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All the particles that make up the matter around us, such electrons and protons, have antimatter versions which are nearly identical, but with mirrored properties such as the opposite electric charge.
Neither the standard model of particle physics nor the theory of general relativity provides a known explanation for why this should be so, and it is a natural assumption that the universe is neutral with all conserved charges. [3] The Big Bang should have produced equal amounts of matter and antimatter. Since this does not seem to have been ...
Once the universe expanded and cooled to a critical temperature of approximately 2 × 10 12 K, [3] quarks combined into normal matter and antimatter and proceeded to annihilate up to the small initial asymmetry of about one part in five billion, leaving the matter around us. [3]
The local geometry of the universe is determined by whether the relative density Ω is less than, equal to or greater than 1. From top to bottom: a spherical universe with greater than critical density (Ω>1, k>0); a hyperbolic, underdense universe (Ω<1, k<0); and a flat universe with exactly the critical density (Ω=1, k=0). The spacetime of ...
Under current theory, the Big Bang explosion that initiated the universe should have produced equal amounts of matter and antimatter. This, however, does not seem to be the case.
Why does the observable universe have more matter than antimatter? (more unsolved problems in physics) In physical cosmology , leptogenesis is the generic term for hypothetical physical processes that produced an asymmetry between leptons and antileptons in the very early universe , resulting in the present-day dominance of leptons over ...
This maximal radiation density corresponds to about 1.2 × 10 17 eV/m 3 = 2.1 × 10 −19 kg/m 3, which is much greater than the observed value of 4.7 × 10 −31 kg/m 3. [4] So the sky is about five hundred billion times darker than it would be if the universe was neither expanding nor too young to have reached equilibrium yet.
If the universe started with even slightly different temperatures in different places, the CMB should not be isotropic unless there is a mechanism that evens out the temperature by the time of decoupling. In reality, the CMB has the same temperature in the entire sky, 2.726 ± 0.001 K. [3]