Currently, string theory represents the only advanced approach to a unification of all interactions, including gravity. In spite of the more than thirty years of its existence it did not make any empirically testable predictions. And it is completely unknown which physically interpretable principles could form the basis of string theory. At the moment, "string theory" is no theory at all, but rather a labyrinthic structure of mathematical procedures and intuitions which get their justification from the fact that they, at least formally, reproduce general relativity and the standard model of elementary particle physics as low energy approximations. However, there are now strong indications that string theory does not only reproduce the dynamics and symmetries of our standard model, but a plethora of different scenarios with different low energy nomologies and symmetries. String theory seems to describe not only our world, but an immense landscape of possible worlds. So far, all attempts to find a selection principle which could be motivated intratheoretically remained without success. So, recently the idea that the low energy nomology of our world, and therefore also the observable phenomenology, could be the result of an anthropic selection from a vast arena of nomologically different scenarios entered string theory. Although multiverse scenarios and anthropic selection are not only motivated by string theory, but lead also to a possible explanation for the fine tuning of the universe, they are concepts which transcend the framework defined by the epistemological and methodological rules which conventionally form the basis of physics as an empirical science.
卡尔·古斯塔夫·亨佩尔（Carl Gustav Hempel，1905-1997）提出了以他的名字命名的两难问题，试图确定物理学的边界。物理学在哪里过渡到形而上学？这篇文章的目的是指出，最近发展起来的一个研究领域，计算物理学，可能会为这个老问题提供一个新的答案：物理学和形而上学之间的边界是宇宙时代什么可以计算，什么不能计算之间的边界。
What is Physics For? Why Classical Physics is not the Limit of Quantum Mechanics
University of Rochester（罗切斯特大学）；Universidade Federal do Rio de Janeiro（里约热内卢联邦大学）；École Normale Supérieure / CNRS（巴黎高等师范学院/法国国家科学研究中心）；Linköping University（林雪平大学）；Dartmouth College（达特茅斯学院）；University of Sydney（悉尼大学）
