The scientist explained the superluminal expansion of the universe
The expansion of space can increase the distance between sufficiently distant galaxies faster than the speed of light, but this does not violate the theory of relativity: the limit set by Einstein refers to the local movement of objects and the transmission of signals through space. This was reported on July 25 in the journal Science Daily.
Observing a distant galaxy does not allow us to determine its current position directly. Telescopes detect light that could have traveled to Earth billions of years ago. During his journey, the universe continued to expand, so the distance to the galaxy increased.
The age of the universe is estimated at about 13.8 billion years, but the radius of its observable part is about 46 billion light-years. There is no contradiction in these figures: as the light moved towards the observer, the space itself between the source and the Earth expanded.
The speed of light limit applies locally. A spacecraft or a particle cannot fly past an observer faster than light, but the general theory of relativity does not prohibit space from expanding so that the distance between distant objects grows at faster-than-light speeds. At the same time, the galaxies themselves do not necessarily move through the surrounding space faster than light.
One of the signs of expansion is the cosmological redshift. As light moves through the expanding universe, its wavelength increases, shifting to the red and infrared parts of the spectrum. The farther away the galaxy is, the more pronounced this effect is, as a rule.
Astronomers can also observe some galaxies that are now moving away at a speed higher than light. Their light, visible today, was emitted in the past when the sources were much closer. Therefore, the Hubble sphere, at the boundary of which the rate of removal is compared with the speed of light, is not the limit of the observable Universe.
At the same time, there is an event horizon in the standard cosmological model. The light emitted by sufficiently distant objects today will never reach Earth if the accelerated expansion continues. As the waves stretch, the radiation from such galaxies will become fainter and shift into ranges inaccessible to observations.
After about 100 billion years, while maintaining the current dynamics of expansion, observers in the Local Group will be able to stop seeing almost all the galaxies beyond its borders. The universe will seem much smaller to them, although objects that have disappeared from view will continue to exist.
Phys.org On July 6, he reported the discovery of a new type of flare in black holes. Scientists have studied the galaxy SDSS J110546.07+145202.4 and found out that the radiation source is located near its central black hole. According to the study, in the case of this particular object, the radio signal not only showed no signs of weakening for several years, but also increased by more than 20 times.
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