Context

Around 95 percent of the Universe is unknown to human beings. It is often referred to as dark which has nothing to do with the colour of any substance but to do with the unknown nature of cosmic entities known as dark matter and dark energy.

In news

• Scientists from the University of Sussex have found a new way to know more about dark matter.
• They have narrowed down the range of masses within which particles that could make up dark matter may lie in.

Finding

• The range they have established — 10^-3 electron-volts to 10^7 electron-volts — is far smaller than the earlier known range of 10^-24 electron-volt to 10^19 giga electron-volt.
• This is the first time anyone has thought of using what we know about quantum gravity to calculate the mass range for dark matter
• Scientists estimate that roughly 68 per cent of the Universe is made up of dark energy which is responsible for the accelerated expansion of the Universe.
• Another 27 per cent is dark matter whose existence was inferred from the observation that ordinary matter in galaxies, including the Milky Way, is far less than that required by gravity to hold the galaxies together.
• Dark matter’s gravitational effects are also necessary to explain the motions of clusters of galaxies and the structure of the entire Universe at the largest scale.
• On smaller scales, dark matter is too diffused to impact the motion of the Solar System, Earth or the origin and evolution of humans in any significant way.