Albert Einstein would have been happy, but perhaps a little surprised, by the announcement of the first image in the foreground of a supermassive black hole. The first speculations about black holes fell directly from Einstein's theory of general relativity in 1915, but the great scientist himself thought that the idea was a bit too strange to manifest in the current universe.
He assumed it was an artifact of mathematics, said physicist Daniel Kennefick, co-author of "An Einstein Encyclopedia" and the upcoming "No Shadow of Doubt". In correspondence with the French physicists in the 20's, Einstein rejected the idea that something could collapse forever, reaching a point of infinite density and also trapping light. (They did not use the term black hole, which did not take hold until the years 60).
Kennefick said he required scientists to overcome some mental barriers to recognize that true black holes hide out there, including the monstrosity in the new image, with an estimated mass equivalent to 6 billion suns. The donut-shaped glow of the image was not the real black hole, but outlined a sort of shadow of the region known as the event horizon, within which not even light can escape. The horizon of events is almost as wide as our solar system, but the mass of all those suns can be packaged within a grain. Exactly. It's strange.
The first person to take the cause of the black holes was a young astronomer named Subrahmanyan Chandrasekhar, who over the years argued with the famous Arthur Eddington that a large enough star could collapse indefinitely. Eddington won by pure authority, but later in the decade, Robert Oppenheimer took the idea of Chandrasekhar, at least until his energies were diverted to the Manhattan Project.
At the end of the 50s, astronomers began to observe distant but ultra-bright objects, nicknamed quasars, which were difficult to explain, except perhaps as a manifestation of some extreme conditions. So the astronomers started a series of collaborative meetings with physicists, called Texas Symposia, to understand what was happening.
Other big names began to understand black holes, assuming they could be real objects. Stephen Hawking and Roger Penrose have broadened our understanding of black holes and another extreme condition – what happens if we extrapolate the big bang in time. All this has helped to boost the search for real black holes, said Kennefick.
Seeing similar things is like watching the wind – watching the way these invisible objects move and affect the things visible around them. In the early 1990s, scientists discovered a number of stars that were shot by what could only be a huge but invisible companion.
Also in the 90s, the Hubble Space Telescope helped to nail down the existence of supermassive black holes that accumulate in the centers of galaxies – including our Milky Way, where something with a mass of 4 million lurks of alone. The black hole announced on Wednesday is about 1,000 times bigger.
Scott Tremaine, an astronomer at the Institute of Advanced Studies, stated this week that the picture is a bit larger than the horizon of real events due to the way the black hole deviates the path of light. So what's inside this no-return point? "We don't know," he said, but Einstein's theory predicts that various quantities, such as density, go on forever – a situation called singularity. A singularity suggests that the theory does not work – that there is a real, explainable physical situation.
Here is the question that we really need to answer: will black holes eventually eat the universe? No, said Tremaine. Even those supermassive monsters grew much faster when they were younger, and eventually slowed down.
Faye Flam is a columnist with Bloomberg Opinion.
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