Analogue Simulation in Modern Physics

现代理论物理学的许多预言极难验证。例如，霍金著名的预言黑洞以特定温度辐射。由于“霍金辐射”的温度非常低，它不能（甚至在原则上）通过观测天文学检测到。此外，我们不太可能在地球上建造黑洞。缺乏对霍金辐射等预测进行直接实验测试的原则上的方法，对传统的科学方法构成了挑战。这一挑战由“模拟模拟”技术来解决，其中使用可访问的“源”系统来模拟难以或不可能在“目标”系统中直接测试的现象。现代物理学中的模拟模拟根据源和目标系统的类型分为两种形式：“量子模拟”和“模拟重力模拟”。在量子模拟中，源系统和目标系统通常都在有限维量子理论的范围内。一个简单的例子是，通过磁场控制离子阵列（即带电原子），使它们共同模拟铁磁性材料（如铁棒磁铁）。量子模拟是潜在的非常强大的工具，可以获得对难以操纵的量子系统的新见解，例如相对论量子系统、纳米材料和量子光学系统。在模拟重力模拟中，凝聚态物质系统，如流体，通常用于模拟引力系统，如黑洞或早期宇宙宇宙学。模拟重力模拟是潜在的非常强大的工具，可以获得对被认为不可能直接测试的现象的新见解，比如霍金辐射。这是一个科学哲学的项目，我们将评估模拟模拟的方法论、认识论和形而上学基础，目的是为科学家、科学哲学家和科学基金决策者提供直接使用的分析工具。我们回答这样的问题：模拟模拟能提供什么样的证据？模拟模拟与计算机模拟和实验有什么共同之处？模拟仿真的科学和经济价值是什么？我们建议，模拟仿真可以被理解为一种“模拟”实验的形式，涉及物理系统的“编程”，这样它就可以用来“模拟”另一个物理系统。一般来说，从特定系统的实验中获得的证据只有在我们有理由将其推广到一类相关相似的“目标”系统时才具有真正的价值。这样的论证被称为实验的“外部验证”。本项目探讨的关键思想之一是模拟仿真的外部验证条件。例如，我们的目标是研究通过凝聚态系统对霍金辐射的模拟模拟可以进行外部验证的条件：即我们可以通过对类似物进行实验来真正了解黑洞。

Many of the predictions of modern theoretical physics are extremely difficult to test. For example, Hawking's famous prediction that black holes radiate at a characteristic temperature. Since the temperature of `Hawking radiation' is very low, it is not (even in principle) detectable via observational astronomy. Furthermore, is is unlikely that we will ever be able to construct black holes here on earth. The lack of an in principle means for direct experimental testing of predictions such as Hawking radiation pose a challenge to conventional scientific methodologies. This challenge is taken up by techniques of `analogue simulation' wherein an accessible `source' system is used to simulate phenomena that are difficult or impossible to test directly within a `target' system. Analogue simulation in modern physics comes in two forms depending upon the type of source and target system: `quantum simulation' and `analogue gravity simulation'. In quantum simulation both source and target systems are typically within the domain of finite dimensional quantum theory. A simple example is where an array of ions (i.e. charged atoms) is controlled via magnetic fields such that they collectively simulate a ferromagnetic material (such as an iron bar magnet). Quantum simulations are potentially very powerful tools for gaining new insights into quantum systems that are hard to manipulate, for example relativistic quantum systems, nano-materials and quantum optical systems. In analogue gravity simulations, condensed matter systems, like fluids, are typically used to simulate gravitational systems, such as black holes or early universe cosmology. Analogue gravity simulations are potentially very powerful tools for gaining new insights into phenomena that are deemed impossible to test directly, such as Hawking radiation. This is a project in the philosophy of science within which we will evaluate the methodological, epistemological and metaphysical foundations of analogue simulation with the goal of providing analytic tools of direct use to scientists, philosophers of science, and science funding decision makers. We answer questions such as: What kind of evidence can analogue simulations provide?; What do analogue simulations have in common with computer simulations and experiments?; What is the scientific and economic value of analogue simulation? We propose that analogue simulation can be understood as a form of `Ersatz' experimentation, involving the `programming' of a physical system such that it can be used to `simulate' another physical system. In general terms, evidence gained from experiments on a particular system is only of real value to the extent to which we have justification for generalising it to a class of relevantly similar `target' systems. Such justificatory arguments are called `external validation' of an experiment. One of the key ideas explored in this project is conditions for external validation of analogue simulations. For example, we aim to examine the conditions in which the analogue simulation of Hawking radiation via condensed matter systems can be externally validated: i.e. when we can genuinely learn about black holes by doing experiments on the analogues.