It was referred to as a ` singularity’ in the classical, pre-(quantum mechanic) days. Well inside the event horizon lies the heart of the black hole. Our Earth would need to be compressed to a size smaller than 1.77 cm across (diameter). For example, our Sun would become a black hole if its mass was contained within a sphere about 2.5 km across. The only requirement is that its physical size is less than the Schwarzschild radius. In theory, any mass can be compressed sufficiently to form a black hole. The limit of this region is called the `event horizon’, a name which signifies that it is impossible to observe any event taking place inside of it (since information is unable to get out).įor a non-rotating black hole, the radius of the event horizon is known as the Schwarzschild radius -with no recognition of Droste – and marks the point at which the escape velocity from the black hole equals the speed of light. Using Einstein’s theory of general relativity, they discovered that matter compressed to a point (possibly no bigger than the Planck length) would be enclosed by a spherical region of space from which nothing could escape. However, it was Karl Schwarzschild (1873-1916) and the little-known Johannes Droste, who independently developed the modern idea for a black hole. The existence of black holes was first suggested as far back as the late 1700s. Outside the event horizon, v esc < c and there is therefore some hope to escape – if you’re quick enough. Within the event horizon, the escape speed ( v esc ) exceeds the speed of light ( c ), and given that nothing can travel faster than the speed of light, anything inside this sphere is trapped forever. This conformed to Hawking’s area law.The basic structure of a black hole consists of an object hidden behind an ` event horizon’. The surface area of the resulting black holes was larger than the combined area of the original black holes. It’s like if you ping a bell, the specific pitches and durations it rings with will tell you the structure of that bell, and also what it’s made out of.” “What you’re left with is a new black hole that’s in this excited state, which you can then study by analyzing how it’s vibrating. “As they spin around each other faster and faster, the gravitational waves increase in amplitude more and more until they eventually plunge into each other - making this big burst of waves,” Isi elaborated. With this information, they calculated the surface areas of the black holes before and after the merger. This allowed them to figure out the mass and spin of the original black holes as well as the mass and spin of the merged black hole. The researchers separated the signal into two parts, depending on whether it was from before or after the black holes merged.
What Stephen Hawking would have discovered if he lived longer | NASA’s Michelle Thaller | Big Think Confirming Hawking’s black hole area theorem