What the traverser brings to the traversal world is not only the system behind the traverser itself, whether it is subjectively changing the world or objectively changing the world, there are two key factors that cannot be denied.

First, the changes brought about by the traversers, whether it is knowledge, technology, equipment or even ready-made science and technology, have the possibility of diffusion. Of course, not everything will proliferate, but those that have no technology, but are very powerful and of great benefits.

For example, if the traveler carries a computer, even if it is obtained by others, it cannot be used, because the ancients did not have the cognition, concept, education and knowledge system related to computers, so it is useless to get it.

However, if it is a technology that does not have any technology itself, but is extremely powerful, or has huge economic benefits, it will cause the proliferation of technology and change the shape of the entire historical process.

For example, glass, itself is formed by silicide and alkali through high-temperature melting and calcination, its composition is silica, which is the composition of natural crystal, as far as the production process of glass is concerned, there is no obstacle at all, as early as in the middle of ancient Rome, glass technology has appeared, of course, glass glass has also appeared in China.

As we all know, before the advent of artificial glass, the value of natural crystal was very high, but if the traverser used it to make a profit and bring wealth to himself, the technology may also spread.

Of course, it is undeniable that this is possible, but a simple process technology can curb its spread, but when the traverser sacrifices a large number of disordered and complex equipment, and the advanced technology with a simple principle, continues to hold the golden finger to cover the non-proliferation, it is both too beautiful and often boring.

Second, scientific contingency.

The principles of many seemingly lofty things in modern society are actually very simple, and at the same time, many modern seemingly lofty "sciences" are often born by chance.

Take nitrocellulose as an example, nitrocellulose was developed by chemist T· Invented by J. Pellouse in 1838, the recipe is actually very simple: nitric acid and cotton, which was discovered in the eighth century by the Arab alchemist Jabir ibn Hayyan.

That is to say, the emergence of nitric acid, to the emergence of nitrocellulose, the difference between more than a thousand years, and the first gunpowder to appear, but the Chinese sulfur, nitrate, charcoal three-element gunpowder, according to nitrocellulose is binary gunpowder, should appear earlier, and its formula chemical reaction is also simpler, why black powder appeared first, and then nitrocellulose cotton.

In fact, in the final analysis, before the systematization of science, non-mechanical and theoretical inventions were often accidental probabilities and luck.

Taking the invention of nitrocellulose as an example, in the course of the experiment, Pellouse knocked over nitric acid, wiped the table with a cotton and linen rag, and then took the rag to bake in front of the fireplace, trying to dry the rag, and then continued to use it. As a result, an unexpected phenomenon was discovered, the nitric acid-contaminated rag exploded, and there were no ashes, and Peluz realized that he had discovered a new type of smokeless and explosive gunpowder.

This discovery process can condense several key pieces of information.

First of all, use a rag to wipe the nitric acid, this is an accidental process, in fact, this situation may occur in many test processes.

However, the second key factor, which is also important, is to use a fireplace for heating in the winter.

Thirdly, nitric acid-contaminated rags are dangerous in modern chemical procedures and should not be used and should be disposed of, whereas in the nineteenth century there were no such rules, so Peluse took them to dry.

In the end, if Pélouse had only treated the nitrocellulose explosion as an accident and had not found its value, the discovery might have to be passed by and delayed until anyone else discovered it, or maybe one day Pélouse would have realized it.

Therefore, nitrocellulose will only be found if the above four fortuitous events occur at the same time.

The essence of many modern scientific categories, especially those that require a large number of repetitive, repetitive, and boring experiments, is to frame a large range through theory, and then carry out infinite exhaustive actions within a large range, to touch the probability, and if it encounters, it is an invention, and if it is not encountered, it is a research failure. So quite a few scientific inventions, both accidental and probabilistic.

Then look back at many inventions in history, the principle is actually very simple, there are not too many complex technologies and high-precision equipment, but the problem is accident, whether this accident can be discovered.

At the same time, since it is a time and space that is completely different from the earth, but with a similar civilization, whether the technological path of historical development must be developed in accordance with the technological history of the earth may not necessarily be necessary, nor does it have to be followed by the historical script, because many technologies are accidental.

For example, nitrocellulose, it can be accidental, maybe when the protagonist comes, the world after crossing may appear nitrocellulose first, instead of black powder.

(Of course, because the power of nitrocellulose is greater than that of black powder, and it has certain advantages in use, at the same time, readers' hearts are often fragile, and they begin to lose their appetite when they see the appearance of nitrocellulose, and then abandon the pit, so authors often avoid it, and many authors often do not know the logic and system behind nitrocellulose, so they do not go back to write, only think that nitrocellulose is a tall technical product, in fact, nitrocellulose is simpler than black powder.) ）

Moreover, the emergence and diffusion of any technology will lead to tremendous changes in war, politics, life, production relations, and productive forces.

For example, the appearance of the Black Turban rebel "Calcium Carbide" in this book has changed the rules of siege warfare and defense warfare in a sense.

