In recent weeks, several groups of scientists have published studies testing some of Albert Einstein's famous theories, finding that they work in previously untested situations.
Now, an international team of researchers, led by Janet Conrad from MIT, has shown that the great German physicist's theory of special relativity applies even to tiny, high-energy subatomic particles known as neutrinos.
The scientists wanted to a test a fundamental principle of special relativity known as Lorentz symmetry—which states that the laws of physics stay the same for all observers no matter which direction they are facing or how fast they're moving.
In some extreme cases, however, it has been hypothesized that certain objects may not adhere to the same rules of physics, leading to a violation of Lorentz symmetry—or Lorentz violation—in which a mysterious, unknown field warps the behavior of objects in a manner Einstein did not predict.
Physicists have been hunting for evidence of Lorentz violations in various phenomena, ranging from photons (particles of light) to gravity, with no definitive success. But the most promising avenue of investigation may be to look for Lorentz violations in the behavior of neutrinos.
These elusive, charge-less forms of matter are the lightest known particles in the universe, capable of traveling over vast distances and passing straight through enormous solid objects like planets. They are produced by extremely high-energy astrophysical phenomena, such as nuclear reactions inside stars.
For their new research, the scientists analyzed two years of data captured by the vast IceCube Neutrino Observatory, buried under the Antarctic ice, to search for instances of neutrinos behaving differently to how special relativity predicts.
The results, which have been published in the journal Nature Physics, threw up no such abnormalities, ruling out the possibility, for now, of Lorentz violation in high-energy neutrinos and suggesting that special relativity can sufficiently describe their behavior. This is all the more remarkable given that neutrinos had not even been discovered when Einstein died.
"People love tests of Einstein's theory," Conrad, from MIT's Department of Physics, said in a statement. "I can't tell if people are cheering for him to be right or wrong, but he wins in this one, and that's kind of great. To be able to come up with as versatile a theory as he has done is an incredible thing."
The new study is just the latest in a series of publications proving Einstein right.
In a paper published earlier this month, scientists demonstrated that Einstein's general theory of relativity (GR) works even in extreme gravitational environments. Meanwhile, another study published in June confirmed that GR can accurately describe the behavior of gravity in distant galaxies.
Finally, new findings from researchers at the Department of Energy's Oak Ridge National Laboratory have supported a theory first proposed by Albert Einstein in 1911 that explains how heat moves through solids.
