Fundamental Physics and Cosmology

基础物理学和宇宙学

• 批准号: 2110466
• 负责人: Mark Hertzberg
• 金额: $ 40.5万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2110466&HistoricalAwards=false
• 关键词: Fundamental; Physics; Cosmology

This award funds the research activities of Professor Alexander Vilenkin at Tufts University.Professor Vilenkin will study the evolution and possible observational signatures of cosmic strings. Cosmic strings are very thin and highly energetic linear objects. Many theories of particle physics predict that such strings must have formed in the early universe, and if so they can produce a variety of effects which are observable at the present time. In particular, such strings could be responsible for a background of gravitational waves and for cosmic rays at the highest energies, which are hard to explain through conventional astrophysical processes. A detection of cosmic strings would be of great importance, as it would open a unique window into the physics of very high energies, inaccessible in particle accelerators. Another direction of Professor Vilenkin's research is the study of bubble formation in a high energy phase of the universe. Bubbles such as these are regions of space in which the laws of physics are in a different "phase", just as water and ice are the same material in different phases. A small bubble of space with a lower energy can be created spontaneously and then rapidly expand. Bubble formation plays a central role in a number of cosmological models, including the theory of inflation (under which the universe is believed to have expanded very rapidly at initial times), but some aspects of this process are still poorly understood. Professor Vilenkin will develop new methods for calculating the probability of bubble creation. This research is in the national interest in that it furthers the development of basic science in the United States. Professor Vilenkin will also continue his efforts to communicate these ideas to the general public.At a more technical level, Professor Vilenkin will study the interaction of cosmic strings with black holes. An oscillating loop of string can be captured by a black hole. The loop can then grow in size by extracting the black hole's rotational energy. It may also self-intersect and split, ejecting a smaller loop. A large number of string loops may be produced as this cycle continues. The probability of loop capture significantly depends on how loops are distributed in space, in particular on the extent to which they are clustered in galaxies. Professor Vilenkin will use numerical simulations to study the gravitational clustering of strings and the interaction of string loops with rotating black holes. The results will be used to derive predictions for observational signatures of strings, especially for the gravitational wave background. The bubble nucleation probability is usually calculated using the standard instanton approach, but this method fails in many relevant situations. Professor Vilenkin will use the Wigner distribution and numerical simulations to study the alternative stochastic method and to determine its limits of applicability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该奖项资助了塔夫茨大学亚历山大·维伦金教授的研究活动。维伦金教授将研究宇宙弦的演化和可能的观测特征。宇宙弦是非常细的高能量线性物体。许多粒子物理学理论预言，这样的弦一定是在早期宇宙中形成的，如果是这样的话，它们可以产生各种各样的效应，这些效应在今天是可以观察到的。特别是，这样的弦可能是引力波和最高能量宇宙射线的背景，这很难通过传统的天体物理过程来解释。对宇宙弦的探测将是非常重要的，因为它将打开一扇独特的窗口，让我们了解在粒子加速器中无法达到的高能物理学。维伦金教授研究的另一个方向是研究宇宙高能相中的气泡形成。像这样的气泡是物理定律处于不同“阶段”的空间区域，就像水和冰是不同阶段的相同物质一样。一个能量较低的空间小气泡可以自发产生，然后迅速膨胀。气泡的形成在许多宇宙学模型中扮演着核心角色，包括暴胀理论（在暴胀理论下，宇宙被认为在初始时期膨胀得非常迅速），但这个过程的某些方面仍然知之甚少。维伦金教授将开发计算气泡产生概率的新方法。这项研究符合国家利益，因为它促进了美国基础科学的发展。维伦金教授也将继续努力将这些想法传达给公众。在更技术性的层面上，维伦金教授将研究宇宙弦与黑洞的相互作用。一个弦的振荡环可以被黑洞捕获。然后，这个环可以通过提取黑洞的旋转能量来扩大大小。它也可以自相交和分裂，喷出一个较小的回路。随着循环的继续，可能会产生大量的字符串循环。环路捕获的概率在很大程度上取决于环路在空间中的分布，特别是它们在星系中聚集的程度。维伦金教授将使用数值模拟来研究弦的引力聚集以及弦环与旋转黑洞的相互作用。这些结果将用于预测弦的观测特征，特别是引力波背景。气泡成核概率的计算通常采用标准的瞬态方法，但这种方法在许多相关情况下是行不通的。Vilenkin教授将使用Wigner分布和数值模拟来研究另一种随机方法，并确定其适用范围。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

The tunneling wavefunction in Kantowski-Sachs quantum cosmology

康托夫斯基-萨克斯量子宇宙学中的隧道波函数

• DOI: 10.1088/1475-7516/2022/08/069
• 发表时间: 2022
• 期刊: Journal of Cosmology and Astroparticle Physics
• 影响因子: 6.4
• 作者: Fanaras, Georgios;Vilenkin, Alexander
• 通讯作者: Vilenkin, Alexander

Black holes and uptunneling suppress Boltzmann brains

黑洞和上隧道抑制玻尔兹曼大脑

• DOI: 10.1103/physrevd.104.023528
• 发表时间: 2021
• 期刊: Physical review
• 作者: Olum, Ken;Vilenkin, Alexander
• 通讯作者: Vilenkin, Alexander

Bubble nucleation as seen by different observers

不同观察者所看到的气泡成核

• DOI: 10.1088/1475-7516/2021/03/035
• 发表时间: 2021
• 期刊: Journal of cosmology and astroparticle physics
• 影响因子: 6.4
• 作者: Chen, Yilin;Vilenkin, Alexander
• 通讯作者: Vilenkin, Alexander

Simulating cosmic string loop captured by a rotating black hole

模拟旋转黑洞捕获的宇宙弦环

• DOI: 10.1103/physrevd.107.123016
• 发表时间: 2023
• 期刊: Physical Review D
• 影响因子: 5
• 作者: Deng, Heling;Gruzinov, Andrei;Levin, Yuri;Vilenkin, Alexander
• 通讯作者: Vilenkin, Alexander

Quantum cosmology, eternal inflation, and swampland conjectures

量子宇宙学、永恒膨胀和沼泽猜想

• DOI: 10.1088/1475-7516/2023/04/034
• 发表时间: 2023
• 期刊: Journal of Cosmology and Astroparticle Physics
• 影响因子: 6.4
• 作者: Fanaras, Georgios;Vilenkin, Alexander
• 通讯作者: Vilenkin, Alexander