It's reasonable for me to have a two-way foil for a second-level civilization, right?

"Of course the easiest industrial method."

"High temperature burning calcium carbonate."

……

Calcium carbonate decomposes into calcium oxide and carbon dioxide at high temperature.

As for calcium carbonate, it is limestone, the main component of marble.

There is water, carbon dioxide, and rocks on Dawn Star, and there are not a lot of calcium carbonate reserves.

After the floods washed away the hematite powder on the surface, a large amount of calcium carbonate minerals were exposed on the surface.

Unlike industrial production, humans at this time do not need to consider the storage of carbon dioxide.

in other words.

They just need to find an area with relatively rich calcium carbonate reserves, and then heat the surface to easily produce a lot of carbon dioxide.

……

time flies.

March 2388, 3 in the Earth calendar.

Under the continuous action of Atmospheric Reformer [-], the concentration of nitrogen in the atmosphere has begun to gradually decrease.

The large reduction of nitrogen gas made the atmosphere of Dawn Star thinner, and the atmospheric pressure also decreased accordingly.

Compared with before, the atmospheric pressure at this time has dropped to 18 standard atmospheres.

Although there is still a big gap from the goal, it has given people living in closed cities real hope.

In the past few years, because of the lack of living space, the Academy of Sciences has not continued to wake up the hibernating humans.

No. [-] City Academy of Sciences headquarters, in an independent office.

Lu Yongchang carefully flipped through the small holographic image in front of him.

In the projection, there are design drawings.

That was the blueprint for an asteroid-class starship.

During this period of time, the Academy of Sciences has basically mastered the basic weapons of the third-level civilization.

It is also true that the manufacturing project of a new generation of warships has also been put on the agenda.

Compared with previous comet-class warships, asteroid-class warships are larger in size and stronger in performance.

Among them, the [Golden Crow] series of battleships has doubled in length - 3000 meters.

As for the functional starships such as [Glutton] Material Reserve Ship, [Engineering Ship], and [Homeland Ship], the size increase is even greater—the design length has reached more than [-] meters.

So far, no issues have arisen.

When it came to the design of the flagship [Earth], problems arose.

During the design process, the scale of the asteroid-class flagship was based on the flagship of the Lator civilization.

Although the flagship of the Lator civilization belongs to the fourth-level civilization, in the eyes of a group of scientific researchers...

Under the circumstances of its ability, the scale of the battleship must be as large as possible.

At least, at the current stage, the larger the warship, the more weapons and equipment it can accommodate, and the more powerful power system it has, which means more powerful combat power.

There is an old saying in the Earth Age.

Bigger and stronger, create greater glories!

The flagship of the Lator civilization, the length has reached the level of [-] meters.

It is also true that the scale of the asteroid-grade [Earth] is also approaching [-] meters in the design process.

So, the problem arises.

According to Zero's simulation, even if they really built the [-]-meter-level [Earth],

This [Earth] would also be a fortress, not a starship - its mobility would drop to a point.

It's not because of the so-called power problem.

At least, at the current stage, humans have not completely "drained" the technology of controllable nuclear fusion.

Adding more Hall thrusters and more nuclear fusion reactors can easily make this giant-class [Earth] move.

Excluding the power problem, the rest is the problem of the hull material.

According to Zero's simulation results, as long as [Earth] enters the forward four state, the hull will undergo a large deformation.

The way to solve this problem, besides taking out stronger hull materials, is to greatly reduce the size of [Earth].

6000 meters, this is the limit size calculated by zero.

In other words, according to the current technology, the size of the human starship is strictly limited by material technology to within 6000 meters.

Chapter 457 Ship Hull Material Restrictions

"Material...Material..."

Lu Yongchang frowned, muttering softly.

Then, he sighed deeply.

Ever since humans entered the second level of civilization, carbyne has become the main material for making starship shells.

Research on new materials has never stopped.

However, until now, carbyne is still the strongest substance that humans can produce.

As elements of the same group, silicon and carbon share many similarities.

However, carbon-carbon bonds are shorter in length than silicon-silicon bonds.

This means that even if there is a so-called silikyne, it is impossible for the material to be stronger than caryne.

Of course, it is not that there is no matter with higher intensity in the universe.

Materials built by strong interactions.

For example, a neutron star.

Under the action of strong gravitational force, even atoms are completely crushed, electrons outside the nucleus are pressed into the nucleus, and combine with protons to form neutrons.

Therefore, there are no so-called atoms and molecules on neutron stars.

