Initial Exploration of a Black Hole

Even back in Earth Era, humans had already mastered several methods for observing black holes, which were also the main methods for observing these "invisible" celestial bodies.

Because black holes cannot be directly observed like stars, they can only be observed indirectly. One method is stellar observation, which involves observing the abnormal movement of stars in a certain region over many years to discover the existence of a black hole that binds these stars in that region.

This method won't work here because there are practically no stars orbiting this black hole.

Another method is to determine the existence of a black hole by observing its Accretion Disk. According to the principle of conservation of angular momentum, as matter gradually approaches and is sucked into a black hole, a rotating Accretion Disk forms around the event horizon. Humans can indirectly detect the existence of black holes by observing the temperature radiation and high-intensity X-rays generated by the collision of gas in the center of the Accretion Disk.

Unfortunately, this method won't work here either, because the matter around this black hole has long been swallowed up by it. It has no Accretion Disk and is a silent black hole.

The third method is also related to stars and is a combination of the first two methods. It determines the existence of a black hole based on the celestial system formed by the black hole and visible stars. In this case, there is usually Accretion Disk, but unfortunately, it is not applicable to the black hole we are talking about today.

The fourth method is the well-known Gravitational Wave, which uses the Gravitational Wave generated by the merger of two black holes to determine their existence. However, this black hole clearly merged a long time ago and is now a quiet black hole again, so this method also fails.

The reason why the Star Alliance Member Civilizations Probe Team sent by humanity was able to discover this black hole was not because of these four observation methods, but because they discovered that there was Gravitational Lensing Effect at the location of the black hole.

In astrophysics, the Gravitational Lensing Effect is a well-known phenomenon. Simply put, a strong Gravity Field distorts the path of light, causing an observer on the other side of the Gravity Field to see a false light source.

It is worth mentioning that if an observer stays in a fixed position, they will not be able to tell whether what they see is the real or an illusion of the light source. However, since humans are always on the move, careful observation and comparison will naturally reveal the changes, which is how this black hole was discovered.

However, now that we are closer to black holes, we can no longer use these indirect methods to observe them, because there is a theoretical way to observe black holes directly: Hawking Radiation.

Also known as Black Hole Radiation.

Hawking Radiation does not follow the Area Law; instead, the larger the black hole, the smaller the Hawking Radiation, and the smaller the black hole, the larger the Hawking Radiation. As a result, a miniature black hole created by Particle Collider in a laboratory will disappear instantly upon its appearance. This is why scientists are not worried about the dangers of black holes created in the laboratory.

The essence of Hawking Radiation is related to Quantum Field Theory, and is related to Virtual Particle that are spontaneously generated in the Void due to vacuum quantum fluctuations.

Human scientific theories describe a possibility that when Virtual Particle are generated by quantum fluctuations near the Event Horizon of a black hole, the negative-energy particles are absorbed into the black hole, while the positive-energy particles escape. From the outside of the black hole, these escaping positive-energy particles are the Hawking Radiation emitted by the black hole.

In this process, the black hole absorbs negative-energy particles, thus reducing its internal energy and causing it to evaporate. Hawking believed that because the ordinary spacetime of a black hole does not allow negative-energy particles to exist stably, the phenomenon of positive-energy particles entering the black hole while negative-energy particles escape is impossible. Therefore, Hawking Radiation can only emit positive-energy particles.

Humans predicted the existence of Hawking Radiation during Earth Era, and of course verified the existence of this phenomenon through other physical facts, but never directly observed a black hole through Hawking Radiation from an astronomical perspective.

The reason is simple: Hawking Radiation from black holes is extremely low. Observing black holes tens or even millions of light-years away from within our Solar System, we simply cannot directly detect their Hawking Radiation. To put it another way, a black hole with the mass of the Sun would have Hawking Radiation of only about 0.0000001 to 1/600 millionth of a Kelvin. If this black hole had a mass 130 times that of the Sun, its Hawking Radiation would be even smaller.

It is far below the temperature of the cosmic microwave background radiation.

Therefore, Hawking Radiation cannot be detected from a distance. Even with current human technology, the only way to detect it is to launch detectors and get closer.

That's exactly what human scientists are doing now. After their Research Ship are safely anchored, they launch probes toward the black hole. To facilitate the real-time transmission of observational information, they also deploy several relay communication spacecraft.

As the detector drew closer, the barely perceptible Hawking Radiation from the black hole was finally detected, allowing humanity to directly "see" a black hole for the first time. From that moment on, every piece of data transmitted to the human Research Ship was invaluable.

Human probes continue to approach and reach the Roche Limit radius of the black hole. Macroscopic celestial bodies exceeding this radius will be directly torn apart by the black hole and then turn into matter. This matter will continue to collide before falling to the Event Horizon, thus emitting a large amount of radiation outward. This is what people usually know as the black hole Accretion Disk.

Black holes are different from ordinary celestial bodies because extreme celestial bodies like black holes have an Innermost Stable Circular Orbit, which lies inside the Roche Limit orbit.

The Innermost Stable Circular Orbit refers to the closest distance an object can get to a black hole. Beyond this point, any object will fall towards the black hole at near the speed of light; this is the black hole's Plunging Region. This radius, calculated according to General Relativity, is a region three times the radius of the black hole.

Human probes cannot reach the boundary of the Plunging Region to observe this black hole because they would be disintegrated if they exceeded the Roche Limit. Of course, the Roche Limit radius cannot be determined solely by the black hole's mass; it also depends on the level of craftsmanship of human probes.

Human probes struggle to even reach the Innermost Stable Circular Orbit, let alone the Schwarzschild Radius. No matter how advanced the materials used in human probes are, once they exceed three times the Schwarzschild Radius, even probes that haven't been torn apart by the black hole's tidal forces will fall into the black hole and crash onto the Event Horizon, never to return.

Yes. The so-called Black Hole Radius is not the actual radius of the black hole's singularity, but rather its Schwarzschild Radius, which is the location of the Event Horizon.

After calculating the Roche Limit radius, the human probe entered a stable orbit and, while stabilizing its orbit, began to observe the black hole.

However, scientists want to do more than just observe. They also want to throw something into the black hole to observe the process of Accretion Disk formation. They plan to use a thruster to push a Rocky Planet here and let it fall into the black hole for observation.

However, such experiments would inevitably take a lot of time, and obviously humans don't have that much time to spend on this. Therefore, these scientists, who were very interested in exploring, could only settle for second best and launch a few probes into the black hole to conduct a fall experiment, and incidentally drop some space debris or minerals carried by that Planetary-Class Spaceship into it, and then conduct observations.

If we don't want to waste any more time transporting asteroids from nearby Star System, this is the only way to do it.

They also want to test whether a detector made of Alloy No. 2 can reach the Innermost Stable Circular Orbit region of a black hole, so as to observe the black hole more closely and accumulate more data for scientific quantitative change.