The definition of a conventional propulsion method is actually very simple, that is, a propulsion method that can be used universally on a large scale. It's like the propulsion method used by the Xinghai spacecraft at this moment, where the fusion engine heats the working fluid and then ejects it out.

The counterpart to the conventional propulsion method is the unconventional propulsion mode. Most of this approach is still in the conceptual stage, and there are many whimsical methods. For example, a nuclear bomb is thrown every second to explode behind the spaceship, and the radiation pressure of the nuclear bomb is used to propel the spacecraft forward. One thing these methods of propulsion have in common is that they are only required in very special circumstances, and they are not capable of large-scale interstellar transportation.

For long-distance interstellar voyages, the only option is conventional propulsion. The reason is simple, because in the future, a large spaceship that may carry hundreds of thousands or even millions of people will need to be propelled by constantly dropping nuclear bombs, which is something that no one can imagine.

In the field of interstellar navigation, it is not feasible to take the sword sideways, and the only feasible way is to honestly develop basic technology and develop conventional propulsion methods.

But...... Chu Hai now tells Wei Feng that some scientists have theoretically proved that the upper speed of conventional propulsion methods is 4,500 kilometers per second. Although this theory has not yet gained universal acceptance, it already has a certain supporter.

This made Wei Feng's heart ripple again.

The scientist argued the topic in terms of materials technology, specific impulse, the ratio between the mass of fuel and working fluid and the total mass of the spacecraft, the distance traveled, and the basic theory. He concluded that long-distance interstellar voyages could not be achieved if our basic theories could not be broken. The upper limit of the speed we can achieve by conventional means is 4,500 kilometers per second. If the speed of a ship exceeds this limit. Then it will slow down because there is not enough fuel. As a result, it has become a cosmic island that can never stop drifting in the universe, and all the people who live in this isolated island will be trapped here because of the exhaustion of fuel. Chu Hai wrote in the letter.

One scientist pointed out a loophole in this theory, and the scientist countered that if the speed of a spaceship depended only on these factors, then one could build a very large spaceship, such as a giant spaceship that is ten kilometers long and one kilometer wide and one kilometer high, and then put fuel on it everywhere in the giant spaceship. Even so, with only 10 percent of the space as a living quarter, the ship could still have at least 10,000 people to survive for thousands of years, and that fuel was enough to accelerate the ship to 40 percent of the speed of light, or 120,000 kilometers per second. After the giant spacecraft runs out of fuel, we don't have to slow down the entire spacecraft, we just need to separate the manned area from the spacecraft, and then only slow down the manned area, because the manned area has a small mass compared to the entire spaceship, so slowing down the manned area only needs to consume limited fuel, so we can break the "conventional propulsion speed ceiling" statement. ”

"In this way. We will be able to send 10,000 people from the solar system to the South Gate II galaxy in just eleven years. ”

See here. Wei Feng's brows furrowed slightly. Wei Feng did not know whether the conclusion that the conventional propulsion speed was capped at 4,500 kilometers per second was correct or wrong, but Wei Feng knew that this method used to refute the above conclusion must be wrong. It also has huge vulnerabilities.

First of all, ignoring the high level of materials and structural technology required to build such a giant spaceship, let's assume that people can build such a huge spaceship, but even so, can this method be widely used? No, it still doesn't work, because this method is still an "unconventional propulsion", and abandoning such a huge ship with every interstellar voyage is obviously unacceptable in terms of cost. In other words, this mode of navigation is not fundamentally different from the way of dropping nuclear bombs, and neither of them is up to the needs of large-scale interstellar navigation.

Sure enough, just like Wei Feng himself thought, Chu Hai wrote down the rebuttal words of the scientist who put forward the theory next, and those words were basically the same as Wei Feng's thoughts.

In this letter, Chu Hai went on to describe the refutations of some of the rest of the scientists to this conclusion, but without exception, none of those refutations could be used for large-scale interstellar voyages. According to Chu Hai, although the "ceiling" theory has not yet been recognized by most people, at least until now, no one has been able to forcefully refute it.