The neutron star matter, built from neutrons, is at its peak density and strength.

Do you think this is over?

of course not.

As of now, it is still in a theoretical state and has not actually discovered quark stars.

The stronger gravity even crushes the neutrons, releasing the quarks within them.

The macroscopic matter directly constructed by quarks far exceeds that of neutron star matter in terms of strength and density.

Of course, with the current human technology, we can only stay away from such mythical and legendary materials.

Not to mention how to take out the neutron star material completely and keep it in its original state, even getting close to the neutron star is impossible for the current human civilization.

Lu Yongchang shook his head helplessly, and withdrew his scattered thoughts.

"Professor, Academician Fang Xu sent a communication request."

Zero's electronically synthesized voice suddenly sounded in the quiet office: "Are you connected?"

Lu Yongchang probably knew Fang Xu's intention in his heart.

He pondered for a moment, raised his hand and waved it in the air, "throwing" aside the layers of holographic images above the desk.

Afterwards, he straightened up and said in a deep voice, "Come on."

The next moment, a brand-new holographic image slowly unfolded above the desk, and the robot on the side also "passed" a camera just right.

"Yongchang, how about the starship design?"

Sure enough, the moment the communication was connected, words that made Lu Yongchang extremely entangled came from the loudspeaker.

At the same time, Fang Xu's big face appeared in the holographic projection.

As if he noticed the bitter expression on Lu Yongchang's face, Fang Xu frowned slightly: "Have you not decided yet?"

Lu Yongchang nodded silently.

Seeing this, Fang Xu frowned even deeper.

"why?"

"Even if we can't make a 6000-meter-level flagship, the [-]-meter-scale asteroid-level [Earth] is still a good choice, isn't it?"

silence.

After a long time, Lu Yongchang sighed lightly, shook his head and said, "Do you still remember the scale of the comet [Earth]?"

Fang Xu hesitated for a moment, then responded in a low voice: "5000 meters?"

"Yes." Lu Yongchang raised his hand and rubbed his face vigorously, "If we follow this blueprint, what we will manufacture will only be an enhanced version of the comet-class flagship."

"You have also seen the flagship of the Rathor civilization."

"Although I learned afterwards that it was a starship of a fourth-level civilization."

"But don't forget!"

"That's not the flagship of a fourth-level civilization!" Lu Yongchang said with a heavy tone, "Once a compromise is made on the highest level of civilization, human civilization will suffer in the interstellar war sooner or later."

"But..." Fang Xu tried to persuade again, "Yongchang, you also know that in the simulation calculation of zero, the material is a hurdle that cannot be bypassed."

"We have to settle for the next best thing."

"As for the [-]-meter-scale starship...it won't be too late to make plans after breakthroughs in material technology."

Lu Yongchang didn't speak, but frowned and looked at the holographic drawing that was "thrown" aside.

"hold on."

After a moment of silence, Lu Yongchang said softly, "Look again."

"Since the ordinary starships of the fourth-level civilization can reach this scale, it means that this kind of material is not scarce."

"It's just that we have entered a misunderstanding, or in other words, we lack a little luck."

Lu Yongchang's eyes moved slightly, and he muttered to himself: "Perhaps, we should look further away..."

"what?"

Fang Xu obviously didn't hear Lu Yongchang's soft murmur, he raised his voice a little, and asked impatiently, "What else could be wrong?"

"I don't know how many experiments have been done in the laboratory. No matter how I adjust it, the manufactured materials can't meet the requirements."

Lu Yongchang in front of the camera ignored Fang Xu's complaints. He stood up suddenly from his chair, stared at the camera handed over by the robot with a serious expression, and said word by word: "Wait a little longer!"

"I feel like I'm about to find my way!"

"Stop all starship manufacturing projects, and no asteroid-class starships shall be built until I speak!"

The picture in the holographic projection seems to be paused.

Fang Xu stared at Lu Yongchang blankly, his face was full of shock mixed with disbelief.

"What did you say?!"

"[Golden Crow], [Gluttony]...these starship manufacturing projects that have already been confirmed should also be stopped?!"

"Yes! Stop!" Lu Yongchang's eyes shone with confidence, "Believe me, give me a little more time, I will find a way out!"

Fang Xu took a deep breath to stabilize his emotions.

He nodded with difficulty: "OK."

"Who made you the chief scientist?"

"I will arrange for the laboratory and factory."

Lu Yongchang smiled and nodded: "Don't worry, I have a very strong hunch."

"After a hundred years, material technology is about to make a breakthrough!"