The Speed of Our Universe Expansion Explained by Gravitational Waves


The universe is always expanding and astronomers have to try for years to estimate the Hubble constant. This is a unit of measurement that presents the rate at which the universe is expanding. Nonetheless, until now the values calculated were quite different.

Scientists were not able to measure exactly how fast the universe is expanding, but this might change. Discovering the rate at which the universe is expanding could offer plenty of answers about the origins of the universe and the future of cosmos.

Gravitational waves

A new way to measure the Hubble constant was discovered, and this time it might be more accurate than ever: gravitational waves. These are emitted by rare systems such as a black hole neutron star binary and the pairing of a black hole and  neutron star.

“Black hole-neutron star binaries are very complicated systems, which we know very little about. If we detect one, the prize is that they can potentially give a dramatic contribution to our understanding of the universe,” explained says Salvatore Vitale, assistant professor of physics at MIT and lead author of the paper.

NASA’s Hubble Space Telescope and the European Space Agency’s Planck satellite were used for two measurements of the Hubble constant. However, new methods are used for Hubble estimates. Scientists use LIGO, the Laser Interferometer Gravitational-Wave Observatory, which is used in order to detect gravitational waves.

“Gravitational waves provide a very direct and easy way of measuring the distances of their sources. What we detect with LIGO is a direct imprint of the distance to the source, without any extra analysis,” Vitale explained. Back in 2017 LIGO and Virgo, its Italian counterpart managed to detect a pair of colliding neutron stars for the first time. There were plenty of gravitational waves released by the collision.


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1 Comment

  1. I only did A level physics, but I don’t understand something about these measurements. Recently it was said that more distant parts of the universe seem to be expanding more slowly than closer parts. However, due to constraints on speed of light more distant places are viewed further back in the past. Thus, how can we seperate the time factor i.e. how do we know that more distant parts of the universe are expanding slower, and not just that the universe expanded slower in the past?

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