New observations confirm that the universe is expanding rapidly; faster than the initial phase.
Scientists have known about the expansion of the universe for a long time, but they have yet to decipher what physical processes are responsible for it.
The latest observations show that the current rate of expansion of the universe is 9% higher than expected. This forces us to develop new cosmological models. It is also important to note that the typical error for calculations of this type is 1 to 2%.
The rate of cosmic expansion as a function of time is described by the Hubble constant. The unit of expansion is considered to be the number of kilometers by which a distance of 1 megaparsec (astronomical unit of length) extends in 1 second. Constant value
Hubble is difficult to determine because it is the result of an accurate determination of the distances of galaxies; It is also a consequence of the fact that galaxies have their own speeds (in addition to those caused by the expanding universe) – this leads to local deviations from Hubble’s law.
Studies show that measurements of the Hubble constant based on observations of background microwave radiation contrast with results obtained by studying young stars (in the Milky Way, for example). These observations also take into account the effect of dark energy which would accelerate the expansion of the universe.
“The rate of expansion of the universe has exceeded our expectations and it’s very difficult to explain,” said Adam Riess of Johns Hopkins University, lead author of the study.
Riess’s team took measurements of the Large Magellanic Cloud and found that the bias in the estimate of the Hubble constant is larger than was recently assumed.
According to scientists, the value of the Hubble constant is 74.03 +/- 1.42 km / s. This value does not correspond to the measurements obtained by the Planck satellite (the value obtained by the satellite is 67.4 +/- 0.5 km / s). The difference between these measurements is approximately 4.4 sigma.
Determining the value of the Hubble constant based on stellar motion requires information about the distance from the observer to the given star and the speed at which the star is moving away.
To obtain this information, scientists are looking for line-spectral shifts in the light emitted by the star. The new studies are based on observations of Cepheids (variable stars) whose luminosity varies regularly.
Riess’s team observed 70 Cepheids in the Large Magellanic Cloud, which allowed them to take measurements with greater precision than before.
If the universe is expanding at a faster rate than we previously thought, there must be some physical phenomenon causing it. Perhaps this phenomenon has something to do with the mysterious properties of dark matter and dark energy.