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Scientists working on the Tibetan Plateau have detected the most powerful cosmic ray ever observed. Photo: Handout

Brightest cosmic light detected on Tibetan Plateau may help rewrite laws of physics

  • Lhaaso cosmic ray detector detects more than a dozen sources of ‘oh-my-God’ particles
  • Detection of the photons, from a constellation in the Milky Way, could help dispel scepticism over their still unexplained existence
A cosmic ray research facility on the Tibetan Plateau has detected the brightest yet of a type of light particle so strong that no law of physics can explain it.

The light particle – or photon – carried an unprecedented amount of energy, at 1.4 peta-electron volts (PeV) – 700 trillion times stronger than can be seen by the human eye, according to a paper by Chinese physicists published in the journal Nature on Monday.

The photon was emitted by an even more powerful particle, with 10 times as much energy, from a “hell-like” constellation in the Milky Way, about 1,470 light years from Earth.

Cosmic ray particles with 1 PeV or more energy are also known as oh-my-God particles, not only because they carry an incredible amount of energy but because, according to the theory of physics, they should not exist at all.


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Chinese archaeologists find sutras dating back to 618 during Tubo period in Tibet

Cao Zhen, lead scientist of the study by China’s Institute of High Energy Physics, said the experiment had discovered in less than a year a dozen cosmic ray accelerators, or pevatrons, that were steadily throwing out these impossible particles.

Pevatrons are the largest particle accelerators in the universe, but according to the new study, they “are everywhere in our own galaxy”, Cao said at a press conference in Beijing on Monday.

The discovery puts China in prime position in the race to solve the mystery of cosmic rays.

More than a century ago, scientists discovered that our planet was hit constantly by high-energy particles. Later dubbed cosmic rays, they carried a significant portion of the energy permeating in the universe, and were linked to a long list of fundamental scientific issues, including the emergence of life.

But where cosmic rays come from remains a mystery. The course of these electrically charged particles could be affected by other forces, such as the magnetic field of stars or planets. Astronomers have come up with many theories to explain their origin, such as supernova explosion, but evidence from astronomical observation has been weak.


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Subtropical forests may have been on Tibetan Plateau 47 million years ago, Chinese scientists say

Scientists agree on one thing: calculations based on Einstein‘s theory and present knowledge of the universe suggest the energy of a cosmic ray particle could not exceed 1 PeV. In other words, the oh-my-God particles should not exist.

The Chinese experiment, which discovered more than a dozen photons, could help dispel scepticism over oh-my-God particles’ existence.

In the past decade, China has invested considerably in cosmic ray research and built up some of the world’s most advanced facilities, including a radio telescope 500 metres (1,640 feet) wide and a particle detector based deeper underground than any other.

In a few years’ time, a telescope 200 times more powerful than Nasa’s Hubble is expected to be in orbit working with China’s space station.

The Large High Altitude Air Shower Observatory (Lhaaso) used in Cao’s experiment last year is the world’s largest cosmic ray detector. Its sensors cover 1.3 sq km on top of a 4,410-metre mountain in the southeast Tibetan Plateau in Sichuan province.

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Detectors in other countries mostly used a single detection method. Lhaaso used four, all with unprecedented sensitivity, despite it being only half-built.

“I am sure there will be many more exciting discoveries when [it] is completed this year,” Cao said. “Scientists from Russia, Switzerland, Poland and other countries hope to move their equipment here, and some international experimental groups have also expressed their desire for cooperation and joint observation.

“After the Lhaaso is completed, China is expected to lead the world in the field of cosmic ray research.”

The Cygnus constellation, where the brightest cosmic ray came from, is so volatile that some astronomers have described it as hell-like.

This article appeared in the South China Morning Post print edition as: Cosmic light may help rewrite physics laws