What happens inside black holes? How did the Big Bang begin? How do all forces unite to form the cosmos? No big deal, they’re just the biggest questions humanity has about the Universe. But a new discovery could bring scientists closer to the answers than ever.
That’s because scientists have finally cracked how to measure gravity in the quantum world. Using a new technique, a team from the UK, Netherlands, and Italy detected weak gravitational pull on a tiny particle. So tiny, in fact, that it is the smallest mass at which gravitational signals have ever been recorded.
The technique involved levitating the particle, weighing just 0.43mg, in extremely cold temperatures (about -273°C). Using levitating magnets and superconducting devices (known as ‘traps’), they then isolated the vibration of the particle.
This helped them measure a weak pull – coming in at just 30 aN. One attoNewton (aN) is one quintillionth (1/1,000,000,000,000,000,000) of a Newton (N). The gravitational force of an apple sitting on a table is roughly 1N – making the pull that the scientists measured even smaller than the pull of a single bacteria on a table’s surface.
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Until now, scientists have not understood how gravity works at the microscopic level. But particles and forces at this scale interact differently from regular-sized objects. Even Einstein was baffled by this: in his theory of General Relativity, he said that there was no realistic experiment which could reveal gravity in the quantum world.
In fact, according to the study’s lead author Tim Fuchs, research fellow at the University of Southampton, for a century scientists have “tried and failed to understand how gravity and quantum mechanics work together”.
Until now, that is. The discovery, published in journal Science Advances, makes scientists closer than ever to figuring out how forces at this scale work and making a so-called 'theory of everything' possible.
It is likely that the team’s method will now pave the way forward in measuring quantum gravity. In the future, researchers can continue scaling the method down to measure even smaller particles – bringing science even closer to unravelling the mysterious forces that govern the Universe.
“We are pushing the boundaries of science that could lead to new discoveries about gravity and the quantum world,” said study author Prof Hendrik Ulbricht.
“Unravelling these mysteries will help us unlock more secrets about the universe's very fabric, from the tiniest particles to the grandest cosmic structures.”
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