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PHOTOGRAPHING THE POINT OF NO RETURN

THE FIRST PHOTOGRAPH of a black hole is a major astronomical achievement. This also relates to several items that appeared here at SimanaitisSays: “Happy Birthday—General Relativity!,” March 27, 2015; “China’s FAST Telescope to Enhance Mankind’s Listening,” February 2016; and “Earth Photobombs the Bad Side of the Moon,” March 12, 2019. There’s also, only peripherally, the recent “Our Four Phantoms,” April 10, 2019. (This last one encouraged my title here for the black hole’s “point of no return.”

Einstein, a Skeptic. Einstein’s Theory of General Relativity, 1915, implies the existence of black holes. Think of these as elusive punctures in the space/time continuum, points in the universe with such tremendous gravity that they literally sucked in everything nearby.

Gravity of a mass warps space. Image by User:Johnstone.

Einstein was reluctant to accept black holes as more than mathematical aberrations: “Black holes,” he said, “are where God divided by zero.”

Stephen Hawking put it another way: “Consideration of particle emission from black holes would seem to suggest that God not only plays dice, but sometimes throws them where they cannot be seen.”

Photographing a Black Hole. Pursuing a black hole’s image is a paradoxical task: It absorbs everything nearby, even light. Thus, in a sense, a black hole contains everything within reach, but displays nothing.

The best we could hope to see is its “event horizon,” the edge of its puncture in the space/time continuum.

Not Nearby, Thankfully…. And, of course, by its very nature, a black hole must be extremely far away. Otherwise, we and our photographic equipment would be beyond this point of no return.

Indeed, there is a black hole in our astronomical neighborhood. Sagittarius A* is a dim radio source near the center of the Milky Way, which is our galaxy, one of an estimated 2 trillion galaxies in the universe. The black hole lurking within Sagittarius A* is 26,000 light-years away; that is, light at its event horizon takes 26,000 years to reach us.

Earth is off in one corner of the Milky Way galaxy. Image by Bill Saxton NRAO, AUI, NSF; Robert Hurt NASA in Scientific American, October 13, 2017.

Scientists compute that this particular black hole in our galaxy weighs as much as 4.1 million suns. A second one, in distant galaxy Messier 87, resides 55 million light-years away and is estimated to weigh more than six billion suns.

Ready for Your Closeup? Because of the vast distance, photographing a black hole’s event horizon makes use of eight radio telescopes arrayed around the world, logically enough dubbed an Event Horizon Telescope.

The Atacama Large Millimeter Array in Atacama, Chile, one of several installations making up the Event Horizon Telescope. Image by Y. Beletsky (LCO)/ESO in “Black Hole Image Revealed for First Time Ever,” by Dennis Overbye, The New York Times, April 10, 2019.

This cooperative effort included radio telescope instillations in Arizona, two in Chile, Greenland, two on the island of Hawaii, Mexico, and the South Pole Station, Antarctica.

The Event Horizon Telescope observed Messier 87 for 10 days in April 2017 and produced 5 petabytes, 5 x 1015 bytes, of data. These data, the equivalent of a lifetime of selfies taken by 40,000 people, took two years of analysis and yielded the first image of a black hole’s event horizon.

The first image of a black hole’s event horizon, from the galaxy Messier 87. Image from The New York Times, April 10, 2019. See also an earlier “At Long Last, a Glimpse of a Black Hole,” by astrophysicist Priyamvada Natarajan, The New York Times, April 8, 2019.

It was a long time in coming, 55 million years for Messier 87, but it was well worth the wait. ds

© Dennis Simanaitis, SimanaitisSays.com, 2019

One comment on “PHOTOGRAPHING THE POINT OF NO RETURN

  1. rulesoflogic
    April 13, 2019

    Love the post! Remember that nothing should be dogma and that science should be about keeping an open mind and not about zealous pursuit.

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