A team of international researchers has found that primordial black holes, formed in the early stages of the universe, are not the primary source of dark matter as previously suggested. This theory was originally introduced by world-renowned physicist Professor Stephen Hawking.
Understanding Dark Matter
Dark matter is believed to be a significant component of our universe, despite the fact that it has never been directly detected. Observable celestial phenomena suggest that the universe must contain far more matter than what we can actually see. It’s estimated that dark matter constitutes over 95% of the entire universe. The gravitational force of dark matter keeps stars in our galaxy, the Milky Way, from scattering into space. Unfortunately, attempts to detect dark matter particles through underground experiments or accelerator experiments, including the world’s largest accelerator, the Large Hadron Collider (LHC), have so far been unsuccessful.
Implications of Dark Matter Presence in the Universe
The presence of dark matter has implications on several aspects of our solar system and beyond. For instance, Mercury, the planet closest to the Sun, completes one revolution around the sun in just 88 days, while Neptune, the furthest planet, takes 165 years for one orbit.
According to the laws of gravity, we would expect stars closer to the center of galaxies to rotate faster than the stars on the edge. Yet, in most galaxies, the stars near the center and those at the outskirts take nearly the same time to complete one revolution. This suggests that an invisible entity, termed as ‘Dark Matter’, is providing additional momentum to the outer stars, accelerating their movements. This mystery has remained unsolved in cosmology since the 1930s.
Nature of Dark Matter
Dark Matter is considered a type of matter because it exhibits gravitational attraction. It is referred to as ‘dark’ due to its apparent lack of interaction with light or any other part of the electromagnetic spectrum.
Introduction to Black Holes
Black holes are regions in space characterized by extreme gravitational fields that prevent the escape of matter or radiation.
Understanding Primordial Black Holes
Following the introduction of the Big Bang theory, Soviet physicists Yakov Borisovich Zel’dovich and Igor Dmitriyevich Novikov proposed that numerous points would have incredibly high densities at the initial instant of the big bang, leading to the formation of small-scale black holes. These entities were termed as ‘primordial black holes’. Professor Stephen Hawking researched these in 1971 and calculated that their mass could range from one-hundredth of a milligram to greater than a thousand suns.
| Facts about Primordial Black Holes | |
|---|---|
| Proposed by | Yakov Borisovich Zel’dovich and Igor Dmitriyevich Novikov |
| Researched by | Stephen Hawking |
| Possible Mass Range | From one-hundredth of a milligram to the mass of over a thousand suns |
Gravitational Lensing
Gravitational lensing is a phenomenon where a black hole aligns with a distant star such that the black hole’s intense gravitational pull bends light rays inwards, similar to a lens. This makes the star appear brighter. The rare occurrence of gravitational lensing only happens when the star, the black hole, and an observer on Earth align perfectly in a straight line. This was first proposed as part of Albert Einstein’s General Theory of Relativity.
