Anixx Anixx There isn't necessarily any material surface there. But it looses much of its energy and becomes redshifted. Featured on Meta. Now live: A fully responsive profile. Linked 1. Related 1. Hot Network Questions. Question feed. It is not a physical surface, but a sphere surrounding the black hole that marks where the escape velocity is equal to the speed of light.
Its radius is the Schwarzschild radius mentioned earlier. One thing about the event horizon: once matter is inside it, that matter will fall to the center. That point is called the singularity. It is vanishingly small, so it has essentially an infinite density. It's likely that the laws of physics break down at the singularity. Scientists are actively engaged in research to better understand what happens at these singularities, as well as how to develop a full theory that better describes what happens at the center of a black hole.
Astronomers don't exactly see black holes directly. Instead, astronomers observe the presence of a black hole by its effect on its surroundings.
A black hole, by itself out in the middle of our galaxy would be very difficult to detect. Imagine you arrive home one night to find the kitchen a mess. You know that it was clean when you left, but now there are dirty dishes in the sink and crumbs strewn about the counter.
You might even be able to identify who in your household was in the kitchen based on what kind of chips they had or what they put on their sandwich. As an illustration of a Boltzman-like distribution, think of cars on the interstate.
Most are moving at speeds close to the speed limit of 65 mph. However, a few are moving faster and a few are moving slower. And perhaps 1 out of ever cars is moving mph while another 1 out of is puttering along at 45 mph.
Now supposed that a highway patrol officer pulls over and tickets the mph driver. What happens? Someone else speeds up and replaces the fastest car so that there is always one bozo driving much too fast. At the distance of the snow line let's call this 5 AU , the temperature of material illuminated and heated by the Sun is about K C.
Thus, the averge velocity of a hydrogen atom. Clearly, even our average H 2 molecule 1. So quickly, all the hydrogen would escape from the Moon to space. This means that the fastest few molecules will escape. Once they escape, a few other molecules will find there way to higher speeds and then they will escape.
And bit by bit, molecule by molecule, all the gas will trickle out this small 'opening' until the atmosphere is completely depleted in this gas. Finally, the other limit: to hold onto H 2 at K we only need an object with v escape greater than This leads the event horizons of rotating black holes, also known as Kerr black holes, to appear oblong — squashed at the poles and bulging at their equators.
A rotating black hole's event horizon separates into an outer horizon and an inner horizon. The outer event horizon of such an object acts like a point of no return, just like the event horizon of a nonrotating black hole. The inner event horizon of a rotating black hole, also known as the Cauchy horizon, is stranger. Past that threshold, cause no longer necessarily precedes effect, the past no longer necessarily determines the future, and time travel may be possible.
In a nonrotating black hole, also known as a Schwarzschild black hole, the inner and outer horizons coincide. A spinning black hole also forces the fabric of space-time around it to rotate with it, a phenomenon known as frame dragging or the Lense-Thirring effect. Frame dragging is also seen around other massive bodies, including Earth. Frame dragging creates a cosmic whirlpool known as the ergosphere, which occurs outside a rotating black hole's outer event horizon.
Any object within the ergosphere is forced to move in the same direction in which the black hole is spinning. Matter falling into the ergosphere can get enough speed to escape the black hole's gravitational pull, taking some of the black hole's energy with it. In this manner, black holes can have powerful effects on their surroundings.
Rotation can also make black holes more effective at converting any matter that falls into them into energy.
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