Studies of Particle Production, Vacuum Polarization, and the Validity of the Semiclassical Approximation in Gravity

粒子产生、真空偏振和重力半经典近似有效性的研究

• 批准号: 1308325
• 负责人: Paul Anderson
• 金额: $ 4.13万
• 依托单位: Wake Forest University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1308325&HistoricalAwards=false
• 关键词: Studies; Particle; Production; Vacuum; Polarization

This award supports research that addresses issues relating to quantum effects in both cosmological and black hole spacetimes. These are questions related to the validity of the semi-classical approximation when it is used to describe the effects of quantized fields on a classical background field and to determine whether observable effects related to the existence of a horizon, in this case a sonic horizon, can be found in certain Bose-Einstein condensates, which can serve as black hole analogues. One project involves determining whether quantum fluctuations in the density and pressure of matter and radiation will be large during a period of inflation when the universe is expanding exponentially. If so, then the semi-classical approximation to gravity breaks down and a different method will be needed to describe what happens. A second project investigates the validity of the semiclassical approximation when the universe contracts for one important model in which the contraction is to a minimal size and is followed by an expansion. Evidence suggesting a quantum instability in this model could indicate that quantum fluctuations become large during the contraction phase. A third project investigates whether quantum effects that could be observed in laboratory studies and which are related to the existence of a horizon exist for a model in which a Bose-Einstein condensate serves as an analog for a black hole. Specifically the density density correlation function is computed in order to determine whether undulations are predicted to occur and whether other new observable effects that require the existence of a horizon can be found.Completion of these projects will elucidate phenomena ranging from the expansion of the universe to potentially observable effects in black hole analogues. If quantum fluctuations prove to be large in important situations, then predictions made using the semi-classical approximation will be suspect, and a different method must be found to treat the effects of the quantized fields. The work on the validity of the semiclassical approximation could have implications for and be extended to other situations in which this approximation has been used such as the production of particles in the presence of a strong electric field and the modeling of heavy ion collisions in nuclear physics. The work on Bose-Einstein condensates which serve as analog black holes may predict specific effects that experimental condensed matter physicists can attempt to observe in laboratory experiments. If observed, these effects would provide significant evidence that predictions of quantum effects relating to black holes, such as black hole evaporation, are correct. It is expected that at least three undergraduate students and at least one graduate student will participate in many aspects of the research, continuing a long history of the training of students in numerical and analytical research techniques and co-authorship on publications. Results will be disseminated to the research community through publications and presentations at national and international meetings.

该奖项支持解决宇宙学和黑洞时空中量子效应相关问题的研究。 这些问题与半经典近似的有效性有关，当它被用来描述量子化场对经典背景场的影响，并确定是否可以在某些玻色-爱因斯坦凝聚体中找到与视界（在这种情况下是声波视界）存在相关的可观察效应时，它可以作为黑洞的类似物。 其中一个项目涉及确定在宇宙呈指数级膨胀的暴胀期间，物质和辐射的密度和压力的量子波动是否会很大。如果是这样的话，那么引力的半经典近似就失效了，需要一种不同的方法来描述发生了什么。 第二个项目调查的半经典近似的有效性时，宇宙合同的一个重要的模型，其中的收缩是一个最小的大小，其次是膨胀。 在这个模型中，量子不稳定性的证据可能表明量子涨落在收缩阶段变得很大。 第三个项目调查是否可以在实验室研究中观察到的量子效应，以及与视界存在有关的量子效应是否存在于玻色-爱因斯坦凝聚作为黑洞模拟的模型中。 具体来说，密度密度相关函数的计算，以确定是否波动预测发生，以及是否其他新的可观察到的影响，需要存在的一个视界可以被发现。这些项目的完成将阐明从宇宙膨胀的现象，在黑洞类似物的潜在可观察到的影响。 如果量子涨落在重要的情况下被证明是很大的，那么使用半经典近似所做的预测将是可疑的，必须找到一种不同的方法来处理量子化场的影响。 半经典近似的有效性的工作可能会产生影响，并被扩展到其他情况下，这种近似已被使用，如在强电场的存在下产生的粒子和重离子碰撞在核物理建模。 玻色-爱因斯坦凝聚体作为模拟黑洞的工作可能会预测实验凝聚态物理学家可以在实验室实验中观察到的特定效应。 如果被观测到，这些效应将提供重要的证据，证明与黑洞有关的量子效应（如黑洞蒸发）的预测是正确的。 预计至少有三名本科生和至少一名研究生将参与研究的许多方面，继续培养学生的数值和分析研究技术和共同撰写出版物的悠久历史。研究结果将通过出版物和在国家和国际会议上的介绍传播给研究界。