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The categories of dark matter are set with respect to the size of a protogalaxy (an object that later evolves into a dwarf galaxy): dark matter particles are classified as cold, warm, or hot if their FSL is much smaller (cold), similar to (warm), or much larger (hot) than a protogalaxy.
A black hole of one solar mass (M ☉ = 2.0 × 10 30 kg) takes more than 10 67 years to evaporate—much longer than the current age of the universe at 1.4 × 10 10 years. [22] But for a black hole of 10 11 kg, the evaporation time is 2.6 × 10 9 years. This is why some astronomers are searching for signs of exploding primordial black holes.
The large difference between these two supports a smooth component of dark energy making up the difference. Much more precise measurements from WMAP in 2003–2010 have continued to support the standard model and give more accurate measurements of the key parameters.
Since the 1990s, studies have shown that, assuming the cosmological principle, around 68% of the mass–energy density of the universe can be attributed to dark energy. [6] [7] [8] The cosmological constant Λ is the simplest possible explanation for dark energy, and is used in the standard model of cosmology known as the ΛCDM model.
Eliminates 4 π G from the Bekenstein–Hawking formula (for the entropy of a black hole in terms of its mass m BH and the area of its event horizon A BH) which is simplified to S BH = π A BH = (m BH) 2. Setting 8 π G = 1 (and therefore setting G = 1 / 8 π ).
The reaction of 1 kg of antimatter with 1 kg of matter would produce 1.8 × 10 17 J (180 petajoules) of energy (by the mass–energy equivalence formula, E=mc 2), or the rough equivalent of 43 megatons of TNT – slightly less than the yield of the 27,000 kg Tsar Bomba, the largest thermonuclear weapon ever detonated.
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The formula defines the energy E of a particle in its rest frame as the product of mass (m) with the speed of light squared (c 2). Because the speed of light is a large number in everyday units (approximately 300 000 km/s or 186 000 mi/s), the formula implies that a small amount of mass corresponds to an enormous amount of energy.