Tour 10 of the Closest Black Holes to Earth. Register or Log In. The Magazine Shop. Login Register Stay Curious Subscribe. The Sciences. Camille M. Carlisle Post Author. Think of the black hole like a hole at the bottom of a steeply sloping valley: the steep ground outside the hole is the space just outside the event horizon.
It's still steep enough that light has to struggle to climb up, but it's outside the hole itself. We can't see the light from after the person crosses the event horizon, but we can see the light from just before. If you could survive crossing the event horizon of a supermassive black hole, wouldn't you be travelling at the speed of light?
A bit like waking up dead! The question " what's inside a black hole" can potentially be answered by asking what the laws of physics are inside, which are all determined by " The Metric of Spacetime" However, due to a sign exchange between the radial and time dimension between the outside and outside, you have to consider the inexorable chute from the event horizon to the central singularity to represent the passage of time, and what was time on the outside becomes space inside, possibly being infinite in extent.
The laws could then turn out to be the same as ours, allowing everything from the Big Bang to the evolution of life to occur inside, given that the "time" from event horizon to central singularity lasts long enough. Black holes can, however, be 'seen' with some special analysis of data collected from a wide range of telescopes more on this later. How black holes' form depends on their type and origin. To date scientists have managed to define at least four different kinds of them:.
Current theories suggest that small, or miniature, black holes some as small as an atom probably formed in the earliest moments of the universe. These tiny black holes are, to date, purely theoretical, and are believed to be tiny vortices of darkness peppered throughout the universe.
Like miniature black holes, intermediate black holes are only really known theoretically. These kinds of black holes have several hundred of thousands of solar masses, rather than millions, or even billions of solar masses like their larger cousins.
Some scientists believe that intermediate black holes form from a merging of miniature black holes. Others believe that, if they do indeed exist, that they would form from the collapse of stars with masses equal to hundreds of thousands of our own Sun. Needless to say, there is little consensus in the field over these enigmatic black holes. Stellar black holes about the mass of 20 of our Suns or more are created when massive stars collapse in on themselves.
Such a burst flings star matter out into space but leaves behind the stellar core. While the star was alive, nuclear fusion created a constant outward push that balanced the inward pull of gravity from the star's own mass. In the stellar remnants of a supernova, however, there are no longer forces to oppose that gravity, so the star core begins to collapse in on itself. If this mass collapses into an infinitely small point, a black hole is born—many times the mass of our own sun.
There may be thousands of these stellar-mass black holes within our own galaxy. Supermassive black holes as much as 1 billion of our Sun's mass or greater are thought to form at the same time as the galaxy they inhabit is formed and are predicted by Einstein's General Theory of Relativity. While everyone has heard of black holes nowadays, have you ever wondered who first discovered them?
Technically speaking, we haven't really "found" a black hole yet, but we can infer their existence through a variety of techniques more on this later. That being said, scientists have speculated about the existence of something like them for hundreds of years.
In , for example, an English cleric and amateur scientist called John Mitchell managed to show that Newton's law of gravity should be able to show a place where gravity was so intense light cannot escape. He even went further. Mitchell suggested that although they would be invisible, they should reveal their presence by interfering with things like stars that might orbit them.
His theoretical work would prove to be years ahead of his time with the later groundbreaking work of the great Albert Einstein. Einstein first predicted that such things should exist way back in , in his General Theory of Relativity. According to him, big enough stars should be able to collapse under their own gravity and create what we call today black holes. For decades after, black holes remained a purely theoretical concept, and the actual term wasn't coined until by the American astronomer John Wheeler.
Mitchell and Einstein's work was later reinforced when two British astronomers, Louise Webster and Paul Murdin independently announced they had discovered one in space. What they had found was an intense x-ray source, called Cygnus X-1, orbiting a blue star around 6, light-years away.
It would be the first of many. As amazing as this all is, it wasn't until very recently that scientists managed to "see" one for the first time. Back in , the Event Horizon Telescope EHT collaboration managed to release a computerized image of what is believed to be a black hole. The image itself is actually a composite rendering of a petabyte of data collected from a series of radio telescopes sited around the world.
This galaxy is somewhere in the region of 54 million light-years away from Earth. It is thought that the black hole in question has a mass of about 6. The team was attempting to examine the black hole's event horizon and accretion disk a large cloud of hot gas and dust trapped in orbit around the black hole. This they did, and they were able to map the sudden loss of photons within the black hole's event horizon.
This discovery has proved to be groundbreaking, as it is hoped that it will open a whole new area of research into the nature of black holes. A black holes' event horizon is its outermost boundary. This is the point at which the gravitational force overcomes light's ability to escape the pull of gravity from the black hole. To escape from the event horizon, you would have to be going faster than the speed of light. It is the literal point of no return - you cannot escape once you pass it. At least that was the traditional view.
The venerable Professor Stephen Hawking , during his life, was adamant that the definition of a black hole should be changed. He believed that event horizons, as they are traditionally understood, don't actually exist at all. They are, in fact, "apparent horizons" at the edge of black holes, where quantum mechanics goes crazy.
He posited that here, virtual particles pop in and out of existence, causing the horizon to fluctuate, rather than act as a specific point in space.. Login or Register Customer Service. RISE —. PHASE —. Tonight's Sky — Change location. US state, Canadian province, or country. Tonight's Sky — Select location. Tonight's Sky — Enter coordinates. UTC Offset:. Picture of the Day Image Galleries. Watch : Mining the Moon for rocket fuel.
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