近日，意大利里雅斯特大学的教授Matteo Carlesso及其研究团队取得一项新进展。经过不懈努力，他们证实自发坍缩模型会导致宇宙经典性的出现。相关研究成果已于2024年2月23日在国际知名学术期刊《高能物理杂志》上发表。
据悉，如果假设量子力学具有普适性，即能够应用于所有尺度，那么宇宙便可能处于量子叠加态，其中每个状态都可能与不同的时空几何相对应。然而，考虑到退相干驱动的量子到经典的跃迁过程依赖于外部物理实体，这一过程并不能解释宇宙经典行为的出现。那么，人们应如何描述观察到的经典、明确界定的几何形状的出现呢？
该研究团队提出了波函数自发坍缩模型，为解释宇宙的量子到经典跃迁提供了可行的机制。研究人员将该模型应用于广义相对论引力动力学模型和完美流体，并发现，从一般量子叠加的不同几何形状出发，坍缩动力学能导致单一几何形状的出现，从而为宇宙的量子到经典跃迁提供了可能的解释。此外，当研究人员将动力学应用于物理等效的参数化幺模引力模型时，他们在宇宙常数的基础上得到了一个坍缩，最终选择了一个精确的值，为宇宙常数问题提供了可行的解释。这种模型可以轻松地应用于其他量子宇宙学模型中，研究人员可以选择一个定义良好的时钟变量来进一步探索。
附：英文原文
Title: Spontaneous collapse models lead to the emergence of classicality of the Universe
Author: Gaona-Reyes, Jos Luis, Menndez-Pidal, Luca, Faizal, Mir, Carlesso, Matteo
Issue&Volume: 2024-02-23
Abstract: Assuming that Quantum Mechanics is universal and that it can be applied over all scales, then the Universe is allowed to be in a quantum superposition of states, where each of them can correspond to a different space-time geometry. How can one then describe the emergence of the classical, well-defined geometry that we observe Considering that the decoherence-driven quantum-to-classical transition relies on external physical entities, this process cannot account for the emergence of the classical behaviour of the Universe. Here, we show how models of spontaneous collapse of the wavefunction can offer a viable mechanism for explaining such an emergence. We apply it to a simple General Relativity dynamical model for gravity and a perfect fluid. We show that, by starting from a general quantum superposition of different geometries, the collapse dynamics leads to a single geometry, thus providing a possible mechanism for the quantum-to-classical transition of the Universe. Similarly, when applying our dynamics to the physically-equivalent Parametrised Unimodular gravity model, we obtain a collapse on the basis of the cosmological constant, where eventually one precise value is selected, thus providing also a viable explanation for the cosmological constant problem. Our formalism can be easily applied to other quantum cosmological models where we can choose a well-defined clock variable.
DOI: 10.1007/JHEP02(2024)193
Source: https://link.springer.com/article/10.1007/JHEP02(2024)193