Higher-spin signatures of holography in the early universe.

早期宇宙中全息术的高自旋特征。

基本信息

批准号：
ST/P004326/1
负责人：
Paul McFadden
金额：
$ 55.56万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FP004326%2F1
关键词：
Higher spin signatures holography early

项目摘要

The early universe is the ultimate experiment in high-energy physics. Through modern telescopes and satellites, we can image a faint glow of light -- the cosmic microwave background -- that is the last surviving trace of the radiation fireball that filled the universe 380,000 years after the big bang. Curiously, the temperature of this fading fire-ball is not quite uniform but varies slightly over different patches of the night sky. These small variations in temperature arise from quantum fluctuations and hold precious clues to the earliest moments of the universe: to correctly predict their statistical properties is a make-or-break test of any new cosmological theory. At the same time, a breathtaking race is now under way to accurately measure similar small variations recently found in the polarisation pattern of this fireball. These small variations in polarisation carry new information about the early universe, and could one day provide evidence for a gravitational wave echo accompanying the primordial fireball.To understand the earliest moments of the universe requires a new understanding of physics. Einstein's theory of gravity describes spacetime in terms of geometry, and as we go back in time to the big bang, it predicts this geometry should become more and more curved, until at some finite time in the past, the curvature becomes infinite. This moment, the big bang singularity, represents a breakdown of Einstein's theory and is thought to be curable only through a fully quantum theory of gravity. Based on current ideas from black hole physics and string theory, our best guess is that this quantum theory of gravity should be "holographic". This means it should allow the early universe to be described in terms of a second, and at first sight, completely different theory. This alternative "holographic'' description takes the form of an ordinary quantum theory, very similar to the kind routinely used to describe particle collisions at the Large Hadron Collider, but with one very surprising feature: it lives in only three spatial dimensions and is missing the dimension of time. My work has shown how to construct just such a holographic description of cosmology, revealing a new solution to the problem of the big bang singularity. At early times, when a geometrical description of spacetime breaks down as in Einstein's theory, we can instead turn to the alternative holographic description in terms of an ordinary quantum theory living in one dimension less. This holographic description remains completely well-behaved, even when spacetime can no longer be described in terms of geometry, meaning there is no longer any loss of predictive capability. In past work, I have shown how to reconstruct the detailed patterns we see in the cosmic microwave background starting directly from this holographic description in terms of an ordinary quantum theory. My new research will explore a key prediction made by this scenario: the existence of a special class of particles, known as higher-spin particles, in the early universe. A famous theorem by Higuchi restricts the masses these particles are allowed to have, and further investigation is urgently needed to determine whether the holographic scenario can satisfy both this theorem and all observational data. The presence of these higher-spin particles at early times could also leave direct tell-tale signatures in the temperature variations and polarisation patterns of the cosmic microwave background. My work will predict the form of these tell-tale signatures and explore new strategies for detecting them in future experiments. The results of this investigation could either confirm, or else rule-out, the natural solution holography offers to the problem of the big bang singularity.

早期宇宙是高能物理学的最终实验。通过现代的望远镜和卫星，我们可以对光线的光芒（宇宙微波背景）形象化，这是大爆炸后380，000年来填充宇宙的最后一个幸存的痕迹。奇怪的是，这种褪色的火球的温度不是很均匀，但在夜空的不同斑块上略有不同。这些温度的小变化是由量子波动引起的，并在宇宙的最早时刻持有宝贵的线索：正确预测它们的统计特性是对任何新宇宙学理论的构成或破坏测试。同时，现在正在进行一场令人叹为观止的比赛，以准确测量该火球两极分化模式中最近发现的类似小型变化。这些极小化的微小变化带有有关早期宇宙的新信息，并且有一天可以为伴随着原始火球的引力波回声提供证据。要了解宇宙的最早时刻需要对物理学有了新的了解。爱因斯坦的重力理论在几何学方面描述了时空，当我们及时回到大爆炸时，它预测这种几何形状应该变得越来越弯曲，直到过去的某个有限的时间，曲率变得无限。这一刻，大爆炸的奇异性代表了爱因斯坦理论的分解，只有通过完全量子的重力理论才能治愈。基于黑洞物理和弦理论的当前思想，我们最好的猜测是，这种重力理论应该是“全息”。这意味着它应该允许早期宇宙以第二，乍一看完全不同的理论来描述。这种替代性的“全息图”描述采用了一种普通量子理论的形式，与通常用来描述大型强子对撞机的粒子碰撞的类型非常相似，但具有一个非常令人惊讶的特征：它仅生活在三个空间维度上，并且缺少时间的维度。我的工作表明了如何构建这种态度的人，以示出了一项新的问题，即在一个问题上，这是一个问题，这是一个问题，这是一个问题，这是一个问题。时空的几何描述像爱因斯坦的理论一样分解，我们可以根据一个全息图描述的替代性全息量子的描述，即使在几何学上不再有任何预测能力，这意味着几何学的损失。宇宙微波背景直接从常规描述从普通量子理论开始。我的新研究将探讨这种情况下的关键预测：在早期宇宙中存在特殊类别的粒子，称为高旋转粒子。 Higuchi的著名定理限制了这些粒子的允许进行的质量，并且迫切需要进行进一步的研究以确定全息图是否可以满足该定理和所有观察数据。这些高自旋颗粒在早期的存在也可能在宇宙微波背景的温度变化和极化模式下留下直接的讲故事标志。我的工作将预测这些讲故事的签名的形式，并探索在未来实验中检测它们的新策略。这项调查的结果可以确认，或者排除自然解决方案全息提供了大爆炸奇点问题。