Physicists measure the loss of dark matter since the birth of the universe

MOSCOW: Scientists have for the first time found that about five per cent of the elusive dark matter in the universe has been lost since the Big Bang.

“The discrepancy between the cosmological parameters in the modern Universe and the Universe shortly after the Big Bang can be explained by the fact that the proportion of dark matter has decreased,” said Igor Tkachev, from the Institute for Nuclear Research (INR) of the Russian Academy of Sciences.

“We have now, for the first time, been able to calculate how much dark matter could have been lost and what the corresponding size of the unstable component would be,” said Tkachev.

Astronomers first suspected that there was a large proportion of “hidden mass” in the universe back in the 1930s, when they discovered “peculiarities” in a cluster of galaxies which moved as if they were under the effect of gravity from an unseen source.

According to data from the European Space Agency (ESA)’S Planck space telescope, the proportion of dark matter in the universe is 26.8 per cent, the rest is “ordinary” matter (4.9 per cent) and dark energy (68.3 per cent).

The properties of dark matter could potentially help scientists solve the problem that arose after studying observa- tions from the Planck telescope. This device accurately measured the fluctuations in the temperature of the cosmic microwave background radiation - the “echo” of the Big Bang.

By measuring these fluctuations, researchers were able to calculate key cosmological parameters using observations of the universe in the recombination era - about 300,000 years after the Big Bang.