Context:
Scientists used observations of quasars to demonstrate time dilation in the early universe, showing how time then passed only about a fifth as quickly as it does today.
Key Findings:
- Continual expansion of the universe –
- Responsible for the slower passage of time in the past compared to the present.
- The observations stretch back to about 12.3 billion years ago.
- Previous Observations –
- Time dilation dating back around 7 billion years based on observations of supernovas, stellar explosions.
- Brightness of these quasars was compared to that of quasars existing today, showing certain fluctuations about a fifth as quickly as it does today.
A supernova is the biggest explosion that humans have ever seen. Each blast is the extremely bright, super-powerful explosion of a star.
What is Time dilation?
- It is the slowing of time as perceived by one observer compared with another, depending on their relative motion or positions in a gravitational field.
- It is a consequence of Einsteinian theory of relativity that showed that time and space are intertwined and that universe has been expanding outward in all directions since the Big Bang.
- It occurs because objects with a lot of mass create a strong gravitational field. Stronger the gravity, more space-time curves, and the slower time itself proceeds.
What are Quasars?
- Tremendously active supermassive black holes millions to billions of times more massive than our sun, usually residing at centers of galaxies.
- Characteristics –
- Draws matter towards them through strong gravitational forces
- Emits powerful radiation and high-energy particle jets
- Surrounded by a glowing disk of matter
- Brightness remains observable from the early stages of the universe
Consider the following phenomena:
- Light is affected by gravity.
- The Universe is constantly expanding.
- Matter warps its surrounding space-time.
Which of the above is/are the prediction/predictions of Albert Einstein’s General Theory of Relativity, often discussed in media?
[UPSC Civil Services Exam – 2018 Prelims]
- 1 and 2 only
- 3 only
- 1 and 3 only
- 1, 2 and 3
Source: The Hindu