Something strange is happening in the Universe: how to explain inconsistencies in the Hubble constant

Data collected by the Hubble Space Telescope over three decades has made it possible to obtain a new, more accurate

measurement of the expansion rate of the universe. But something strange is happening in the universe - the data does not agree with theoretical predictions.

Universe expansion

The search for the expansion rate of the universe was one of thethe main tasks of cosmology of the twentieth century. Indeed, without any observational data about the expansion, contraction or stillness of space, scientists would not have a clue whether the Universe is moving or not, and also the slightest idea of ​​\u200b\u200bits age. One of the scientists who made a huge contribution to this issue is Edwin Hubble.

One hundred years ago this American astronomerdiscovered many galaxies outside the Milky Way. And they didn't stand still. Hubble found that the farther away a galaxy is, the faster it is moving away from us. This can be interpreted as a uniform expansion of space. The astronomer even said that he studied galaxies simply as "markers of space." However, he was never fully convinced of the idea of ​​a uniformly expanding universe. The scientist suspected that his measurements could indicate that something even stranger was happening in space.

Hubble constant

After years of work, the Hubble constant appeared -coefficient, which is included in the law of the same name, which relates the distance to an extragalactic object with the speed of its removal. In simple terms, this constant sets the rate of expansion of the universe and provides a basis for estimating the size and age of the universe.

The value of the Hubble constant has been refined for many years.In 2015, the most accurate value was thought to be close to 70 km/s per megaparsec (1 Mpc is about 3 million light years). For example, if some galaxy is at a distance of 100 Mpc from us, then we can expect that it is moving away from our Galaxy at a speed of about 70⋅100 = 7300 km/s.

In general, this number is difficult to determine, becausedifferent observatories studying different regions of the universe gave different results. A new study and analysis of the Hubble data may have just got the right answer, according to a NASA press release.

New constant

In a new study, scientific collaborationThe Expansion Rate Study of the Universe (SHOES) analyzed 42 supernovae, about one of which exploded once a year. The results of scientists are almost twice the previous sample of cosmic distance markers. The researchers also reanalyzed all previous data. As a result, the new figures for the Hubble constant are based on a data set that includes more than 1,000 orbits of the space telescope of the same name.

When NASA conceived it in the 1970sconstruction, one of the main justifications for the expense and enormous work was the ability to observe Cepheids. These are stars that periodically become brighter and dim. Cepheids have long been the gold standard for measuring cosmic distances, ever since their usefulness was discovered by astronomer Henrietta Swan Leavitt in 1912. To calculate much larger distances, astronomers use Type Ia supernovae.

Together, these objects have built a "cosmic distance ladder" in the universe.

As a result, the Hubble constant, which was calculatedcommand was 73±1 km/s per 1 Mpc. This reduces the error to just 1.4%, which is much more accurate than other measurements. The improved data will help astronomers improve models of cosmology, including more accurate estimates of the age of the universe and its future.

Space inconsistency

The problem is that by combining the Standardcosmological model of the universe and measurements by the Planck mission of the European Space Agency (which observed the relic cosmic microwave background 13.8 billion years ago), astronomers predict a lower value of the Hubble constant: 67.5±0.5 km/s per megaparsec.

Astronomers explain this by saying that it is possiblethe Hubble constant is larger in our local universe, and smaller in its more distant places. It is noteworthy that the authors of the new work believe that both indicators are correct. It's just that there is still undiscovered physics that will help explain it.

At the same time, Nobel laureate Adam Riess,who leads the Science Collaboration on the Expansion Rate of the Universe (SHOES), he "doesn't care about the specific value, but likes to use it to study the universe."

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