Why was the early universe so uniform and nearly spatially flat?
The horizon problem asks why distant regions share such similar conditions; the flatness problem asks why spatial curvature was so close to the value needed for the observed evolution. Inflation offers one established framework for investigating both. OPH explores a different candidate based on observer-screen synchronization and a changing record-density description. The candidate must explain which regions can share records, how their correlations are prepared and how the effective geometry evolves. Local agreement alone does not prove early-universe coherence, flatness or the spectrum of primordial fluctuations. The inflation-free branch explicitly needs those physical premises and tests. Replacing a field called the inflaton with the word synchronization would not count as deriving the observations.
See also Why is the universe expanding?, Why did the universe begin in such a low-entropy state?, What was the Big Bang?
Sources: Observer-screen synchronization as a candidate inflation-free branch
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 25: Why Does Gravity Look Like Geometry?watch a universe make its own particles