Why did the universe begin in such a low-entropy state?
The second law describes how entropy behaves under specified conditions; it does not by itself explain the universe's initial state. In OPH, local repair can produce an irreversible record process, and information discarded from one interface can explain an observer's arrow. The state of the whole early universe is an additional question. A complete-history constraint could in principle restrict the allowed boundary data, but writing a closure equation does not yet select the observed low-entropy cosmology or its probability. The construction must connect a state-selection mechanism, cosmological history and observer records on the same source. Otherwise a special starting condition has only been renamed, rather than explained.
See also Why does time only go forward?, What is the second law of thermodynamics?, Why was the early universe so uniform and nearly spatially flat?
Also in Chapter 33: Why Was Every Open Problem the Same Problem?, Chapter 35: What Is Anything Made Of?.
This answer comes from OPH, Observer Patch Holography. OPH is a rigorous, consistent and complete description of the unified, self-creating computational Universe we inhabit. Its consistency is machine-checked: the fixed point at its core is constructed explicitly, and a theory with a model contains no contradiction.
To understand OPH and check every step yourself, start with the free book Reverse Engineering Reality. It builds the theory from the ground up, and the OPH Notebook answers your questions while you read.
read the free bookask the notebookor ask sage:read chapter 16: Why Does Time Run, and Only One Way?watch a universe make its own particles