Astronomers have found the missing matter of the universe

For a long time it has been a mystery where half of the universe's ordinary matter exists. It is the type of matter that everything on earth is made up of, protons, neutrons and electrons. We also see it shining in all the stars and galaxies of the universe.

But according to astronomers' calculations, we have only seen half of all matter that should be out there.

- It has been very annoying that half were missing, says Matthew Hayes, astrophysicist at Stockholm University.

By observing the really young universe, which is more than ten billion light years away, astronomers have been able to observe nearly a hundred percent of the ordinary matter that calculations show should be. But when they have looked at the part of the universe that is closest to us, then half have been missing.

- If there is no process that destroys matter in the universe, it should be somewhere. We know that it is not in the galaxies so we have assumed it exists between the galaxies, he says.

Now an international research group has been able to detect this missing matter with the help of very remote radio flashes. Radio flashes are light from a newly discovered astronomical phenomenon that you do not yet know what it is.

For a very short period, they emit enormous amounts of energy. In recent years, astronomers have been able to locate the lightning's sources of galaxies a few billion light years away.

Astronomers have now taken advantage of this phenomenon to find the matter that the suspects were hiding among the galaxies.

The lightning of the radio flashes rush through space and when they hit the earth after a few billion years of travel, they carry with them information about the space they have traveled through, for example if the light has collided with particles in a thin gas.

In an article published in this week's Nature, astronomers have analyzed the light from four different radio flashes observed by the ASKAP telescope in Australia. Wavelength shifts in the light allow them to calculate how many particles have been in the path of the radio flash.

Other telescopes have measured the distance to the four radio flashes - and in this way astronomers have been able to calculate the density of the gas that propagates in the almost empty space between galaxies.

- The density corresponds to about one hydrogen atom per cubic meter, which is about the luggage space of a Volvo, says Matthew Hayes.

It is thus an extremely thin gas, but since space is so very large, it together still becomes very much, namely half of all ordinary matter that exists in the universe.