Weekend ‘Galaxy’ Insight — “The Warping of Space and Time”

 

 

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"A big misconception is that a black hole is made of matter that has just been compacted to a very small size. That's not true. A black hole is made from warped space and time. It may have been created by an imploding star [where the gravity becomes so concentrated that nothing, not even light, can escape]. But the star's matter is destroyed at the hole's center, where space-time is infinitely warped. There's nothing left anywhere but warped space-time.

"A black hole really is an object with very rich structure, just like Earth has a rich structure of mountains, valleys, oceans,and so forth. Its warped space whirls around the central singularity like air in a tornado. It has time slowing as you approach the hole's edge, the so called horizon, and then inside the horizon, time flows toward and into the singularity [the central spot of infinite density and zero volume], dragging everything that's inside the horizon forward in time·to its destruction.

"Looking at a black hole from the outside, it will bend light rays that pass near it,and in this way it will distort images of the sky.You will see a dark spot where nothing can come through because the light rays are going down the hole. And around it you will see a bright ring of highly distorted images of the star field or whatever is behind it.

"Gravitational waves will bring us exquisitely accurate maps of black holes-maps of their space-time. Those maps will make it crystal clear whether or not what we're dealing with are black holes as described by general relativity. It's extremely unlikely that they are anything else, but that's the exciting thing-we've been wrong."

Kip Thorne, theoretical physicist, and colleague of Stephen Hawking and Carl Sagan, was the Feynman Professor of Theoretical Physics at the California Institute of Technology, and is one of the world's leading experts on Einstein's general theory of relativity. He was the scientific consultant and an executive producer for Interstellar.

 

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The black hole at the center of the super giant elliptical galaxy M87 shown at the top of the page in cluster Virgo fifty million light-years away is the most massive black hole for which a precise mass has been measured -6.6 billion solar masses. Orbiting the galaxy is an abnormally large population of about 12,000 globular clusters, compared to 150-200 globular clusters orbiting the Milky Way. The team theorized that the M87 black hole grew to its massive size by merging with several other black holes. M87 is the largest, most massive galaxy in the nearby universe, and is thought to have been formed by the merging of 100 or so smaller galaxies. The M87 black hole’s large size and relative proximity, astronomers think that it could be the first black hole that they could actually “see.”

In 2011, using the Frederick C. Gillett Gemini Telescope on Mauna Kea, Hawaii, a team of astronomers calculated the black hole’s mass, which is vastly larger than the black hole in the center of the Milky Way, which is about 4 million solar masses. The black hole’s event horizon, 20 billion km across “could swallow our solar system whole.”

In order to calculate the black hole’s mass, the astronomers measured how fast surrounding stars orbit the black hole. They found that, on average, the stars orbit at speeds of nearly 500 km/s (for comparison, the sun orbits the black hole at the center of the Milky Way at about 220 km/s). From these observations, the astronomers could come up with what they say is the most accurate estimate for the mass of a supermassive black hole.

Future calculations may attempt to calculate the size of another black hole with a roughly estimated mass of 18 billion solar masses, which is located in a galaxy about 3.5 billion light-years away.

In the image, a central jet is surrounded by nearby bright arcs and dark cavities in the multimillion degree Celsius atmosphere of M87. Much further out, at a distance of about fifty thousand light years from the galaxy's center, faint rings can be seen and two spectacular plumes extend beyond the rings. These features, shown in X-rays, together with VLA radio observations, are dramatic evidence that repetitive outbursts from the central supermassive black hole have been affecting the entire galaxy for a hundred million years or more.

The Daily Galaxy via Chandra X-Ray Observatory and pas.rochester.edu

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