The underground stockpile of gold reserves on the planet is currently estimated at around 50,000 tonnes, according to the United States Geological Survey.
But, with each passing day, this reserve only diminishes – and, in the Middle Ages, the hard work of the alchemists has already shown that metal is impossible to be synthetically recreated.
However, there is a “place” where there is an enormous amount of gold: the Universe.
In fact, the quantity is so surprising that scientists they have also been trying to discover the origin of this material in the universe for years.
In fact, a study released this week indicates that the amount of gold outside the Earth is much greater than previously thought.
The publication, in the Astrophysical Journal, shows that the main means of gold formation in the Universe, the collisions of neutron stars, is not enough to explain the amount of the existing metal.
“Gold and other heavy metals are produced in processes involving a lot of energy in the Universe. However, according to current calculations, these processes alone are not enough to produce all the gold seen in the Universe today,” he explained to BBC News Mundo (service in BBC Spanish) to astronomer Chiaki Kobayashi, study leader and researcher at the University of Hertfordshire, UK.
Kobayashi says that her and her colleagues’ research seeks to trace the origins of this and other metals.
“It is not just about gold, which is part of many things in our lives. It is also about calcium, for example, which was also created from an explosion of stars”, he explains.
How gold is produced in the Universe
To form a single gold particle, it is necessary to form atomic nuclei composed of 79 protons and 118 neutrons each.
“This means that there needs to be a nuclear fusion beyond the capacity of the human being. And although it exists in the Universe, it is not very frequent and, mainly, not in close places.”
The collision of neutron stars – bodies that are remnants of ancient supernovae or large stars – have the ability to create these particles with more neutrons than protons.
As a result of collisions in the Universe, many meteorites containing gold ended up falling to Earth when the planet was in formation.
And that has been the most accepted explanation so far for the presence of gold in the Universe and on our planet. However, Kobayashi’s research indicates that there must be other sources of the metal.
“Another possibility could be when a supernova is extinguished. It is known that this extinction can create a large amount of gold for a short period of time, but even so, it is still insufficient,” explains Kobayashi.
“The study contains measurements and data from more than 340 scientific articles describing how chemical elements arise, so we were able to reach other important conclusions”, says the scientist.
It was possible to explain the formation of elements such as carbon 12 and uranium, among others.
“For example, our model was able to calculate the amount of strontium produced by a collision of neutron stars.”
The model created by Kobayashi’s team also tried to estimate the total amount of gold available.
“According to our model, the mass of gold produced in the Universe during its 13.8 billion years is 4.0 × 1042 kg, which is only between 10% and 20% of what is estimated from observations in meteorites , the Sun and other nearby stars. ”
And this, of course, is restricted by the very limitations of human knowledge about the Universe.
“It can be infinite – we don’t know for sure – but we know that we can only see part of the Universe,” he says.
And considering the future scarcity of gold on Earth, can research pave the way for extraterrestrial gold exploration?
“It is very difficult”, anticipates the specialist. “Because although our Sun, for example, has a significant amount of gold, the truth is that many of these collisions of stars that produce metal in space are far out of reach.”
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