Overview

All the inventions and infrastructure that characterize our modern life and enable the functioning and development of our civilization hang in balance. We rarely think about how vulnerable we are to the hostility of the universe, but we must be on the lookout for events that could trigger global chaos. That’s why a group of doctoral students from the University of Queensland in Australia has analyzed ancient tree samples showing high radiation exposure, seeking to understand the causes of these periods to better prepare our modern civilization for the next one.

The science and other stuff to know

The team of experts led by Dr. Benjamin Pope analyzed ancient tree samples to measure the amount of carbon-14, an element characteristic of radiation bursts, according to the study published in the journal Proceedings of the Royal Society A. This compound adheres to plants, rocks, and other materials, allowing tree rings to tell atmospheric history by reading the marks left by past events between their fibers. The researchers discovered a record of a Miyake Event, which occurs approximately once every millennium and whose origin is unknown.

Miyake-type events are huge bursts of cosmic radiation, but experts still disagree on the radiation sources that produce them. It has been proposed that the previously recorded events of this type (so far, there are six) were due to supernovae outbursts, neutron star collisions, or some other high-energy astrophysical phenomenon. But still, there is no evidence to support these proposals. The main hypothesis that attempts to make sense of these events is that of solar storms.

The sun has an 11-year cycle where the incandescent plasma layers of its outermost layers move and mix. Magnetic dynamics cause surface loops of coronal mass to be generated that grow considerably and, when cut, end up ejecting huge amounts of matter and radiation. This phenomenon is known as a solar storm, and in 1859 one of them, the Carrington storm, caused chaos and unleashed the largest collapse of communications infrastructure recorded to date.

Pope and his colleagues say that there is little chance that all these Miyake bursts are related to solar activity since the concentration of carbon-14 showed that the radioactive phenomenon was persistent for considerably longer than solar storms.

So what?

The urgency of researchers to find the phenomenon that is producing these intense bursts of cosmic radiation has to do with the fact that an event of this type has an unimaginable destructive potential for our modern civilization. Storm Carrington destroyed the precarious telegraphy system that existed in Victorian times and could destroy all telecommunications networks today. But we are well aware of events of this type since we quite understand the solar phenomena that can cause a Carrington-type event, so solar physicists can predict storms and coronal ejections well in advance to keep us safe.

Miyake-type events can be a hundred times more radioactive than solar storms, and as of today, we have no mechanism to predict them. One could come at any moment and whip us mercilessly.

What’s next?

“Based on available data, there is about a one percent chance of seeing another one in the next decade. But we don’t know how to predict it or what damage it can cause. These odds are quite alarming and lay the groundwork for future research,” Pope said in an official statement from the University of Queensland.

Andrew Smith is a physicist who was not involved in the study but is working on looking for signs of radiation in blocks of ancient ice. He told ABC that although he is not surprised by the poor correlation between solar storms and the Miyake events, it cannot be ruled out that this is the main cause of it.