In simpler terms, they carry the gravitational force, much like how photons carry the electromagnetic force. When you toss something upward, and it gracefully descends due to gravity, it's essentially the gravitons at work.
Like photons, gravitons are expected to be massless and electrically uncharged. Gravitons too travel at the speed of light, zipping through the fabric of spacetime. Their existence is rooted in the quest for a unified theory that combines quantum mechanics and gravity.
Gravitons are the focus of the search for the "theory of everything", which would unify Einstein's General Relativity (GR) theory of gravity with quantum theory
Gravitons remain elusive and unobserved and continue to intrigue scientists as we seek to unravel the mysteries of gravity and the cosmos.
In a latest however, scientists have glimpsed into graviton-like particles and these particles of gravity have shown their existence in a semiconductor.
An international research team led by Chinese scientists has, for the first time, presented experimental evidence of a graviton-like particle called chiral graviton modes (CGMs), with the findings published in the scientific journal Nature on Thursday.
By putting a thin layer of semiconductor under extreme conditions and exciting its electrons to move in concert, researchers from eastern China’s Nanjing University, the United States and Germany found the electrons to spin in a way that is only expected to exist in gravitons.
Despite the breakthrough, Loren Pfeiffer at Princeton University, who wrote the paper of this findings, said "This is a needle in a haystack [finding]. And the paper that started this whole thing is from way back in 1993." He wrote that paper with several colleagues including Aron Pinczuk, who passed away in 2022 before they could find hints of the gravitons.
The discovery of chiral graviton modes (CGMs) and their shared characteristics with gravitons, a still-undiscovered particle predicted to play a critical role in gravity, could potentially connect two subfields of physics: high-energy physics, which operates across the largest scales of the universe, and condensed matter physics, which studies materials and the atomic and electronic interactions that give them their unique properties.
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| Scientists in China, the US and Germany used polarised laser light to measure graviton-like excitation and spin in a quantum material. (Image - SCMP.org) |
The ability to study graviton-like particles in the lab could help fill critical gaps between quantum mechanics and Einstein’s theories of relativity, solving a major dilemma in physics and expanding our understanding of the universe.
The term "graviton" was coined in 1934 by Soviet physicists Dmitrii Blokhintsev and F. M. Gal'perin. Paul Dirac later reintroduced the term, envisioning that the energy of the gravitational field should come in discrete quanta—these quanta he playfully dubbed "gravitons."
Just as Newton anticipated photons, Laplace also foresaw "gravitons," albeit with a greater speed than light and no connection to quantum mechanics or special relativity.
The term "graviton" was coined in 1934 by Soviet physicists Dmitrii Blokhintsev and F. M. Gal'perin. Paul Dirac later reintroduced the term, envisioning that the energy of the gravitational field should come in discrete quanta—these quanta he playfully dubbed "gravitons."
Just as Newton anticipated photons, Laplace also foresaw "gravitons," albeit with a greater speed than light and no connection to quantum mechanics or special relativity.
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