what is dark matter n dark energy.
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While dark energy repels, dark matter attracts. ... About one-quarter of the universe consists of dark matter, which releases no detectable energy, but which exerts a gravitational pull on all the visible matter in the universe. Because of the names, it's easy to confuse dark matter and dark energy.
While dark energy repels, dark matter attracts. ... About one-quarter of the universe consists of dark matter, which releases no detectable energy, but which exerts a gravitational pull on all the visible matter in the universe. Because of the names, it's easy to confuse dark matter and dark energy.
Dark matter produces an attractive force (gravity), while dark energy produces a repulsive force (antigravity). Together, they make up 96 percent of the universe—and we can't see either. Astronomers know dark matter exists because visible matter doesn't have enough gravitational muster to hold galaxies.
The rest of the universe appears to be made of a mysterious, invisible substance called dark matter (25 percent) and a force that repels gravity known as dark energy (70 percent).
There is no current problem of greater importance to cosmology than that of dark matter. Dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observing electromagnetic radiation. Dark matter is material that cannot be seen directly.
In physical cosmology and astronomy, dark energy is an unknown form of energy which is hypothesized to permeate all of space, tending to accelerate the expansion of the universe.Astronomers are at the dawn of such a revolution today. In the 1990s, they discovered a previously unknown "dark energy" that is causing the universe to expand faster as it ages. And they calculated that this energy constitutes about 70 percent of all the matter and energy in the universe.