As mentioned earlier, the first discovery was accidental through dry distillation, using lime and charcoal to obtain calcium carbide, and later because of the popularization of electric power technology, electric heating began to be used, and the industrial scale production of calcium carbide was realized. However, in principle, calcium carbide in ancient times, even in the Stone Age, there is a possibility of accidental discovery, because its reaction principle and the required raw materials are too simple.

The discovery of the design in this book comes from the kiln factory, because the kiln factory has a lot of use of lime as a heat-resistant coating, which is common to charcoal kilns, and it is difficult to appear in other fields at the same time, so it has a chance. But the key is still whether it can be discovered and used, and this chance is very important.

Therefore, once the principle and raw materials are simple and accidental technical products are rapidly spread, it will definitely change the mentality of history, war, politics, economy, production and life.

The biggest hazard of calcium carbide is to burn in water, and the main way to extinguish fire in ancient times is to splash water, and the biggest principle of attacking the city is to break the door, followed by climbing the wall, but breaking the city gate can bring faster speed of breaking the city, and at the same time the difficulty of attacking the city gate is above the city wall, which is why there are "first captains" and no "school captains" in ancient times, because the probability of climbing the city wall to break the city is higher than breaking the city gate, and the risk factor is relatively low.

The appearance of calcium carbide, but instantly changed the rules of war, once the calcium carbide was piled up under the city gate, it is undoubtedly disastrous for the defenders, because as long as the water is splashed, the calcium carbide will spontaneously combust, and once burned, even if it is no longer splashed with water, relying on the carbon composition of calcium carbide itself, it can maintain continuous combustion.

In this way, it is undoubtedly disastrous for the defenders of the city. But at the same time, it is also a test of the protagonist's cognitive use, the author's writing ability, how to turn the danger into a disaster, solve the threat of calcium carbide, and at the same time, the psychological tolerance of readers, whether they can withstand the changes brought about by the appearance of calcium carbide.

Finally, if any advanced accidental simple technology is to be applied on a large scale, two conditions must be met, one is the scale of the talent base, and the other is the systematization of production.

In short, taking nitrocellulose as an example, theoretically the discovery of nitrocellulose should be earlier than gunpowder, but industrial-grade concentrated nitric acid cannot be produced on a large scale, because industrial-grade nitric acid could not be industrialized on a large scale before the eighteenth century, and it was even more impossible in the tenth century, which lacked talents, education, systems, scientific cognition and advanced concepts.

The reaction between dilute nitric acid and cotton is not so sensitive, so the use of dilute nitric acid to make nitrocellulose cotton is costly, inefficient and low-yield.

Second, cotton was introduced to China and Europe very late, so the probability of discovering nitrocellulose in Europe and China is theoretically lower than that of the Arabs, and the use of hemp silk can also make nitrocellulose, so the Chinese theoretically found that nitrocellulose is higher than Europe, because Europe neither introduced cotton nor suitable for growing hemp in the early days. Of course, this is an assumption based on an equal level of technology.

Third, cotton and linen were high value-added cash crops in ancient times, which required a lot of manpower and farmland, which also restricted the production of nitrocellulose.

Therefore, even if nitrocellulose appears, it is impossible to apply it on a large scale before the lack of talents, equipment, agricultural improvement and industrial-scale production technology, and it is possible to use it on a small scale, as well as simple advanced technologies such as calcium carbide.

When a large number of simple and accidental advanced technologies appear, especially technological changes in the military field, they will certainly change the shape of warfare.

For example, the emergence of the steel filling method in the book has crossed the hundred steelmaking and frying steel, because the technology can be realized, and the question is whether it can be recognized and whether there is a concept. At the same time, steel chain mail appeared in the Bronze Age, which is equivalent to the existence of the invincible god of war, which changed the course of the war, but at the same time, the existence of the mole also means the diffusion of technology since then, and at the same time, the chain mail is not a universal magic weapon, and it also has its drawbacks and Achilles' heel.

If chain mail appeared in the Stone Age, Xiaozuo thought that most of it would be useless, because the Stone Age used blunt tools such as stones and sticks, and the armor was most afraid of blunt weapons. Therefore, advanced technology may not necessarily be suitable, and it depends on the characteristics.

Therefore, the emergence of advanced technology, while changing the protagonist's own side, may also change the entire historical form, and at the same time, the contingency of early science and technology can also change the form and development of history, the key depends on whether the author of the writing can arrange the structure reasonably with reasonable logic and article organization.

Often in order to simply figure out a certain technology, they use words to pile up, open the external gold finger, or a hammer in the east and a stick in the west, and make this and that.

In addition, the accidental technology in the opponent's role, standing in the position of the protagonist, through the protagonist's advanced cognition, concept, scientific thinking and knowledge system, you can reverse the opponent's technical form, technical source, and technical reserves.

For example, in the text, the black turban army used nitric acid to dissolve silver, since the black turban army has accidentally discovered nitric acid, will it be found again by chance in the future, so as to use it to fight against the protagonist, these are all problems and variables that the protagonist needs to think about and watch out for.

But back to the three points mentioned before, industrial-grade nitric acid and agricultural production, as well as accidental discoveries are indispensable, requiring the accumulation of talents and equipment.