研究在早期宇宙中可能形成原始黑洞（PBH）的可能性，可能是一种称为轴子的极轻粒子，或者可能是另一种称为早期宇宙中形成的域壁的粒子。许多人认为早期宇宙经历了一个短暂的指数膨胀阶段，称为暴胀。我们将研究暴胀模型，以确定是否可以在弦理论中找到成功的模型。最近在诺丁汉出现了一个新的领域，那就是在实验室里通过模拟实验来检验引力理论的可能性。虽然在与早期宇宙完全不同的能量尺度上，他们享有类似的方程，因此希望通过这样的实验，我们可以模拟早期宇宙的影响，甚至使用实验来预测那些最早的时刻。引力在黑洞和中子星周围最强。我们将利用这一特性来检验修正的引力理论，并寻找新的引力特征--比如从黑洞上长出的标量场毛发！我们将使用涉及量子理论的数值模拟来演示黑洞一旦形成，实际上是如何通过发射霍金辐射而蒸发的。我们正在开发宇宙学模型，使我们能够谈论宇宙中最早的时刻，在那里引力和量子力学的作用至关重要，并打算开发方法来约束和测试这些模型与天文数据，如在与大爆炸相关的热辐射中看到的波动。