Search results
Results from the WOW.Com Content Network
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 ...
Baryon asymmetry: Why is there far more matter than antimatter in the observable universe? Cosmological constant problem: Why does the zero-point energy of the vacuum not cause a large cosmological constant? [33] [34] Size and shape of the universe:
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.
This imbalance has to be exceptionally small, on the order of 1 in every 1 630 000 000 (≈ 2 × 10 9) particles a small fraction of a second after the Big Bang. [6] After most of the matter and antimatter was annihilated, what remained was all the baryonic matter in the current universe, along with a much greater number of bosons.
Another question for astroparticle physicists is why is there so much more matter than antimatter in the universe today. Baryogenesis is the term for the hypothetical processes that produced the unequal numbers of baryons and antibaryons in the early universe, which is why the universe is made of matter today, and not antimatter.
The vacuum energy density of the Universe based on 2015 measurements by the Planck collaboration is ρ vac = 5.96 × 10 −27 kg/m 3 ≘ 5.3566 × 10 −10 J/m 3 = 3.35 GeV/m 3 [16] [note 1] or about 2.5 × 10 −47 GeV 4 in geometrized units.
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).
In November 2010, the ALPHA collaboration announced that they had trapped 38 antihydrogen atoms for a sixth of a second, [23] the first confinement of neutral antimatter. In June 2011, they trapped 309 antihydrogen atoms, up to 3 simultaneously, for up to 1,000 seconds. [24] They then studied its hyperfine structure, gravity effects, and charge.