Wei Feng's heart was filled with a little melancholy. If the "ceiling" theory turns out to be true, then what it portends will be a terrible scenario. In the future it predicts, human civilization will be trapped in a small solar system forever, and will not be able to take the step of interstellar voyage until the end comes. At the same time, it will also indicate that the interstellar voyage he is carrying out at this moment is also meaningless, after all, the interstellar voyage through long-term hibernation is also strictly a "non-conventional voyage" method, and it is also not capable of large-scale interstellar voyage needs.

This is different from the moon missions of human civilization hundreds of years ago. With the development of science and technology, it will inevitably send 10,000 or 100,000 people to the moon, in other words, this method has the potential for large-scale application. Now, hibernation can send Wei Feng to another star system alone, but if the sailing speed cannot be increased, even if it takes another 10,000 years, this method will still only send a few people to another star system. That is, this mode of navigation has no potential for development.

What human civilization needs is a safe, reliable, and fast way of interstellar navigation that can be applied on a large scale within a life cycle time. Even if this approach can't be applied on a large scale at this stage, it must at least show the potential to be applied on a large scale. For example, if there is a spacecraft at this moment, and it can travel at 50 percent of the speed of light, that is, 150,000 kilometers per second, then it will only take more than eight years to travel back and forth to the South Gate 2 galaxy, even if it can only take one person, this method has potential, because it indicates the feasibility of large-scale interstellar voyages in the future. Whether it is a nuclear bomb dropping navigation, a super-giant spaceship, or a hibernation navigation used by Wei Feng at this moment, none of these three methods have the potential for large-scale application.

But now, the scientist's upper limit theory locks the speed of conventional propulsion at 4,500 kilometers per second. Unless people can increase this speed tenfold, or increase the average life expectancy tenfold, he declares, any remaining attempts are doomed to fail to be applied on a large scale.

"Whether it's a tenfold increase in speed, or a tenfold increase in the average life expectancy of humans, that's not possible for us at the moment." Chu Hai wrote, "The development of science and technology needs the support of basic theories, and if we cannot achieve breakthroughs in basic theories, these two requirements are extravagant hopes for us." ”

"Science is the weapon with which we understand the nature of the universe, and it follows the process of discovery, hypothesis, and argumentation. We must first discover what is different from our theory in the universe, then formulate hypotheses about it, supplement it with more observation and thinking, and finally come up with new theories, and then continue to repeat the process, so that our level of technology will improve. But my friend, do you know, there are already some scientists who have come up with a new theory that our vision is limited to the solar system, that is, if we can't get out of the solar system, we won't be able to discover more of the peculiarities of this universe, we won't be able to better understand this universe, and our technology will naturally not be able to develop. ”

And if the "ceiling" theory is true, then it means that with our current technology, it is impossible to go out of the solar system on a large scale. But without going out of the solar system, according to the above theory, our technology will not be able to develop. ”

"Wei Feng, do you understand, this is a dead knot, a dead knot that can't be opened."

Wei Feng took his gaze off the display screen for a moment, and fell into deep thought.

To simplify this knot, it is that in order to achieve higher speeds, people must go out of the solar system and gain more knowledge. Without more knowledge, you can't get higher speeds, you can't get out of the solar system. And if you want to get a higher speed out of the solar system, the premise is indeed to have more knowledge and higher technology.

"Getting out of the solar system" and "acquiring more knowledge" are a pair of events that presuppose each other. It's like a key being locked on a lock. To open the lock, you must first remove the key, whereas to remove the key, you must first open the lock.

It is this paradox that limits the pace of human civilization to the solar system.

"So...... Through unconventional methods such as hibernation voyages and super-giant spaceships, a small number of people are first allowed to go out of the solar system to obtain knowledge, and then this knowledge is fed back to the people trapped in the solar system, and finally the knowledge level of human civilization is raised to the point where it is enough to carry out large-scale interstellar voyages, which may be regarded as a way to open the dead knot. Wei Feng thought, "Maybe the island plan is an attempt by human civilization to open the dead knot." (To be continued......)