# Quantum Theory of the Universe Based on Bayesian Probability

## TL;DR

This paper develops a quantum universe model using Bayesian probability, allowing for the calculation of universe probabilities from a single occurrence rather than repeated experiments.

## Contribution

It introduces a Bayesian probability framework into quantum cosmology, enabling probability definitions for unique universe events.

## Key findings

- Derived explicit probability of the universe in a scalar field model.
- Demonstrated the application of Bayesian quantum theory to cosmological models.

## Abstract

We formulate a quantum theory of the Universe based on Bayesian probability. In this theory, the probability of the Universe is not a frequency probability, which can be obtained by observing experimental results several times, but is a Bayesian probability, which can define a probability of an event that occurs just once. As an example, by applying the quantum theory of the Universe to an action of a scalar field theory in the four dimensions as a toy model for the theory of the Universe, we explicitly obtain the probability of the Universe and the action of matters in the Universe.