DARK MATTER

Dark Matter:

• What is it? Dark matter is a hypothetical invisible mass thought to be responsible for adding gravity to galaxies and other bodies.
  
  
• How much is dark matter?
  • According to NASA, Dark matter seems to outweigh visible matter roughly six to one, making up about 27% of the universe.
    
    
  • Roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest visible matter is 5% of the universe.
    
    
  
  
  
• Why called dark matter? It is called so because unlike normal matter (i.e. stars and galaxies), dark matter does not interact with the electromagnetic force.
  
  
• Detection: As it does not interact with the electromagnetic force, thus it does not absorb, reflect or emit light or electromagnetic radiation of any kind. And this makes it extremely hard to spot/detect. It can be detected only through its gravitational effects.
  
  
• Importance: Its gravitational force prevents stars in our Milky Way from flying apart.
  
  

Summary of the recent study published in the journal Nature Astronomy:

• Attempts to detect dark matter particles using underground experiments or Large Hadron Collider have failed so far.
  
  
• This has led scientists to consider Hawking's 1974 theory of the existence of primordial black holes, born shortly after the Big Bang, and his speculation that they could make up a large fraction of the elusive dark matter scientists are trying to discover.
  
  
• Researchers used the gravitational lensing effect to look for primordial black holes between Earth and the Andromeda galaxy.
  
  
• The team's results showed primordial black holes can contribute no more than 0.1 per cent of all dark matter mass. Therefore, it is unlikely the theory is true.