The Past Hypothesis and the Nature of Physical Laws

Governing Without A Fundamental Direction of Time: Minimal Primitivism about Laws of Nature

The Great Divide in metaphysical debates about laws of nature is between Humeans, who think that laws merely describe the distribution of matter, and non-Humeans, who think that laws govern it. The metaphysics can place demands on the proper formulations of physical theories. It is sometimes assumed that the governing view requires a fundamental / intrinsic direction of time: to govern, laws must be dynamical, producing later states of the world from earlier ones, in accord with the fundamental direction of time in the universe. In this paper, we propose a minimal primitivism about laws of nat…

Time's Arrow and Self-Locating Probability

One of the most difficult problems in the foundations of physics is what gives rise to the arrow of time. Since the fundamental dynamical laws of physics are (essentially) symmetric in time, the explanation for time's arrow must come from elsewhere. A promising explanation introduces a special cosmological initial condition, now called the Past Hypothesis: the universe started in a low-entropy state. Unfortunately, in a universe where there are many copies of us (in the distant "past" or the distant "future"), the Past Hypothesis is not enough; we also need to postulate self-locating (de se) p…

分离玻尔兹曼脑、记忆的时间不对称性以及第二定律

Disentangling Boltzmann brains, the time-asymmetry of memory, and the second law

本文通过形式化熵动态为时间对称的马尔可夫过程，分离了玻尔兹曼脑假设、记忆时间不对称性、过去假设和第二定律之间的依赖关系，揭示其在条件化假设上的相似性。

为什么你无需担心你是玻尔兹曼大脑的标准论证

Why you do not need to worry about the standard argument that you are a Boltzmann brain

本文指出玻尔兹曼大脑论证自相矛盾：它依赖关于过去的可靠数据推断动力学定律，却据此否定这些数据的真实性，且基于不完整证据，因此无需担忧。

Three Merry Roads to T-Violation

This paper is a tour of how the laws of nature can distinguish between the past and the future, or be T-violating. I argue that, in terms of the basic argumentative structure, there are really just three approaches currently being explored. I show how each is characterized by a symmetry principle, which provides a template for detecting T-violating laws even without knowing the laws of physics themselves. Each approach is illustrated with an example, and the prospects of each are considered in extensions of particle physics beyond the standard model.

Genesis of a Pythagorean Universe

The full-blown multiverse hypothesis, chaosogenesis, is refuted on the grounds of the large scale and high precision of the already discovered laws of nature. A selection principle is required not only to explain the possibility of life and consciousness, but also theoretizability of our universe. The weak anthropic principle provides the former, but not the latter. As chaosogenesis is shown to be the only thinkable scientific answer to the question of why the laws of nature are the way they are, its refutation means that this question cannot be answered scientifically.