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Dark matter
Why is it in news?
- Researchers led by Kavli Institute for the Physics and Mathematics of the Universe in Japan used the gravitational lensing effect to look for primordial black holes between the earth and the Andromeda galaxy.
- Scientists who have put the theory put forward by the late Stephen Hawking said Dark matter is not made up of primordial black holes smaller than a tenth of a millimetre.
More in news
- What is dark matter?:(1) Dark matter is a hypothetical form of matter that is thought to account for approximately 85% of the matter in the universe and about a quarter of its total energy density.(2) Normal matter, including all the visible stars, planets and galaxies, makes up less than 5 percent of the total mass of the universe.(3) Astronomers cannot see dark matter directly, but can study its effects.
- Composition: The majority of dark matter is thought to be non-baryonic in nature, possibly being composed of some as-yet undiscovered subatomic particles.
- Why is it called dark?: Dark matter is called dark because it does not appear to interact with observable electromagnetic radiation, such as light, and is thus invisible to the entire electromagnetic spectrum, making it extremely difficult to detect using usual astronomical equipment.
- various techniques for Detecting dark matter:(1) Particle colliders such as the Large Hadron Collider.(2) Cosmology instruments such as WMAP and Planck.(3) Direct detection experiments: It includes CDMS, XENON, Zeplin, WARP, ArDM and others.(4) Indirect detection experiments: It includes Gamma ray detectors (Fermi from space and Cherenkov Telescopes from the ground); neutrino telescopes (IceCube, Antares); antimatter detectors (Pamela, AMS-02) and X-ray and radio facilities.
- However, attempts to detect such dark matter particles using underground experiments, or accelerator experiments including the world’s largest accelerator, the Large Hadron Collider, have failed so far.
Source
The Hindu