In the snow, a black shadow streaked smoothly between the hills, stopping after climbing a hill.

This shadow is naturally Cheng Zheng.

In rags, he stuck the snowball fight on the ground, took off his handsome ski goggles, stretched out his right hand and gave a thumbs up, closed his left eye and aimed his thumb at the distant peak, then closed his right eye and used his left eye to observe the direction of his thumb.

He's measuring distances.

Without precision instruments, all that can be relied upon is these ancient methods, and the results are naturally only for reference.

However, compared to Cheng Zheng's map with a scale that is all based on feeling, this is accurate enough.

After simply drawing the shape of a mountain peak on the map and marking it as "to be checked, it is speculated to be worthless", Cheng Zheng put on his ski goggles and continued to move forward.

His route has already made a simple plan, and it is not difficult to find from the map that Cheng Zheng's route is expanded outward with his wooden house as the center of the circle, if it is drawn to look like half a plate of mosquito coils, as for the other half of the mosquito coils...... It's an empty sea, and there's not much value to explore.

Cheng Zheng's homemade backpack was piled with a lot of rocks and some dry plants, which were all specimens collected along the way.

Now the place that Cheng Zheng explored is far away from the camp, and the collection of plant and mineral samples is also for emergencies. If you need it when you need it, if you don't have any preparation, you'll have to re-explore the path you've walked, and if you can't remember where you can find it, you'll have to re-explore it along the way.

Although he has gained more or less from every exploration, Cheng Zheng has not found the iron ore he wants until now.

It stands to reason that iron should be the most common thing in the entire universe. After all, the ultimate product of fusion and fission is iron. On the periodic table, the fusion of elements lower than iron releases energy and absorbs energy by fission, while the fission of elements higher than iron releases energy and absorbs energy by fusion.

If you were to plot the energy contained in all the elements, then iron would be a trough.

Because of this, iron has the widest distribution of all elements, whether it is found in asteroids, in the mantle of the bottom crust, and even the vast majority of the final products after the stars have burned out.

Although iron is so widely distributed, Cheng Zheng can be sure that there will be iron on this planet, but until now he has not encountered iron ore that is easy to mine and bury.

The same is true today.

Returning to the cabin with a tired body, Cheng Zheng took out the specimens in his bag one by one, marked them on the map, and then put them on the specimen shelves full of small squares according to their numbers.

At first glance, this tall specimen rack looks like a Chinese medicine store, but without those little drawers. The number on the small square on the specimen rack was already close to 100, and after Cheng Zheng put in the last stone specimen, the number on the square just rose to 108.

After processing today's specimens, Cheng Zheng hung the drawn map on the wall and put together a larger detailed map with other wooden tablets hanging on it.

The above is Cheng Zheng's daily life.

The fish soup was already bubbling on the stove, and there was a slightly fishy smell in the air.

Cheng Zheng's stomach was already screaming from his aunt, but he didn't have the slightest interest in eating.

Even if the strange fish meat is a rare delicacy, if you eat it every day without any seasoning other than salt, it will be enough after a few meals, and it can even be considered torture if you continue to eat it after you have eaten enough.

Bringing the copper pot off the fire and putting it aside to cool, Cheng Zheng opened the cabinet and took out a lot of small parts from it, both wooden and copper.

These things are Cheng Zheng's latest "research" results: electromagnetic guns......

…… The prototype of the project.

It's really just a prototype, and most of the east-west expeditions are not yet ready, except for two straight copper rails, the others are basically wooden models.

Today's electromagnetic weapons have developed to the point where there are many mature schemes.

For example, the magnetoresistive coil cannon – also known as the Gauss cannon.

The magnetoresistive coil cannon actually uses a coil to create a magnetic field to "suck" or "squeeze" the magnetic projectile in the barrel, and the earliest application is actually a particle accelerator.

The advantage of the coil gun is that the projectile does not come into contact with the barrel, there is no friction, and the loss of kinetic energy can be negligible. In addition, the advantages of the coil gun are simple structure, easy maintenance, long life, and the ability to freely change the caliber of the projectile, weight and even shape.

As for the disadvantages, the projectile that the reluctance coil gun can throw can only be a strong magnet projectile, so the high cost of the strong magnet is a major obstacle to the application of the Gauss gun, but compared to another obstacle, the cost of the projectile is nothing.

Another fatal drawback of the magnetoresistive coil cannon is the calculation of the explosion meter. Magnetic projectiles of different masses are accelerated in the magnetic circuit, and the calculation of their acceleration force and winding inductance becomes a huge problem. Finite element calculations can only be performed by supercomputers, and once the projectile weight, barrel length, current and voltage are changed, they have to be calculated from scratch!

Even if the results were calculated for each case, this placed difficult demands on the processing of the projectile: the weight and magnetic force had to be extremely precise. The former is easy to say, but the latter is embarrassing. The reluctance coil gun is different from the traditional artillery, once the projectile does not meet the requirements, the power will be greatly reduced, and the heavy will not even be able to shoot the projectile at all!

In addition to the more famous "Gauss cannon", there are many other branches in the coil cannon family, what brushed, brushless, DC, AC...... There are even inductive ones, and there are all kinds of things that I won't repeat.

Another more famous electromagnetic cannon is because of a certain science ...... at Tokiwadai Middle School Ahem, and a household name (fog).

It is the famous electromagnetic railgun.

The principle of the railgun is very simple, that is, a conductor projectile is placed between the energized tracks, and when the current flows through one rail to another, the current interacts with the magnetic field, generating a huge Lorentz force to push the projectile, and its theoretical speed can even reach sub-light speed.

The advantage of the railgun is that it does not pick a projectile, theoretically as long as it is a conductor, and the projectile fired also carries a high amount of heat, which further improves the ability to destroy the target. Moreover, the railgun is very simple to implement, so simple that some enthusiasts have tried to build it.

However, the disadvantages of the railgun are also very obvious.

First of all, the projectile is in contact with the track, which on the one hand produces wear, and on the other hand, high temperatures. Continuing to fire projectiles at high temperatures further wears out the track, so an efficient cooling system is essential, which in turn increases the weight and complexity of the railgun, which means that the probability of failure of the entire system is greatly increased.

However, that's not all......