The most unthinkable distances – and not a single surprise.
Gravity was once again tested for strength. But where it is especially difficult to expect surprises: not within the same galaxy and not inside a separate cluster, but at distances of hundreds of millions of light-years. And (this is a miracle!) The test ended in favor of classical physics.
A group led by scientists from the University of Pennsylvania used data from the Atacama Cosmos Telescope and traced how galaxy clusters are moving at great distances. The researchers wanted to understand whether there were deviations in gravity that could explain the old cosmological problem without involving dark matter.
The problem has been known for a long time. Stars on the outskirts of galaxies rotate faster than the mass of visible matter allows. At the level of clusters, the picture is similar: galaxies inside them also move as if there is an additional mass in the system. Because of this, cosmology has been holding between two explanations for many years. Either gravity at very large distances works differently, or there is an invisible substance in the universe that cannot yet be detected directly.
To test the first version, scientists used relic radiation, that is, a weak background that has survived since the early universe. When such a signal passes through a massive galaxy cluster, the hot gas within the structure changes its properties slightly. According to these weak distortions, it is possible to restore the movement of the clusters themselves and assess how quickly they approach under the influence of mutual attraction.
It was this approach that made it possible to measure the behavior of gravity on a scale of hundreds of millions of light-years. The resulting values coincided with the calculations of standard physics. There are no indications that the force of gravity decreases under another law, the researchers found. For cosmology, this is an important result. The law of inverse squares, formulated in the 17 century, argues that the force of attraction decreases in proportion to the square of the distance. If the distance is doubled, the effect drops by 4 times.
The conclusion of the study hits theories that are trying to neutralize dark matter by revising the gravity itself. Among them is a modified Newtonian dynamics, where the behavior of gravitation at long distances is described differently. At the same time, a more familiar explanation is increasing. If gravity on a large scale behaves normally, then the discrepancy between the observed motion and the visible mass still indicates the hidden component of the substance. Dark matter from this does not become clearer in composition, but the hypothesis itself receives an additional support.
Gravity was once again tested for strength. But where it is especially difficult to expect surprises: not within the same galaxy and not inside a separate cluster, but at distances of hundreds of millions of light-years. And (this is a miracle!) The test ended in favor of classical physics.
A group led by scientists from the University of Pennsylvania used data from the Atacama Cosmos Telescope and traced how galaxy clusters are moving at great distances. The researchers wanted to understand whether there were deviations in gravity that could explain the old cosmological problem without involving dark matter.
The problem has been known for a long time. Stars on the outskirts of galaxies rotate faster than the mass of visible matter allows. At the level of clusters, the picture is similar: galaxies inside them also move as if there is an additional mass in the system. Because of this, cosmology has been holding between two explanations for many years. Either gravity at very large distances works differently, or there is an invisible substance in the universe that cannot yet be detected directly.
To test the first version, scientists used relic radiation, that is, a weak background that has survived since the early universe. When such a signal passes through a massive galaxy cluster, the hot gas within the structure changes its properties slightly. According to these weak distortions, it is possible to restore the movement of the clusters themselves and assess how quickly they approach under the influence of mutual attraction.
It was this approach that made it possible to measure the behavior of gravity on a scale of hundreds of millions of light-years. The resulting values coincided with the calculations of standard physics. There are no indications that the force of gravity decreases under another law, the researchers found. For cosmology, this is an important result. The law of inverse squares, formulated in the 17 century, argues that the force of attraction decreases in proportion to the square of the distance. If the distance is doubled, the effect drops by 4 times.
The conclusion of the study hits theories that are trying to neutralize dark matter by revising the gravity itself. Among them is a modified Newtonian dynamics, where the behavior of gravitation at long distances is described differently. At the same time, a more familiar explanation is increasing. If gravity on a large scale behaves normally, then the discrepancy between the observed motion and the visible mass still indicates the hidden component of the substance. Dark matter from this does not become clearer in composition, but the hypothesis itself receives an additional support.
