Time Dilation in Early Universe

Context:  Scientists observed a ferocious class of black holes called quasars that demonstrate “time dilation” in the early universe, showing how time then passed only about a fifth as quickly as it does today. About Quasars:
  • Quasars are extremely active supermassive black holes found at the centers of galaxies. 
  • They are millions to billions of times more massive than our sun.
  • These black holes draw in matter with their strong gravitational pull and emit intense radiation, including high-energy particle jets.
  • They are surrounded by a glowing disk of matter.
  • Quasars’ brightness allows scientists to study the early stages of the universe, as they can be observed from great distances.
Findings of the Study:
  • In their study, scientists looked at 190 very bright objects in space called quasars.
  • These quasars were from a time about 1.5 billion years after the Big Bang, which created the universe.
  • The scientists compared the brightness of these ancient quasars to the brightness of quasars we see today.
  • They found that certain changes that happen in quasars today happened five times slower in the ancient ones. 
  • This tells us that time used to pass more slowly in the early universe compared to now.
Additional Information: About Black Hole:
  • A black hole is a place in space where gravity pulls so much that even light can not get out. 
  • The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
  • Because no light can get out, people can’t see black holes. They are invisible. Space telescopes with special tools can help find black holes.
How Big Are Black Holes?
  • Black holes can be big or small.
  • Small black holes: Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain.
    • Mass is the amount of matter, or “stuff,” in an object.
  • Stellar black hole:
    • Its mass can be up to 20 times more than the mass of the sun.
    • There may be many, many stellar mass black holes in Earth’s galaxy. Earth’s galaxy is called the Milky Way.
  • Supermassive black holes:
    • These black holes have masses that are more than 1 million suns together. Scientists have found proof that every large galaxy contains a supermassive black hole at its centre.
    • The supermassive black hole at the centre of the Milky Way galaxy is called Sagittarius A. 
How Do Black Holes Form?
  • Scientists think the smallest black holes formed when the universe began.
  • Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space.
  • Scientists think supermassive black holes were made at the same time as the galaxy they are in.
 News Source: The Hindu
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