Why Does the First Picture of a Black Hole Look Like a SpaghettiO?
Our galaxy, the Milky Way, is circling the cosmic drain. A vast and inescapable void pulses at its center, devouring all energy and matter in its path-a black hole.
Astronomers believe that nearly every galaxy circles these voids, in fact, but nobody has ever seen one until today. On Wednesday, an international team of scientists revealed the first-ever image of a supermassive black hole in action. It has the same mass as 6.5 billion Suns, and is located in the Messier 87 galaxy 55 million light years from Earth.
The image is strange and beautiful, but why does it look like a SpaghettiO?
The first thing to understand is that the image we saw today, while being the first direct observation of a black hole, is not a photo of the kind Earthlings are familiar with. The Event Horizon Telescope project-a globe-spanning effort that basically turned the whole Earth into one giant radio receiver-looked to the stars and captured radio data to construct an image of the Messier 87 black hole.
What scientists actually recorded is what they call the black hole's "shadow." See, the supermassive black hole is so dense that it warps space and time around it, consuming nearby light. Since a black hole is basically the absence of light, it's impossible to see through traditional means.
However, an "event horizon" surrounds every black hole-the point beyond which no light escapes the black hole's maw. Outside the event horizon is a ring of matter called the "accretion disk" that forms a superhot swirl of chaotic matter and energy that's destined to either slip into the black hole, or be ejected into space.
Within the accretion disk, photons-particles of light with no mass-swirl around the edges of the black hole, which is, again, a void that emits no light. It's this ring-like "shadow" that the EHT captured.
"If immersed in a bright region, like a disc of glowing gas, we expect a black hole to create a dark region similar to a shadow-something predicted by Einstein's general relativity that we've never seen before," Heino Falcke, chair of the Event Horizon Telescope Science Council, said in a press release. "This shadow, caused by the gravitational bending and capture of light by the event horizon, reveals a lot about the nature of these fascinating objects and allowed us to measure the enormous mass of M87's black hole.
So, we are not really seeing the black hole itself, but rather the distortion of spacetime the black hole leaves in its wake-which is still amazing, considering it's the first direct observation of a phenomenon theorized by Albert Einstein a century ago.
"Not simulation or conjecture, but chaotic photons surrounding an unimaginable void," the NSF said in a video explaining the phenomenon.
Even 55 million light years away, traces from the doomed photons found their way to earth.
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