Form of energy that is gravitationally repulsive, due to a negative effective pressure. Dark energy is spread almost uniformly throughout space and appears to contribute about 70% of the present energy Mass of an object divided by its volume. Density is a characteristic property of a substance (rock vs. ice, e.g.). Some substances (like gases) are easily compressible and have different densities depending on how much pressure is exerted upon them. The Sun is composed of compressible gases and is much Click on Term to Read More of the That which contains and subsumes all the laws of nature, and everything subject to those laws; the sum of all that exists physically, including matter, energy, physical laws, space, and time. Also, a cosmological model of the universe.. Its existence was recently inferred from observations of distant Type Ia supernovae from combining CMBR anisotropy measurements with measurements of the density of Form of matter that does not emit light, absorb light, or otherwise interact with electromagnetic radiation. Its only interactions are gravitational and dark matter particles can clump under the force of gravity (unlike "dark energy" which is evenly distributed throughout space). The existence of dark matter has been inferred from Click on Term to Read More. The cosmological constant is a particular form of dark energy.
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