Chapter 830: Yesterday Reappears
Chapter 830: Yesterday Reappears
The final merger of the two black holes at the core of the Andromeda Galaxy into a single, larger black hole was an unchangeable fact. Even Xiao Yu had no way to alter it. These were stellar bodies with masses of several hundred million times that of the sun interacting with one another. Xiao Yu might be able to spend an extremely long time and immense effort to destroy these two black holes, but he had no ability to stop their eventual merger.
When two stars collide, there is a high probability that they merge into a single, larger star, releasing an extremely violent outburst of energy in the process. When two white dwarfs collide, depending on conditions, they might form a heavier white dwarf, they might explode, or they might form a neutron star, but in every case an enormous amount of energy is released. As for neutron star collisions, there was no need to say more. The violent energy burst of colliding neutron stars was the most intense form of energy release in the universe, and one of the sources of gamma-ray bursts.
In theory, the collision of two black holes should release an even more violent outburst of energy, but in reality this was not the case. The key point was that a black hole only allowed matter and energy to go in, not out. Aside from losing mass and information through negative matter particles and information storms, a black hole did not allow any other matter or energy to escape from within it. This meant that the process of two black holes merging was smooth. They would merge into one essentially without any loss of matter or energy.
The reason this was described as ‘essentially’ rather than absolutely was that under special circumstances, unexpected situations could still arise, such as now, with large amounts of matter orbiting around each of the two black holes.
The enormous gravity of a black hole would accelerate the material orbiting it to extremely high speeds, forming an accretion disk. In this process, tremendous energy would be ejected along the black hole’s poles, sometimes stretching millions of light years into space. This was one of the most spectacular sights in the universe, black hole jets.
In the course of the merger of these two black holes, the black holes themselves would not lose any matter or energy, but it was different for the dust clouds orbiting them at high speed. In the collision process, they would collide at extremely high energy levels, releasing an unparalleled burst of energy, more violent than neutron star collisions or supernova explosions.
At that time, the entire core of the Andromeda Galaxy would blaze with light, even surpassing the total brightness of all the stars in the galaxy. From the Milky Way, the brightness of the Andromeda Galaxy would increase many times over. It might even reach the level of Jupiter’s brightness as seen from Earth in the Earth era.
If Earth still existed then, there would be yet another beautiful sight in Earth’s night sky at that time.
This was a galactic collision. Several billion years from now, the collision between the Milky Way and the Andromeda Galaxy would replay this scene. The only difference was that by then, the energy released from the galactic core would be even more intense. After all, the black hole at the core of the Milky Way had a much greater mass than the smaller of these two black holes.
“Galactic collisions will trigger a new wave of star formation. At that time, the Milky Way-Andromeda galaxy will become a starburst galaxy. The explosive birth of vast numbers of new stars will completely transform the appearance of this new galaxy. Unfortunately, that is tens of billions of years from now.” Xiao Yu thought silently. “By then, I do not even know if I will still exist, or whether I will have the chance to see that scene.”Simply put, a starburst galaxy was one that contained large numbers of newly born stars. The reason for this was that galactic collisions disturbed the gas and dust clouds in both galaxies. When those gas and dust clouds compressed and merged, new stars would be born.
Xiao Yu stayed at the core of the Andromeda Galaxy for several decades. During these decades he made detailed observations of the motion of all kinds of celestial bodies and gas flows here, and further refined his theory of galactic evolution.
If nothing unexpected had happened, Xiao Yu would have stayed here even longer. But an unforeseen event disrupted his plans.
Through layers of interstellar gas, bright stellar bodies, and the barrier of immense distance, Xiao Yu observed a supernova explosion occurring in the distant Milky Way. What was more, one of the explosion’s polar axes happened to point directly toward Xiao Yu’s current position. As a result, to Xiao Yu, the exploding supernova’s brightness instantly reached that of an entire galaxy. It was as conspicuous as a lamp suddenly being switched on in a dark room.
Supernova explosions were quite common. Although they only occurred when suitable stars died, thanks to the sheer number of stars, if one searched carefully, one could find several supernova explosions in the universe every day. But this particular supernova was unusual.
Because it came from his homeland, any stellar change in the Milky Way drew Xiao Yu’s particular attention. He carefully recorded all the data from this supernova explosion, and then, almost subconsciously, compared it with the many sets of supernova data stored in his database.
That one comparison produced a conclusion that sent a chill through Xiao Yu’s heart. In disbelief, he repeated his checks on the comparison results, but the conclusion remained the same.
Xiao Yu grew confused. He did not know whether this was a coincidence, an observational error on his part, or whether such a thing had truly occurred in the Milky Way.
What he had observed was a perfectly ordinary supernova explosion, but in terms of timing it was anything but ordinary. Back when he was still in the Milky Way, Xiao Yu had already detected the remnants of this supernova explosion and had sent probes there. From Earth, this remnant lay in the direction of the constellation Lynx, about nine thousand light years away.
Yes, although Xiao Yu was only now seeing the light from this supernova explosion, he had already visited and investigated its remnant while still in the Milky Way.
This was amazing and illogical, yet the data from his instruments clearly told him that the supernova he was now observing was the same one he had once explored.
“What is going on?” Xiao Yu thought in disbelief. “I clearly already explored its remnant. How is it that here, I am seeing its explosion again?”
In fact, according to existing theory, such a situation was not impossible, mainly due to the appearance of faster-than-light travel technology. For example, suppose that while Xiao Yu was still in the Milky Way, a supernova exploded ten thousand years earlier and left behind a remnant. Xiao Yu then went there to explore it. By that time, the light from the explosion had already traveled ten thousand light years. Then Xiao Yu spent two million four hundred thousand years traversing two million five hundred thousand light years to reach the Andromeda Galaxy. At that point, he would arrive at the same place and time as the light from that supernova explosion.
In that case, Xiao Yu could first explore the supernova remnant, and later see the explosion’s image. There would be nothing surprising about that. But that was not what was happening now. The central contradiction was that the timing of the supernova Xiao Yu was now observing did not match.
Xiao Yu had once made extremely detailed observations of that remnant and concluded that the supernova had exploded five million years ago. If that were the case, the light from that explosion should have reached the Andromeda Galaxy long ago and faded by now. Yet at this moment, in the Andromeda Galaxy, Xiao Yu was seeing that scene again.
This was a contradiction with no explanation. The probability of two supernova explosions this similar occurring independently was infinitely close to zero, but aside from this explanation, Xiao Yu could find no other way to account for the event.
After observing this supernova image, Xiao Yu focused even more attention on the Milky Way. Gradually, more and more events that filled him with shock appeared one by one before him.
Xiao Yu began monitoring several benchmark stars and neutron stars in the Milky Way. His conclusion was that their current positions were completely different from his calculations. They should have been at those observed positions two million five hundred thousand years ago, not now.
Over the next few decades, Xiao Yu observed more events that should only have existed in the historical record, such as several gamma-ray bursts and several other supernova explosions.
All of this looked like history repeating itself, or time flowing backward. In that distant galaxy millions of light years away, something unfathomably mysterious seemed to be happening.
When Xiao Yu saw that another planet existed, he knew he had to return to the Milky Way. This event was far too bizarre. He had to find out what was really happening there. Only after understanding it could he calmly continue his journey through the universe.
That was, after all, his homeland. If he did not clarify what was happening there, Xiao Yu absolutely would not leave it behind.
Xiao Yu saw Earth. That was right. Though Earth had been destroyed long ago, it now appeared before Xiao Yu once more, orbiting the sun along an orbit that felt strangely unfamiliar to him. The Solar System he saw also differed greatly from where his calculations said it should be.
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