Why are natural constants constant

The relationship between proton and electron mass has not changed in the past six billion years.

Quasar B0218 + 367

Bonn - How constant are the physical constants of nature? Many researchers consider it possible that the supposed constants change in the course of cosmic development. However, an international team of astronomers has now succeeded in showing that the relationship between the mass of a proton and the mass of an electron has not changed in the past six billion years. In a distant galaxy it is 1836.15 to 1, just as it is today on Earth, the scientists report in the journal "Science"

"By comparing the radiation absorption by ammonia molecules with that of other molecules, it was possible for us to derive the exact value of the proton-electron mass ratio in a distant galaxy and to confirm that it corresponds to the value valid on earth", says Christian Henkel from the Max Planck Institute for Radio Astronomy in Bonn. Henkel and his colleagues from Australia and Taiwan used the 100-meter radio telescope in Effelsberg to study the radiation from quasar B0218 + 367, which is around 7.5 billion light years away. Quasars are extremely luminous nuclei of distant galaxies.

On its way to us, the light from the quasar crosses another galaxy around six billion light years away. The gas in this galaxy absorbs part of the quasar radiation. The absorption by ammonia is of particular interest to astronomers, since ammonia molecules are excellently suited to determining nuclear physical quantities - as in this case the mass ratio of electron and proton.

The measurements by Henkel and his colleagues show that the mass ratio of the two particles in the absorbing galaxy is the same as on Earth. This also means that this value was just as great six billion years ago as it is today. Because a look into the depths of the universe is also a look into the cosmic past. Since the galaxy is six billion light years away from us, the radiation received on Earth today passed through the galaxy six billion years ago. Henkel and his team now want to further check the constancy of the natural constants by measuring the molecular absorption in as many galaxies as possible.