Astronomers and physicists studying the M87 black hole, recently renamed Pōwehi (which means “embellished dark source of unending creation”), made history earlier this year when they released the first photographic image of a black hole. In their new paper, they argue that the ghostly ring of fire we see could harbor historical records – which some have called “movies” – of the cosmos.
The argument is based on an interferometric study of the vast swirling wreaths of light that are trapped in perpetual orbit around the black hole’s event horizon. This light is comprised of photons, which scientists believe may behave like the rings inside a tree trunk, concentric sequences of information that betray overall age and development.
In the paper, entitled “Universal Interferometric Signatures Of A Black Hole’s Photon Ring,” they write:
“Together, the set of subrings are akin to the frames of a movie, capturing the history of the visible universe as seen from the black hole.”
Studying these rings of photons could help scientists learn more about theories like Einstein’s general relativity.
They could also crack more of the mysteries of black holes, which continue to be one of the most puzzling and monstrous objects predicted by physics. For example, do black holes defy the mandates of quantum mechanics and destroy all information? Do they contain dark matter? Do they curve space-time so severely that matter is sent to the future? Can black holes break the laws of physics by existing in five-dimensional space?
The list goes on and on. Many of the world’s most prominent physicists, including Stephen Hawking and Einstein himself, have spent careers and lifetimes trying to unravel the enigmatic existence of black holes. This has led some thinkers to some very strange theories. For example, mathematical physicist Sir Roger Penrose has suggested that we may actually be able to see the imprints of black holes from alternate universes.
Because of the many related puzzles, the opportunity to study historical records left behind by rings photons inside black holes is tantalizing to scientists.
However, the rings do not exist in perpetuity. Each one is only six days older than its predecessor and is eventually obliterated inside the black hole singularity. So while they cannot be used to peer into the entire history of the universe, “measuring the size, shape, and thickness of the subrings would provide new and powerful probes of a black hole spacetime.”
Scientists have described the discovery as approaching a “cosmic hall of mirrors, where the black hole’s gravity takes light from all directions, warps it and beams it to us as an infinitely recast image of the hole’s surroundings. The result is an epic movie of the history of the universe, as witnessed by a black hole, playing on a dramatically curved screen tens of billions of kilometres across.”
As we continue to learn more about black holes, what will they whisper to us about the nature of reality and the secrets of the cosmos?