VOA科学技术2023--Scientists Find Time Was Slower in Quasars of Early Universe

Scientists Find Time Was Slower in Quasars of Early Universe

A team of scientists has observed time moving slower than usual in quasars of the early universe. This effect is known as "time dilation¹."

Quasars are some of the brightest things in the universe and scientists use them as "clocks" to keep track of time in the past. They are created by extremely large black holes, many times more massive than the sun, often in the center of galaxies². Black holes take in matter by gravitational pull and release radiation. That release is a quasar.

The scientists studied the brightness of 190 quasars that existed about 1.5 billion years after the universe was created. They compared the brightness of those quasars to some that exist today. They found that some movements that happen over a specific amount of time now, were five times slower back then.

Famous scientist Albert Einstein proved that time and space have been growing in all directions since the start of the universe.

Scientist Geraint Lewis is an expert in astrophysics at the University of Sydney in Australia. He led the study, which appeared in the publication Nature Astronomy. Lewis said the expanding universe is why time flowed slower billions of years ago.

However, time did not feel like slow motion. If you were sent back in time, a second would feel like a second. But a second would take five times as long for a person today.

Lewis said: "In modern physics, time is a complicated thing."

Scientists had reported time dilation from 7 billion years ago by studying supernovas, the explosions of huge stars at the end of their life. Over time, the light created by supernovas disappears. Scientists studied explosions from billions of years ago and saw that they happened much slower then compared to now.

We cannot see individual exploding stars from a set distance away, so scientists are not able to study the early universe that well. Quasars are much brighter, so scientists are able to observe the activity from much further away and deeper in the past.

"What is observed over time is the quasar brightness. This fluctuates up and down, the result of lots of complicated physics in the disk of matter spinning around a black hole at almost light speed," Lewis said.

Words in This Story

galaxy³ – n. any of the very large groups of stars and associated matter that are found throughout the universe

specific – adj. clearly and exactly presented or stated

astrophysics – n. a branch of astronomy dealing⁴ especially with the behavior, physical properties, and dynamic processes of celestial⁵ objects and phenomena⁶

complicated – adj. consisting of parts intricately combined

fluctuate – v. to be constantly changing especially up and down

spin – v. to turn or cause to turn round and round quickly

1 dilation   

n.膨胀，扩张，扩大

参考例句：

• Time dilation works both ways. 时间膨胀在两方面都起作用。 来自辞典例句
• The ciliary body is an anterior dilation of the choroid at the level of the lens. 晶状体是脉络膜石晶状体平面上向前扩大的部分。 来自辞典例句

2 galaxies   

星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）

参考例句：

• Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
• We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。

3 galaxy   

n.星系；银河系；一群(杰出或著名的人物)

参考例句：

• The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
• The company has a galaxy of talent.该公司拥有一批优秀的人才。

4 dealing   

n.经商方法，待人态度

参考例句：

• This store has an excellent reputation for fair dealing.该商店因买卖公道而享有极高的声誉。
• His fair dealing earned our confidence.他的诚实的行为获得我们的信任。

5 celestial   

adj.天体的；天上的

参考例句：

• The rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
• Gravity governs the motions of celestial bodies.万有引力控制着天体的运动。

6 phenomena   

n.现象

参考例句：

• Ade couldn't relate the phenomena with any theory he knew.艾德无法用他所知道的任何理论来解释这种现象。
• The object of these experiments was to find the connection,if any,between the two phenomena.这些实验的目的就是探索这两种现象之间的联系，如果存在着任何联系的话。