They say the universe is constantly expanding. However, no one has yet figured out how quickly this happens. At least it was not unanimous and therefore, it remains a big puzzle. In fact, such controversy arose due to the different discovery of the Hubble constant explaining this expansion. However, scientists have now found such clues that can answer this question. When black holes or neutron stars collide in the universe, gravity waves emanating from them can be observed. Common telescopes can’t see it, but detectors can detect them.
What is the Hubble constant?
Based on such an observation, scientists hoped that the expansion of the universe will also be understood. Indeed, as the universe expands, galaxies move away from Earth. The speed at which they move away from the earth depends on the distance between them and the earth. The relationship between these is called the Hubble constant. It was first calculated by the American astronomer Edwin Hubble in 1920 and this is why it bears his name. Many researchers have accurately measured the Hubble constant based on the twinkling of the Cepheid stars, but in a different way, the second value is derived based on the microwave cosmic background produced 3.8 million years ago. after the Big Bang. For this reason, there is no consensus among scientists.
Waves emanating from the collision
Pennsylvania State University physicist Sohrab Bourhanian told Live Science, “Gravitational waves give a different approach to the Hubble constant.” When massive black holes or neutron stars collide, gravitational waves are emitted. Since 2015, the US Laser Interferometer Gravitational Wave Observatory (LIGO) and its European partner Virgo have been trying to detect such signals. Scientists calculate from their sound where the collision must have taken place. Many times the light emanating from them is visible by telescopes, which can be used to detect how fast they are going.
How will the dark siren respond?
Physicists calculated the value of the Hubble constant when in 2017, the signal was detected by LIGO when two neutron stars first collided. However, the scope of the error is something that is similar to the brightness of stars and the results of the CMB. It is believed that after at least 50 more such incidents, the exact Hubble constant will be found. This can be done quickly with the help of Dark Siren. In fact, they are not associated with the brightness of light. It is believed that with the upgrade of LIGO’s detector in the next five years, more information about these waves will be collected. Sohrab states that the Hubble constant can be calculated accurately using a signal instead of 50 which is produced by collisions in objects of large, fast and variable mass.