- The theory of baryogenesis: In physical cosmology, baryogenesis is the biological process hypothesized to have taken place during the early universe to produce baryonic asymmetry, i.e., the imbalance of matter (baryons) and antimatter (antibaryons) in the observed universe. One of the outstanding problems in modern physics is the predominance of matter over antimatter in the universe. Electroweak baryogenesis (EWBG) remains a theoretically attractive and experimentally testable scenario for explaining the cosmic baryon asymmetry.
- The theory of leptogenesis: In the standard model, the difference between the lepton number and the baryon number is precisely conserved so that leptogenesis without baryogenesis is impossible. Leptogenesis is a class of scenarios where the baryon asymmetry of the Universe is produced from a lepton asymmetry generated in the decays of a heavy sterile neutrino.
- Fundamental constants set the timescales for chemical, thermodynamic, and gravitational interactions. Thermodynamic equilibrium is an axiomatic concept of thermodynamics. It is an internal state of a single thermodynamic system or a relation between several thermodynamic systems connected by more or less permeable or impermeable walls. In thermodynamic equilibrium, there are no net macroscopic flows of matter or of energy, either within a system or between systems.
- Chemical reactions obey two fundamental laws. The first of these, the law of conservation of mass. The second, the law of conservation of energy, states that energy can be neither created nor destroyed. energy takes various forms that can be converted from one form to another. For example, the energy stored in chemical bonds can be released as heat during a chemical reaction.
- Thermochemistry is the study of energy changes that occur during chemical reactions. Thermochemistry is the branch of physical chemistry (as well as thermodynamics) concerned with heat changes of chemical reactions (including phase transformations and reactions occurring in solution). All chemical reactions involve energy. Energy is used to break bonds in reactants, and energy is released when new bonds form in products. Endothermic reactions absorb energy, and exothermic reactions release energy. The law of conservation of energy states that matter cannot be created or destroyed. Chemical reactions that absorb (or use) energy overall are called endothermic. In endothermic reactions, more energy is absorbed when the bonds in the reactants are broken than is released when new bonds are formed in the products.
- The maximum mass of a star needs to be greater than the minimum mass of a star. The typical energy of chemical reactions needs to be much smaller than typical nuclear energies.
