![]() There is really nothing more arbitrary about assuming that the initial conditions of the observable universe had more matter than antimatter, than there is about assuming that the initial conditions of the observable universe had non-zero aggregate mass-energy. Matt Strassler, another physicist who blogs, likewise acknowledge that using general relativity and the Standard Model to extrapolate from the existing universe backward in time only as far as those theories have been validated experimentally, or at least by a consensus very well motivated theoretical argument to extend those theories from the region where they have been validated experimentally, does not take you all of the way back to a Big Bang singularity. (LHCb Collaboration), "Observation of CP Violation in Charm Decays." 122 Phys. However, the size of CP violation in the SM appears to be too small to account for the observed matter-antimatter asymmetry, ![]() The realization of CP violation in weak interactions has been established in the K- and B-meson systems by several experiments, and all results are well interpreted within the CKM formalism. For example, this recent paper on CP violation said: ![]() Likewise, after that point, sphaleron processes should be so rare that they can't explain the baryon asymmetry of the universe. The mainstream view among physicists, although there are some theorists, is that Standard Model sphaleron processes in the twenty minutes during which Big Bang Nucleosynthesis is believed to have taken place, or the preceding ten seconds between the Big Bang and the onset of Big Bang Nucleosynthesis, can't account for the massive asymmetry between baryons made of matter and baryonic anti-matter that is observed in the universe (also here) without beyond the Standard Model physics (also here). Indeed, the sum total of the observational evidence that we have and the experimentally established theories that we have point to the conclusion that the initial conditions of the universe had more matter than antimatter. The laws of physics only provide that matter and antimatter creation must be equal in amount in events after any given set of initial conditions (with small exceptions not large enough to account for the observed differences). There is no evidence based or experimentally established theory basis for the conclusion that the initial conditions of the Universe needed to have equal amounts of matter and antimatter. If a physicist tries to tell you otherwise, ask them where they get their initial state from. You always have to choose an initial state, and you do that just because it explains what we observe. ![]() But within the framework of the theories that we currently have, such an explanation is not possible. Of course it would be nice to have a deeper explanation for that initial value. It can be solved by using an initial value that agrees with observations, and that’s that. The brief summary is that the matter antimatter asymmetry is a pseudo-problem.
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