People could not have appeared without gravitational waves: what the new theory says

 For the emergence of life, only a few chemical elements are needed, but for the emergence of humans, something more is needed, scientists say.

The authors of a new study published on the arXiv preprint server argue that without cosmic phenomena such as gravitational waves, people could not have appeared on Earth, writes IFLScience.

Chemical elements necessary for the emergence of life

For the simplest life to arise, only a few chemical elements are needed: hydrogen, carbon, nitrogen, oxygen, phosphorus and sulfur. Hydrogen was created as a result of the Big Bang. Carbon, nitrogen and oxygen appeared as a result of thermonuclear fusion in the cores of ordinary stars. Phosphorus, like many other chemical elements, arises as a result of supernova explosions, which also create sulfur. These same explosions disperse chemical elements throughout space.

All mammals on Earth need at least 20 chemical elements, but the authors of a new theory suggest that creating two of them requires more than just a supernova explosion. Instead, they arise from the r-process, which occurs during kilonova explosions when two neutron stars merge.

Neutron star collision

Neutron star mergers are a product of gravitational waves. The likelihood that two objects as small as neutron stars will collide with each other in the vastness of the Universe is very small. Neutron stars arise from supernova explosions, when stars have too little mass to turn into black holes at the end of their lives. But neutron stars often exist in pairs and circle each other.

The powerful acceleration caused by the gravitational interaction of two dense objects creates gravitational waves that carry away energy. This energy comes from the motion of two neutron stars that merge over time, then a kilonova explosion occurs and chemical elements are created through the r-process.

Without gravitational waves there would be no people

Without gravitational waves, kilonovae would appear much less often or would not appear at all, which means that elements of the r-process would appear less often or would not appear at all, scientists believe. Since the elements of the r-process include iodine and bromine, both of which are essential for humans, without gravitational waves there would be no humans.

Obviously, if there had been a deficiency of iodine and bromine on Earth, the evolutionary path of man would have been different, that is, people could have appeared, but they would have been completely different. Humans depend on iodine supplied to the thyroid gland to regulate metabolism, as well as bromine for tissue development. However, given millions of years, it is possible that animals could evolve to perform similar roles using other elements.

A theory that is difficult to test

Such a scenario cannot be proven or disproved unless planets are discovered where there are no elements of the r-process. But we still need to find planets where developed intelligent life exists.

On the other hand, iodine and bromine are not the only r-process elements that humans need. Scientists note that molybdenum is used by both animals and plants to transport oxygen atoms, and that thorium and uranium are likely responsible for plate tectonics, perhaps one of the most important characteristics of the Earth.

The study authors acknowledge that there are still many things that need to be tested. Moreover, a small portion of the iodine on Earth comes from the s-process, which does not require gravitational waves. And this amount might have been enough to support the evolution of mammals.