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arXiv 1409.0917gr-qchep-th
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时间的引力箭头

Identification of a gravitational arrow of time

Julian Barbour, Tim Koslowski, Flavio Mercati

摘要:

人们普遍认为,如果任何时间对称定律的解要表现出定义“时间箭头”的任何一种行为,就必须对它施加特殊的初始条件。我们表明,这是不是这样。最简单的非平凡的时间对称定律,可以用来模拟一个动态封闭的宇宙是牛顿$N$体的问题与消失的总能量和角动量。由于这个系统的特殊性质(可能是宇宙中任何定律所共有的),它的典型解都在一个唯一定义的点上分成两半。在每一个定义明确的形状复杂性的措施波动,但增长之间的上升界限从这一点不可逆转。存储动态信息的结构随着复杂性的增长而产生,并充当“记录”。每一个解都可以被看作是有一个过去和两个不同的未来,任何内部观察者都必须在解的一半,并且只能知道一个分支的记录,并通过检查可用的记录推断出一个唯一的过去和未来方向。

英文摘要:

It is widely believed that special initial conditions must be imposed on any time-symmetric law if its solutions are to exhibit behavior of any kind that defines an `arrow of time'. We show that this is not so. The simplest non-trivial time-symmetric law that can be used to model a dynamically closed universe is the Newtonian $N$-body problem with vanishing total energy and angular momentum. Because of special properties of this system (likely to be shared by any law of the Universe), its typical solutions all divide at a uniquely defined point into two halves. In each a well-defined measure of shape complexity fluctuates but grows irreversibly between rising bounds from that point. Structures that store dynamical information are created as the complexity grows and act as `records'. Each solution can be viewed as having a single past and two distinct futures emerging from it. Any internal observer must be in one half of the solution and will only be aware of the records of one branch and deduce a unique past and future direction from inspection of the available records.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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