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The Cosmology of the Early and Late Universe

早期和晚期宇宙的宇宙学

基本信息

批准号：
ST/T000732/1
负责人：
Edmund Copeland
金额：
$ 116.53万
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：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FT000732%2F1
关键词：
Cosmology Early Late Universe

项目摘要

We live in a Universe in which distant galaxies are accelerating apart from one another, but the cause for this can not 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. Whatever is causing this acceleration must be a new substance that we have not come across before in nature, we call it Dark energy (DE). The best candidate for this is the Cosmological Constant (CC), however, there can't be much of it around today because if there was, it would have caused galaxies to blow apart by now. The problem is reconciling the observed amount of DE with the predicted amount that should be present in the form of a CC. The latter is much higher and reconciling this has been a problem for many years. Recently, we proposed a resolution to the problem in which the CC is cancelled, effectively removing it. We intend to develop our understanding of the mechanism involved in resolving this problem and establish whether it can be found to exist in particle theory models of our Universe. This leaves open the question of what is the nature of DE and we will be working on models proposed to account for this in which the force driving the acceleration is screened from view in regions of high density such as here on Earth. Such models are hard to rule out, but we have established a number of features they have that would allow us to test for them in the laboratory and on galactic scales. There is an alternative point of view to DE driving the acceleration of our universe, and that is that on large scales we need to modify Einstein's General Theory of Relativity (GR). This is a big field of enterprise and we are heavily involved in working on models in which GR is modified. We will be testing many of these models, both on vast cosmological scales and by seeing how they effect 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 test whether it can be in the form of primordial black holes formed in the early universe or maybe as an extremely light particle called the axion. Many people think the early Universe underwent a period 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, something that has recently been questioned by many. We will also ask how did the universe establish that there was more matter than antimatter in it, something known as Baryogenesis.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 mimc early universe effects and even use the results to make predictions about those earliest moments. Another area we are developing at Nottingham for the first time is to use the power of Machine Learning to create neural networks to analyse data. We are hoping to apply this new technology to search for cosmic strings, dark energy and provide new ways to analyse astronomical data. It is very exciting. In Quantum Gravity, we attempt to establish a connection between General Relativity and Quantum Mechanics. We are developing models of cosmology that allow us to talk about the earliest moments in the universe where the role of Quantum Mechanics is 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.

我们生活在一个宇宙中，在这个宇宙中，遥远的星系彼此加速分离，但造成这种情况的原因不可能是宇宙中存在的普通物质，因为宇宙应该由于引力对它所包含的物质的吸引力而减速。无论是什么导致了这种加速，一定是一种我们以前在自然界中从未遇到过的新物质，我们称之为暗能量（DE）。最好的候选者是宇宙常数（CC），然而，今天不可能有太多的宇宙常数，因为如果有，它现在已经导致星系爆炸了。问题是使观察到的DE量与应该以CC形式存在的预测量相一致。后者要高得多，调和这一点多年来一直是一个问题。最近，我们提出了一个解决方案，其中的CC被取消，有效地消除它的问题。我们打算发展我们的理解，在解决这个问题所涉及的机制，并确定它是否可以被发现存在于我们的宇宙的粒子理论模型。这就留下了DE的本质是什么的问题，我们将研究为解释这一点而提出的模型，其中驱动加速度的力在地球等高密度区域被屏蔽。这种模型很难排除，但我们已经确定了它们所具有的一些特征，这些特征将使我们能够在实验室和银河系尺度上对其进行测试。有一种观点可以替代DE驱动我们宇宙的加速，那就是在大尺度上我们需要修改爱因斯坦的广义相对论（GR）。这是一个很大的企业领域，我们大量参与了GR修改模型的工作。我们将测试这些模型中的许多模型，无论是在巨大的宇宙尺度上，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。我们将测试它是否可以以早期宇宙中形成的原始黑洞的形式存在，或者可能是一种称为轴子的极轻粒子。许多人认为早期宇宙经历了一段短暂的几乎指数膨胀的时期，称为通货膨胀。我们将研究暴胀的模型，以确定是否可以在弦理论中找到成功的模型，这是最近被许多人质疑的。我们还将问宇宙是如何确定其中物质多于反物质的，这就是所谓的重子生成论。最近在诺丁汉出现的一个新领域是通过创建模拟实验在实验室中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，我们可以模仿早期宇宙的影响，甚至使用结果来预测那些最早的时刻。我们在诺丁汉首次开发的另一个领域是利用机器学习的力量来创建神经网络来分析数据。我们希望应用这项新技术来寻找宇宙弦、暗能量，并提供分析天文数据的新方法。这是非常令人兴奋。在量子引力中，我们试图建立广义相对论和量子力学之间的联系。我们正在开发宇宙学模型，使我们能够谈论宇宙中量子力学的作用至关重要的最早时刻，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。