What is so hard to understand that this property, which does not even escape light, only applies to a certain distance?Otherwise the night sky would be completely black.
Gravity gradually changes with the distance and decreases in distance. This also applies to black holes, why should it be different?Each scientific description makes the statement of the question with the addition of the so-called Black Shield radius as a decisive distance.
In the blanket analogy, a black hole is illustrated by the fact that the cowl, which causes the black hole as space-time curvature is not only particularly deep, but has a demolition edge, just from this distance without recurrence.Mind you, this demolition edge represents a leap in space-time, but that does not mean a jump in gravity, which changes gradually. One does not need to care about the interior and its exact theory, the outer behavior behaves with the same distance behavior as any normal mass.
I have already repeated what others have already said, so what is the consequence?Light is bent, not as if from an atmosphere, but just as one could prove it in the sun during solar eclipses. And with the higher strength, there is a lens effect that can be imagined in reverse as a collection lens with a focus. The geometry is a bit different, but it runs out on the same thing.
Light coming from our direction parallel to the black hole in a cross section much larger than it itself (i.e. no bundled light, rather that from a huge flashlight) will come in to a large extent near the black hole and not focused end behind, decentralized enough but end behind the black hole and continue to bundle even a little.
If you measure the distances from the central light coming directly into the center of the black hole and then also captured there, then all light up to 2.6 black shield radii is doomed to fall into the black hole.Light at approximately 2.6 times the black shield radius radial distance is bent just so that this ring is merged by light in a point behind the black hole, or vice versa, luminous mass or light emits at the exact point behind the black hole and there radiating in all directions will again fall to a fairly high part into the black hole, but light emanating from a light source on the side is bent just so that it becomes visible as the so-called photon ring.
Here is an illustration
(taken from the page Matroids Matheplanet – The Math Editor)
That is the situation I have described from the side.
The right side corresponds to the back, the earth is here 55 million light-years away to the left. The one focus I was talking about is seen here in the bow with the two arrowheads. Light what is initially emitted from there still above is bent to the left.
Now the ring has an extension on the image of the EHT, mainly due to the image blur, because unfortunately we do not have any even larger telescopic distances that could improve the image resolution and of course also because there is not only a point of luminous mass, but also swirls a whole disk of accretion mass around the black hole.If not even several accretion currents, as simulated here under various viewing angles:
It also becomes clear here that one looks at the black hole almost no matter from which direction one looks at the black hole and how accretion currents or discs are exactly, there is always a ring.In some angles, it even seems almost as if the black hole is something transparent around which there is a light phenomenon. The simulated situation is not very real with many mass streams, in order to illustrate the geometry of it with light, which comes from close up instead of the distorting effect on a typical star back-grround, as one has probably seen several times already in the form:
That it almost doesn’t matter what swirls around the hole at high speed should be clear, it gets hot and alone from the theory of thermodynamics then has a radiation of far below to far above visible light, from which the EHT refers to the radio area as the detectable area that can also penetrate all the way through the rest of the M87 galaxy before the black hole.
Then there is the fact that of course the light reaches us, which is emitted in front of the black hole and mass that rotates around the hole in almost all viewing angles has a part that moves towards us and a part that then rotates half a rotation late. r away from us, which causes a blue and red shift by the Doppler effect of the light as well as an intensity gain or