DARK MATTER




 DARK MATTER MAP:

Astronomers have made the most 
detailed map of dark matter
showing that both the ‘lumpiness’
(piece of a solid substance, usually 
with no particular shape) of the 
universe and the rate at which the 
universe is growing.

● They have created a map by using the microwave detectorof the Atacama Cosmology Telescope (ACT).

●Astronomers were observing the data collected by the ACT to find out whether Einstein’s predictions in his theory are correct regarding the expansion of the Universe. 

●They also observed the sanctity of the standard model of cosmology (SMC).




Big Bang Model

● It is the only model that is able to explain the existence of the Cosmic Microwave 
Background (CMB). 

● According to this model, the Universe started with a very dense and hot phase that 
expanded and cooled itself; for several hundreds of thousands of years the  temperature was so high that neutral atoms could not form. 

● Matter consisted mostly of neutrons and charged particles (protons and electrons). 

● Electrons interacted closely with the light particles, and therefore light and matter 
were tightly coupled at that time (that is, light could not travel for a long distance
in a straight line). 

● Light could therefore not propagate and the Universe was opaque.

● It took about 300 000 years for the Universe to cool down to a temperature at which atoms can form (about 3000°C). 

● Matter then became neutral, and allowed the light to travel freely, then Universe.




Einstein's Theory of Relativity




●It was propounded by him in 1915.

●In this theory, he contradicted Isaac Newton’s concept of space who saw space and time as fixed. 

●But according to his theory, space is fluid and malleable.

●Gravity is not a force, but rather a distortion of time and space.

●Tiny ripples are caused by colliding black holes.



Observation Made by Astronomers:

● Invisible world: Features of the invisible world (dark matter and energy) were observed which are hundreds of 
millions of light-years across. 

● Cosmic Microwave Background (CMB) radiation: Gravitational pull of large, heavy structures including dark matter warps
 the CMB radiation on its 14-billion-year journey to Earth.

■CMB or fossil radiation is the cooled remnant of the first light (or leftover of the Big Bang) that could ever travel freely throughout the Universe.

■The CMB light gets deflected by dark matter, just like a magnifying glass deflects light that passes through it. 

● Lumpiness: Measurements showed that the 'lumpiness' of the universe is of the exact right size as per SMC. 

● Expansion: Rate at which it is growing is just what was expected from our SMC based on Einstein's theory.

●Gravitational lensing: It was observed while recording the movement of the CMB.


■It is a phenomenon in which light moving 
through a region of space-time warped (bend or twist out of shape) by powerful 
gravitational fields travels, in a curve until it emerges as a stretched-out arc called an Einstein ring.


■Gravitational lensing helps in detecting dark matter.

Composition of the Universe

●Unlike normal matter, dark matter does not interact with electromagnetic force.

■ This means it does not absorb, reflect or emit light, making it extremely hard 
to spot. 

●Researchers have been able to infer the existence of dark matter only from the 
gravitational effect it seems to have on visible matter. 

● It seems to outweigh visible matter roughly six to one, making up about 27% of 
the universe.

● Astronomer Fritz Zwicky first used the term "dark matter" in the 1930s.

● It makes up approximately 68% of the 
universe and appears to be associated
with the vacuum in space. 

●It is distributed evenly throughout the 
universe, not only in space but also in 
time.

●It makes up 5% of the Universe.
 
●It includes Earth, the sun, other stars, and galaxies.

● It is made of protons, neutrons, and electrons bundled together into atoms.

Einstein’s Prediction in the Theoryof General Relativity (GR)

● Motion in Space: 
Concentrations of mass and energy curve the structure of spacetime, affecting the motion of anything passing near, including light.

■He expected a beam of starlight should bend when passing through the sun’s gravity.

● Expansion of Universe: He provided the mathematical framework for describing the structure and evolution of the universe (once hotter and denser than it is today) from its beginnings 13.8 billion years ago and into the future.

■ Galaxies are moving away from each other.

■Also, he predicted that the universe is lumpy.

How does the new map confirm Einstein’s Prediction?

● Crisis in Cosmology: Previous maps indicated that the lumpiness of the universe was not as dense as Einstein’s theory 
had proposed, under the standard model of cosmology and led to concerns that the model may be broken.

■ These findings used a different background light, one emitted from stars in galaxies rather than the CMB. 

■However, the latest results from ACT were able to precisely assess that the lumpiness seen are as per Einstein’s 
theory.

● Standard Model of Cosmology (SMC): Findings proved that the expansion of the universe is as per the SMC. 

■It is also called the “Concordance Cosmological Model” or the “ΛCDM Model,”.

■It is based on the principle that the universe was created by the “Big Bang” from pure energy.

■ Also, it believes that Universe is composed of about 5% ordinary matter (visible), 27% dark matter, and 68% dark energy. 

● Presence of CMB shows that Universe started with a very dense and hot phase that expanded and cooled itself and later released CMB. Its movement depicts it is Universe is still expanding. 

■Also, its deflection by Massive object upheld that Gravity is not a force, but rather a distortion of time and space.

Conclusion

The latest finding with the help of the ACT has upheld the SMC and solved the crisis in cosmology up to a large extent. It will give new opportunities to astronomers and researchers for space-related research. Space agencies such as NASA, ISRO, etc. can use these findings for their space exploration programs.






























































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