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