Dark matters

Why in news?

• Recently, researchers have created a detailed map of the invisible dark matter that makes up 85% of the universe.

More about the news:

• The new findings align with the standard model of cosmology based on Einstein's theory of gravity.
• The researchers used the Atacama Cosmology Telescope (ACT) to map dark matter using light from the early universe, known as the cosmic microwave background (CMB) radiation.
• They used the CMB radiation to map dark matter by observing how it interacts with the gravity of massive objects like galaxy clusters and lumps of dark matter.
• The gravitational field generated by these objects bends and distorts the light that passes through them, which helps in detecting dark matter.

About Dark Matter:

• Dark matter is a hypothetical form of matter that is believed to exist in the universe but is invisible and does not interact with light.
• Dark matter is essential to explaining the observed structure of the universe.
• It helps to account for the distribution of matter in galaxies and the cosmic web.
• Understanding dark matter is important for developing a complete understanding of the universe and its evolution.
• The visible universe we see is the result of various interactions among the four Fundamental forces acting upon the particles, namely-
  • Strong nuclear force
  • Weak nuclear force
  • Electromagnetic force
  • Gravitation
• Only a small percentage of the entire visible universe is made up of all matter and the rest of is dark matter and dark energy.

What is ‘Dark Energy’?

• It is a type of energy that is thought to be responsible for the accelerating expansion of the universe.
• It is a form of energy that fills the entire universe and exerts a negative pressure, pushing galaxies and other matter away from each other.
• Dark energy is estimated to make up about 68% of the total energy content of the universe.

Evidence Related to Dark Matter:

• There is strong indirect evidence, as reflected in various levels like distance scales. For example, as we move from the centre of the galaxy to its periphery, there is a significant disparity between the observed plot of star speeds and their estimated figure. This implies that the galaxy has a significant amount of dark matter.
• There are Bullet clusters of galaxies that are formed through the merging of two galaxies, as per scientists their merger could only be explained through the presence of some dark matter.

PRACTICE QUESTION:

In the context of our current understanding of universe, which of the following statements are correct regarding ‘dark matter’?

1. They are made up of particles that do not have a charge

2. They do not emit light

3. They possess mass like normal matter and hence interact through gravity

Select the correct answer using the code given below:

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1,2 and 3

Answer