Of the four forces known to contemporary physics, only one has not yet integrated with the Standard Model, which describes how subatomic particles behave, but an experiment carried out by researchers at the University of Vienna, Austria, can help in the search for a unified principle. The scientists leading the study detected the smallest gravitational field ever recorded, which could extend the presence of the property beyond the Theory of Relativity.
It is known how strong and weak interactions and electromagnetic forces, for example, act on matter even on tiny scales. However, affirming this in relation to gravity is a little more difficult, since it tends to “come undone” in the almost invisible world, preventing the full comprehension of singularities in the centers of black holes, for example. So, with discovery, provided by two gold spheres measuring 2 millimeters in diameter, illuminating clues may be on the way.
“This was just a proof of concept analysis for creating a sensor capable of measuring very small accelerations and establishing methods that would allow us to detect even smaller gravitational forces”, explains co-author Jeremias Pfaff to Live Science. “In the long run, we would like to answer what the gravitational field of a quantum object looks like in a superposition, but there is much to be done along the way.”
Technologies that have long been present in laboratories have made it possible for the approach to work. After all, the torsion balance, essential to the results of the research, was created in 1798 by the English scientist Henry Cavendish, who sought to measure the density of the Earth and, from it, the gravitational constant.
As expected, this time, a minuscule version of the device came into play, because the strength the team was looking for was equivalent to that experienced by a third of a human blood cell on our planet.
The device consists of a horizontal bar suspended in its center by a wire with two masses attached, one at each end. If a small force is applied along the horizontal axis of the bar, the wire will twist and scientists can measure it based on how far the bar has rotated.
In this case, the gold spheres participated in the experiment, together with the addition of a third one in close proximity. Soon, the researchers were able to measure the force of gravity between the invader and the attached spheres – making sure that nothing hindered the progress of the process.
“The urban environment is also far from ideal,” said Pfaff, after indicating that the force under analysis was 9 × 10 ^ minus 14 N. “It was impressive to see that we are not only sensitive to small earthquakes, but also to the local tram and to individual buses. We were even able to see the Vienna city marathon in our data “, joked the scientist.
To circumvent such obstacles, the researchers responsible flooded the area around the device with ionized nitrogen before placing it in a vacuum and highlighted the tiny signal moving the two spheres attached to the torsion balance very, very slowly, since it would be much easy to find anything compared to a stationary configuration.
The result? In addition to detecting the intensity of the objects’ strength and their own measurement for the gravitational constant, they noticed that gravity followed the same rules perceived on larger scales. The knowledge accumulated for centuries, then, is out of danger.
Gaps in images of the Universe, it is hoped, will gradually be filled with the evolution of the method. Among Jeremias and his team’s plans is to make the experiment even more sensitive so that they can capture smaller mass signals at least a thousand times lighter and over shorter distances.
According to them, such an achievement would bring advances to the creation of a theory that applies to what is known and to what remains, for the most part, mysterious, such as the existence of dark matter.
“Expanding our knowledge of this elusive force can help us gather tips to find a more fundamental understanding of our physical reality,” concludes Pfaff, excited by what gravity still has to reveal.